EP1859049A2 - Marqueurs de mélanome - Google Patents
Marqueurs de mélanomeInfo
- Publication number
- EP1859049A2 EP1859049A2 EP06709980A EP06709980A EP1859049A2 EP 1859049 A2 EP1859049 A2 EP 1859049A2 EP 06709980 A EP06709980 A EP 06709980A EP 06709980 A EP06709980 A EP 06709980A EP 1859049 A2 EP1859049 A2 EP 1859049A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- melanoma
- expression
- seq
- tspyl
- gene
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
- C12Q1/68—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving nucleic acids
- C12Q1/6876—Nucleic acid products used in the analysis of nucleic acids, e.g. primers or probes
- C12Q1/6883—Nucleic acid products used in the analysis of nucleic acids, e.g. primers or probes for diseases caused by alterations of genetic material
- C12Q1/6886—Nucleic acid products used in the analysis of nucleic acids, e.g. primers or probes for diseases caused by alterations of genetic material for cancer
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q2600/00—Oligonucleotides characterized by their use
- C12Q2600/112—Disease subtyping, staging or classification
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q2600/00—Oligonucleotides characterized by their use
- C12Q2600/136—Screening for pharmacological compounds
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q2600/00—Oligonucleotides characterized by their use
- C12Q2600/154—Methylation markers
Definitions
- the present invention relates to methods and products useful for diagnosing melanoma and is based around the unexpected finding of new markers associated with melanoma and its progression.
- cutaneous melanoma The incidence of cutaneous melanoma is at epidemic proportions, with rates steadily rising in Western countries over the past few decades (1, 2) . However, effective treatment for patients with advanced melanoma is currently- unavailable. Moreover, the prognosis of such patients is poor, with a 10% survival rate after 5 years. Less than a decade ago, cutaneous melanoma was described as a "black tumor” and a "black box" (3) . While considerable insights have recently been made with respect to mapping out central events in melanoma development, the molecular basis of tumor progression in this disease remains ill-defined. One approach towards understanding melanoma is to compare gene expression patterns between melanocytic cells from different stages of tumor progression.
- DNA microarray-based gene expression profiling has had a far- reaching impact on the study of numerous tumor types (4) , including melanoma (5) .
- melanoma new subgroups of melanoma have been identified (6) , along with a wealth of marker genes that correlate with melanoma progression and drug response (7-13) .
- Cutaneous melanoma is a pigmented, readily accessible lesion that has been well-defined in histopathological terms (3) .
- Early radial growth phase (RGP) melanomas can invade into the epidermis and papillary dermis, but have no capacity for metastasis; resection at this stage is almost completely curative.
- RGP radial growth phase
- VGP vertical growth phase
- the present invention relates to methods and products useful for diagnosing melanoma and is based around the unexpected finding of new markers associated with melanoma and its progression.
- a method of diagnosing melanoma in a subject comprising, in a test sample, determining expression levels of at least one gene selected from TSPYl, CYBA, MT2A, GPNMB, BST2, GIP3, ACTG2, TACl, IFITl, TNFAIP6, MXl, S100A9, COL8A1, HLA-DQAl, CIS, LGALS3, GPM6B, AZGPl, CCL2 , RGS3, UGT2B7, ClR, ISGF3G, ANKSl, CHNl, CALDl, BRD2 , RPL37A, RPLPO, PHB, PBX2, SNRK, DAP, HOXD4 , AEBPl, ENO2 , MGP, PRKl, MSX2/HOX8, SIAT7B, NPTX2 , RARB, AFlQ, IGFBP4 , PTPRN2 ,
- the method is most preferably an in vitro method carried out on an isolated sample.
- the method may also include the step of obtaining the sample.
- the method may preferably be utilised to determine if a potential melanoma is in early radial growth phase (RGP) or a subsequent vertical growth phase (VGP) .
- RGP early radial growth phase
- VGP vertical growth phase
- the methods of the invention are capable of determining the aggressiveness of a melanoma, in particular whether VGP has been reached which may lead to different treatment regimes being selected.
- the expression of these genes is linked to the incidence of melanoma and is down- or up- regulated respectively as melanoma progresses to more aggressive forms, which are eventually capable of metastasis.
- the method may be utilised in order to monitor progression of a melanoma to ensure it does not progress to a potentially metastatic lesion and to allow suitable treatment if melanoma is suspected.
- the test sample is most preferably a tissue sample, taken from the subject, which is suspected of being tumorigenic.
- the sample comprises melanocytes suspected of being a melanoma.
- any other suitable test sample in which expression of the novel markers of the present invention can be measured to indicate the presence of a melanoma in particular a melanoma in VGP are included within the scope of the invention.
- Test samples for diagnostic, prognostic, or personalized medicine uses can be obtained from surgical samples, such as biopsies or fine needle aspirates, from paraffin embedded tissues, or from a body fluid.
- the increased or decreased level of expression must be statistically significant in order to provide a reliable test for monitoring melanoma. Any method for determining whether the expression level of the gene is significantly increased or decreased may be utilised. Such methods are well known in the art and routinely employed. For example, statistical analyses may be performed-using an analysis of variance test. A typical P value for use in such a method would be P values of ⁇ 0.05 when ' determining whether the relative expression is statistically significant. A change in expression may be deemed significant if there is at least a 10% increase or decrease for example. The test may be made more selective by making the change at least 15%, 20%, 25%, 30%, 35%, 40% or 50%, for example, in order to be considered statistically significant.
- the increased or decreased level of expression is determined with reference to a control sample.
- This control sample is preferably taken from normal (i.e. non malignant) melanocytes in the subject.
- control sample is taken from the same tissue as that under test at an earlier time point. This is particularly relevant for monitoring progression of a melanoma, for example in order to ensure that treatment has been effective to prevent progression to an aggressive form of the melanoma. Thus, the progression, or effective prevention of progression, of a potential melanoma for example from radial to vertical growth phase can be monitored .
- Suitable additional controls may also be included to ensure that the test is working properly, such as measuring expression of a suitable reference gene in both test and control samples.
- the subject is a human subject.
- the subject will be a patient wherein a potential melanoma has been identified and the method may be . used to determine if indeed there is a potentially dangerous lesion and also to guide treatment depending upon the stage of progression of the melanoma.
- the method may be carried out by determining expression of at least one of the genes listed, all of which represent novel melanoma markers. In one embodiment, expression levels of all of the genes is measured. This may be done utilising microarray technology for example (as described in more detail in the experimental section below) , which provides ⁇ a convenient method of analysing expression of multiple genes at the same time and from a single test sample. Microarray technology is well known in the art and commercial entities will prepare and supply suitable arrays as. required.
- expression of any number of the genes representing novel melanoma markers may be assessed, for example 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 etc up to all of the genes may be assessed in the method of the invention. Preferably, all genes are assessed in the same test sample to prevent inter-sample viability.
- the method according to the present invention is carried out wherein the expression of at least TSPYl is determined.
- TSPYl is massively down-regulated in melanoma (over 300 fold) and so it is believed that this marker is particularly useful in the diagnosis, prognosis and for monitoring the progression, of melanoma.
- the expression of at least CYBA and/or MT2A (MTlE) is determined. Bisulphite sequencing has revealed that the promoter regions of these genes become hypermethylated in more aggressive melanoma cell lines. Thus, changes in expression associated with methylation reflect the progression of melanoma to more aggressive forms .
- Expression of a gene can be assessed using any means known in the art. Either mRNA or protein can be measured. Methods employing hybridization to nucleic acid probes can be employed for measuring specific mRNAs . Such methods include using nucleic acid probe arrays (microarray technology) and using Northern blots. Messenger RNA can also ' be assessed using amplification techniques, such as RT- PCR. Advances in genomic technologies now permit the simultaneous analysis of thousands of genes, although many are based on the same concept of specific probe-target hybridization. Sequencing-based methods are an alternative; these methods started with the use of expressed sequence tags (ESTs) , and now include methods based on short tags, such as serial analysis of gene expression (SAGE) and massively parallel signature sequencing (MPSS) .
- ESTs expressed sequence tags
- MPSS massively parallel signature sequencing
- Differential display techniques provide yet another means of analyzing gene expression; this family of techniques is based on random amplification of cDNA fragments generated by restriction digestion, and bands that differ between two tissues identify cDNAs of interest.
- Specific proteins can be assessed using any convenient method including immunoassays and immuno-cytochemistry but are not limited to that. Most such methods will employ antibodies which are specific for the particular protein or protein fragments.
- the levels of gene expression are determined using RT-PCR.
- Reverse transcriptase polymerase chain reaction is a well known technique in the art which relies upon the enzyme reverse transcriptase to reverse transcribe mRNA to form cDNA, which can then be amplified in a standard PCR reaction. Protocols and kits for carrying out RT-PCR are extremely well known to those of skill in the art and are commercially available.
- the RT-PCR is carried out in real time and in a quantitative manner.
- Real time quantitative RT-PCR has been thoroughly described in the literature (see Gibson et al for an early example of the technique) and a variety of techniques are possible. Examples include use of Taqman, Molecular Beacons, LightCycler (Roche), Scorpion and Amplifluour systems. All of these systems are commercially available and well characterised, and may allow multiplexing (that is, the determination of expression of multiple genes in a single sample) which is particularly advantageous in the method of the present invention.
- Taqman ® probes are widely commercially available, and the Taqman ® system (Applied Biosystems) is well known in the art.
- Taqman ® probes anneal between the upstream and downstream primer in a PCR reaction. They contain a 5 ' -fluorophore and a 3 '-quencher. During amplification the 5 '-3' exonuclease activity of the Taq polymerase cleaves the fluorophore off the probe. Since the fluorophore is no longer in close proximity to the quencher, the fluorophore will be allowed to fluoresce. The resulting fluorescence may be measured, and is in direct proportion to the amount of target sequence that is being amplified.
- the beacons are hairpin-shaped probes with an internally quenched fluorophore whose fluorescence is restored when bound to its target.
- the loop portion acts as the probe while the stem is formed by complimentary "arm" sequences at the ends of the beacon.
- a fluorophore and quenching moiety are attached at opposite ends, the stem keeping each of the moieties in close proximity, causing the fluorophore to be quenched by energy transfer.
- the beacon detects its target, it undergoes a conformational change forcing the stem apart, thus separating the fluorophore and quencher. This causes the energy transfer to be disrupted to restore fluorescence.
- Fluorophores that may possibly be used in the method of the invention include, by way of example, FAM, HEXTM, NEDTM, ROXTM, Texas RedTM etc.
- Quenchers for example Dabcyl and TAMRA are well known quencher molecules that may be used in the method of the invention.
- EDANS and DABCYL form a particularly efficient fluorophore/quencher pair (62) , as do fluorescein/DABCYL (67) .
- a further real-time fluorescence based system which may be incorporated in the methods of the invention is Zeneca's Scorpion system, see Detection of PCR products using self- probing amplicons and fluorescence by Whitcor ⁇ be et al. Nature Biotechnology 17, 804 - 807 (01 Aug 1999) (37). This reference is incorporated into the application in its entirety.
- the method is based on a primer with a tail attached to its 5 ' end by a linker that prevents copying of - li ⁇
- the probe element is designed so that it hybridizes to its target only when the target site has been incorporated into the same molecule by extension of the tailed primer. This method produces a rapid and reliable signal, because probe-target binding is kinetically favoured over intrastrand secondary structures .
- Amplifluour primers (as described in US Patent 5,866,336 to Nazarenko and WO98/02449 both of which are incorporated herein by reference) rely upon a similar principle to molecular beacons.
- the hairpin structure is- part of the amplification primer itself.
- the primer binds to a nucleic acid strand and directs synthesis and thus becomes part of the amplification product.
- the complementary strand is synthesised amplification occurs through the hairpin structure. This separates the fluorophore and quencher molecules, thus leading to generation of fluorescence as amplification proceeds.
- the method of the invention utilises at least one primer pair taken from primer pairs comprising the sequences of :
- GPNMB - forward 5'-TGCATAAAGCCAATGTAGTCCA-S' (SEQ ID NO:
- PRKl - forward 5'-GGGCTGTTTCTTCACATCTTC-SMSEQ ID NO: 11
- reverse ⁇ '-GTGGACTGGTGGGGACTG-S' (SEQ ID NO: 12) (231 bp amplicon) ;
- the genes listed are selected examples of the genes de-scribed which belong to the present invention and which represent novel melanoma markers.
- TSPYl, CYBA, GPNMB and MXl are all significantly down regulated in melanoma, whereas the expression of all of H0XD4, PRKl and RARB is up regulated in melanoma.
- the primers may, in one embodiment, be Amplifluour primers.
- PCR is a preferred amplification method
- equivalents may. also be included within the scope of the invention.
- examples include isothermal amplification techniques such as NASBA, 3SR, TMA and triamplification, all of which are well known in the art and commercially available (and are described in more detail below) .
- Other suitable amplification methods include the ligase chain reaction (LCR) (Barringer et al, 1990) , selective amplification of target polynucleotide sequences ⁇ US Patent No. 6,410,276), consensus sequence primed polymerase chain reaction (US Patent No 4,437,975), arbitrarily primed polymerase chain reaction (WO90/06995) , nick displacement amplification (WO2004/067726) .
- LCR ligase chain reaction
- WO90/06995 consensus sequence primed polymerase chain reaction
- nick displacement amplification WO2004/067726
- the method of the invention incorporates use of microarrays in order to detect expression of the genes which represent novel melanoma markers. Suitable microarrays are described in further detail below.
- the method of the invention is used to determine whether the melanoma is likely to have metastatic capabilities.
- the novel marker genes are significantly down- or up- regulated in more aggressive forms of melanoma which may be capable of metastasis. Therefore, significantly decreased or increased levels of expression, respectively, may be indicative of a form of melanoma capable of metastasis (which may correspond to vertical growth phase) .
- the reduced expression of a selection of the novel markers of the invention can be reverted to wild type levels of expression by treatment with a suitable DNA methyltransferase inhibitor. It has also been discovered that reduced expression of a selection of markers already known to be associated with melanoma can similarly be reverted to wild type levels of expression by treatment with a suitable DNA methyltransferase inhibitor. Thus, methylation is likely to be responsible, at least indirectly, for the reduced expression of these genes seen in melanoma. For a selection of these genes, methylation appears to directly regulate their expression. CpG islands in these genes have been identified using CpGPlot (see below, including Fig 10 and the Experimental section) . Therefore, detection of the methylation status of these genes, which represent novel methylation sensitive markers for melanoma proves a useful test for diagnosis, including prognosis, of melanoma.
- the invention provides a method of diagnosing melanoma in a subject comprising, in a test sample, determining the methylation status of at least one gene selected from TSPYl, CYBA, MXl, MT2A, RPL37A, HSPBl wherein hypermethylation of at least one of the genes indicates the presence of melanoma.
- the method is one which allows melanoma progression to be monitored, in parituclar to determine whether the melanoma is likely to have metastatic capabilities.
- the method is most preferably an in vitro method carried out on an isolated sample.
- the method may also include the step of obtaining the sample.
- test sample is most preferably a tissue sample taken from the subject which is suspected of being a tumor.
- sample comprises melanocytes suspected of being a melanoma.
- any other suitable test sample in which methylation status of the genes, which represent the novel markers of the present invention and markers with a known link to melanoma but without any knowledge of importance of methylation for melanoma progression, can be determined to indicate the presence of a melanoma are included within the scope of the invention.
- Hypermethylation is a well known term in the art which denotes increased and aberrant methylation at specific CpG sites in a gene. Hypermethylation most often occurs in the promoter regions of genes and acts to depress expression of the gene. Accordingly, in a preferred embodiment, the method is carried out wherein the promoter regions of the relevant genes are assessed to determine their methylation status .
- the CpG islands identified for the appropriate genes are investigated for their methylation status. These CpG islands are represented in SEQ ID NOs: 15 and 29 (TSPYl CpG islands), 30 and 31 (CYBA CpG islands) , 32 and 33 (RPL37A CpG islands) , 38 (MXl CpG islands) , 39 (HSPBl CpG islands) and 40 (MT2a CpG islands) .
- any number of the genes which represent novel methylation related melanoma markers can be assessed in order to provide a diagnosis.
- 1, 2, 3, 4, 5 or 6 of the genes may be assessed in terms of their methylation status in the method of this aspect of the invention.
- the methylation status of at least TSPYl is determined.
- the methylation status of at least CYBA and/or MT2A (MTlE) is determined.
- the methylation status of the genes is determined using methylation specific PCR (MSP) .
- MSP methylation specific PCR
- any technique may be utilised to determine the methylation status of the genes, such as, for example, the well known techniques of COBRA (for more details reference is made to the experimental section below) , bisulphite sequencing and use of arrays which can distinguish between bisulphite treated nucleic acid molecules following amplification. A review of some useful techniques is provided in Nucleic acids research, 1998, Vol. 26, No. 10, 2255-2264, which reference is incorporated herein in its entirety.
- DNA methylation analysis has been performed successfully with a number of techniques which include the MALDI-TOFF, MassARRAY , MethyLight, Quantitative analysis of ethylated alleles (QAMA) , enzymatic regional methylation assay (ERMA), HeavyMethyl , QBSUPT, MS-SNuPE,
- MethylQuant, Quantitative PCR sequencing, Oligonucleotide- based microarray systems Still another way for the identification of methylated CpG dinucleotides utilizes the ability of the MBD domain of the McCP2 protein to selectively bind to methylated DNA sequences (Cross et al, 1994; Shiraishi et al , 1999). Restriction enconuclease digested genomic DNA is loaded onto expressed His-tagged methyl-CpG binding domain that is immobilized to a solid matrix and used for preparative column chromatography to isolate highly methylated DNA sequences.
- DNA may be amplified using primer pairs designed to distinguish methylated from unmethylated DNA by taking advantage of sequence differences as a result of sodium-bisulfite treatment (Herman et al (65) and see WO 97j ' 46705 , incorporated herein by reference) . After sodium- bisulfite treatment unmethylated cytosines are converted to uracil whereas methylated cytosines remain unconverted.
- QMSP real- time quantitative MSP
- These methods are generally based on the continuous optical monitoring of a fluorogenic PCR and represent a specific application of the well, known and commercially -available real-time PCR techniques such as Taqman ® , Molecular
- nucleic acid amplification techniques may also be modified to detect the methylation status of at least one of the panel of genes which represent novel melanoma markers .
- amplification techniques are well known in the art, and include methods such as NASBA (Compton, 1991 (45)), 3SR (Fahy et al . , 1991 (46)) and Transcription Mediated Amplification (TMA) .
- NASBA Computer, 1991 (45)
- 3SR Frahy et al . , 1991 (46)
- TMA Transcription Mediated Amplification
- Other suitable amplification methods include the ligase chain reaction (LCR) (Barringer et al, 1990) , selective amplification of target polynucleotide sequences (US Patent No.
- Sequence variation that reflects the methylation status at CpG dinucleotides in the original genomic DNA offers two approaches to PCR primer design.
- Exemplary of such other residues may be sites for restriction endonuclease cleavage, for ligand binding or for factor binding or linkers or repeats.
- the oligonucleotide primers may or may not be such that they are specific for modified methylated residues.
- One way to distinguish between modified and unmodified DNA is to hybridize oligonucleotide primers which specifically bind to one form or the other of the DNA. After hybridization, an amplification reaction can be performed and amplification products assayed. The presence of an amplification product indicates that a sample hybridized to the primer. The specificity of the primer indicates whether the DNA had been modified or not, which in turn indicates whether the DNA had been methylated or not .
- oligonucleotide probes which may also be specific for certain products. Such probes can be hybridized directly to modified DNA or to amplification products of modified DNA. Oligonucleotide probes can be labeled using any detection system known in the art . These include but are not limited to fluorescent moieties, radioisotope labeled moieties, bioluminescent moieties, luminescent moieties, chemiluminescent moieties, enzymes, substrates, receptors, or ligands.
- Amplification is achieved with the use of primers specific for the sequence of the gene whose methylation status is to be assessed.
- primer binding sites corresponding to a suitable region of the sequence may be selected.
- the nucleic acid molecules may also include sequences other than primer binding sites which are required for detection of the methylation status of the gene, for example RNA Polymerase binding sites or promoter sequences may be required for isothermal amplification technologies, such as NASBA, 3SR and TMA.
- TMA (Gen-probe Inc.) is an RNA transcription amplification system using two enzymes to drive the reaction, namely RNA polymerase and reverse transcriptase.
- the TMA reaction is isothermal and can amplify either DNA or RNA to produce RNA amplified end products.
- TMA may be combined with Gen-probe's Hybridization Protection Assay (HPA) detection technique to allow detection of products in a single tube. Such single tube detection is a preferred method for carrying out the invention.
- HPA Hybridization Protection Assay
- the method of this aspect of the invention is carried out using a technique selected from NASBA, 3SR and TMA.
- the methods described above can be used in conjunction with one another to confirm a diagnosis of melanoma including an assessment of how aggressive the melanoma is, and also in prognostic applications, since they provide complementary information about the subject.
- HDAC Histone deacetylase inhibitors
- a method of treating melanoma in a subject comprising administering a therapeutically effective amount of a DNA methyltransferase inhibitor and/or a histone deacetylase inhibitor to the subject such that expression of at least one gene selected from TSPYl, CYBA, MT2A, BST2 , GIP3, SlOOAl, IFITl, MXl, RGS3, ISGP3G, APOD, RPL37A, HSPBl is increased.
- the subject is a human.
- the subject will be one who has been diagnosed with melanoma; for example using the methods according to the present invention.
- the method is preferably one carried out to prevent the melanoma from reaching a stage in which it is capable of mestastis.
- the method may, for example, be used to treat a melanoma which is already in the vertical growth phase (VGP) .
- VGP vertical growth phase
- the effect of the treatment is to increase the level of gene expression to the levels of gene expression found in normal melanocytes.
- any increase in expression will be beneficial for treatment of melanoma.
- the DNA methyltransferase inhibitor or histone deacetylase inhibitor is provided in a therapeutically relevant amount to ensure that a controlled increase in gene expression is achieved.
- the therapeutic agent is a DNA methyltransferase inhibitor.
- the agent may be one which reduces expression of DNMT genes, such as suitable antisense molecules, RNAi molecules or siRNA molecules for example.
- the antisense molecule comprises MG98. Clinical trials by MethylGene have been carried out to study this antisense reagent that specifically inhibits DNMTl (Reid et al (2002) Selective inhibition of DNA methyltransferase enzymes as a novel strategy for cancer treatment, Curr. Opin. MoI. Ther. 4, 130-137, and see www.methylgene.com for details of phase II clinical trials in metastatic renal cancer patients) .
- the agent may be a direct inhibitor of DNMTs.
- modified nucleotides such as phosphorothioate modified oligonucleotides (fig 6 of ref (68)) and nucleosides and nucleotides such as cytidine analogues.
- cytidine analogues include 5-azacytidine, 5-aza-2 ' -deoxycytidine, 5-fluouro-2 ' - deoxycytidine, pseudoisocytidine, 5, 6-dihydro-5-azacytidine, l- ⁇ -D-arabinofuranosyl-5-azacytosine (known as cambarine) (see figure 4 of ref (68)) .
- the DNA methyltransferase inhibitor comprises Decitabine. Full details of this drug can be found at www.supergen.com for example.
- Additional DNMT inhibitors include S-Adenosyl-Methionine
- SAM S-adenosyl- homocysteine
- SAH S-adenosyl- homocysteine
- S sinefungin
- S -6-methyl-6-deaminosine fungin
- 6-deaminosinefungin N4-adenosyl -N4 -methyl-2
- 4- diaminobutanoic acid 5 ' -methylthio-5 ' -deoxyadenosine (MTA) and 5 ' -amino-5 ' -deoxyadenosine .
- agents which may alter DNA methylation and which may, therefore, be useful in the present methods and uses include organohalogenated compounds such as chloroform etc, procianamide, intercalating agents such as mitomycin C, 4- aminobiphenyl etc, inorganic salts of arsenic and selenium and antibiotics such as kanamycin, hygromycin and cefotaxim.
- organohalogenated compounds such as chloroform etc, procianamide
- intercalating agents such as mitomycin C, 4- aminobiphenyl etc
- inorganic salts of arsenic and selenium such as kanamycin, hygromycin and cefotaxim.
- any suitable DNA methyltransferase inhibitor which is capable of increasing the expression of at least one of the genes listed above, and thus can contribute to the treatment of melanoma, is included within the scope of the invention.
- the therapeutic agent is additionally or alternatively a histone deacetylase (HDAC) inhibitor.
- HDAC histone deacetylase
- Preferred non-limiting examples include, trichostatin A (TSA), suberoyl hydroxamic acid (SBHA), 6- (3- chlorophenylureido) caproic hydroxamic acid (3-Cl-UCHA), m- carboxycinnamic acid bishydroxylamide (CBHA) , suberoylanilide hydroxamic acid (SAHA) , azelaic bishydroxamic acid (ABHA) , pyroxamide, scriptaid, aromatic sulfonamides bearing a hydroxamic acid group, oxamflatin, trapoxin, cyclic-hydroxamic-acid containing peptides, FR901228, MS-275, MGCD0103 (see www.methylgene.com), short- chain fatty acids and N-acetyldinaline .
- TSA trichostatin A
- SBHA suberoyl hydroxamic acid
- 6- 6- (3- chlorophenylurei
- Combination therapy using both a DNMT inhibitor and a HDAC inhibitor may give cumulative effects greater than either agent utilised in isolation.
- complementary dosage regimes or combination compositions are envisaged in the present invention.
- the therapeutic agent may, for example, be encapsulated and/or combined with suitable carriers in solid dosage forms for oral administration which would be well known to those of skill in the art or alternatively with suitable carriers for administration in an aerosol spray.
- suitable carriers for administration in an aerosol spray examples include tablets, capsules and liquids.
- the therapeutic agent may be administered parenterally.
- specific examples include intradermal injection, subcutaneous injection (which may advantageously give slower absorption of the therapeutic agent) , intramuscular injection (which can provide more rapid absorption) , intravenous delivery (meaning the drug does not need to be absorbed into the blood stream from elsewhere) , sublingual delivery (for example by dissolving of a tablet under the tongue or by a sublingual spray) , rectal delivery, vaginal delivery, topical delivery, transdermal delivery and inhalation.
- compositions include pharmaceutically acceptable carriers including, for example, non-toxic salts, sterile water or the like.
- a suitable buffer may also be present allowing the compositions to be lyophilized and stored in sterile conditions prior to reconstitution by the addition of sterile water for subsequent administration.
- the carrier may also contain other pharmaceutically acceptable excipients for modifying other conditions such as pH, osmolarity, viscosity, sterility, lipophilicity, somobility or the like.
- Pharmaceutical compositions which permit sustained or delayed release following administration may also be used.
- the specific dosage regime may be calculated according to the body surface area of the patient or the volume of body space to be occupied, dependent on the particular route of administration to be used.
- the amount of the composition actually administered will, however, be determined by a medical practitioner based on the circumstances pertaining to the disorder to be treated, such as the severity of the symptoms, the age, weight and response of the individual .
- a DNA methyltransferase inhibitor or a histone deacetylase inhibitor in the manufacture of a medicament for the treatment of melanoma by increasing expression of at least one gene -selected from TSPYl, CYBA, MT2A, BST2 , GIP3, SlOOAl, IFITl, MXl, RGS3 , ISGF3G, APOD, RPL37A, HSPBl.
- the use described above gives rise to a medicament which provides a therapeutic effect wherein the level of gene expression is increased to the levels of gene expression found in normal melanocytes. Since the novel markers for melanoma identified in the studies described below are numerous, there is benefit in being able to screen for expression of this panel of genes in a simple and rapid manner.
- the invention provides, in a fifth aspect, a microarray for use in the methods of the invention which involve determining levels of expression of genes, comprising probes immobilised on a solid support hybridizing with transcripts or parts thereof of at least one gene selected from TSPYl, CYBA, MT2A, GPNMB, BST2, GIP3, ACTG2 , TACl, IFITl, TNFAIP6, MXl, S100A9,
- Microarrays and their means of manufacture are well known and can be manufactured to order by commercial entities such as Affymetrix, for example.
- the probes are the sequences which are immobilized onto the array, by known methods, and which represent selected sequences from the genes of interest, in this case the novel markers for melanoma listed above.
- Probe selection and array design lie at the heart of the reliability, sensitivity, specificity, and versatility of the microarrays of the invention. The methods for selecting suitable probes would be readily apparent for one of skill in the art and may involve optimization using data collected from multiple databases, bioinformatics tools, and experiment-trained computer models. The key elements of probe selection and design are common to . the production of all arrays, regardless of their intended application and as such would be well known to one of skill in the art. Strategies to optimize probe hybridization, for example, are invariably included in the process of probe selection. Hybridization under particular pH, salt, and temperature conditions can be optimized by taking into account melting temperatures and using empirical rules that correlate with desired hybridization behaviours.
- the GeneChip arrays produced by Affymetrix involve a Perfect Match/Mismatch probe strategy. For each probe designed to be perfectly complementary to a target sequence, a partner probe is generated that is identical except for a single base mismatch in its centre. These probe pairs, called the “Perfect Match probe (PM)” and the “Mismatch probe (MM)”, allow the quantitation and subtraction of signals caused by non-specific cross-hybridization. The difference in hybridization signals between the partners, as well as their intensity ratios, serve as indicators of specific target abundance. Such an array design may be applicable to, and incorporated into, the arrays of the present invention.
- the microarray preferably comprises at least 10 probes representing each gene on the array. However, other numbers of probes may be utilised provided that the expression of each gene which is selected to form part of the array can be accurately and specifically measured.
- the array includes probes which represent each and every one of the genes listed. However, this may not be necessary in order to be able to accurately diagnose melanoma. Probes representing only one or 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 etc of the genes may be utilised in the array.
- the microarray comprises probes representing transcripts of at least the TSPYl gene.
- the microarray comprises probes representing transcripts of at least the CYBA and/or MT2A (MTlE) genes.
- Each probe is preferably at least about 20 nucleotides in length such that a probe of sufficient length to ensure sensitivity and specificity of hybridization is provided.
- any length of probe may be utilised within the scope of the invention, provided that accurate results are achieved in terms of detecting expression of the genes which represent novel melanoma markers.
- Possible lengths for the probes include at least 10 nucleotides and up to 250 nucleotides and preferably between about 20 and about 50 nucleotides.
- the invention also provides a microarray for use in the methods which involve determining the methylation status of the genes representing novel methylation sensitive melanoma markers comprising probes immobilised on a solid support hybridizing with methylated only or both unmethylated and methylated versions of at least one gene or parts thereof selected from TSPYl, CYBA, MT2A, MXl, RPL37A, HSPBl following bisulphite treatment.
- the probes allow the methylation status of at least TSPYl to be deteremined.
- the probes allow the methylation status of at least CYBA and/or MT2A (MTlE) to be determined.
- the probes correspond to appropriate portions of the CpG islands of the genes, the nucleotide sequences of which are presented in SEQ ID NOs: 15 and 29 (TSPYl CpG islands) , 30 and 31 (CYBA-CpG islands) , 32 and 33 (RPL37A CpG islands) , 38 (MXl CpG islands) , 39 (HSPBl CpG islands) and 40 (MT2a CpG islands) .
- the microarray may contain two sets of probes, one which is specific for genes methylated at particular sites and one specific for genes which are unmethylated at those particular sites.
- each probe will represent only one potential site of methylation to allow full specificity of binding and detection for each methylation site, although this is not essential.
- the microarray may be a "methylation specific" array in that it contains probes designed to solely bind targets which are methylated at the specific CpG sites in the relevant genes and thus are protected from the effects of bisulphite treatment.
- Such an array could be utilised in conjunction with an array which comprises probes • specific only for targets which are unmethylated at specific CpG sites. The same sample may be utilised with each array in order to determine relative levels of methylation.
- the target nucleic acid is hybridised to the array in order to determine whether the genes of interest are methylated at specific sites.
- the positive identification of methylation is indicative of melanoma or a more aggressive form of melanoma (such as VGP melanoma) .
- Either the probes or the target, or both, may be labelled with a suitable label to allow detection of hybridization of the target to its complementary probe.
- a suitable label is a fluorescent label although other labels such as radiolabels and mass-labels may also be utilised.
- tissue sample to be used is as described above and the subject from which the sample containing the test (target) nucleic acid is derived is most preferably a human subject.
- the present invention also identifies and characterises for the first time the specific methylation sites in the promoter region of the genes TSPYl, CYBA, RPL37A, MXl, HSPBl and MT2A. Due to the fact that these genes appear to be hypermethylated leading to down regulation of expression and (more aggressive forms of) melanoma, there is particular diagnostic, including prognostic, value in being able to determine the methylation status of the genes in the respective CpG island regions.
- primers which can bind to the sequence of any one of SEQ ID NOs : 15 and 29 (TSPYl CpG islands), 30 and 31 (CYBA CpG islands), 32 and 33 (RPL37A CpG islands), 38 (MXl CpG islands), 39 (HSPBl CpG islands) and 40 (MT2a CpG islands) , (see figure 8, 9 and 10 also) following bisulphite treatment.
- the primers may be methylation specific primers, which serve to discriminate between whether there is methylation at a particular CpG site.
- one set of primers will be specific for the sequence following bisulphite treatment under circumstances where the cytosine residue was (or were if more than one CpG site is covered by the primers binding site) methylated and therefore unaffected by bisulphite treatment.
- a second set of primers may be specific for the sequence following bisulphite treatment under circumstances where the cytosine residue was (or cytosine residues were if more than one CpG site is covered by the primer binding) unmethylated and therefore would be converted to uracil following bisulphite treatment.
- a third set of primers acts as a control and is specific for the sequence prior to bisulphite treatment.
- the primers may not bind to sites which may be methylated, provided that they amplify a sequence which includes a potential methylation site.
- the products may then be bound to an appropriate array as described above in order to determine the methylation status of the amplified products (the probes are specific for methylated or unmethylated residues and provide the distinguishing function) .
- Primers are well known and their design is routine.
- a typical primer is of length between approximately 5 and 50 nucleotides, preferably between 10 and 30 nucleotides. Primers in use must be single stranded nucleic acid molecules and are generally designed to prevent self annealing.
- primers comprising, or consisting essentially of or consisting of the sequence of SEQ ID NO: 16- and 17 are provided. These primers are useful for COBRA analysis of the TSPYl CpG island in conjunction with use of a suitable restriction enzyme such as BsiEI (see experimental section below, particularly figure 4) .
- the expression pattern linked to melanoma and in particular progression of melanoma to more aggressive (metastatic) forms may be used as a research tool to identify new pharmaceuticals which may be used to treat, prevent or control melanoma.
- the invention provides an in vitro method of identifying a compound capable of treating or reducing the effects or progression of melanoma comprising the steps of; (a) administering the compound to a melanoma sample;
- the invention also provides a similar compound screening and lead identification method which involves use of non-human animals; a method of identifying a compound capable of treating or reducing the effects or progression of melanoma comprising the steps of;
- the experimental animal may be sacrificed following the testing.
- these methods allow leads to be identified which either are effective in preventing melanoma from reaching a metastatis form and/or which are capable of regressing a melanoma from an aggressive phase, such as VGP, to- a less dangerous form of melanoma.
- control sample is taken from an experimental non-human animal which does not have a melanoma.
- control sample is taken from normal melanocytes in the same non-human animal .
- Preferred gene panels include at least TSPYl and/or CYBA and/or MT2A (MTIE) .
- the invention also provides the compounds identified by the methods described above. These compounds may be formulated into suitable pharmaceutical compositions, including suitable carriers, for administration to a patient in need thereof. Details of such compositions are provided above, and it is thought that some of the specific DNMT and HDAC inhibitors may prove to act positively in the screening methods according to this aspect of the invention.
- a method of treating melanoma comprising administering to a subject in need thereof a therapeutically effective amount of a compound which has been identified using the screening methods of the invention.
- Fig. 1 Phenotypic characteristics of melanoma cells in vitro .
- WM793-P1, WM793-P2, and 1205-Lu parental WM793 cells and isogenic derivatives.
- Cells (20 , 000/well) were seeded into 12-well tissue culture plates and left to grow for 7 days. Growth rates were measured using an alamarBlue assay for cell proliferation.
- AU arbitrary units.
- WM793-P1 and WM793-P2 The 66 genes identified as consistently differentially expressed between WM793 cells and the derivative cell lines, WM793-P1 and WM793-P2, are listed above.
- Panel A Duplicate data with respect to gene expression obtained from WM793, WM793-P1 and WM793-P2 cell lines (separate cultures; replicate data listed beside each other) . Pairwise comparison of gene expression between different cell lines yielded the following numbers of altered transcripts: WM793 versus WM793-P1 (129 transcripts) ; WM793 versus WM793-P2 (114 transcripts) ; WM793-P1 versus WM793-P2 (14 transcripts) .
- Panel B Independent dataset showing expression of 66 gene cohort in untreated (WM793 and 1205-Lu) and DAC treated (all four cell lines) cells.
- Gene expression profile information is represented using a color-coded scheme (key provided) in which dark grey refers to genes expressed at a low level (below mean absolute intensity) and white refers to genes expressed at a high level (above mean absolute intensity) .
- the tabular columns refer to the Affymetrix probe set identifier, the corresponding UniGene cluster (Build_ #166) , associated chromosomal location and Human Genome Organisation- approved gene symbol for each transcript. The additional three columns detail the fold change values between WM793 and respective derivative cells.
- Fig. 3 Validation of DNA microarray results by two RT-PCR analysis methods.
- the vertical white and black bars refer to genes that were identified from the prior DNA microarray study as either down-regulated or up-regulated, respectively, in derivative cells as compared to parental WM793 cells.
- RT-PCR analysis via a cycle limitation limitation method, of transcripts previously shown to be down- regulated [CYBA, GPNMB, DCT, TYRPl, TYR, MXl) or up- regulated ⁇ H0XD4, PRKl 1 SIAT7B, RARB) in the derivative cell lines.
- Level of 18 S rRNA served as a loading control .
- Expression measurements were normalized to 18 S rRNA levels.
- the parental WM793 cells were defined as the calibrator to which all three derivative cell lines were compared.
- the three data columns to the right represent the mean normalized relative quantities of target gene expression between WM793 cells and relevant derivative cells across duplicate measurements from independent stocks of exponentially growing cells.
- Gene expression profile information is represented to the right using a color-coded scheme (key provided below) in which white and black refer to down-regulated and up-regulated genes (as compared to WM793 cells) , respectively. Grey indicates no change in expression level .
- E Presence of 191 bp fragment signifies DNA methylation at CpG within BsiEI site.
- D same order of samples as in A.
- E genomic DNA from 20 randomly assigned metastatic melanomas (5 male, 15 female) . Samples in lanes 1, 2, 7, 8 and 13 were derived from male patients, with the remainder being from female patients. Only male- derived samples generated PCR products by COBRA, which is as expected given the chromosomal localization of the TSPYl gene.
- Pig. 5 Effect of DAC treatment on melanoma cells in vitro and in vivo.
- Results are expressed as mean values with standard errors of the mean represented by bars .
- a Student t test was performed for each comparison of untreated and DAC treated cells; *** indicates the difference is highly significant, as indicated by a P value ⁇ 0.001.
- Exons 1 through 6 exemplified by M98524, specifically the sequence of unmodified DNA (bases 834 to 1102) .
- Bolded text indicates the 269 bp sequence within Exon 1 amplified by PCR (following bisulfite modification of DNA) , which was used for COBRA. Italicised text indicates forward and reverse primer regions (see COBRA diagram for exact primers used to amplify bisulfite-modified DNA) . Underlined sections represent the exons.
- -2,000bp prior to the first exon and 1,000 downstream of the first exon was selected.
- Length 369 (1875..2243) [Region where COBRA was performed] Length 397 (2446..2842) Note, the second and third islands are merged in the sequence data due to their proximity to one another.
- Length 311 (1867..2177)
- Length 231 (2212..2442)
- Length 313 (1811..2123) Length 413 (2138..2550)
- melanoma The incidence of melanoma is increasing rapidly, with advanced lesions generally failing to respond to conventional chemotherapy.
- DNA microarray- based gene expression profiling techniques to identify molecular determinants of melanoma progression within a unique panel of isogenic human melanoma cell lines.
- a poorly tumorigenic cell line derived from an early melanoma
- two increasingly aggressive derivative cell lines the expression of 66 genes was significantly changed.
- a similar pattern of differential gene expression was found with an independently derived metastatic cell line.
- a considerable proportion of the differentially expressed genes found have been previously associated with melanoma development and progression, including CDKN2A, IL-24 and MAGEA4.
- TSPYl a Y chromosome-specific gene that displayed extensive down- regulation in expression (between 137 and 317 fold) between the parental and derivative cell lines. Examination of a putative CpG island within the TSPYl gene demonstrated that this region was hypermethylated in the derivative cell lines, as well as metastatic melanomas from male patients.
- DAC 2' -
- Cutaneous melanoma is a pigmented, readily accessible lesion that has been well defined in histopathological terms (3) .
- Early radial growth phase (RGP) melanomas can invade into the epidermis and papillary dermis, but have no capacity for metastasis; resection at this stage is almost completely curative.
- a subsequent vertical growth phase (VGP) denotes a transition to a more aggressive stage, which is capable of metastasis. Changes in gene expression occurring at the RGP/VGP transition are, thus, of great interest.
- the parental cell line in the series, WM793, was originally isolated from a superficial spreading melanoma (14) .
- the patient concerned has had no re-occurrence of the disease to date, suggesting that these cells had low metastatic potential. Accordingly, WM793 cells displayed poor tumorigenicity in nude mice (15) .
- the WM793 . cell line was used as the basis for in vivo selection of several aggressive, tumorigenic sublines (15) .
- the derivative cell lines, WM793-P1 and WM793-P2 were established after inoculation in the presence of Matrigel (a reconstituted basement membrane extract) .
- WM793 and 1205-Lu cells were a gift from Prof. Meenhard Herlyn (Wistar Institute, Philadelphia)
- WM793-P1 and WM793-P2 cells were a gift from Prof. Robert Kerbel (University of Toronto, Canada).
- Cells were maintained in Dulbecco's Modified Eagle's Medium with GlutaMAX (Invitrogen) , supplemented with 10% foetal calf serum, 100 U/mL penicillin, 100 ⁇ g/ml streptomycin and 4 ⁇ g/mL insulin (Sigma-Aldrich) .
- Genomic DNA and total RNA were extracted from monolayer cells in culture and melanoma biopsies using the QIAamp DNA Mini (Qiagen) kit .
- Total RNA was extracted from monolayer cells using the Tri Reagent (Sigma) kit.
- Cell growth rates were determined using an alamarBlue assay (Biosource International) , which recorded cell proliferation each day.
- Flow Cytometric Analysis A total of IxIO 6 cells were used for flow cytometric analysis of DNA content. Exponentially growing cells were isolated by trypsinization, washed with 500 ⁇ L PBS, and fixed with 500 ⁇ L of ice-cold 100% ethanol .
- CGH and FISH Analysis Comparative genomic hybridization (CGH) experiments were carried out as previously described (19) . Briefly, test and reference DNA samples were labeled by nick translation with spectrum green-dUTP and red-dUTP, respectively, under conditions recommended by the supplier (Vysis) . Labeled test (melanoma cells) and reference (normal lymphocyte) DNA (500 ng) were then denatured and hybridized to normal human metaphase , chromosomes in a solution containing 50x Cotl fractionated DNA, 50% formamide, IX SSC, and 10% dextran sulfate (Vysis) . Images were acquired and analyzed using hardware and software from Applied Imaging Inc.
- FISH fluorescence in situ hybridization
- Seeded cells were treated with 2 ⁇ g/mL 2'-deoxy-5- azacytidine (DAC) on Days 1, 3 and 5, with fresh drug- containing medium being added at each timepoint (20) . On Days 2 and 4, drug-containing medium was exchanged for drug-free medium. On Day 6, cells were harvested and total RNA extracted as above. Global DNA Methylation Analysis.
- DAC 2'-deoxy-5- azacytidine
- 5-methylcytosine (5mC) genomic content was determined by high-performance capillary electrophoresis, as previously described (21) . Briefly, genomic DNA samples were boiled, treated with nuclease Pl (Sigma) for 16 hours at 37 0 C, and with alkaline phosphatase (Sigma) for an additional 2 hours at 37 0 C. After hydrolysis, total cytosine and 5mC content were measured by capillary electrophoresis using a P/ACE MDQ system (Beckman-Coulter) . Relative 5mC content was expressed as a percentage of total cytosine content (methylated and non-methylated) .
- RNA Micr ⁇ array Analysis Ten micrograms of total RNA from each cell line was re-verse transcribed into single-stranded cDNA using the Superscript Choice kit (Invitrogen) .. For this purpose, an oligo-dT primer containing a T7 RNA polymerase promoter (Genset) was utilized. Following double-stranded cDNA synthesis, biotin-labelled cRNA was generated by in vitro transcription using the BioArray RNA labelling kit (Enzo) . These complex cRNA targets, which are representative of the transcriptome of a particular sample, were hybridised against HuGeneFL arrays (7,129 probe sets) . Detection was accomplished via a streptavidin-labelled fluorochrome
- RNA extracts were pre-digested with DNase I prior to cDNA synthesis using the DNA-Free kit (Ambion) .
- Single-stranded cDNA was synthesized from 1 ⁇ g total RNA using the ImProm- II Reverse Transcription kit (Promega) .
- Recombinant RNasin Ribonuclease Inhibitor (20 U/20 ⁇ L reaction; Promega) was added to prevent RNase-mediated degradation.
- Two negative controls were also utilised, namely minus reverse transcriptase enzyme control and minus template control .
- RNA samples were subjected to polymerase chain reaction (PCR) amplification via a cycle limitation approach.
- PCR polymerase chain reaction
- the following primer pair combinations were used: 18 S - forward, 5'-AGGGTTCGATTCCGGAG-S' (SEQ ID NO: 19) and reverse, S'-ACCAGACTTGCCCTCC-S' (SEQ ID NO: 20) (195 bp amplicon) ;
- SIAT7B forward, 5'-GGCACATCCTACCCCAGA-S' (SEQ ID NO: 27) and reverse, S'-AAGCAACTAACCCCCATCAA-S' (SEQ ID NO: 28) (272 bp amplicon) ;
- PRKl - forward 5'-GGGCTGTTTCTTCACATCTTC-SMSEQ ID NO: 11
- reverse S'-GTGGACTGGTGGGGACTG-S' (SEQ ID NO: 12) (231 bp amplicon) ;
- PCR products were subcloned into the pCRII-TOPO vector via the Topo TA Cloning kit (Invitrogen) , with insert- containing plasmids then subjected to automated DNA sequencing via a commercial route (MWG) .
- MWG commercial route
- Pre-designed TaqMan probe and primer sets for target genes were chosen from an on-line catalogue (Applied Biosystems) . Once selected, the sets were factory-loaded into the 384 wells of TaqMan Low Density Arrays. Array format was customized on-line with two replicates per target gene. Expression levels of target genes were normalized to concentration of 18 S rRNA. Samples were analyzed using the 7900HT system with a TaqMan Low Density Array Upgrade (Applied Biosystems) , according to the manufacturer's instructions.
- ⁇ Ct represents the threshold cycle (Ct) of the target minus that of 18 S rRNA and ⁇ Ct represents the ⁇ Ct of each target minus that of the calibrator.
- RNA from each cell line was subjected to electrophoresis through an agarose- formaldehyde gel, followed by transfer to nitrocellulose membranes (17) .
- a TSPYl-specific cDNA probe derived from the above-mentioned RT-PCR amplicon, was labeled by random hexanucleotide priming, with hybridization conditions as described previously (17) . Integrity and loading of RNA were determined by probing for GAPDH expression.
- EcoRI-digested DNA (15 ⁇ g) was subjected to agarose gel electrophoresis, followed by transfer to nylon membrane, as described previously (23) .
- Use of the radiolabeled TSPYl-specific cDNA probe was as detailed above. Loading of DNA was determined by ethidium bromide staining.
- genomic DNA was first subjected to bisulfite modification via the CpGenome DNA Modification kit (Intergen) ; this process converts unmethylated, but not methylated, cytosine residues to uracil .
- the genomic DNA sequence of the TSPYl gene was retrieved from GenBank (accession number: M98524) .
- a putative CpG island within the first exon of the TSPYl gene was identified using CpGPlot ( Figure 4C) .
- primer pairs designed against bisulfite-modified DNA were used to amplify this region by PCR: forward, 5 ' -GGTAGTATAGGTTTTGGTGTGTG-3 ' (SEQ ID NO: 17) and reverse, 5'-CCAACACCTCCTCCAATACAAAC-S' (SEQ IDfNO: 18).
- Amplified PCR products (269 bp in length) were incubated with BsiEI (20 U/20 ⁇ L PCR product) for 2 hours at 60oC, with restriction digests subsequently examined by agarose gel electrophoresis.
- DAC 5 mg/kg/mouse
- total dose 15 mg/kg/mouse
- mice were injected with PBS where 10 ⁇ L of PBS was given per gram of mouse bodyweight.
- the behavior of the WM793-based isogenic cell line model series has been well documented in vivo (15, 16) . However, there is only limited data available -with respect to characteristic features of these cell lines in vitro (15, 24) .
- the growth rate of the parental WM793 cells and three isogenic derivatives was examined over a period of 7 days (Figure IA) .
- the derivative cell lines exhibited more rapid rates of cell growth than the parental cells .
- the 1205-Lu cells showed an intermediate rate of cell growth, which may be due to the apparent increased propensity of this cell type to detach from the surface in monolayer culture.
- the isogenic derivatives also displayed increased invasive capacity over WM793 cells, with the most striking difference seen between 1205-Lu and parental cells (Figure IB) .
- FISH and flow cytometric analysis showed evidence of increased ploidy in association with progression in the model system, which is further indicative of genomic instability (see Figure 6) .
- FISH analysis showed increases in X, Y and Hq chromosomal regions in the derivative cells that were consistent with an increase in the numbers of tetraploid, triploid or hyperdiploid cells found in these cell line populations.
- TSPYl a Y chromosome-specific gene that displayed marked down-regulation in expression (between 137 and 317 fold, as determined from DNA microarray study) between the parental and derivative cell lines ( Figures 2, 3 and 4A).
- the TSPYl gene has previously been shown to exhibit dysregulated expression in a number of cancer types, including gonadoblastoma, as well as testicular and prostate cancer (20, 27-30) .
- Y chromosome loss has been described for certain melanomas, this is not a common event.
- FISH analysis showed retention of this chromosome in all four cell lines under study (see Figure 6) .
- TSPYl gene expression is regulated by androgens and DNA methylation (20) . This suggested that aberrant DNA methylation may have a role transcriptional silencing of TSPYl gene expression between early and advanced melanoma cell lines.
- DAC treatment may facilitate tumorigenic reversion of advanced melanomas.
- TSPYl displayed the most striking change in gene expression terms within the WM793 series.
- the TSPYl gene is found in multiple copies (20 - 40 based on current predictions) on both the long and short arm of chromosome Y (30, 33) .
- the TSPYl gene is normally expressed in the germ cells of the testis and distinct subsets of spermatogonia (34, 35). Apart from an assumed activity in spermatogenesis (34, 36), the functional role of TSPYl remains to be elucidated (33) . Previous work had implicated TSPYl as a putative oncogene based on its elevated expression in some gonadoblastomas, as well as testicular and prostate cancers (27-30, 37) .
- TSPYl gene expression is a promising marker for melanoma progression and, potentially, DAC activity, further work will be required to clarify its role in cancer.
- Our data provides an interesting hypothesis that there may be sex-specific markers of melanoma, which may be useful in discriminating differences in terms of disease progression between males and females (2) , with the TSPYl gene being a promising candidate in this respect .
- DNA hypermethylation in carcinogenesis is complex: global hypomethylation and region-specific hypermethylation co-exist (38) .
- DNA hypermethylation at CpG islands is known to be associated with epigenetic silencing of tumor suppressor gene expression and may increase genomic instability (39) .
- DNA hypermethylation can occur at all stages of tumor development and progression (40) .
- Previous studies have identified a number of genes that are affected by alterations in DNA methylation patterns in melanoma cells, including CDKN2A (41), PTEN (42), APAF-I (43), MAGEAl ' (44), TIMP3 (13), GAGED2 (45) , various human leukocyte class I antigens (46) , and CASP8 (47) .
- Our data adds a further collection of putative methylation-sensitive genes in melanoma.
- DNA microarray-based gene expression profiling technology has been previously utilized in several cancer-related model systems to identify genes that are regulated by DNA methylation (13, 44, 48, 49) .
- van der Velden et al . (13) identified 19 genes, including TIMP3 and TYRPl, that were differentially expressed between a demethylated de-rivative clone of a primary uveal melanoma cell line and its untreated control.
- Our study provides further insight by linking changes in gene expression between early and advanced melanoma with DNA methylation.
- DAC in combination with the inhibitory cytokine, IFN- ⁇ , enhanced the expression of human leucocyte class I antigens together with certain co- stimulatory molecules, such as ICAM-I and LFA-3, in a panel of 12 metastatic melanoma cell lines.
- co- stimulatory molecules such as ICAM-I and LFA-3
- DAC treatment yielded a persistent (> 60 days) expression of MAGE-I in one of the melanoma cell lines.
- This DAC/IFN- ⁇ combination may enhance the immunogenic potential of melanoma cells, thereby increasing the efficacy of immunotherapy. More recently, Kozar et al .
- DAC suppressed tumor cell growth in vitro.
- systemic treatment of mice with DAC attenuated growth of 1205-Lu-derived xenografts, with consequent re- expression of TSPYl mRNA. While this data might, in some part, be due to a direct cytotoxic action by DAC, our overall data point towards the concept that regional DNA hypermethylation at multiple loci is likely to be involved in the epigenetic regulation of melanoma progression.
- DAC also has an inhibitory effect on growth of WM793 cells in vitro, as well as being able to mediate complex changes in gene expression in this cell type.
- Bisulphite sequencing of gene promoter regions was carried out for the MT2A (MTlE) and CYBA genes to determine whether there was differential methylation in the more invasive derivative cells compared to the parental cells.
- the protocol utilised was as follows :
- Hydroquinone 2OmM [H9003/l00g/99+% SIGMA] o Hydroquinone is photosensitive so wrap tube in tinfoil prior to beginning. Dissolve 90mg in 50ml dH 2 O.
- Final solution should be at a concentration of 25ng/ ⁇ l. 50ng (2 ⁇ l) is used in the PCR. Following PCR, the band is excised and purified using the QIAquick Gel Extraction Kit (Qiagen) .
- sequencing primers were as follows:
- TSPY testis specific protein
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Abstract
L'invention concerne des méthodes de surveillance de la progression d'un mélanome chez un sujet. Lesdites méthodes consistent à déterminer des niveaux d'expression de nouveaux gènes marqueurs dans un échantillon pour essai. Lesdits gènes sont sélectionnés dans, entre autres, TSPY1, CYBA et MT2A. Les méthodes de diagnostic d'un mélanome consistent également à déterminer l'état de méthylation de marqueurs dont l'état de méthylation s'avère désormais être lié à la progression d'un mélanome. L'invention concerne également des microréseaux, des méthodes de criblage, des amorces et des méthodes de traitement d'un mélanome fondées sur les nouveaux gènes marqueurs.
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AU2008345036A1 (en) * | 2007-12-28 | 2009-07-09 | John Wayne Cancer Institute | Use of methylation status of MINT loci and tumor-related genes as a marker for melanoma and breast cancer |
GB0917457D0 (en) | 2009-10-06 | 2009-11-18 | Glaxosmithkline Biolog Sa | Method |
EA019599B1 (ru) * | 2010-09-13 | 2014-04-30 | Федеральное государственное бюджетное учреждение науки Институт биологии гена Российской академии наук | Способ диагностики меланомы человека на основании определения уровня экспрессии гена phf10, диагностический набор |
GB201204785D0 (en) | 2012-03-19 | 2012-05-02 | Queen Mary & Westfield College | Method for determining prognosis of prostate cancer in a subject |
US20140271545A1 (en) | 2013-03-14 | 2014-09-18 | Castle Biosciences, Inc. | Methods for predicting risk of metastasis in cutaneous melanoma |
EP2971156B1 (fr) * | 2013-03-15 | 2020-07-15 | Myriad Genetics, Inc. | Gènes et signatures géniques pour le diagnostic et le traitement du mélanome |
WO2016003810A1 (fr) | 2014-07-02 | 2016-01-07 | Myriad Genetics, Inc. | Gènes et signatures génétiques pour le diagnostic et le traitement du mélanome |
EP3314020A1 (fr) * | 2015-06-29 | 2018-05-02 | The Broad Institute Inc. | Expression génique tumorale et micro-environnementale, compositions de matières et ses procédés d'utilisation |
CN110241219B (zh) * | 2019-07-18 | 2024-04-16 | 北京泱深生物信息技术有限公司 | Myom3在黑色素瘤转移中的应用 |
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EP1274463A2 (fr) * | 1999-12-10 | 2003-01-15 | Whitehead Institute For Biomedical Research | Genes de metastase et utilisations de tels genes |
JP2006500946A (ja) * | 2002-09-30 | 2006-01-12 | オンコセラピー・サイエンス株式会社 | 精巣精上皮腫の診断方法 |
EP2003196A3 (fr) * | 2003-06-09 | 2009-01-07 | The Regents of the University of Michigan | Compositions et procédés de diagnostic et de traitement des cancers |
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2005
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- 2006-03-02 CA CA002600337A patent/CA2600337A1/fr not_active Abandoned
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- 2006-03-02 EP EP06709980A patent/EP1859049A2/fr not_active Withdrawn
Non-Patent Citations (1)
Title |
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DASARI ET AL: "DNA METHYLATION REGULATES THE EXPRESSION OF Y CHROMOSOME SPECIFIC GENES IN PROSTATE CANCER", JOURNAL OF UROLOGY, vol. 167, no. 1, 1 January 2002 (2002-01-01), BALTIMORE, MD, US, pages 335 - 338, XP005543608 * |
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CA2600337A1 (fr) | 2006-09-08 |
WO2006092610A2 (fr) | 2006-09-08 |
WO2006092610A3 (fr) | 2006-12-07 |
GB0504302D0 (en) | 2005-04-06 |
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