WO2004031239A2 - Metastasis inducing compounds - Google Patents

Abstract

There is provided methods and compounds relating to the diagnosis and treatment of metastatic cancer. Compounds which conjugate or interact with anterior gradient 2 (AGR2) and methods using the same are provided.

Description

Metastasis Inducing Compounds

The present invention relates to metastasis inducing compounds and their use in diagnosis and therapy, in particular for use in the diagnosis and therapy of mammals, more particularly humans.

Most cancers are thought to be due to alterations in specific genes caused either by mutations making their gene-product in some way more effective or by over expression of a normal gene giving an enhanced effect. These oncogenes have largely been identified by introducing gene-length fragments of DNA from human cancers into a mouse fϊbroblast cell line, in culture, and selecting those cell lines that grow in an uncontrolled manner in liquid or semi-solid medium. The oncogenes themselves have been isolated by cloning the human DNA fragments away from the mouse DNA by standard recombinatorial techniques. Alternatively, mutations can arise in genes that suppress cell growth and division such as, for example, p53 or which suppress the levels of their products such as for example NM-23. These are referred to as tumour suppressor oncogenes.

Metastatic spread of tumours from the site of primary growth to distant organs, where seedling tumours are formed by disseminated cells, is one of the most clinically important properties of malignant tumours. It endows the tumour cells with the ability to survive surgical excision of the primary growth. Additionally, because metastases can themselves provide the basis for further shedding and dissemination of tumour cells, this process forms the basis for a geometric increase in the impact of the tumour on the host and increases the clinical management due to the wide dispersal of the tumour cells. Modern array techniques are now being used to relate patterns of gene expression to both pathological appearance and malignant behaviour of breast (1,2) and other cancers (3-5). However, it is also important to identify the key changes in gene expression that cause the malignant properties of cancer cells. Such an approach has led to the discovery of the metastasis-inducing proteins S 100A4 (6, 7) and osteopontin (8) that have been shown to have such a dramatic effect on patient survival in a group of breast cancer patients (9,10). These discoveries have provided targets for the development of diagnostics and drug therapies for the treatment of certain metastatic tumours.

Advantageously, the present invention provides an alternative target for metastatic cancer diagnoses and therapies.

In accordance with a first aspect of the present invention there is provided a prognostic indicator for metastatic cancer comprising a compound which selectively conjugates or interacts with AGR2 and/or AGR2 mRNA. cDNAs representing mRNAs differentially expressed (12-14) between an estrogen receptive α (ERα) - negative benign human mammary epithelial cell line, Human 123 (15), and the ERα - positive malignant human mammary epithelial cell line , MCF-7 (16). The resulting subtracted libraries not only contain well-characterised, differentially-expressed cDNAs that have been associated previously with tumour progression (12), but they also contain a large number of other cloned cDNAs. One such cloned cDNA, M36, matches identically to the coding sequence of human cDNA anterior gradient 2 (AGR2), the human homologue (previously known as hAG-2) ofXenopus laevis cement gland-specific gene, XAG-2. AGR2 has been reported to be expressed in ERα - positive, MCF-7, breast cancer cell lines (17). The inventors of the present invention have surprisingly discovered that human AGR2 is differentially expressed between benign and malignant human carcinoma specimens.

The present invention relates to any one or more selected from the group comprising colon cancer, prostate cancer, lung cancer, melanoma, gliomas and breast cancers. More preferably the present invention relates to breast cancers.

The compound may conjugate or interact chemically, structurally or functionally with AGR2 and/or AGR2 mRNA or in any other way.

Preferably, the compound comprises an antibody.

Antibodies capable of specifically recognising AGR2 epitopes or epitopes of conserved variants of the AGR2 nucleotide sequence (SEQ ID No. 1) or immunologically effective peptide fragments of AGR2 may be produced by any technique well known in the art.

Such antibodies may comprise polyclonal antibodies, monoclonal antibodies (mAbs), humanised or chimeric antibodies, single chain antibodies, Fab fragments, F(ab')2 fragments, fragments produced by a Fab expression library, anti-idiotypic (anti - Id) antibodies and epitope-binding fragments of the above.

Such antibodies may be used in the detection of AGR2 in a biological sample and may therefore be utilised as part of a diagnostic or prognostic technique whereby patients may be tested for abnormal levels of AGR2, and/or abnormal forms of the protein.

Such antibodies may also be utilised in conjunction with, for example, compound screening schemes for the evaluation of the effect of test compounds on AGR2 levels and/or activity. Such antibodies may additionally be used as a method for the inhibition of abnormal AGR2 activity and/or levels. Thus, such antibodies may be utilised as part of anti-metastatic tumour treatment.

For the production of antibodies against AGR2 and/or AGR2 mRNA and/or immunologically effective, i.e. antigenic fragments thereof and/or variants of AGR2 or AGR2 mRNA having at least 70% homology thereto, preferably 90% homology thereto, various host animals may be immunised by injection with AGR2 and/or AGR2 mRNA and/or an immunologically effective fragment thereof and/or a variant thereof. Such host animals may be any one selected from the group comprising rabbits, mice, sheep, goat and rats. Various adjuvants may be used to increase the immunological response, depending on the host species, and may be any one or more selected from the group comprising Freund's (complete and incomplete), mineral gels such as aluminium hydroxide, surface active substances such as lysolecithin, pluronic polyols, polyanions, peptides, oil emulsions, keyhole limpet hemocyanin, dinitrophenol, and potentially useful human adjuvants such as BCG (Bacilli Calmette-Guerin).

Polyclonal antibodies are heterogeneous populations of antibody molecules derived from the sera of animals immunised with an antigen, such as AGR2 or an immunologically effective fragment thereof. For the production of polyclonal antibodies, host animals such as those described hereinabove, may be immunised by injection with AGR2 or AGR2 mRNA or an immunologically effective fragment thereof or a variant thereof and may be supplemented by adjuvants as described hereinabove.

Monoclonal antibodies are homogeneous populations of antibodies to a particular antigen and may be obtained by any technique which provides for the production of antibody molecules by continuous cell lines in culture. These techniques comprise the hybridoma technique of Kohler and Milstein (41), the human B-cell hybridoma technique (42) and the EBV-hybridoma technique (43).

Such antibodies may be selected from any one or more of the group comprising IgG, IgM, IgE, IgA, IgD and any subclass thereof. The hybridoma producing the monoclonal antibody may be cultivated in vitro or in vivo. Preferably, the mAbs are cultured in vivo.

Techniques developed for the production of chimeric antibodies whereby genes from a mouse antibody molecule of the appropriate antigen specificity are spliced together with genes from a human antibody molecule of appropriate biological activity may also be used (44,45). A chimeric antibody is a molecule in which different portions are derived from different animal species, such as those having a variable region derived from a murine mAb and a human immunoglobulin constant region.

In addition, techniques described for the production of single chain antibodies may be used to produce single chain antibodies against AGR2 or an immunologically effective fragment thereof or a variant thereof (46). Single chain antibodies are formed by linking the heavy and light chain fragments of the Fv region via an amino acid bridge, giving rise to a single chain polypeptide.

Antibody fragments which recognise specific epitopes may be generated by known techniques. Such fragments may comprise F(ab')2fragments which may be produced by pepsin digestion of the antibody molecule and the Fab fragments which can be generated by reducing the disulfϊde bridges of the F(ab')2 fragments. Alternatively, Fab expression libraries may be constructed^ 7) to permit rapid identification of monoclonal Fab fragments having the requied specificity.

Immunologically effective fragments of AGR2 may comprise about 20 consecutive amino acids of SEQ ID NO. 2. Preferably, the fragment comprises less than 16 consecutive amino acids of SEQ ID NO. 2. More preferably the fragment comprises 8- 15 consecutive amino acids of SEQ ID NO. 2. More preferably still the fragment is selected from the following two sequences (SEQ ID NO 3 and 4 respectively): ARDTTVKPGAKK or DTKDSRPKLPQT.

The immunologically effective fragment may comprise synthetic peptides corresponding to regions of SEQ ID NO. 2 or corresponding to SEQ ID NO 3 or SEQ ID NO. 4, or regions thereof.

The immunologically effective fragment may be at least 70% homologous with regions of SEQ ID NO. 2 or at least 70% homologous with SEQ ID NO 3 or SEQ ID NO. 4, or regions thereof. Preferably the fragment is at least 90% homologous with regions of SEQ ID NO. 2 or at least 90% homologous with SEQ ID NO 3 or SEQ ID NO. 4, or regions thereof. Assays for the Diagnosis Prognosis of Metastases

A variety of methods can be employed for the diagnostic and/or prognostic evaluation of metastases and for the identification of patients having a predisposition to such disorders.

In accordance with a second aspect of the present invention there is provided a method of diagnosis for metastatic cancer comprising the steps of: obtaining a patient sample; contacting the patient sample with a compound which selectively conjugates or interacts with AGR2 and/or AGR2 mRNA; and detecting any conjugation or interaction. Such methods may comprise the use of reagents and or compounds comprising antibodies directed against AGR2 and/or AGR2 mRNA and/or immunologically effective fragments thereof and/or variants thereof as described hereinabove.

The methods described herein may comprise the use of pre-packaged diagnostic kits comprising at least one specific antibody directed against AGR2 and/or AGR2mRNA and/or an immunologically effective fragment thereof and/or a variant thereof, which may be used to screen and diagnose patients exhibiting cancer and to screen and identify those individuals exhibiting a predisposition to developing metastases.

Such diagnostic methods may be used to detect abnormalities in the level of AGR2 gene expression or abnormalities in the tissue, cellular or subcellular location of AGR2.

In vitro immunoassays may be used to, for example, assess the efficacy of cell based gene therapy for metastatic tumours. Antibodies directed against AGR2 may be used in vitro to determine the level of AGR2 gene expression achieved in cells engineered to produce AGR2. Such an assessment may be carried out using cell lysates or extracts or in vivo using fluorescent imaging techniques. Such analysis will allow for a determination of the number of transformed cells necessary to achieve therapeutic efficacy in vivo. The tissue or cell type to be analysed may comprise those which are known, or suspected , to express AGR2 , such as, for example pathological tissue specimens. The protein isolation methods employed herein may, for example, be those such as those described by Western blotting (48). The isolated cells may be derived from cell culture or a patient sample. The analysis of a cell taken from culture may be a necessary step in the assessment of cells to be used to test the effect of compounds on the expression of AGR2 gene.

The diagnostic methods may comprise immunoassays wherein AGR2 or AGR2 mRNA are detected by their interaction with an anti-AGR2 or anti-immunologically effective fragment of AGR2 or anti -AGR2 mRNA or anti-variant thereof specific antibody or nucleic acid probe.

The antibodies described hereinabove may be used to quantitatively or qualitatively detect the presence of AGR2 and/or AGR2 mRNA and/or immunologically effective fragments thereof. This may be achieved, for example, by immunofluorescence techniques employing a fluorescently labelled antibody coupled with light microscope, flow cytometric or fluorometric detection.

The antibodies of the present invention may also be employed histologically, as in immunofluorescence or immunoelectron microscopy, for in situ detection of AGR2. ' In situ detection may comprise the removal of a histological sample from a patient and contacting the sample with and detected by a second specific antibody or reagent of the present invention. The antibody is preferably applied by overlaying the labelled antibody onto said sample. Through the use of such a method it is possible to determine not only the presence of AGR2 or AGR2 mRNA but also the distribution of AGR2 or AGR2 mRNA in the sample.

Immunoassays may comprise incubating a patient sample, such as a biological fluid (such as blood, urine etc.) a tissue extract, freshly harvested cells or lysates of cells which have been incubated in cell culture, in the presence of a detectably labelled antibody capable of identifying AGR2 and detecting the bound antibody by any of a number of techniques well known in the art.

The biological fluid may be any one or more selected from the group comprising blood, urine, plasma, tears, milk and sweat.

The patient sample may be contacted with and immobilized onto a solid phase support or carrier such as nitrocellulose, or other solid support which is capable of immobilizing cells, cells particles or soluble proteins. The support may then be washed with suitable buffers followed by treatment with the detectably labeled AGR2 or immunologically effective fragments thereof antibody. The solid phase support may then be washed with the buffer a second time to remove unbound antibody. The amount of bound label on solid support may then be detected by conventional means.

'Solid phase support or carrier' is intended to comprise any support capable of binding an antigen or an antibody. Well known supports or carriers comprise nitrocellulose, glass, polystyrene, polypropylene, polyethylene, dextran, nylon, amylases, natural and modified celluloses, polyacrylamides, gabbros and/or magnetite. The nature of the carrier may be either soluble to some extent or insoluble for the purposes of the present invention. The support material may have virtually any possible structural configuration so long as the coupled molecule is capable of binding to an antigen or antibody. Thus, the support configuration may be spherical, as in a bead, or cylindrical, as in the inside of a test tube or the external surface of a rod. Alternatively, the surface mat be flat such as a sheet, test strip, etc. Preferred supports comprise nylon.

The binding activity of a plurality of anti-AGR2 or anti-AGR2 mRNA or anti- immunologically effective fragments thereof or anti -variants thereof antibodies or nucleic acid probe may be determined according to well known methods. Those skilled in the art will be able to determine operative and optimal assay conditions for each determination by employing routine experimentation.

Preferably, one of the means by which AGR2 can be detectably labeled is by linking the antibody to an enzyme and use in an enzyme immunoassay (EIA) (49). The enzyme which is bound to the antibody will react with an appropriate substance, preferably a chromogenic substrate, in such a manner as to produce a chemical moiety which may be detected.

The means for detection may comprise spectrophotometric , fluorometric, chemiluminescent or visual means. Enzymes which may be used to detectably label the antibody comprise malate dehydorgenase, staphylococcal nuclease, delta-5-steroid isomerase, horseradish peroxidase, alkaline phosphatase, ribonuclease and acetylcholinesterase.

Detection may be achieved by colourimetric methods which employ a chromogenic substrate for the enzyme. Detection may also be accomplished by visual comparison of the extent of enzymatic reaction of a substrate in comparison with similarly prepared standards. Other immunoassays may be employed such as radioactively labeling the antibodies. It is thereby possible to detect AGR2 via radioimmunoassay (50). The radioactive isotope may be detected by means of a gamma counter or a scintillation counter or autoradiography.

Detection may additionally be accomplished by means of an antibody labeled with a fluorescent compound. When fluorescently labeled antibodies are exposed to light of a particular wave length, its presence can be detected due to fluorescence. Such fluorescent labels comprise rhodamine, phycoerythrin, phycocyanin, fluorescamine, Cy3 and Cy5 and other cy series of dyes.

The antibodies may also be detectably labeled using fluorescence emitting metals such as ^I52 Eu. These metals may be attached to the antibody using metal chelating groups such as diethylenetriaminepentacetic acid (DTP A) or ethylenediaminetetraacetic acid (EDTA).

The antibodies may also be detectably labelled by coupling it to a chemiluminescent compound or using a chemiluminescent system (e.g. Super Signal West Pico Chemiluminescence System obtainable from Pierce and Warriner, Chester, UK). The presence of the chemiluminescent-tagged antibody may then be determined by detecting the presence of luminescence that arises during the course of a chemical reaction. Such chemiluminescent compounds may comprise any one or more selected from the group comprising luminol, isoluminol, theromatic acridinium ester, imidazole and oxalate ester.

In a further embodiment, a bioluminescent compound may be used to label the antibody of the present invention. Bioluminescence is a form of chemiluminescence found in biological systems in which a catalytic protein increases the efficacy of the chemiluminescent reaction. The presence of a bioluminescent protein is determined by detecting the presence of luminescence. Such bioluminescent compounds may comprise luciferin and/or luciferase.

In accordance with a further aspect of the present invention there is provided a method of screening for a compound useful in the treatment of metastatic cancer comprising the steps of: contacting a test compound with AGR2, AGR2 mRNA or a fragment thereof; detecting whether the test compound has conjugated or interacted with AGR2, AGR2 mRNA or the fragment thereof.

Compounds identified via assays such as those described herein may be useful, for example, in elaborating the biological function of AGR2 and/or controlling, preventing or ameliorating metastasis. Such compounds may also be useful, for example, in modulating the activity of AGR2 and/or levels of expression of AGR2 genes.

The assays may comprise the preparation of a reaction mixture of AGR2 and the test compound under conditions and for a time sufficient to allow the two components to interact and bind, thus forming a complex which can be removed and/or detected in the reaction mixture. The assays may be conducted in a number of manners. For example, the assay may comprise anchoring AGR2 or the test compound onto a solid support and detecting AGR2 /test compound complexes anchored on the solid support at the end of the reaction. In one embodiment, AGR2 may be anchored as described below onto a solid support and the test compound which is not anchored may be labelled either directly or indirectly. Preferably, microtiter plates are used as the solid support. The anchored component may be immobilized by non-covalent or covalent attachment. Non-covalent attachment may comprise coating the solid support with a solution of the protein followed by drying. Alternatively, an immobilized antibody, preferably a monoclonal antibody, specific for AGR2 may be used to anchor the protein to the solid support.

The assay may comprise contacting the nonimmobilised component with the coated solid support containing the anchored component. After the reaction is complete, unreacted components are removed, preferably by washing, under conditions whereby any complexes formed will remain immobilized on the solid support. Detection of anchored complexes may then be carried out by a number of means.

Detection may be carried out using pre-labelled nonimmobilised components wherein the detection of the label on the immobilized component indicates that complexes were formed or alternatively, non-immobilised components which are not pre- labelled, an indirect label may be used to detect complexes anchored to the solid support using, for example, a labelled antibody specific for the previously nonimmobilised component (the antibody may in turn be directly labelled or indirectly labelled with a labelled anti-Ig antibody).

In one embodiment, a reaction may be conducted in a liquid phase, the reaction products subsequently separated from unreacted components and any complexes detected. Such a method may comprise the use of an immobilized antibody specific for AGR2 or the test compound to anchor any complexes formed in solution, and a labelled antibody specific for the other component of the possible complex to detect anchored complexes. In accordance with a further aspect of the present invention there is provided a compound for the treatment of metastatic cancer identified by the screening method described hereinabove. Assays to identify Intracellular Proteins That Interact with AGR2

In accordance with a further aspect of the present invention there is provided a method to identify an intracellular protein which conjugates or interacts with AGR2 for use in the development of a compound for use in treating metastatic cancer comprising:

Contacting a sample comprising at least one intracellular protein with labeled AGR2; and

Detecting whether said labeled AGR2 has conjugated or interacted with said at least one intracellular protein.

Any method suitable for detecting protein-protein interactions may be employed for identifying AGR2 protein-intracellular protein interactions.

Among the traditional methods which may be employed are co- immunoprecipitation, crosslinking and co-purification through gradients or chromatographic columns. Among newer developments which may be employed, is the use of surface plasmon resonance. Utilizing procedures such as these allows for the indentification of intracellular proteins which interact with AGR2 . Once isolated, such intracellular protein can be identified and can, in turn, be used, in conjunction with standard techniques, to identify proteins which it interacts with. For example, at least a portion of the amino acid sequence of the intracellular protein which interacts with the AGR2 can be ascertained using techniques well known to those of skill in the art, such as via the Edman degradation technique (51). The amino acid sequence obtained may be used as a guide for the generation of oligonucleotide mixtures that can be used to screen for gene sequences encoding such intracellular proteins. Screening may be accomplished, for example, by standard hybridization or PCR techniques. Techniques for the generation of oligonucleotide mixtures and the screening are well-known (52).

Additionally, methods may be employed which result in the simultaneous identification of genes which encode the intracellular protein interacting with AGR2 protein. These methods include, for example, probing expression libraries with labeled

AGR2 protein, using AGR2 protein in a manner similar to the well known technique of antibody probing of λgt 11 libraries.

In one embodiment protein interactions are detected in vivo by means of the two- hybrid system ( (53) commercially available from Clontech Palo Alto, CA).

Utilizing such a system, plasmids may be constructed that encode two hybrid proteins. One consists of the DNA-binding domain of a transcription activator protein fused to the AGR2 protein and the other consists of the transcription activator protein's activation domain fused to an unknown protein that is encoded by a cDNA which has been recombined into this plasmid as part of a cDNA library. The DNA-binding domain fusion plasmid and the cDNA library are transformed into a strain of the yeast

Saccharomyces cerevisiae that contains a reporter gene, such as HBS or LacZ, whose regulatory region contains the transcription activator's binding site. Either hybrid protein alone cannot activate transcription of the reporter gene. The DNA-binding domain hybrid cannot because it does not provide activation function and the activation domain hybrid cannot because it cannot localize to the activator's binding sites. Interaction of the two hybrid proteins reconstitutes the functional activator protein and results in expression of the reporter gene, which is detected by an assay for the reporter gene product.

The two-hybrid system or related methodology may be used to screen activation domain libraries for proteins that interact with the "bait" gene product. AGR2 may be used as the bait gene product. Total genomic or cDNA sequences are fused to the DNA encoding an activation domain. This library and a plasmid encoding a hybrid of AGR2 fused to the DNA-binding domain are cotransformed into a yeast reporter strain, and the resulting transformants are screened for those that express the reporter gene. AGR2 sequence, such as the open reading frame set out in SEQ ID No. 1 of the AGR2 gene, can be cloned into a vector such that it is translationally fused to the DNA encoding the DNA-binding domain of the GAL4 protein. These colonies are purified and the library plasmids responsible for reporter gene expression are isolated. DNA sequencing may then be used to identify the proteins encoded by the library plasmids.

A cDNA library of the cell line from which proteins that interact with AGR2 may be detected can be made using methods routinely practiced in the art. In a preferred embodiment, the cDNA fragments may be inserted into a vector such that they are translationally fused to the transcriptional activation domain of GAL4. This library can be co-transformed along with the AGR2 nucleotide sequence - GAL4 fusion plasmid into a yeast strain which contains a lacZ gene driven by a promoter which contains GAL4 activation sequence. A cDNA encoded protein, fused to GAL4 transcriptional activation domain, that interacts with AGR2 will reconstitute an active GAL4 protein and thereby drive expression of the HIS3 gene. Colonies which express HIS3 can be detected by their growth on petri dishes containing semi-solid agar based media lacking histidine. The cDNA can then be purified from these strains, and used to produce and isolate the AGR2 nucleotide sequence- interacting protein using techniques routinely practiced in the art.

In accordance with a further aspect of the present invention there is provided a method to identify an intracellular macromolecule which conjugates or interacts with AGR2 for use in the development of a compound for use in treating metastatic cancer comprising:

Contacting a sample comprising at least one intracellular macromolecule with labeled AGR2; and

Detecting whether said labeled AGR2 has conjugated or interacted with said at least one intracellular macromolecule.

Assays for Compounds that interfere with AGR2 Intracellular Macromolecular

Interaction

AGR2 may, in vivo, interact with one or more intracellular macromolecules, such as proteins. Such macromolecules may comprise nucleic acid molecules, peptides and those proteins identified via methods such as those described hereinabove (hereinafter referred to as "binding partners"). Compounds that disrupt AGR 2 binding in this way may be useful in regulating and activity of AGR2.

The basic principle of the assay systems used to identify compounds that interfere with the interaction between AGR2 and its intracellular binding partner or partners involves preparing a reaction mixture containing AGR2, and the binding partner under conditions and for a time sufficient to allow the two to interact and bind, thus forming a complex. In order to test a compound for inhibitory activity, the reaction mixture may be prepared in the presence or absence of the test compound. The test compound may be initially included in the reaction mixture, or may be added at a time subsequent to the addition of AGR2 and its intracellular binding partner. Control reaction mixtures are incubated without the test compound or with a placebo. The formation of any complexes between AGR2 and the intracellular binding partner may then be detected. The formation of a complex in the control reaction, but not in the reaction mixture containing the test compound, indicates that the compound interferes with the interaction of AGR2 and the interactive binding partner.

The assay for compounds that interfere with the interaction of AGR2 and binding partners can be conducted in a heterogeneous or homogeneous format. Heterogeneous assays may comprise anchoring either AGR2 or its nucleotide sequence or the binding partner onto a solid phase and detecting complexes anchored on the solid phase at the end of the reaction. In homogeneous assays, the entire reaction may be carried out in a liquid phase. In either approach, the order of addition of reactants may be varied to obtain different information about the compounds being tested. For example, test compounds that interfere with the interaction between AGR2 and the binding partners, e.g., by competition, may be identified by conducting the reaction in the presence of the test substance i.e., by adding the test substance to the reaction mixture prior to or simultaneously with AGR2 and the interactive intracellular binding partner. Alternatively, test compounds that disrupt preformed complexes, e.g., compounds with higher binding constants that displace one of the components from the complex, may be tested by adding the test compound to the reaction mixture after complexes have been formed.

In a heterogeneous assay system, either AGR2 or the interactive intercellular binding partner, may be anchored onto a solid support, while the non-anchored species may be labeled, either directly or indirectly. Preferably, microtiter plates are conveniently utilized. The anchored species may be immobilized by non-covalent or covalent attachments. Non-covalent attachment may comprise coating the solid surface with a solution of AGR2 or binding partner and drying. Alternatively, an immobilized antibody specific for the species to be anchored may be used to anchor the species to the solid support.

The assay comprises exposing the partner of the immobilized species to the coated solid support with or without the test compound. After the reaction is complete, untreated components are removed (e.g., by washing) and any complexes formed will remain immobilized on the solid support. The detection of complexes anchored on the solid support may be accomplished in a number of ways. Where the non- immobilized species is pre-labeled, the detection of label immobilized on the support indicates that complexes were formed. Where the non-immobilized species is not pre-labeled, an indirect label can be used to detect complexes anchored on the support; e.g., using a labeled antibody specific for the initially non-immobilized species (the antibody, in turn, may be directly labeled or indirectly labeled with a labeled anti-Ig antigody). Depending upon the order of addition of reaction components, test compounds which inhibit complex formation or which disrupt preformed complexes can be detected.

Alternatively, the reaction may be conducted in a liquid phase in the presence or absence of the test compound, the reaction products separated from unreacted components, and complexes detected, e.g., using an immobilized antibody specific for one of the binding components to anchor any complexes formed in solution, and a labeled antibody specific for the other partner to detect anchored complexes. Again, depending upon the order of addition of reactants to the liquid phase, test compounds which inhibit complex or which disrupt preformed complexes can be identified.

In one embodiment of the invention, a homogeneous assay may be used. A preformed complex of AGR2 and the interactive intracellular binding partner is prepared in which either AGR2 or its binding partners is labeled, but the signal generated by the label is quenched due to complex formation (e.g. US Patent No. 4 109 496 which utilizes this approach for immunoassays). The addition of a test substance that competes with and displaces one of the species from the preformed complex will result in the generation of a signal above background. In this way, test substances which disrupt AGR2 protein/intercellular binding partner interaction can be identified.

Preferably, AGR2 can be prepared for immobilization using recombinant DNA techniques (54). For example, the coding region for AGR2 may be fused to a glutathione-S-transferase (GST) gene using a fusion vector, such as pGEX-5X-l, in such a manner that its binding activity is maintained in the resulting fusion protein. The interactive intracellular binding partner may be purified and used to raise a monoclonal antibody, using methods routinely practiced in the art and described above. This antibody may be labeled with the radioactive isotope ^l25I, for example by methods routinely practiced in the art. In a heterogeneous assay, e.g., the GST-AGR2 fusion protein can be anchored to glutathione-agarose beads. The interactive intracellular binding partner may then be added in the presence or absence of the test compound in a manner that allows interaction and binding to occur. At the end of the reaction period, unbound material can be washed away, and the labeled monoclonal antibody can be added to the system and allowed to bind to any complexed components. The interaction between the AGR2 protein and the interactive intracellular binding partner may be detected by measuring the amount of radioactivity that remains associated with the glutathione-agarose beads. A successful inhibition of the interaction by the test compound will result in a decrease in measured radioactivity.

Alternatively, in a further embodiment the GST-AGR2 gene fusion protein and the interactive intracellular binding partner can be mixed together in liquid in the absence of the solid glutathione-agarose beads. The test compound may be added either during or after the species are allowed to interact. This mixture can then be added to the glutathione-agarose beads and unbound material washed away. Again the extent of inhibition of the AGR2/binding partner interaction can be detected by adding the labeled antibody and measuring the radioactivity associated with the beads.

In another embodiment of the invention, these techniques can be employed using peptide fragments that correspond to the binding domains of AGR2 and/or the interactive intracellular or binding partner (where the binding partner comprises a protein), in place of one or both of the full length proteins. Any number of methods routinely practiced in the art can be used to identify and isolate the binding sites. These methods include, but are not limited to, mutagenesis of the gene encoding one of the proteins and screening for disruption of binding in a co-immunoprecipitation assay. Compensating mutations in the gene encoding the second species in the complex can then be selected. Sequence analysis of the genes encoding the respective proteins will reveal the mutations that correspond to the region of the protein involved in interactive binding. Alternatively, one protein may be anchored to a solid surface using methods described in the Section above, and allowed to interact with and bind to its labeled binding partner, which has been treated with a proteolytic enzyme, such as trypsin. After washing, a short, labeled peptide comprising the binding domain may remain associated with the solid material, which can be isolated and identified by amino acid sequencing. Also, once the gene coding for the intracellular binding partner is obtained, short gene segments can be engineered to express peptide fragments of the protein, which can then be tested for binding activity and purified or synthesized.

In a preferred embodiment, AGR2 may be anchored to a solid material as described above, by making a GST-AGR2 fusion protein and allowing it to bind to glutathione agarose beads. The interactive intracellular binding partner can be labeled with a radioactive isotope, such as ³⁵S and cleaved with a proteolytic enzyme such as trypsin. Cleavage products can then be added to the anchored GST-AGR2 fusion protein and allowed to bind. After washing away unbound peptides, labeled bound material, representing the intracellular binding partner binding domain, can be eluted, purified, and analyzed for amino acid sequence by well-known methods. Peptides so identified can be produced synthetically or fused to appropriate facilitative proteins using recombinant DNA technology.

In accordance with a further aspect of the present invention there is provided a therapeutically effective compound identified by the screening method described above for use in the treatment of metastatic cancer.

A therapeutically effective compound refers to a compound which will be useful for ameliorating the symptoms, arresting the activity etc. of metastatic cancer. A therapeutically effective dose of the compound refers to that amount of the compound sufficient to result in amelioration of symptoms or arresting the activity of metastatic cancer.

Toxicity and therapeutic efficacy of such compounds may be determined by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., for determining the LD₅₀ (the dose lethal to 50% of the population) and the ED₅₀ (the dose therapeutically effective in 50% of the population). The dose ratio between toxic and therapeutic effects is the therapeutic index and it can be expressed as the ratio LD₅₀/ED₅0. Compounds which exhibit large therapeutic indices are preferred. While compounds that exhibit toxic side effects may be used, care should be taken to design a delivery system that targets such compounds to the site of affected tissue in order to minimize potential damage to uninfected cells and, thereby, reduce side effects.

The data obtained from the cell culture assays and animal studies may be used in formulating a range of dosage for use in humans. The dosage of such compounds lies preferably within a range of circulating concentrations that include the ED₅₀ with little or no toxicity. The dosage may vary within this range depending upon the dosage form employed and the route of administration utilized. For any compound used in the method of the invention, the therapeutically effective dose can be estimated initially from cell culture assays. A dose may be formulated in animal models to achieve a circulating plasma concentration range that includes the IC₅₀ (i.e., the concentration of the test compound which achieves a half-maximal inhibition of symptoms) as determined in cell culture. Such information can be used more accurately to determine useful doses in humans. Levels in plasma may be measured, for example, by high performance liquid chromatography. Therapeutically effective compositions for use in accordance with the present invention may be formulated in conventional manner using one or more physiologically acceptable carriers or excipients.

Thus, the compounds and their physiologically acceptable salts and solvates may be formulated for administration by inhalation or insufflation (either through the mouth or the nose) or oral, buccal, parenteral or rectal administration.

For oral administration, the pharmaceutical compositions may take the form of, for example, tablets or capsules prepared by conventional means with pharmaceutically acceptable excipients such as binding agents (e.g., pregelatinised maize starch, polyvinylpyrrolidone or hydroxypropyl methylcellulose); fillers (e.g., lactose, microcrystalline cellulose or calcium hydrogen phosphate); lubricants (e.g., magnesium stearate, talc or silica) disintegrants (e.g., potato starch or sodium starch glycolate); ot wetting agents (e.g., sodium lauryl sulphate). The tablets may be coated by methods well known in the art. Liquid preparations for oral administration may take the form of, for example, solutions, syrups or suspensions, or they may be presented as a dry product for constitution with water or other suitable vehicle before use. Such liquid preparations may be prepared by conventional means with pharmaceutically acceptable additives such as suspending agents (e.g., sorbitol syrup, cellulose derivatives or hydrogenated edible fats); emulsifying agents (e.g. , lecithin or acacia); non-aqueous vehicles (e.g., almond oil, oi.lly esters, ethyl alcohol or fractionated vegetable oils); and preservatives (e.g. methyl or propyl-p-hydroxybenzoates or sorbic acid). The preparations may also contain buffer salts, flavoring, coloring and sweetening agents as appropriate. Preparations for oral administration may be suitably formulated to give controlled release of the active compound.

For buccal administration the compositions may take the form of tablets or lozenges formulated in conventional manner.

For administration by inhalation, the compounds for use according to the present invention may be conveniently delivered in the form of an aerosol spray presentation from pressurized packs or a nebuliser, with the use of a suitable propellant, e.g., dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, carbon dioxide or other suitable gas. In the case of a pressurized aerosol the dosage unit may be determined by providing a valve to deliver a metered amount. Capsules and cartridges of e.g., gelatin for use in an inhaler or insufflator may be formulated containing a powder mix of the compound and a suitable powder base such as lactose or starch.

The compounds may be formulated for parenteral administration by injections, e.g., by bolus injection or continuous infusion. Formulations for injection may be presented in unit dosage form, e.g., in ampoules or in multi-dose containers, with an added preservative. The compositions may take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilizing and/or dispersing agents. Alternatively, the active ingredient may be in powder form fro constitution with a suitable vehicle, e.g., sterile pyrogen-free water, before use.

The compounds may also be formulated in rectal compositions such as suppositories or retention enemas, e.g., containing conventional suppository bases such as cocoa butter or other glycerides. In addition to the formulations described previously, the compounds may also be formulated as a depot preparation. Such long acting formulations may be administered by implantation (for example subcutaneously or intramuscularly) or by intramuscular injection. Thus, for example, the compounds may be formulated with suitable polymeric or hydrophobic materials (for example as an emulsion in an acceptable oil) or ion exchange resins, or as sparingly soluble derivatives, for example, as a sparingly soluble salt.

The compositions may, if desired, be presented in a pack or dispenser device which may contain one or more unit dosage forms containing the active ingredient. The pack may for example comprise metal or plastic foil, such as a blister pack. The pack or dispenser device may be accompanied by instructions for administration. Assays for Identifying Receptors to which AGR2 Binds.

In accordance with a further aspect of the present invention there is provided a method for identifying a receptor for AGR2 comprising:

Contacting labelled AGR2 or a variant thereof with a cell; Removing unbound labelled AGR2 or a variant thereof; and Detecting bound labelled AGR2 or variant thereof.

Preferably AGR2 or a variant thereof is labeled with radioactive '^■"' iodine. The parameters of the binding of labeled AGR2 or a variant thereof to cells in culture may be determined in the presence of a range of concentrations of unlabelled AGR2 or a variant thereof according to standard methodology known to the skilled man. From an analysis of the data, binding parameters for the interaction between AGR2 protein and receptors on the cell surface may be obtained. In accordance with a further aspect of the present invention there is provided an isolated nucleic acid molecule for inducing metastatic cancer, comprising a nucleotide sequence that: a) encodes a polypeptide comprising the amino acid sequence shown in SEQ ID NO 2; b) encodes a protein comprising the amino acid sequence encoded by the cDNA as shown in SEQ ID NO 1 ; or c) hybridizes to the complement of a) or b). Preferably, the nucleic acid encodes AGR2.

In accordance with a further aspect of the present invention there is provided a method for inducing metastatic cancer in a subject comprising contacting a subject with AGR2, nucleic acid as described above and/or a polypeptide having the amino acid sequence as shown in SEQ ID NO 2.

AGR2 may be contacted with a subject via a suitable expression vector as described herein.

The subject may be a non-human mammal, a mammalian cell or an element thereof. Preferably, the non-human mammal is a rodent.

In accordance with a further aspect of the present invention there is provided a vaccine against metastatic cancer comprising an immunologically effective fragment derived from AGR2.

In accordance with a further aspect of the present invention there is provided an expression vector for inducing metastatic cancer comprising a nucleic acid molecule comprising a nucleotide sequence that: a) encodes a polypeptide comprising the amino acid sequence shown in SEQ ID NO 2; b) encodes a protein comprising the amino acid sequence encoded by the cDNA as shown in SEQ ID NO 1 ; or c) hybridizes to the complement of a) or b).

In accordance with a further aspect of the present invention there is provided a compound for inducing metastatic cancer comprising a polypeptide comprising the amino acid sequence shown in SEQ ID NO 2 or an isolated nucleic acid molecule comprising a nucleotide sequence that: a) encodes a polypeptide comprising the amino acid sequence shown in SEQ ID NO 2; b) encodes a protein comprising the amino acid sequence encoded by the cDNA as shown in SEQ ID NO 1 ; or c) hybridizes to the complement of a) or b).

In accordance with a further aspect of the present invention there is provided a method of treating metastatic cancer comprising administering a compound that modulates the expression of AGR2 gene.

The compound may comprise a compound identified as described herein above or may provide anti-sense, iRNA or ribozyme molecule that blocks translation of AGR2 mRNA.

The present invention will now be described, by way of example only, with reference to the following Figures and examples: Fig. 1. (SEQ ID NO. 1) Sequence alignments of M36 cDNA and AGR2 cDNA. The cDNA sequences of M36 and AGR2 (GenBank accession number NM_006408) exhibited 100% identity over the ranges shown, and yielded the same open reading frame (ORF) of 175 amino acids, shown in single letter amino acid code. The termination codon is marked with an asterisk.

Fig. 2. Northern hybridization of M36 mRNA in human mammary cell lines derived from benign and malignant breast tumours. Panel A: total RNAs were isolated from the SV40-immortalised normal human mammary cell line, Huma 7 (lane 1), the benign human mammary derived cell line Huma 123 (lane 3), benign myoepithelial-like converted cell line, Huma 109, derived from Huma 123 (lane 2), the malignant human mammary epithelial cell lines, MDA-MB-231 (lane 4), MCF-7 Gane 5), T47-D (lane 6), ZR-75 (lane 7), and subjected to Northern blotting and hybridisation as described in

Methods using a 3-*-P-labelled probe to AGR2 cDNA (Panel A, upper panel) or to the mRNA for ribosomal phosphoprotein cDNA, 36B4 (Panel A, lower panel) for normalisation purposes. Panels B-D: total RNA was isolated from human breast cancer cell line MCF-7 grown in the presence of estrogen (lane 1) or under estrogen-depleted conditions (lane 2) as described in Methods, and subjected to Northern blotting and

I hybridisation using 32p-labelled cDNA probes to AGR2 mRNA (Panel B), the estrogen responsive pS2 mRNA (Panel C), or the estrogen independent mRNA for the ribosomal phosphoprotein, 36B4 (Panel D) for normalisation purpose.

Fig. 3. Identification of AGR2 mRNA from human breast tumour specimens by using RT-PCR. RNA from human breast carcinoma specimens (lanes 1-28) was amplified by RT-PCR using primers specific for AGR2 cDNA (Panel A) or human glyceraldehyde-3-phosphate dehydrogenase (GPDH) cDNA (Panel B) to yield PCR products of 354 bp and 452 bp, respectively. The ER status of specimens were recorded (+) or (-) as described in Methods. The resulting RT-PCR products were subjected to agarose gel electrophoresis and stained with ethidium bromide, as described in Methods. Lane M, DNA molecular weight markers.

Fig. 4. Immunocytochemical staining of human breast specimens for AGR2. Histological sections of human normal breast showing ducts and lobules (Panel A), a benign fibroadenoma (Panel B) and ER-positive (Panel C, D and E) or ER-negative (Panel F) invasive ductal carcinoma specimens were stained with affinity-purified antibodies to recombinant AGR2 protein (Panel A-D and F) or with antibodies preincubated with 0.1 mg/ml recombinant AGR2 protein (Panel E) as described in Methods. Magnification: Panels A-C and E-F, 206 X, bar (shown on Panel A) = 49 mm ; Panel D, 643 X, bar = 16 mm.

Fig. 5. Histology and immunocytochemical staining of primary tumours and metastases produced by M36 cDNA transfectants. Histological sections of tissues from animals injected with Rama 37 cells transfected with the pcDNA3-M36 construct were stained with haematoxylin and eosin or immunocytochemically stained. Carcinoma cells (T) of a primary tumour in the mammary gland locally invades muscle tissue (M) visualised by haematoxylin and eosin staining (Panel A). A cannon-ball metastasis (M) in the lung (L) (Panel B), or metastatic tumour cells in the lungs (large arrrow) possibly in a lymphatic space adjacent to a blood vessel (small arrow) (Panel C), and within blood vessels (Panel D) stained by antibodies to vimentin. Tumour cells within a lung metastasis stained by antibodies to milk fat globule membrane antigen (Panel E), keratin (Panel F) and peanut lectin (Panel G), (Panels B and E-G: L = lung; M = metastatic tumour cells). Smooth muscle elements within a lung metastasis stained by antibodies to smooth muscle actin (Panel H) and myoglobin (Panel I). Magnification: Panels A and E- I, 206 X, bar (shown on Panel A) = 49 mm ; Panel B, 51 X, bar = 196 mm; Panels C and

D, 514 X, bar (shown on Panel C) = 19.5 mm.

Fig. 6. Immunocytochemical staining by antiserum to AGR2 of primary tumours and metastases generated by M36 cDNA transfectants. Histological sections of primary tumours from animals injected by Rama 37 cells transfected with pcDNA3 control vector (Panel A), or primary tumours (Panel B) and metastases in the lungs (Panels C and D), produced from animals injected by Rama 37 cells transfected with vector containing M36 cDNA (Panels B, C and D) were stained with affinity-purified antibodies to recombinant AGR2 protein (Panels A, B and C) or with antibodies preincubated with 0.1 mg/ml recombinant AGR2 protein (Panel D) as described in Methods. Magnification: Panels A- D, 206 X, bar (shown on Panel A) = 49 mm.

Figs. 7A to C show the visualisation of fluorescence in a HeLa cell line transfected with pEGFP-Nl. Fig. 7A shows fluorescence alone; Fig. 7B shows phase alone; and, Fig. 7C shows fluorescence and phase combined. There is a high level of fluorescence throughout the cells but none is seen in the medium.

Figs. 8A to C show the visualisation of fluorescence in a HeLa cell line transfected with pEGFP-Nl-AGR2. Fig. 8A shows fluorescence alone; Fig. 8B shows phase alone; and, Fig. 8C shows fluorescence and phase combined.

Fig. 9 shows Kaplan-Meier cumulative relapse-free survival plots by AGR2 status in estrogen receptor (ER) positive and ER negative cases. METHODS

Cell lines and cell culture

The normal human mammary epithelial cell line, Huma 7 had been subcloned from primary cultures of reduction mammoplasty specimens of normal breast tissue, immortalised with SV40 virus (19). The benign human mammary epithelial cell line, Huma 123, and the derivative benign human mammary myoepithelial-like cell line, Huma 109 (15) were derived from HMT-3522, itself obtained from a primary cell culture of human benign breast disease displaying prominent epithelial hyperplasia (20). These cell lines, and the malignant human mammary epithelial cell lines derived from pleural effusions of breast cancer patients, MCF-7, T-47D, ZR-75 and MDA-MB-231 (21), were cultured as described previously (12,15,19). The benign rat mammary epithelial cell line, Rama 37, was cultured in Routine Medium (RM) comprising Dulbecco's modified Eagles' medium (DMEM), 5% (v/v) foetal calf serum (FCS), 50 ng/ml hydrocortisone, 50 ng/ml insulin as described previously (22). The transfected derivative cell lines were grown in RM containing 1 mg/ml Geneticin. All cells were passaged upon reaching 70% confluency. Hormone-stripped cell culture

MCF-7 cells were grown initially in 9 cm diameter perri dish in a humidified atmosphere of 90% (v/v) air, 10% (v/v) C0₂ at 37°C in DMEM containing 5% (v/v) FCS, 50 ng/ml insulin and 10^"8 M estradiol. They were grown to 70% confluence, washed twice with phosphate-buffered saline (PBS) and transferred into phenol red-free DMEM medium containing 5% "steroid-stripped" new-born calf serum, which had been treated with dextran-coated charcoal containing 0.5% (w/v) activated charcoal and 0.05% (w/v) dextran T70, and depleted of endogenous steroids for 6 days (23,24). Medium was changed daily and cells were washed once with PBS prior to each medium change. Subtractive hybridisation and reverse Northern screening

A suppression subtracted (11) library consisting of PCR products representing mRNAs expressed at a higher level in the malignant breast epithelial cell line MCF-7, relative to a benign human breast-derived cell line, Huma 123 was constructed using a PCR-Select™ cDNA Subtraction Kit (Clontech, Palo Alto, California, USA), as described previously (14). Reverse Northern screening of the subtracted cDNA library was carried out as described previously (12). Northern hybridization

Total cellular RNA was prepared using the guanidinium-isothiocyanate-caesium chloride method (25-27). Poly(A)-containing RNA was isolated from total RNA using the Fast Track mRNA isolation kit (Invitrogen, Groningen, Netherlands). Gel electrophoresis of formaldehyde-treated RNA, Northern blotting, hybridisation and washing of the filters were performed as described previously (12). The cDNA probes were radioactively labelled to 1 x 10⁹ d.p.m/μg DNA by random-primed DNA synthesis (28) using a labelling kit (Roche Molecular Biochemicals, Mannheim, Germany). The constitutive probe, 36B4, a cDNA to human acidic ribosomal phosphoprotein PO mRNA (29,30), was used to normalize RNA loading on the gel.

Coupled transcription and translation assay in vitro Transcription and translation assays in vitro were carried out using a TNT T7/T3 coupled reticulocyte lysate system (Promega, Madison, USA) to produce a protein

product labelled with [*"S] methionine in vitro. Two μg of DNA template were transcribed and translated in 50 μl containing 40U RNAsin ribonuclease inhibitor, 25 μl TNT rabbit reticulocyte lysate, 20 μM amino acid mixture without methionine, 20 units

(T3 or T7) RNA polymerase, 20 μCi [³⁵S] methionine (> 1 ,000Ci/mmol at lOmCi/ml) and 2 μl TNT reaction buffer. The mixture was incubated at 30°C for 90 min. The

resulting *-*-*S-labelled proteins and non-radioactive standards were fractionated on urea- containing SDS, 15% (w/v) polyacrylamide gels with 6% (w/v) polyacrylamide stacking gels (31). Following electrophoresis, the gels were stained with Coomassie blue and destained with 40% (v/v) methanol, 7% (v/v) acetic acid. The gel was dried under vacuum and autoradiographed with Kodak X-Omat films at -70°C for 3 to 10 days. Production and purification of recombinant protein AGR2 and its antiserum The full length M36 cDNA was cloned into the expression vector, pET-16b (Novagen, Madison, USA), downstream of the His tag, to yield a recombinant cDNA construct designated pET-M36, which was first verified by automated DNA sequencing, and then transformed into E.coli BL21DE3 cells. Induction of recombinant protein was carried out by adding isopropyl-1-thio-β-D-galactopyranoside (final concentration, 1 mM) to the culture medium (OD₆oo = 0.5) for 2h. Purification of recombinant AGR2 protein from inclusion bodies to a single band on SDS-polyacrylamide gel was carried out using His- Bind resin (Novagen, Madison, USA). The amino acid sequence of the purified recombinant AGR2 protein was confirmed by an automated sequencer. (SEQ ID No. 2) The production of rabbit anti-AGR2 serum was conducted by Eurogentec (Seraing, Belgium). The anti-AGR2 antibodies were affinity-purified by their binding to antigen immobilised on a PVDF membrane. Briefly, 1 mg of recombinant AGR2 was subjected to SDS -polyacrylamide gel electrophoresis, electrophoretically transferred to a PVDF membrane and the part of the membrane containing the immobilised antigen was incubated with serum from a rabbit immunised with recombinant AGR2. Bound antibody was eluted with a 100 mM glycine buffer at pH 2.5 followed by neutralisation with IM Tris buffer (pH 8.0). The purified AGR2 antibodies were specific to a single band of 20 kDa for AGR2-containing cell extracts isolated from MCF-7 cells on Western blots, which was abolished by prior incubation with 0.1 mg/ml of recombinant AGR2 protein (not shown). Reverse transcription PCR

Two μg of total RNA were reverse transcribed in 10 μl with 200 units of Superscript™ RNase H^" Reverse Transcriptase (Invitrogen Ltd., Paisley, UK). Subsequently lμl of this first strand cDNA reaction mixture was amplified by PCR with Taq DNA polymerase (Invitrogen Ltd., Paisley, UK). For M36 cDNA the forward primer (5' position at nucleotide 87, of GenBank accession number NM_006408.2) was 5' GCT CCT TGT GGC CCT CTC CTA CAC- 3' and the reverse primer (5' position at nucleotide 440, of GenBank accession number NM_006408.2) was 5' ATC CTG GGG ACA TAC TGG CCA TCA G 3'. For the human glyceraldehyde 3-phosphate dehydrogenase cDNA the forward, 5' -ACCACAGTCCAT GCCATCAC -3' and reverse primer, 5'-TCCACCACCCTGTTGCTGTA -3' were used to provide a normalisation control. RT-PCR was performed as follows: 94°C for 3 min; 25 cycles at 94°C for 30 s, 60°C for 30 s and 72°C for 1.5 min. RT-PCR products were visualised with ethidium bromide following agarose gel electrophoresis (32). Transfection of plasmid DNA into rat cells

Exponentially growing benign rat mammary epithelial Rama 37 cells were harvested, seeded at a density of 0.5 to 0.7 x 10⁶ cells per 9 cm-diameter cell culture dish in RM and incubated for 24 h at 37°C. Five μg of the pcDNA-M36 construct containing full-length M36 cDNA, which has been verified by automated DNA sequence analysis, were transfected into Rama 37 cells using calcium phosphate as described previously (33). Five μg of pcDNA vector without insert were transfected separately into Rama 37 cells as a negative control. Colonies were visible after about 7 days, following selection in 1 mg/ml Geneticin. A number of single colonies were picked, expanded and subsequently transferred several times, before being frozen for storage. Tumorigenesis and metastasis

Cultured cells were harvested by trypsinisation, resuspended in PBS containing 10% (v/v) FCS at 4°C, and centrifuged at 800 rpm for 5 min at room temperature in an MSE bench-top centrifuge. The cell pellet was washed twice and resuspended in cold PBS (4^CC) at a concentration of 10⁷ viable cells/ml.

Female rats, 5 to 6 weeks old, were injected subcutaneously at the site of the left or right inguinal mammary fat pad with 0.2 ml of the suspension of cells. All rats were observed at 3 to 4 day intervals up to 5 months. Tumour-bearing rats were autopsied when their primary tumours were greater than 5 cm in diameter, or earlier if the tumours ulcerated or caused serious morbidity. The lungs, liver, axillary lymph nodes, spleen, kidney, heart and bones were examined for gross metastases. Samples of the primary tumours and lungs with abnormal appearance were fixed in Methacarn (methanol: trichloroethane: acetic acid, 6:3:1 (v/v)) and processed for histology (7). Histology and immunocytochemistry

The histology of 4 μm tissue sections was determined after staining with haematoxylin and eosin. Immunocytochemical staining for vimentin, skeletal muscle actin, myoglobin and ERα was carried out as described previously (34,35). Immunocytochemical staining for AGR2 was performed with affinity-purified AGR2 antibodies with and without prior incubation with 0.1 mg/ml of recombinant protein AGR2, either for sections of human specimens, at 1/500 dilution in PBS buffer containing 2% (w/v) bovine serum albumin (BSA), and incubated at room temperature for 2h, or for sections of rat specimens, at 1/200 dilution in PBS buffer containing 0.5% (w/v) BSA, and incubated at room temperature overnight. The bound antibodies were detected using biotinylated donkey antirabbit antibodies and followed by AB Complex / HRP kit (Dako Ltd. Cambridgeshire, UK), according to the manufacturer's methodology. The sections were visualised as a brown stain by incubating with 3, 3'-diaminobenzidine (Sigma, Dorset, UK) and 0.075% H₂0₂, counterstained with Mayers' hemalum and mounted in DPX (Merck, Dorset, UK). All staining results were examined by three independent observers and scored as plus/minus scales using 5% cells staining as a cut off. Photography was carried out as described previously (34). Human breast specimens and animals experiments

Human breast specimens were obtained from the Liverpool Cancer Tissue Bank Research Centre with full and informed patient consent and with ethical approval. They consisted of normal specimens from reduction mammoplasties, benign fϊbroadenomas and invasive ductal carcinoma of no special type. The carcinomas were subdivided into two groups based on immunocytochemical staining for ERα, a cut off at 5% of the carcinoma cells stained by antibodies to ERα divided the negative from the positive group (35).

Female Ludwig Wistar OLA strain of Furth-Wistar rats were obtained from Olac Ltd., Banbury, Oxon. Statistical analysis

Statistical analyses were performed by the two-tailed Fisher Exact Test unless otherwise specified, using Arcus Pro-Stat Dos version 3.28 software (Medical Computing, Aughton, UK). Determination that AGR2 is a secreted protein

A plasmid vector containing a fusion gene of AGR-2 and enhanced green fluorescent protein (EGFP) was constructed.

The plasmid was suitable for transfection of a mammalian cell line to visualize the localisation of the fusion protein AGR-2 EGFP using a confocal microscope.

The plasmid was used to rransfect HeLa cells. The fusion protein was expressed in HeLa cells and its localization visualised. Two groups of cells were transfected, one with pEGFP-Nl-AGR2 plasmid and a control group with pEGFP-Nl . The cells were visualised using a confocal microscope and the areas of fluorescence studied. RESULTS

Over-expressed M36 cDNA in the malignant human breast cancer cell lines corresponds to AGR2 mRNA A suppression subtracted library has been constructed (14) containing cDNAs expressed at a higher level in the malignant mammary cell line, MCF-7, than in the cell line, Huma 123, derived from a benign mammary lesion. Four cloned cDNAs (M36, M40, M202, M234) of 174 cloned cDNAs sequenced, each exhibited 100% identity to the sequence of human cDNA AGR2 (GenBank accession number NM_006408; Fig. 1). AGR2 is the human homologue of the Xenopus laevis Anterior Gradient-2 (XAG-2) gene, which is expressed by the cement gland of the developing Xenopus embryo (18). The nucleotide sequences for M36 or M202 cDNA contained an open reading frame of 175 amino acids that was identical in amino acid sequence to that of AGR2 protein (GenBank accession number NP 006399; Fig. 1). In order to find out whether a translation product could be obtained from the mRNAs represented by clones M36 and M202, a T7/T3 RNA polymerase-coupled transcription/translation system was used. Both of these cloned cDNAs yielded a single ³⁵S-labelled primary translation product of 20 kDa upon urea-containing SDS polyacrylamide gel electrophoresis (not shown), a size which corresponds to the 20 kDa derived from the amino acid sequence. The 20 kDa band was not seen when the transcription / translation lysates were incubated with empty vector (not shown).

Quantitative reverse Northern hybridisations using as probes double-stranded mixed cDNAs, derived from the mRNA populations of either MCF-7 and Huma 123 cell lines, showed that the level of AGR2 mRNA was over 15-fold higher in the RNA from MCF-7 cells than in the RNA from the Huma 123 cells (not shown). Northern hybridisation experiments, using radioactively labelled M36 cDNA as probe, showed that the AGR2 mRNA was present in all three ER-positive breast cancer cell lines, MCF-7, T47D and ZR-75-1, but not in the ER-negative MDA-MB-231 breast cancer cell line (Fig. 2). The AGR2 mRNA was also undetectable in the SV40-immortalised normal human breast cell line, Huma 7, the benign human breast tumour cell line Huma 123 and its myoepithelial-like convert, Huma 109 (Fig. 2). The M36 probe hybridised to a major band of RNA with a molecular size of 0.9 ± 0.15 kb (mean ± standard deviation of three independent experiments) and an additional faint band was evident at a molecular weight of 1.6 ± 0.1 kb in all the positive lanes. The results suggest that the expression of AGR2 mRNA correlates with the presence of ERα, at least in these cell lines. This result was extended by showing that AGR2 mRNA was present at a 7.3 ± 0.25-fold (mean ± SD of three independent experiments) higher level in MCF-7 cells grown in the presence of estrogen, than in cells grown in estrogen-depleted conditions (Fig. 2). Under the same experimental conditions, the level of a previously-described, estrogen-dependent mRNA, that of pS2 (30), was increased 3.4 ± 0.1-fold. In these quantitative results, mRNA levels were normalised with respect to 36B4 mRNA, a mRNA that is not dependent upon the presence of estrogen and its receptor for its production (29).

Identification of AGR2 mRNA and protein in human breast tumour specimens Reverse transcript PCR (Table 1) was used to study the occurrence of AGR2 mRNA in benign breast lesions and malignant human breast carcinoma specimens (Fig. 3). Using 25 cycles of PCR, only 33% of normal and 52% of benign samples were positive for AGR2 mRNA, whereas 79% of breast carcinoma samples were positive for AGR2 mRNA (Table 1). This proportion is significantly different from the normal and benign specimens (Fisher Exact Test, P = 0.0029). Moreover, 91% of the ER-positive carcinoma specimens yielded a strong PCR product, whereas only 59% of the ER- negative carcinomas were positive for AGR2 mRNA, values that were also significantly different (P = 0.007). These results show that AGR2 mRNA is dependent on the presence of ERα in the majority of breast carcinoma specimens as well as in the breast carcinoma cell lines.

The affinity-purified AGR2 antibodies, which were specific for AGR2 protein as described in Methods, were used to immunocytochemically stain histological sections of human breast specimens. The epithelial cells of human normal breast tissue and benign lesions were either moderately stained for AGR2 or negative (Fig. 4, A and B), but the epithelial cells of ER-positive breast carcinomas were strongly stained for AGR2 (Fig. 4, C and D). The immunocytochemical staining for AGR2 also showed a granular appearance, reminiscent of secretory granules (Fig. 4, D). The positive staining for AGR2 was completely abolished by prior incubation of the antibodies with recombinant AGR2 protein (Fig. 4, E). Overall AGR2 was detectable in only 40% of normal specimens, and 47% of benign breast tumour specimens, but 75% of breast carcinoma specimens were positive for AGR2 protein. This value was significantly different from normal and benign specimens (Table \) (P - 0.025). As with the RT-PCR experiments, 90% of ER- positive specimens were positively stained, whilst only 47% of the ER- negative carcinomas were positive for AGR2 protein, a significantly different result (P = 0.0033). These experiments demonstrated similar quantitative results for AGR2 protein as obtained for mRNA by RT-PCR (Table 1).

Table 1. Identification of M36 / AGR2 mRNA and protein in breast specimens using RT- PCR and immunocytochemistry. Clinical specimens RT-PCR screening of Immunocytochemistry specimens screening of specimens

Number Number Tota Number Number Tota of of 1 of of 1 positive negative* positive^ negative-*

1

Normal 3 6 9 2 3 5

Benign 13 12 25 7 8 15

Total 16 18 34 9 1 1 20

ER-positive ι carcinomas 31 3 34 26 3 29

ER-negative carcinomas 133 9 22 75 8 15

Total 44 12 56 33⁶ 1 1 44

1 Positive RT-PCR is defined as a single band of molecular weight 354 bp for AGR2 and 452 bp for GPDH on the gel; negative RT-PCR is defined as no clear band on the gel.

2 Positive immunocytochemistry is defined as more than 5% of epithelial cells staining; negative immunocytochemistry is defined as less than 5% of epithelial cells staining.

3 Statistically significantly different from ER-positive, P = 0.007 (Fisher Exact Test).

4 Statistically significantly different from normal and benign specimens, P = 0.0029 (Fisher Exact Test).

-> Statistically significantly different from ER-positive, P = 0.0033 (Fisher Exact Test). 6 Statistically significantly different from normal and benign specimens, P = 0.025

(Fisher Exact Test).

Identification of AGR2 as a novel metastasis inducer

The full length M36 (AGR2) cDNA was inserted into the multiple-cloning site of, the mammalian expression vector pcDNA3, downstream of the CMV promoter, to yield a recombinant cDNA construct designated pcDNA-M36. The pcDNA-M36 construct, or the same amount of pcDNA vector without insert as a negative control (pcDNA), was transfected into the benign rat mammary epithelial cell line, Rama 37 (Methods). Following selection in Geneticin, single colonies were detected after 7 days. Twenty- seven single colonies from the Rama 37 pcDNA-M36 transfectants and nine colonies from the control pcDNA3 transfectants were picked and expanded. Northern hybridisation analysis for AGR2 mRNA, using an M36 probe, identified a pcDNA-M36 Rama 37 transfectant cell line, which exhibited a positive band of hybridisation at 0.9 kb which was completely absent in the AGR2 -negative recipient Rama 37 cells (not shown).

A single subcutaneous injection of 2 x 10^ viable cells transfected with the control vector, Rama 37pcDNA, yielded primary tumours in the mammary glands with a mean latent period of 49 ± 11 days, and with an incidence of 50% (10/20 rats) (Table 2). This incidence that was not significantly different from that obtained previously with Rama 37 cells (7) (Fisher Exact Test, P = 1.00). None of the tumour-bearing rats exhibited lung metastases, and this was confirmed by subsequent histological examination of selected tissues, including lung and lymph nodes. Rats injected with the Rama 37 cells transfected with pcDNA-M36 containing AGR2 yielded tumours with a mean latent period of 81-fc 6 days, significantly longer than that for Rama 37 cells transfected with pcDNA plasmid control vector (Mann- Whitney (/-test, P = 0.0001), but the incidence of primary tumours in the mammary glands was 50% (30/60 rats) (Table 2), the same as that for cells transfected with pcDNA vector (Fisher Exact Test, P =. 1.00). However, 77% (23/30) of the rats injected with the Rama 37 cells transfected with pcDNA-M36 containing AGR2 developed either gross metastases of the lungs which were visible at autopsy (Table 2, Fig. 5) or micrometastases evident on subsequent histological examination. That value was significantly different from the control group of pcDNA- transfected Rama 37 cells (Fisher exact test, P = 0.001), in which no lung macro- or micro-metastases were found.

Table 2. Incidence of tumours and metastases produced by M36 cDNA transfected cells Cell lines Presence of Incidence of Incidence of

AGR2 mRNA¹ tumours² (%) metastasis³ (%)

Rama 37 - 22/46 (48%)⁴ 0/22 (0%)⁴

Rama 37 -pcDNA vector - 10/20 (50%)⁵ 0/10 (0%)

Rama 37-pcDNA-M36 + 30/60 (50%)⁶ 23/30 (76.7%)?

I

1 The presence or absence of AGR2 (M36) mRNA in the injected cell line was determined by Northern blotting as described in Methods, - = absent; + = present.

2 Number of rats with primary tumours / number of rats injected.

³ Number of rats with metastases / number of rats with primary tumours.

⁴ Data from (7). ⁵ Not significantly different from Rama 37 (Fisher Exact Test, P= 1.00).

6 Not significantly different from Rama 37 and Rama 37 cells transfected with pcDNA vector (Fisher Exact Test, P= 0.85 and 1.00, respectively).

7 Significantly different from Rama 37 cells transfected with pcDNA vector (Fisher Exact Test, P < 0.0001).

Histology and immunocytochemistry of tumours produced by transfected cells

Some of the primary tumours from rats injected with Rama 37 cells transfected with pcDNA-M36 were composed of cuboidal cells, many forming cords which were surrounded by neoplastic spindle cells, while others consisted predominantly of neoplastic spindle cells. Many tumours showed central necrotic cores. In many primary tumours arising from cells transfected with the pcDNA-M36 construct, extensive numbers of blood vessels were seen. Some tumour cells had breached the surrounding connective tissue capsules and had invaded the adjacent host skeletal muscle (Fig. 5, A). In general the histology of the metastases was the same as that of the primary tumour. Both cannon-ball metastases and tumour cells penetrating the surrounding lung tissue were evident (Fig. 5, B). The primary tumours and metastases were also extensively stained by antibodies to vimentin (Fig. 5, B) and in that case tumour cells in endothelia cell-lined spaces, possibly lymphatics (Fig. 5, C) and in blood vessels (Fig. 5, D) were observed. The primary tumour cells and lung metastases also exhibited staining for milk fat globule membrane antigen (Fig. 5, E) and were also stained by pan-keratin antibodies (Fig. 5, F) and by peanut lectin (Fig. 5, G). Differentiation of tumour cells to smooth muscle-like elements was common in both the primary tumour and its metastases, sometimes forming large multinucleate cells (Fig. 5, H). These smooth muscle-like elements were immunocytochemically stained by antisera to smooth muscle actin (Fig. 5, H) and to myoglobin (Fig. 5, 1). Skeletal smooth muscle elements were not found in any of the primary tumours arising from cells transfected with the control pcDNA vector. Whilst there was no immunocytochemically staining for AGR2 in the histological sections of primary tumours arising from animals injected by Rama 37 cells transfected with control pcDNA plasmid vector alone (Fig. 6, A), both carcinoma cells of primary tumours and metastases in the lungs produced from animals injected by Rama 37 cells transfected with vector containing AGR2 (M36) cDNA were stained positively by the affinity-purified antibodies directed against recombinant AGR2 protein (Fig. 6, B and C). The immunocytochemical staining with the AGR2 antibodies was blocked by their prior incubation with recombinant AGR2 protein (Fig. 6, D). Determination that AGR2 is a secreted protein

Cells transfected with pEGFP showed fluorescence throughout the cells, both in the cytoplasm and in the nucleus (Fig. 7). There was no secretion of the fluorescent protein into the medium and the fluorescence within the cells was very strong. This is the expected pattern for EGFP expression.

When cells were transfected with pEGFP-Nl -AGR-2 plasmid, a significantly

I different pattern of fluorescence was seen (Fig. 8). The fluorescent protein is totally excluded from the nucleus, and the levels of fluorescence within the cytoplasm are much lower. Within the cytoplasm, some areas show higher levels of fluorescence than others. In particular, a bright area near the nucleus, which corresponds to the Golgi apparatus of the cell, suggests that AGR-2 is a secreted protein. The lower levels of fluorescence in the cells, by comparison to the control confirms that the protein is secreted in human cells.

Breast carcinoma specimens were obtained from the Liverpool Cancer Tissue

Bank Research Centre. Immunocytochemical staining for AGR2 using affinity-purified rabbit anti AGR2 serum and statistical analyses of the results were carried out as described previously by Rudland et al. for osteopontin (55).

The association of positive immunocytochemical staining for AGF2 with other tumour variables, including tumour size, nodal status, stage, tumour grade, or with positive immunocytochemical staining for estrogen receptor (ER) alpha or ER beta, progesterone receptor, Ki67 (a marker of cell proliferation) and osteopontin, or with the presence of mutations in the p53 gene were assessed by Fisher Exact test (56) (Table 3). Table 3 shows that tumour grade showed a statistically significant association with AGR2 staining. There were statistically significant associations between staining for AGR2 with staining for ER alpha (but not ER beta), for progesterone receptor, for Ki67, for osteopontin and with identifiable p53 mutations using multiplexing PCR.

Fig. 9, shows Kaplan-Meier cumulative relapse-free survival plots by AGR2 status in estrogen receptor (ER) positive and ER negative cases. It is clearly evident that a trend is discernable towards poorer survival of patients with AGR2.

Table

Relationships between staining for AGR2 staining and other tumour variables

Tumour variable AGR2 negative AGR2 positive Statistical no(%) no (%) significance

Size > 2cm 32 (64) 62 (56.4) 0.39 <2cm 18 (36) 48 (43.6)

Nodal status Positive 19 (46.3) 44 (47.8) 1 Negative 22 (53.7) 48 (52.2)

Stage I 11 (22) 26 (23.2) 1 >I 39 (78) 86 (76.8)

Grade 3 37 (74) 35 (31.3) 0.0005* l or2 13 (26) 77 (68.9)

ERα status Positive 16 (32) 89 (84) <σ.ooo5* Negative 34 (68) 17 (16)

PR status Positive 9 (20.5) 51 (53.7) <0.0005* Negative 35 (79.5) 44 (46.3)

Ki67 status Positive 34 (75.6) 35 (38.9) <O.00O5* Negative 11 (24.4) 55 (61.1)

ERβ lHC Positive 30 (73.2) 54 (60.7) 0.24 Negative 11 (26.8) 35 (39.3)

pS3 mutation Present 17 (37) 19 (19.2) 0.03* Absent 29 (63) 80 (80.8)

OPN Positive 24 (48) 74 (66.1) 0.02* Negative 26 (52) 38 (33.9)

a Using cut-Off of 60% positive cells. * Significant at 5% level or less. IDENTIFICATION OF M36 PROTEIN. SEQ ID NO.2

MEKIPVSAFLLLVALSYTLARD

TTVKPGAKKDTKDSRPKLPQ

TLSRGWGDQLIWTQTYEEAL

YKSKTSNKPLMIIHHLDE CP

HSQALKKVKFAENKEIQKLAE

QFVLLNLVYETTDKHLSPDG

QYVPRIMFVDPSLTVRADIT

GRYSNRLYAYEPADTALLLD

NMKKALKLLKTEL

REFERENCES

(1) Martin K, Kritzman DM, Price LM, Koh B, Kwan CP, Zhang XH, et al. Linking gene expression patterns to therapeutic groups in breast cancer. Cancer Res 2000;60: _t 2232-8.

(2) Perou CM, Sorlie T, Eisen MB, van de Rijn M, Jeffrey SS, Rees CA, et al. Molecular portraits of human breast tumours. Nature 2000;406: 747-52.

(3) Smid-Koopman E, Blok LJ, Chadha-Ajwani S, Helmerhorst TJ, Brinkmann AO, Huikeshoven FJ. Gene expression profiles of human endometrial cancer samples using a cDNA-expression array technique: assessment of an analysis method. Br J Cancer 2000;83: 246-51.

(4) Wang T, Hopkins D, Schmidt C, Silva S, Houghton R, Takita H, et al. Identification of genes differentially over-expressed in lung squamous cell carcinoma using combination of cDNA subtraction and microarray analysis. Oncogene 2000; 19: 1519-28.

(5) Xu JC, Stolk JA, Zhang XQ, Silva SJ, Houghton RL, Matsumura M, et al. Identification of differentially expressed genes in human prostate cancer using subtraction and microarray. Cancer Res 2000;60: 1677-82.

(6) Barraclough R, Savin J, Dube S, Rudland P. Molecular cloning and sequence of the gene for p9Ka, a cultured myoepithelial cell protein with strong homology to S-100, a calcium-binding protein. J Mol Biol 1987;198: 13-20.

(7) Davies BR, Davies MPA, Gibbs FEM, Barraclough R, Rudland PS. Induction of the metastatic phenotype by transfection of a benign rat mammary epithelial cell line with the gene for p9Ka, a rat calcium-binding protein but not with the oncogene EJ ras-1. Oncogene 1993;8: 999-1008.

(8) Oates AJ, Barraclough R, Rudland PS. The identification of osteopontin as a metastasis-related gene product in a rodent mammary tumour model. Oncogene 1996; 13: 97-104.

(9) Rudland PS, Platt-Higgins A, Renshaw C, West CR, Winstanley JHR, Robertson L, et al. Prognostic significance of the metastasis-inducing protein S100A4 (p9Ka) in human breast cancer. Cancer Res 2000;60: 1595-603.

(10) Rudland PS, Platt-Higgins A, El-Tanani M, De Silva Rudland S, Barraclough R, Winstanley JH, et al. Prognostic significance of the metastasis-associated protein osteopontin in human breast cancer. Cancer Res 2002;62: 3417-27.

(11) Diatchenko L, Lau Y-FC, Campbell A, Chenchik A, Moqadaam F, Huang B, et al. Suppression subtractive hybridisation: A method for generating differentially- regulated or tissue-specific cDNA probes and libraries. Proc Natl Acad Sci U S A 1996;93: 6025-30.

(12) Liu D, Rudland PS, Sibson DR, Platt-Higgins A, Barraclough R. Expression of calcium-binding protein S100A2 in breast lesions. Br J Cancer 2000; 83: 1473-9.

I

(13) Liu D: The Identification of Genes Differentially Expressed in Human Breast Lesions. Ph. D. Thesis, School of Biological Sciences, University of Liverpool, UK 2001, pp 268.

(14) Liu D, Rudland P, Sibson D, Barraclough R. Identification of mRNAs differentially-expressed between benign and malignant breast tumour cells. Br J Cancer 2002;87: 423-31. (15) Ke Y, Fernig DG, Wilkinson MC, Winstanley JHR, Smith JA, Rudland PS, et al. The expression of basic fibroblast growth factor and its receptor in cell lines derived from normal human mammary gland and a benign mammary lesion. J Cell Sci 1993;106: 135- 43.

(16) Soule HD, Vazquez A, Long A, Albert S, Brennan MA. Human cell line from a pleural effusion derived from a breast carcinoma. J Natl Cancer Inst 1973; 51 : 1409 - 13.

(17) Thompson DA, Weigel RJ. hAG-2, the human homologue of the Xenopus laevis cement gland gene XAG-2, is coexpressed with estrogen receptor in breast cancer cell lines. Biochem Biophys Res Commun 1998;251 : 111-6.

(18) Aberger F, Weidinger G, Grunz H, Richter K. Anterior specification of embryonic ectoderm: the role of the Xenopus cement gland-specific gene XAG-2. Mech Dev 1998;72: 115-30.

(19) Rudland PS, Ollerhead G Barraclough R. Isolation of simian virus 40 transformed human mammary epithelial stem cell line that can differentiate to myoepithelial-like cells in culture and in vivo. Develop Biol 1989; 136: 167-80.

(20) Briand P, Petersen OW, Van Deurs B. A new diploid non-tumorigenic human breast epithelial cell line isolated and propagated in chemically-defined medium. In vitro 1987;23: 181-8.

(21) Engel L W, Young NA. Human breast carcinoma cells in continuous culture : a review. Cancer Res 1978;38: 4327-39.

(22) Dunnington DJ, Monaghan P, Hughes CM, Rudland PS. Phenotypic instability of rat mammary tumor epithelial cells. J Natl Cancer Inst 1983;71 : 1227-40. (23) El-Tanani M, Green C. Estrogen-induced genes, pLiv-1 and pS2, respond divergently to other steroid-hormones in MCF-7 cells. Mol Cell Endocrinol 1995; 111 : 75-81.

(24) Darbre P, Yates J, Curtis S, King R. Effect of estradiol on human breast cancer cells in culture. Cancer Res 1983;43: 349-54.

(25) Barraclough R, Kimbell R, Rudland PS. Differential control of mRNA levels for Thy-1 antigen and laminin in rat mammary epithelial and myoepithelial-like cells in culture. J Cell Physiol 1987; 131 : 393-401.

(26) Chirgwin JM, Przybyla AE, Macdonald RJ, Rutter WJ. Isolation of biologically active ribonucleic acid from sources enriched in ribonuclease. Biochemistry 1979;18: 5294-9.

(27) Han JH, Stratowa C, Rutter WJ. Isolation of full-length putative rat lysophospholipase cDNA using improved methods for mRNA isolation and cDNA cloning. Biochemistry 1987; 26: 1617-25.

(28) Feinberg AP, Vogelstein B. A technique for radiolabelling DNA restriction endonuclease fragments to high specific activity. Anal Biochem 1984; 137: 266-7.

(29) Laborda J. 36B4 cDNA used as an estradiol-independent mRNA control is the cDNA for human acidic ribosomal phosphoprotein PO. Nucleic Acids Res 1991;19: 3998.

(30) Masiakowski P, Breathnach R, Bloch J, Gannon F, Krust A, Chambon P. Cloning of cDNA sequences of hormone-regulated genes from the MCF-7 human breast cancer cell line. Nucleic Acids Res 1982; 10: 7895-903. (31) Laemmli UK. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 1970; 227: 680-5.

(32) Sambrook J, Fritsch EF, Maniatis T. Molecular Cloning : A Laboratory Manual. Cold Spring Harbor, N. Y.: Cold Spring Harbor Laboratory Press; 1989.

(33) Jamieson S, Barraclough BR, Rudland PS. Generation of metastatic variants by transfection of a nonmetastatic rat mammary epithelial cell line with DNA from a metastatic rat mammary cell line. Pathobiology 1990;58: 329-42.

(34) Rudland PS, Dunnington DJ, Gusterson B, Monaghan P, Hughes CM. Production of skeletal muscle elements by cell lines derived from neoplastic rat mammary epithelial stem cells. Cancer Res 1984;44: 2089-101.

(35) Anandappa S, Sibson R, Platt-Higgins A, Winstanley J, Rudland P, Barraclough R. Variant estrogen receptor alpha mRNAs in human breast cancer specimens. Int J Cancer 2000;88: 209-16.

(36) Kuang WW, Thompson DA, Hoch RV, Weigel RJ. Differential screening and suppression subtractive hybridization identified genes differentially expressed in an estrogen receptor-positive breast carcinoma cell line. Nucleic Acids Res 1998;26: 1116- 23.

(37) Komiya T, Tanigawa Y, Hirohashi S. Cloning of the gene gob-4, which is expressed in intestinal goblet cells in mice. Biochim Biophys Acta 1999;1444: 434-8.

(38) Jing C, Beesley C, Foster CS, Rudland PS, Fujii H, Ono T, et al. Identification of the messenger RNA for human cutaneous fatty acid-binding protein as a metastasis inducer. Cancer Res 2000;60: 2390-8. (39) Lloyd B, Platt-Higgins A, Rudland P, Barraclough R. Human S 100A4 (p9Ka) induces the metastatic phenotype upon benign tumour cells. Oncogene 1998; 17: 465-73.

(40) Rudland P, Paterson F, Monaghan P, Twiston-Davies A, Warburton M. Isolation and properties of rat cell lines morphologically intermediate between cultured mammary epithelial and myoepithelial-like cells. Develop Biol 1986;113: 388-405.

(41) Kohler and Milstein (1975, Nature 256, 495-497

(42) Kosbor et al., 1983, Immunology today 4, 72

(43) Cole et al., 1985, Monoclonal Antibodies and Cancer Therapy.

(44) Morrison et al., 1984, Proc. Natl. Acad. Sci., 81, 6851-6855

(45) Neuberger et al., 1984, Nature, 312, 604-608

(46) Ward et al., 1989, Nature 334, 544-546

(47) Huse et al., 1989, Science, 246, 1275-1281

(48) Burnette W.N. (1981) "Western blotting" Anal. Biochem. 112, 195-203

(49) Voller, A. 'The Enzyme Linked Immunosorbent Assay', 1978, Diagnostic Horizons 2, 1-7

(50) Yalow, RS (1978) Radiommunoassay Science 200:1236-1240

(51) Creighton, 1983, "Proteins'. Structures and Molecular Principles", W.H. Freeman & Co., N.Y. , pp. 34-49

(52) PCT Protocols: A Guide to Methods and Applications, 1990, Innis, M. et al., eds. Academic Press, Inc, New York

(53) Chien et al, 1991, Proc. Natl. Acad. Sci. USA, 88:9578-9582

(54) Sambrook J et al., 1989. Molecular Cloning: A laboratory Manual. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY USA (55) Rudland PS, Platt-Higgins A, EI-Tanani M, De Silva Rudland S, Barraclough R, Winstanley JHR, Howirt R and West CR (2002) Prognostic significance of the metastasis-associated protein osteopontin in human breast cancer. Cancer Res. 62, 3417- 3427.

(56) Alman DG. Practical Statistics for Medical Research. Chapman and Hall, London, P258-359. (1991).

Claims

1. A prognostic indicator for metastatic cancer comprising a compound which selectively conjugates or interacts with AGR2 and/or AGR2 mRNA.

2. A prognostic indicator as claimed in claim 1 for any one or more cancer selected from the group comprising colon cancer, prostate cancer, lung cancer, melanoma, gliomas and breast cancers.

3. A prognostic indicator as claimed in claim 1 or 2 wherein the compound conjugates or interacts chemically, structurally or functionally with AGR2 and/or AGR2 mRNA.

4. A prognostic indicator as claimed in claim 3 wherein the compound comprises an antibody.

5. A prognostic indicator as claimed in claim 4 wherein the antibody is capable of specifically recognising AGR2 epitopes or epitopes of conserved variants of the AGR2 nucleotide sequence (SEQ ID No. 1) or immunologically effective peptide fragments of AGR2.

6. A prognostic indicator as claimed in claim 5 comprising any one or more selected from the group comprising polyclonal antibodies, monoclonal antibodies (mAbs), humanised or chimeric antibodies, single chain antibodies, Fab fragments, F(ab')2 fragments, fragments produced by a Fab expression library, anti-idiotypic (anti - Id) antibodies and epitope-binding fragments.

7. A prognostic indicator as claimed in any one of the preceding claims further comprising any one or more adjuvant selected from the group comprising Freund's complete, Freund's incomplete, mineral gels, surface active substances, pluronic polyols, polyanions, peptides, oil emulsions, keyhole limpet hemocyanin, dinitrophenol and Bacilli Calmette-Guerin.

8. A prognostic indicator as claimed in any one of claims 5 to 7 wherein the immunologically effective fragment of AGR2 comprises about 20 consecutive amino acids of SEQ ID NO. 2.

9. A prognostic indicator as claimed in claim 8 wherein the fragment comprises less than 16 consecutive amino acids of SEQ ID NO. 2.

10. A prognostic indicator as claimed in claim 9 wherein the fragment comprises 8-15 consecutive amino acids of SEQ ID NO. 2.

11. A prognostic indicator as claimed in claim 10 wherein the fragment comprises SEQ ID NO 3 or 4.

12. A prognostic indicator as claimed in claim 10 wherein the immunologically effective fragment has at least 70% homology with SEQ ID NO. 2.

13. A prognostic indicator as claimed in claim 11 wherein the immunologically effective fragments has at least 70% homology with SEQ ID NO 3 or SEQ ID NO. 4.

14. A method of diagnosis for metastatic cancer comprising the steps of: obtaining a patient sample; contacting the patient sample with a compound which selectively conjugates or interacts with AGR2 and/or AGR2 mRNA; and detecting any conjugation or interaction.

15. A method as claimed in claim 14 comprising the use of a compound as claimed in any one of claims 1 to 13.

16. A method as claimed in claim 14 or 15 wherein the patient sample comprises blood, urine, plasma, tears, milk, sweat, tissue extract, freshly harvested cells and/or lysates of such cells.

17. A method as claimed in claim 14, 15 or 16 wherein the the compound is detectably labeled.

18. A method as claimed in claim 17 wherein the compound is detectably labeled with any one or more selected from the group comprising malate dehydorgenase, staphylococcal nuclease, delta-5 -steroid isomerase, horseradish peroxidase, alkaline phosphatase, ribonuclease and acetylcholinesterase.

19. A diagnostic kit comprising at least one specific antibody directed against AGR2 and/or AGR2mRNA and/or an immunologically effective fragment thereof and/or a variant thereof.

20. A kit as claimed in claim 19 comprising a solid phase support.

21. A kit as claimed in claim 20 wherein the support comprises nitrocellulose, glass, polystyrene, polypropylene, polyethylene, dextran, nylon, amylases, natural and modified celluloses, polyacrylamides, gabbros and/or magnetite.

22. A method of screening for a compound useful in the treatment of metastatic cancer comprising the steps of: cotacting a test compound with AGR2, AGR2 mRNA or a fragment thereof; detecting whether the test compound has conjugated or interacted with AGR2, AGR2 mRNA or the fragment thereof.

23. A compound for the treatment of metastatic cancer identified by the method of claim 22.

24. A method to identify an intracellular protein which conjugates or interacts with AGR2 for use in the development of a compound for use in treating metastatic cancer comprising:

Contacting a sample comprising at least one intracellular protein with labeled AGR2; and

Detecting whether said labeled AGR2 has conjugated or interacted with said at least one intracellular protein.

25. A cDNA library of the A cell line comprising proteins which conjugate to or interact with AGR2, AGR2 mRNA or immunologically effective fragments thereof.

26. A cDNA library of the cell line claims in claim 24.

27. An expression vector comprising at least one cDNA fragment obtained from a cDNA library as claimed in claim 26 translationally fused to the transcriptional activation domain of GAL4.

28. A method to identify an intracellular macromolecule which conjugates or interacts with AGR2 for use in the development of a compound for use in treating metastatic cancer comprising:

Contacting a sample comprising at least one intracellular macromolecule with labeled AGR2; and

Detecting whether said labeled AGR2 has conjugated or interacted with said at least one intracellular macromolecule.

29. A therapeutically effective compound identified by the screening method of claim 22 for use in the treatment of metastatic cancer.

30. A compound as claimed in claim 29 comprising one or more physiologically acceptable carriers and/or excipients.

31. A compound as claimed in claim 30 comprising any one or more selected from the group comprising pregelatinised maize starch, polyvinylpyrrolidone, hydroxypropyl methylcellulose, lactose, microcrystalline cellulose, calcium hydrogen phosphate, magnesium stearate, talc, silica, potato starch, sodium starch glycolate and sodium lauryl sulphate.

32. A method for identifying a receptor for AGR2 comprising: Contacting labelled AGR2 or a variant thereof with a cell; Removing unbound labelled AGR2 or a variant thereof; and Detecting bound labelled AGR2 or variant thereof.

33. A method as claimed in claim 32 wherein AGR2 or the variant thereof is labeled with radioactive ' "^ iodine.

34. An isolated nucleic acid molecule for inducing metastatic cancer, comprising a nucleotide sequence that: a) encodes a polypeptide comprising the amino acid sequence shown in SEQ ID NO 2; b) encodes a protein comprising the amino acid sequence encoded by the cDNA as shown in SEQ ID NO 1 ; or c) hybridizes to the complement of a) or b).

35. A method for inducing metastatic cancer in a subject comprising contacting a subject with AGR2, nucleic acid as described above and/or a polypeptide having the amino acid sequence as shown in SEQ ID NO 2.

36. A vaccine against metastatic cancer comprising an immunologically effective fragment derived from AGR2.

37. An expression vector for inducing metastatic cancer comprising a nucleic acid molecule comprising a nucleotide sequence that: a) encodes a polypeptide comprising the amino acid sequence shown in SEQ ID NO 2; b) encodes a protein comprising the amino acid sequence encoded by the cDNA as shown in SEQ ID NO 1 ; or c) hybridizes to the complement of a) or b).

38. A compound for inducing metastatic cancer comprising a polypeptide comprising the amino acid sequence shown in SEQ ID NO 2 or an isolated nucleic acid molecule comprising a nucleotide sequence that: a) encodes a polypeptide comprising the amino acid sequence shown in SEQ ID NO 2; b) encodes a protein comprising the amino acid sequence encoded by the cDNA as shown in SEQ ID NO 1 ; or c) hybridizes to the complement of a) or b).

39. A method of treating metastatic cancer comprising administering a compound that modulates the expression of AGR2 gene.

40. A method as claimed in claim 39 comprising administering a compound as claimed in claim 29 and/or an anti-sense, iRNA and/or ribozyme molecule that blocks translation of AGR2 mRNA.