WO1997027289A1 - Proteine kinase de brca-1 et son utilisation - Google Patents

Proteine kinase de brca-1 et son utilisation Download PDF

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WO1997027289A1
WO1997027289A1 PCT/US1997/001261 US9701261W WO9727289A1 WO 1997027289 A1 WO1997027289 A1 WO 1997027289A1 US 9701261 W US9701261 W US 9701261W WO 9727289 A1 WO9727289 A1 WO 9727289A1
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ser
glu
leu
lys
brca
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PCT/US1997/001261
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Richard P. Beckmann
Teresa Faye Burke
Kimberly S. Cocke
Stephanie J. Lemke
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Eli Lilly And Company
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Priority claimed from GBGB9603149.7A external-priority patent/GB9603149D0/en
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Priority to AU18414/97A priority Critical patent/AU1841497A/en
Publication of WO1997027289A1 publication Critical patent/WO1997027289A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
    • C12N9/10—Transferases (2.)
    • C12N9/12—Transferases (2.) transferring phosphorus containing groups, e.g. kinases (2.7)
    • C12N9/1205—Phosphotransferases with an alcohol group as acceptor (2.7.1), e.g. protein kinases

Definitions

  • the present invention relates generally to a BRCA-1 protein kinase and its manipulation for the control of cellular processes.
  • the present invention also relates to the use of the BRCA-1 protein kinase as a molecular target for therapeutic intervention and/or as a therapeutic tool for diagnosing and treating breast and/or ovarian cancer.
  • An estimated 182,000 new cases of invasive breast cancer occurred in the United States during 1995 and over 46,000 deaths resulted from this disease.
  • the search for and identification of specific genetic elements which contribute to the development of breast cancer is an essential part of achieving better treatment and earlier diagnosis.
  • BRCA-1 The discovery of BRCA-1 is a recent example of a burgeoning effort in molecular biology which is focused on the identification of specific disease-associated genes. BRCA-1 is the first gene discovered in an intensive worldwide search for genes associated with enhanced susceptibility to breast and ovarian cancer.
  • the BRCA-1 gene consists of 100 Kb of DNA which comprises 22 coding exons and encodes a protein of 1863 amino acids. (Gene Bank Accession No. U14680) . Sequence analysis has provided little insight into BRCA-1 function since only a short region within the amino terminus (comprising less than 10% of the coding sequence) shows significant homology to known protein sequences. Specifically, this region consists of a putative RING finger domain which may be critical in facilitating interactions between BRCA-1 and other proteins. Although the role this gene plays in breast cancer development is unknown, it is clear that germline mutations within this gene are associated with an 87% and 44% lifetime risk for breast cancer and ovarian cancer, respectively. Studies suggest that mutations in BRCA-1 may play a role in nearly half the cases of familial breast cancer. However, there is little evidence indicating that this gene is involved in spontaneous (non-hereditary) breast cancer.
  • the present invention is the result of an effort to identify protein kinases which functionally interact with BRCA-1 in order to gain insight into BRCA-l's functional activity in regulatory pathways or other physiological processes of the cell.
  • Protein kinases are known to mediate cellular signals important for growth and differentiation. Typically, increased expression is associated with alterations in normal cellular processes. Some of these affected cellular processes include cell proliferation, differentiation and cancer, including, for example, breast cancer and ovarian cancer.
  • the identification and characterization of one or more novel protein kinases should provide important insights into the mechanisms underlying oncogenesis and cellular growth control pathways. Such kinases may also be an important target for the development of chemotherapeutic agents.
  • the present invention satisfies this need and provides a variety of related advantages as well.
  • the present invention is directed to protein kinases, or functional fragments thereof which interact with and phosphorylate specific amino acid residues within the BRCA-1 protein.
  • the present invention also is directed to a method of diagnosing and/or treating cancer, more particularly, breast and/or ovarian cancer utilizing these protein kinases.
  • Base pair refers to DNA or RNA.
  • the abbreviations A,C,G, and T correspond to the 5'- monophosphate forms of the deoxyribonucleosides (deoxy)adenosine, (deoxy)cytidine, (deoxy)guanosine, and (deoxy) thymidine, respectively, when they occur in DNA molecules.
  • the abbreviations U,C,G, and A correspond to the 5 ' -monophosphate forms of the ribonucleosides urodine, cytidine, guanosine, and adenosine, respectively when they occur in RNA molecules.
  • base pair may refer to a pairing of A with T or C with G.
  • DNA/RNA, heteroduplex base pair may refer to a pairing of A with U or C with G. (See the definition of "complementary", nfr .)
  • cleavage or “restriction” of DNA refers to the catalytic cleavage of the DNA with a restriction enzyme that acts only at certain sequences in the DNA (“sequence-specific endonucleases”) .
  • restriction enzymes used herein are commercially available and their reaction conditions, cofactors, and other requirements were used as would be known to one of ordinary skill in the art. Appropriate buffers and substrate amounts for particular restriction enzymes are specified by the manufacturer or can be readily found in the literature.
  • Ligation refers to the process of forming phosphodiester bonds between two nucleic acid fragments (T. Maniatis, ⁇ t ⁇ i. , supra.. p. 146). Unless otherwise provided, ligation may be accomplished using known buffers and conditions with a DNA ligase, such as T4 DNA ligase.
  • Plasmid refers to an extrachromosomal (usually) self-replicating genetic element. Plasmids are generally designated by a lower case “p” followed by letters and/or numbers.
  • the starting plasmids herein are either commercially available, publicly available on an unrestricted basis, or can be constructed from available plasmids in accordance with published procedures. In addition, equivalent plasmids to those described are known in the art and will be apparent to the ordinarily skilled artisan.
  • reading frame means the nucleotide sequence from which translation occurs “read” in triplets by the translational apparatus of transfer RNA (tRNA) and ribosomes and associated factors, each triplet corresponding to a particular amino acid.
  • tRNA transfer RNA
  • a frameshift mutation occurs when a base pair is inserted or deleted from a DNA segment. When this occurs, the result is a different protein from that coded for by the DNA segment prior to the frameshift mutation. To insure against this, the triplet codons corresponding to the desired polypeptide must be aligned in multiples of three from the initiation codon, i.e. the correct "reading frame” being maintained.
  • Recombinant DNA cloning vector refers to any autonomously replicating agent, including, but not limited to, plasmids and phages, comprising a DNA molecule to which one or more additional DNA segments can or have been added.
  • recombinant DNA expression vector refers to any recombinant DNA cloning vector in which a promoter and other regulatory elements to control transcription of the inserted DNA.
  • expression vector system refers to a recombinant DNA expression vector in combination with one or more trans-acting factors that specifically influence transcription, stability, or replication of the recombinant DNA expression vector.
  • the trans-acting factor may be expressed from a co-transfected plasmid, virus, or other extrachromosomal element, or may be expressed from a gene integrated within the chromosome.
  • Transcription refers to the process whereby information contained in a nucleotide sequence of DNA is transferred to a complementary RNA sequence.
  • transfection refers to the taking up of an expression vector by a host cell whether or not any coding sequences are in fact expressed. Numerous methods of transfection are known to the ordinarily skilled artisan, for example, calcium phosphate co-precipitation, and electroporation. Successful transfection is generally recognized when any indication of the operation of this vector occurs within the host cell.
  • transformation means the introduction of DNA into an organism so that the DNA is replicable, either as an extrachromosomal element or by chromosomal integration.
  • Methods of transforming bacterial and eukaryotic hosts are well known in the art, many of which methods are summarized in J. Sambrook, et al.. "Molecular Cloning: A Laboratory Manual” (1989) .
  • translation refers to the process whereby the genetic information of messenger RNA is used to specify and direct the synthesis of a polypeptide chain.
  • vector refers to a nucleic acid compound used for the transformation of cells with polynucleotide sequences corresponding to appropriate protein molecules which when combined with appropriate control sequences confer specific properties on the host cell to be transformed. Plasmids, viruses, and bacteriophage are suitable vectors. Artificial vectors are constructed by joining DNA molecules from different sources.
  • vector as used herein includes Recombinant DNA cloning vectors and Recombinant DNA expression vectors.
  • complementary or complementarity refers to the pairing of bases, purines and pyrimidines, that associate through hydrogen bonding in double stranded nucleic acid. The following base pairs are complementary: guanine and cytosine; adenine and thymine; and adenine and uracil.
  • hybridization refers to a process in which a strand of nucleic acid joins with a complementary strand through base pairing.
  • the conditions employed in the hybridization of two non-identical, but very similar, complementary nucleic acids varies with the degree of complementarity of the two strands and the length of the strands. Such techniques and conditions are well known to practitioners in this field.
  • isolated amino acid sequence refers to any amino acid sequence, however constructed or synthesized, which is locationally distinct from the naturally occurring sequence.
  • isolated DNA compound refers to any DNA sequence, however constructed or synthesized, which is locationally distinct from its natural location in genomic DNA.
  • isolated nucleic acid compound refers to any RNA or DNA sequence, however constructed or synthesized, which is locationally distinct from its natural location.
  • a “primer” is a nucleic acid fragment which functions as an initiating substrate for enzymatic or synthetic elongation.
  • promoter refers to a DNA sequence which directs transcription of DNA to RNA.
  • a “probe” as used herein is a nucleic acid compound or a fragment thereof which hybridizes with a nucleic acid compound which encodes either the entire sequence SEQ ID NO:2, a sequence complementary to SEQ ID NO:2, or a part thereof.
  • PCR refers to the widely- known polymerase chain reaction employing a thermally-stable polymerase.
  • DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the identification and characterization of a novel BRCA-1 protein kinase which regulates a variety of cellular processes with regard to the BRCA-1 gene. By identifying this novel protein kinase, the control of different cellular processes regarding breast and/or ovarian cancer is contemplated.
  • this novel protein kinase provides a novel molecular target for therapeutic intervention in the form of using the protein kinase as a reagent in an assay for screening BRCA-1 phosphorylation or in an assay to screen compounds for their ability to inhibit/prevent or promote BRCA-1 phosphorylation.
  • the use of BRCA-1 protein kinase in gene therapy is also contemplated.
  • BRCA-1 related protein kinase refers to specific protein kinase(s) which interact with and phosphorylates specific amino acid residues (as further defined hereinafter) within the BRCA-1 protein. Additional factors and/or proteins associated with the protein kinase of the present invention which alter its activity toward BRCA-1, are intended to also be encompassed within the scope of the present invention.
  • the BRCA-1 protein kinase of the present invention was first identified as a protein which co-purified with BRCA-1 when the protein fragments were expressed and purified from insect cells.
  • the BRCA-1 protein kinase of the present invention is characterized as requiring either Mg ++ or Mn ++ for activity but is independent of Ca ++ .
  • the kinase activity is unstable in insect cell lysates treated with 0.1% SDS but is stable in lysates containing urea at concentrations at 3M or less.
  • the kinase appears to reside in the cytoplasm since it can be solubilized from cells in the absence of detergents.
  • Lysates prepared from insect cells have active kinase in isotonic buffers containing 0.5% NP-40 (a non-ionic detergent) and in hypotonic buffers containing no detergent.
  • Preliminary data indicates that the kinase binds Sepharose SP resin (a cation ion exchange resin) at pH's below about 8 and a low ionic strength thereby indicating that the protein kinase has a pi (isoelectric point) between about pH 5 and about pH 8.
  • the above physical properties provide skilled artisians with the information necessary to isolate the BRCA-1 protein kinase of the present invention. Identification of the BRCA-1 protein kinase can be readily confirmed by examining the phosphorylation patterns of BRCA-1 protein as disclosed herein. Because of distinct patterns of phosphorylation demonstrated in specific amino acid residues of the BRCA-1 protein, aberrations in the normal cellular processes associated with the BRCA-1 gene, such as those leading to uncontrolled malignant cell growth, can be detected utilizing the present invention.
  • fragments of the BRCA-1 protein kinase which retain the function of the entire protein as well as functional domains that contain at least one function of the intact protein are included within the definition.
  • Functional domains can include, for example, active ligand binding and catalytic domains. The boundaries of such domains are not important as long as activity is maintained. It is also understood that minor modifications of the primary amino acid sequence can result in proteins which have substantially equivalent or enhanced function. These modifications may be deliberate, as through site-directed mutagenesis, or may be accidental such as through mutation in hosts which produce such kinases. All of these modifications are included as long as biological function is retained. Further, as noted above, additional factors and/or proteins can play a role with regard to the activity of the present invention.
  • Various molecules can be attached to the protein kinase of the present invention.
  • other proteins, carbohydrates, lipids or phosphate groups can be attached to the protein kinase of the present invention. Such modifications are intended to be encompassed within the present invention.
  • substantially purified when used to describe the state of the kinase denotes the protein free of a portion of the other proteins and molecules normally associated with or occurring with such kinases in their native environment.
  • Such substantially purified kinases can be derived from natural sources, recombinantly expressed or synthesized by in vitro methods so long as some portion of normally associated molecules are absent.
  • the present invention provides a BRCA-1 protein kinase or functional fragment thereof.
  • the present invention also provides a substantially purified BRCA-1 related protein kinase, or functional fragment thereof.
  • the kinase activity demonstrated in the present invention showed that a BRCA-1 fragment from exon 11 (produced in Sf9 insect cells and partially purified over glutathione agarose) could be phosphorylated when it was incubated in the presence of ⁇ 3 2 P-ATP.
  • the amino acid sequence which corresponds to the region of BRCA-1 where phosphorylation mediated by BRCA-1 protein kinase has been demonstrated is set forth below:
  • SEQ ID NO:l amino acid sequences which correspond to the region of BRCA-1 where phosphorylation mediated by BRCA-1 protein kinase has been demonstrated are set forth below as: Asn Asp Arg Arg Thr Pro Ser Thr Glu Lys Lys Val Asp Leu Asn Ala 1 5 10 15
  • SEQ ID NO:2 which is hereinafter referred to as SEQ ID NO:2 or as:
  • SEQ ID NO:5 20 25 30 which is hereinafter referred to as SEQ ID NO:5.
  • SEQ ID NO:6 Arg Met Ser Met Val 305 which is hereinafter referred to as SEQ ID NO:6.
  • kinase and substrate proteins of the present invention can be synthesized by a number of different methods. All of the amino acid compounds of the invention can be made by chemical methods well known in the art, including solid phase peptide synthesis, or recombinant methods. Both methods are described in U.S. Patent 4,617,149, incorporated herein by reference. The principles of solid phase chemical synthesis of polypeptides are well known in the art and may be found in general texts in the area. See, e. ⁇ .. H. Dugas and C. Penney, BIOORGANIC CHEMISTRY, (1981) Springer-Verlag, New York, pgs. 54- 92.
  • peptides may be synthesized by solid-phase methodology utilizing an Applied Biosystems 430A peptide synthesizer (commercially available from Applied Biosystems, Foster City California) and synthesis cycles supplied by Applied Biosystems.
  • Protected amino acids such as t-butoxycarbonyl-protected amino acids, and other reagents are commercially available from many chemical supply houses.
  • Sequential t-butoxycarbonyl chemistry using double couple protocols are applied to the starting p-methyl benzhydryl amine resins for the production of C-terminal carboxamides.
  • the corresponding pyridine-2-aldoxime methiodide resin is used for the production of C-terminal acids.
  • Asparagine, glutamine, and arginine are coupled using preformed hydroxy benzotriazole esters.
  • the following side chain protection may be used: Arg, Tosyl Asp, cyclohexyl
  • Removal of the t-butoxycarbonyl moiety may be accomplished with trifluoroacetic acid (TFA) in methylene chloride.
  • TFA trifluoroacetic acid
  • the peptides may be deprotected and cleaved from the resin with anhydrous hydrogen fluoride containing 10% meta-cresol. Cleavage of the side chain protecting group(s) and of the peptide from the resin is carried out at zero degrees centigrade or below, preferably -20"C for thirty minutes followed by thirty minutes at O'C.
  • the peptide/resin is washed with ether, and the peptide extracted with glacial acetic acid and then lyophilized. Purification is accomplished by size-exclusion chromatography on a Sephadex G-10 (Pharmacia Biotech, Inc., Piscataway, N.J.) column in 10% acetic acid.
  • the proteins (kinase and substrate) of the present invention may also be produced by recombinant methods. Recombinant methods are preferred if a high yield is desired.
  • a general method for the construction of any desired DNA sequence is provided in J. Brown, et al.. Methods in Enzvmolo ⁇ v. 68:109 (1979). See also. J. Sambrook, et al.. supra.
  • prokaryotes can be used for cloning of DNA sequences in constructing the vectors of this invention.
  • Prokaryotes may also be employed in the production of the protein of interest.
  • the Escherichia coli K12 strain 294 (ATCC No. 31446) is particularly useful for the prokaryotic expression of foreign proteins.
  • a commercialy available E. coli strain which is preferred for prokaryotic expression of the fusion proteins of the invention is designated DH10B.
  • DH10B is available from Gibco BRL, P.O. Box 68, Grand Island, N.Y. 14072-0068.
  • Other strains of E. coli which may be used (and their relevant genotypes) include the following.
  • JM109 recAl, el4 " (mcrA) , supE44, endAl, hsdRl7(r ⁇ - ⁇ i ⁇ + ) gyrA96, relAl, thi-1, ⁇ (lac-proAB) , F' [traD36, proAB+ lacl ⁇ , lacZ ⁇ M15]
  • strains are all commercially available from suppliers such as: Bethesda Research Laboratories, Gaithersburg, Maryland 20877 and Stratagene Cloning Systems, La Jolla, California 92037; or are readily available to the public from sources such as the American Type Culture Collection, 12301 Parklawn Drive, Rockville, Maryland, 10852- 1776.
  • bacterial strains can be used interchangeably.
  • the genotypes listed are illustrative of many of the desired characteristics for choosing a bacterial host and are not meant to limit the invention in any way.
  • the genotype designations are in accordance with standard nomenclature. See, for example, J. Sambrook, et al .. supra.
  • a preferred strain of E. coli employed in the cloning and expression of the genes of this invention is RV308, which is available from the ATCC under accession number ATCC 31608, and is described in United States Patent 4,551,433, issued November 5, 1985. While they are still preferred when substantial amounts of fusion protein are desired, the facile nature of numerous eukaryotic expression systems results in a preference for these systems when modest amounts of the biologically active fusion proteins are desired.
  • the strains of E. coli discussed are illustrative of many of the desired characteristics for choosing a bacterial host and are not meant to limit the invention in any way.
  • the genotype designations are in accordance with standard nom
  • bacilli such as Bacillus subtilis.
  • enterobacteriaceae such as Salmonella tvnhimnrinm or Serratia marcescans. and various Pseudomonas species may also be used.
  • other bacteria especially Streptomvces. spp., may be employed in the prokaryotic cloning and expression of the proteins of this invention.
  • Promoters suitable for use with prokaryotic hosts include the j-lactamase [vector pGX2907 (ATCC 39344) contains the replicon and jb-lactamase gene] and lactose promoter systems fChancr et al.. Nature (London) .
  • trp tryptophan promoter system
  • vector pATHl ATCC 37695
  • hybrid promoters such as the tac promoter (isolatable from plasmid pDR540 ATCC-37282) .
  • the proteins of this invention may be synthesized either by direct expression or as a fusion protein comprising the protein of interest as a translational fusion with another protein or peptide which may be removable by enzymatic or chemical cleavage. It is often observed in the production of certain peptides in recombinant systems that expression as a fusion protein prolongs the lifespan, increases the yield of the desired peptide, or provides a convenient means of purifying the protein of interest.
  • a variety of peptidases e.g. trypsin which cleave a polypeptide at specific sites or digest the peptides from the amino or carboxy termini (e.g. diaminopeptidase) of the peptide chain are known.
  • particular chemicals e.g.
  • cyanogen bromide will cleave a polypeptide chain at specific sites.
  • the skilled artisan will appreciate the odifications necessary to the amino acid sequence (and synthetic or semi-synthetic coding sequence if recombinant means are employed) to incorporate site-specific internal cleavage sites. See e.g., P. Carter, "Site Specific Proteolysis of Fusion Proteins", Chapter 13 in PROTEIN
  • the proteins of the present invention may also be produced in eukaryotic systems.
  • the present invention is not limited to use in a particular eukaryotic host cell.
  • a variety of eukaryotic host cells are available from depositories such as the American Type Culture Collection (ATCC) and are suitable for use with the vectors of the present invention.
  • ATCC American Type Culture Collection
  • the choice of a particular host cell depends to some extent on the particular expression vector used to drive expression of the protein-encoding nucleic acids of the present invention.
  • Exemplary host cells suitable for use in the present invention are listed in Table I.
  • a preferred eukaryotic cell line of use in expresing the fusion proteins of this invention is the widely available cell line AV12-664 (hereinafter "AV12").
  • AV12 This cell line is available from the American Type Culture Collection under the accession number ATCC CRL 9595.
  • the AV12 cell line was constructed by injecting a Syrian hamster in the scruff of the neck with human adenovirus 12 and isolating cells from the resulting tumor.
  • the sequences encoding the proteins of the invention are easily removed from the deposited strains by selection of the appropriate restriction endonucleases and inserted in any of the vectors described herein through routine purification, ligation and transfection techniques.
  • the pSV2-type vectors comprise segments of the simian virus 40 (SV40) genome that constitute a defined eukaryotic transcription unit-promoter, intervening sequence, and polyadenylation site.
  • the plasmid pSV2-type vectors transform mammalian and other eukaryotic host cells by integrating into the host cell chromosomal DNA.
  • Plasmid pSV2-type vectors such as plasmid pSV2-gpt, pSV2-neo, pSV2-dhfr, pSV2-hyg, and pSV2-b-globin, in which the SV40 promoter drives transcription of an inserted gene.
  • These vectors are suitable for use with the coding sequences of the present invention and are widely available from sources such as the ATCC or the Northern Regional Research Laboratory (NRRL) , 1815 N. University Street, Peoria, Illinois, 61604.
  • the plasmid pSV2-dhfr (ATCC 37146) comprises a murine dihydrofolate reductase (dhfr) gene under the control of the SV40 early promoter. Under the appropriate conditions, the dhfr gene is known to be amplified, or copied, in the host chromosome. This amplification can result in the amplification of closely-associated DNA sequences and can, therefore, be used to increase production of a protein of interest. See, e.g.. J. Schimke, Cell. 35:705-713 (1984).
  • dhfr murine dihydrofolate reductase
  • Plasmids constructed for expression of the proteins of the present invention in mammalian and other eukaryotic host cells can utilize a wide variety of promoters.
  • the present invention is in no way limited to the use of the particular promoters exemplified herein.
  • Promoters such as the SV40 late promoter, promoters from eukaryotic genes, such as, for example, the estrogen-inducible chicken ovalbumin gene, the interferon genes, the gluco-corticoid-inducible tyrosine aminotransferase gene, and the thymidine kinase gene, and the major early and late adenovirus genes can be readily isolated and modified to express the genes of the present invention.
  • Eukaryotic promoters can also be used in tandem to drive expression of a coding sequence of this invention. Furthermore, a large number of retroviruses are known that infect a wide range of eukaryotic host cells. The long terminal repeats in the retroviral DNA frequently encode functional promoters and, therefore, may be used to drive expression of the nucleic acids of the present invention.
  • Plasmid pRSVcat (ATCC 37152) comprises portions of a long terminal repeat of the Rous Sarcoma virus, a virus known to infect chickens and other host cells. This long terminal repeat contains a promoter which is suitable for use in the vectors of this invention. H. Gorman, et al P ,
  • the plasmid pMSVi (NRRL B-15929) comprises the long terminal repeats of the Murine Sarcoma virus, a virus known to infect mouse and other host cells.
  • the mouse metallothionein promoter has also been well characterized for use in eukaryotic host cells and is suitable for use in the expression of the nucleic acids of the present invention.
  • the mouse metallothionein promoter is present in the plasmid pdBPV-MMTneo (ATCC 37224) which can serve as the starting material of other plasmids of the present invention.
  • a useful expression vector system employs one of a series of vectors containing the BK enhancer, an enhancer derived from the BK virus, a human papovavirus.
  • the most preferred such vector systems are those which employ not only the BK enhancer but also the adenovirus-2-early region IA (EIA) gene product.
  • the EIA gene product (actually, the EIA gene produces two products, which are collectively referred to herein as "the EIA gene product”) is an immediate-early gene product of adenovirus, a large DNA virus.
  • a eucaryotic expression vector that can be employed in the present invention is the phd series of vectors which comprise a BK enhancer in tandem with the adenovirus late promoter to drive expression of useful products in eukaryotic host cells .
  • the construction and method of using the phd plasmid, as well as related plasmids, are described in U.S. Patents 5,242,688, issued September 7, 1993, and 4,992,373, issued February 12, 1991, each of which are incorporated herein by reference.
  • Escherichia coli K12 GM48 cells harboring the plasmid phd are available as part of the permanent stock collection of the Northern Regional Research Laboratory under accession number NRRL B-18525. The plasmid may be isolated from this culture using standard techniques.
  • the plasmid phd contains a unique Bell site which may be utilized for the insertion of the gene encoding the protein of interest.
  • the skilled artisan understands that linkers or adapters may be employed in cloning the gene of interest into this Bell site.
  • the phd series of plasmids functions most efficiently when introduced into a host cell which produces the EIA gene product, cell lines such as AV12- 664, 293 cells, and others, described supra.
  • Transformation of the mammalian cells can be performed by any of the known processes including, but not limited to, the protoplast fusion method, the calcium phosphate co-precipitation method, electroporation and the like. See, e.g. , J. Sambrook, et al. , supra, at 3:16.30-
  • eukaryotic microbes such as yeast cultures may also be used.
  • Saccharomyces cerevisiae or common baker's yeast, is the most commonly used eukaryotic microorganism, although a number of other strains are commonly available.
  • the plasmid YRp7 ATCC-40053
  • yeast cultures are commonly used. See, e.g. , L. Stinchcomb, ej ⁇ al. , Nature (London) . 282:39
  • This plasmid already contains the trp gene which provides a selectable marker for a mutant strain of yeast lacking the ability to grow in tryptophan.
  • Suitable promoting sequences for use with yeast hosts include the promoters for 3-phosphoglycerate kinase [found on plasmid pAPl2BD (ATCC 53231) and described in U.S. Patent No.
  • glycolytic enzymes such as enolase [found on plasmid pACl (ATCC 39532)], glyceraldehyde- 3-phosphate dehydrogenase [derived from plasmid pHcGAPCl (ATCC 57090, 57091)], hexokinase, pyruvate decarboxylase, phosphofructokinase, glucose-6-phosphate isomerase, 3-phosphoglycerate mutase, pyruvate kinase, triosephosphate isomerase, phosphoglucose isomerase, and glucokinase, as well as the alcohol dehydrogenase and pyruvate decarboxylase genes of Zvmomonas mobilis (United States Patent No.
  • yeast promoters which are inducible promoters, having the additional advantage of their transcription being controllable by varying growth conditions, are the promoter regions for alcohol dehydrogenase 2, isocytochrome C, acid phosphatase, degradative enzymes associated with nitrogen metabolism, metallothionein [contained on plasmid vector pCL28XhoLHBPV (ATCC 39475) and described in United States Patent No. 4,840,896, incorporated herein by reference], glyceraldehyde 3-phosphate dehydrogenase, and enzymes responsible for maltose and galactose [e.g.
  • GAL1 found on plasmid pRYl21 (ATCC 37658)] utilization.
  • Suitable vectors and promoters for use in yeast expression are further described in R. Hitzeman e£ al- European Patent Publication No. 73,657A.
  • Yeast enhancers such as the UAS Gal from Saccharomyces cerevisiae (found in conjuction with the CYC1 promoter on plasmid YEpsec—hllbeta ATCC 67024), also are advantageously used with yeast promoters. Other routes of production are well known to skilled artisans.
  • the adenovirus for example, the adenovirus, the adeno- associated virus, the vaccinia virus, the herpes virus, the baculovirus, and the rous sarcoma virus are useful.
  • a method is described in U.S. Patent 4,775,624, incorporated herein by reference.
  • Several alternate methods of expression are described in J. Sambrook, et al.. supra, at 16.3-17.44.
  • the proteins of the present invention may also be produced using a variety of other organisms, including, for example, Spodoptera (Sf9 as host for baculovirus), and Saccharomyces.
  • the more preferred cell line for use in the present invention is Sf9.
  • the preferred expression systems for use in the present invention are the various Baculovirus systems.
  • One such expression system is the pFastBacl expression system, which is commercially available from the Life Technologies group of Gibco BRL Products as Catalog No. 10360-016. Life Technologies, P.O. Box 68, Grand Island, NY 14072, Telephone: 800 828 6686.
  • pFastBacl which was derivatized by adding a GST (glutathione-S-transferase) sequence from pGEX-2 (commercially available from Pharmacia Biotech, Inc., Piscataway, N.J., Catalog # 27-4801-01, GeneBank Accession # U13850) was also used.
  • Bac- To-Bac Baculovirus Expression System is available from Life Technologies (Catalog No. 10359-016).
  • pVLl393 commercially available from Invirogen Corp., San Diego, CA, Catalog # V1392-20
  • GST glutthione-S-transferase sequence from pGEX-2 (commercially available from Pharmacia Biotech, Inc.,
  • Baculovirus expression systems are well known in the art and numerous scientific articles and "methods" books are available on the subject.
  • the Life Technologies technical literature provides excellent guidance for producing products of interest via Baculovirus expression.
  • the preferred techniques for Baculovirus expression of the sequences of the present invention are those provided in the product literature. Minor variations such as linker construciton and the like are considered in light of the advanced state of this art as too trivial to warrant discussion.
  • the present inventors recommend Baculovirus Expression Vectors-A Laboratory Manual. O'Reilly, David R., Miller, Lois K., and Luckow, Verne A., W. H. Freeman and Company, New York, New York as a source of additional information on any protocol required for successful expression of polypeptides in Baculovirus systems.
  • Skilled artisans also recognize that some alterations of the amino acids will fail to change the function of the amino acid compound. For instance, some hydrophobic amino acids may be exchanged for other hydrophobic amino acids. Those altered amino acid compounds which confer substantially the same function in substantially the same manner as the exemplified amino acid compound are also encompassed within the present invention. Typical such conservative substitutions attempt to preserve the: (a) secondary or tertiary structure of the polypeptide backbone; (b) the charge or hydrophobicity of the residue; or (c) the bulk of the side chain. Some examples of such conservative substitutions of amino acids, resulting in the production of proteins which are functional equivalents of the protein kinases of the present invention are shown in Table II, infta.
  • substitutions may be introduced into the protein in a variety of ways, such as during the chemical synthesis or by chemical modification of an amino acid side chain after the protein has been prepared.
  • Alterations of the protein may also be induced by alterations of the nucleic acid compounds which encode these proteins. These mutations of the nucleic acid compound may be generated by either random mutagenesis techniques, such as those techniques employing chemical mutagens, or by site- specific mutagenesis employing oligonucleotides. Those nucleic acid compounds which confer substantially the same function in substantially the same manner as the exemplified nucleic acid compounds are also encompassed within the present invention.
  • amino acid compounds of the present invention can be encoded by a multitude of different nucleic acid sequences because most of the amino acids are encoded by more than one nucleic acid triplet due to the degeneracy of the amino acid code.
  • the present invention further comprises these alternate nucleic acid sequences .
  • the genes encoding the DNA molecules of the present invention may be produced using synthetic methodology. This synthesis of nucleic acids is well known in the art. See, e.g. , E.L. Brown, R. Belagaje, M.J. Ryan, and H.G. Khorana, Methods in Enzvmolo ⁇ v. 68:109-151 (1979) .
  • the DNA segments corresponding to the proteins are generated using conventional DNA synthesizing apparatus such as the Applied Biosystems Model 380A or 380B DNA synthesizers (commercially available from Applied Biosystems, Inc., 850 Lincoln Center Drive, Foster City, CA 94404) which employ phosphoramidite chemistry.
  • the more traditional phosphotriester chemistry may be employed to synthesize the nucleic acids of this invention. See, e.g. M.J. Gait, ed.,
  • DNA sequences of the present invention may be designed to possess restriction endonuclease cleavage sites at either end of the transcript to facilitate isolation from and integration into expression and amplification plasmids.
  • restriction sites are chosen so as to properly orient the coding sequence with control sequences to achieve proper in-frame reading and expression of the molecule.
  • a variety of other such cleavage sites may be incorporated depending on the particular plasmid constructs employed and may be generated by techniques well known in the art.
  • the coding regions of the desired DNA sequences can be generated using the polymerase chain reaction as described in U.S. Patent No. 4,889,818, which is incorporated herein by reference.
  • Skilled artisans wishing to practice the recombinant DNA aspects of the present invention are directed to the NIH guidelines for information on research involving recombinant DNA molecules.
  • a copy of the current guidelines can be obtained from Office of Recombinant DNA Activities, National Institutes of Health, Building 31, Room 4B11, Bethesda, MD 20892. Compliance with all such current regulations regarding vector selection, expression of human and animal genes and containment requirements is reguired by law.
  • the present invention also provides a method of diagnosing cancer and determining cancer prognosis.
  • the method includes removing a tissue or cell sample from a subject suspected of having cancer and determining the level or activity of BRCA-1 related kinase in said sample, wherein a change in the level or activity of the BRCA-1 protein kinase compared to a normal sample indicates the presence of a cancer or indicates the level of malignancy of a cancer and, therefore, the most appropriate course of treatment.
  • the protein kinase of the present invention can be involved in signal transduction events that regulate important cellular processes.
  • Other kinases have been identified previously for other tumor suppressor genes and oncogenes. And these kinases have provided important leads for cancer drug development.
  • Such processes include, for example, cell differentiation and proliferation.
  • Abnormal regulation or expression of the signal transduction machinery can lead to aberrant and malignant growth of the abnormally regulated cells.
  • Abnormal expression might be associated with breast and or ovarian cancer.
  • abnormal expression may also lead to the development of other types of cancers.
  • the important role that the protein kinase of the present invention plays in cellular processes can be advantageously used to diagnose early stages of cancer within a cell sample or tissue.
  • a change in the amount or activity of such a protein kinase in a suspected sample, compared to a normal sample can be indicative of cancerous stages and of their level of malignancy.
  • the change can involve either an increase or decrease in the amount or activity of the kinase.
  • One skilled in the art can measure these parameters and compare them to those obtained from a normal sample.
  • RNA and protein blot analysis methods for determining the levels or activity of the kinase are known to one skilled in the art and include, for example, RNA and protein blot analysis, ELISA using specific antibodies to the protein kinase and direct measurement of catalytic activity such as kinase activity.
  • ELISA electrospray assay
  • GST fusion proteins were partially purified in a single step using gluthathione-Sepharose. A control which did not include GST was included to ensure that GST was not the substrate.
  • agents which act to prevent/inhibit or promote the phosphorylation of the BRCA-1 protein it would be desirable, therefore, to determine those agents which activate or inactivate and/or increase or decrease expression of BRCA-1 protein kinase.
  • assays include: a) direct inhibition/direct activation assays which directly bind the protein kinase; b) indirect inhibition/indirect activation assays which enhance or limit the activity of any associated factors involved in the phosphorylation of BRCA-1; and c) agents which increase or decrease the level of expression either through transcription or post- transcriptional events .
  • the physically detectable means include assays in which binding of a labelled or tagged ligand is measured.
  • assays are readily known to those skilled in the art such as scintillation proximity assays, radioimmuno assays, etc.
  • the instant invention provides such a screening system useful for discovering agents which prevent/inhibit or promote the phosphorylation of BRCA-1 protein, said screening system comprising the steps of:
  • Utilization of the screening system described above provides a sensitive and rapid means to determine compounds which prevent/inhibit phosphorylation.
  • This screening system may also be adapted to automated procedures such as a PANDEX ® (Baxter-Dade Diagnostics) system allowing for efficient high-volume screening of potential therapeutic agents.
  • the BRCA-1 protein kinase as described hereinbefore, can be prepared using recombinant DNA technology. A sample of a test compound is then introduced to the reaction vessel containing the BRCA-1 protein kinase followed by the addition of the BRCA-1 protein. In the alternative, the BRCA-1 protein may be added simultaneously with the test compound. The BRCA-1 protein kinase can then be inspected to determine the degree of binding exhibited.
  • radioactively or chemically labeled test compound may be used.
  • these assays are performed such that the practitioner measures the radioactivity or fluorescence remaining with the protein kinase, not in the eluent.
  • the eluent is then scored for the chemical label or radioactivity.
  • the absence or diminution of the chemical label or radioactivity indicates the formation of the BRCA-1 protein kinase/compound complex. This indicates that the test compound has effectively formed a complex with the BRCA-1 protein kinase.
  • the reaction mixture is then passed through a filter, the filter retaining the protein kinase and whatever is complexed with the protein kinase.
  • the radioactivity on each filter is then measured in a scintillation counter. In such an assay higher amounts of radiolabel present indicate greater affinity for the receptor by the test compound.
  • the protein kinase may be free in solution or bound to a solid support. Whether the protein kinase is bound to a support or is free in solution, it is generally important that the conformation of the protein be conserved. In a preferred practice of the invention, therefore, the protein kinase is suspended in a hydrophobic environment employing natural or synthetic detergents, membrane suspensions, and the like.
  • Preferred detergent complexes include, but are not limited to zwitterionic detergent 3-[ (3-cholamidopropyl)- dimethylammonio] -1-propane sulfonate ("CHAPS") as well as sodium deoxycholate and various nonionic detergents.
  • K ⁇ dissociation constant
  • a compound with a Ki which is less than 10 nM is generally considered an excellent candidate for drug therapy.
  • a compound which has a lower affinity, but is selective for the particular receptor may be an even better candidate.
  • the present invention provides radiolabeled competition assays, whether results therefrom indicate high affinity or low affinity to protein kinase, because skilled artisans will recognize that any information regarding binding or selectivity of a particular compound is beneficial in the pharmaceutical development of drugs.
  • a transcription-based screen can be used to ascertain the effect of a agent on gene expression. Since this type of screen measures activity from a transcriptional promoter, it will only assess a drug's ability to induce a change at the level of transcription. It does not measure effects that may occur post-transcriptionally.
  • the assay relies on establishing a "reporter construct" which will mimic the expression characteristics of the gene of interest (the BRCA-1 protein kinase in the present case) .
  • the general reporter construct requires the use of the transcriptional promoter from the gene of interest since this is the region of the gene that controls its expression. This promoter region is cloned in front of (at the 5' end) a gene (called a reporter) whose activity is easily measured.
  • the most common genes used as reporters include Chloramphenicol Acetyl Transferase (CAT), Luciferase, and ⁇ -Galactosidase. Each one of the genes produce proteins that have activities which can be measured accurately, and easily. in addition, the assays which have been developed are quite sensitive.
  • the basic design of the assay involves transfecting the reporter construct (Promoter from gene of interest fused to the reporter gene) into a cell line (usually mammalian) and then treating the transfected cells with the agents to be tested.
  • Agents which alter or modulate (decrease or increase) the expression from the construct relative to untreated controls are considered as potential lead compounds.
  • Preferably screens which measure the level of kinase activity will be used.
  • the following examples are intended to further illustrate the present invention and are not to be interpreted as limiting the scope thereof. While the examples and detailed description sections of the present invention are sufficient to guide anyone of ordinary skill in the art in the practice of the present invention, skilled artisans are also directed to Molecular Cloning A Laboratory Manual Second Edition, Sambrook, J. , Fritsch, E.
  • B63 which encodes amino acid residues 329-629 of BRCA-1
  • B71 which encodes amino acid residues 329-435
  • B73 which encodes amino acids 329-435
  • B74 SEQ ID NO:3
  • B90 which encodes amino acid residues 329-421
  • B102 SEQ ID NO:5
  • B72 SEQ ID NO:8
  • SEQ ID NO:9 which encodes amino acid residues 433-525.
  • BRCA-1 All fragments of BRCA-1 were generated by PCR using the full length BRCA-1 cDNA as the template.
  • the PCR fragments (with the exception of B73) were subsequently cloned into the baculovirus expression vectors containing a GST handle and were expressed using standard techniques known to those of ordinary skill in the art.
  • B73 was cloned into a similar baculovirus expression vector which lacked the GST handle.
  • the resulting proteins were used as reagents to identify proteins or activities which associate with or are a part of BRCA-1. Other regions of BRCA-1 were expressed but failed to show any associated kinase activity.
  • B63 was expressed as a fusion protein with glutathione-S-transferase (GST) whereas B73 was a later version of the same clone which was expressed without a GST handle.
  • B45 was the clone which directs the synthesis of GST.
  • Cells expressing B45, B63, B73 or full-length BRCA-1 were lysed by the addition of lysis buffer. These proteins were then captured from cell lysates using either Glutathione-Sepharose (B45 and B63) or Protein G agarose bound with BRCA-1 antibody (B73 and full-length BRCA-1) .
  • B73, B74, B90 and B102 all are substrates indicating that at least one region of phosphorylation can be defined between amino acids 329-435.
  • MCF-7 or 184-Al cells (human breast cell lines) , grown on 60 mm culture dishes, were incubated with 1.0 mCi of 32p_ or t ophosphate for 4 hours.
  • Immune complexes were captured using Protein G agarose, solubilized and resolved on a 8-16% SDS-PAGE gradient gel.
  • 32p_ ⁇ a b e ec j proteins were analyzed by autoradiography.
  • In vivo phosphorylation of BRCA-1 was confirmed by the presence of a radiolabelled band of the appropriate molecular weight (approximately 210 kDa) . No such radiolabelled band appeared in Ig
  • B63 was prepared as described previously. The Sepharose bound fragment was then incubated with either lysate from Sf9 cells or with purified preparations of either PKA, PKC or CKII (each commercially available from Boehringer Mannheim) . After a one hour incubation, the Sepharose-bound complexes were washed and then incubated with ⁇ 32p_ATP as described previously. No phosphorylation of B63 was evident in samples that were incubated with either PKA or PKC and only minor phosphorylation was observed following incubation with CKII. Thus these data indicate that PKA, PKC or CKII are not the kinases responsible for phosphorylation of exon 11.

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Abstract

La présente invention concerne une protéine kinase modulatrice de la phosphorylation de la protéine BRCA-1. L'invention concerne également l'utilisation de la protéine kinase de BRCA-1 comme cible moléculaire pour une intervention thérapeutique et/ou comme outil thérapeutique de diagnostic et de traitement du cancer du sein ou des ovaires.
PCT/US1997/001261 1996-01-29 1997-01-28 Proteine kinase de brca-1 et son utilisation WO1997027289A1 (fr)

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Non-Patent Citations (6)

* Cited by examiner, † Cited by third party
Title
"Program PROSITE at http://www.expasy.ch/tools.html.", PROSITE Version 2.1.4, 04 March 1992, PROSITE Library Version 10.2, July 1993. *
ANTICANCER RES., November-December 1993, Vol. 13, LI et al., "Evaluation of Protein Kinase Inhibitors in an Assay System Containing Multiple Protein Kinase Activities", pages 1957-1964. *
CANCER RES., 15 July 1996, Vol. 56, CHEN et al., "BRCA1 is a 220-kDA Nuclear Phosphoprotein that is Expressed and Phosphorylated in a Cell Cycle-Dependent Manner", PAGES 3168-3172. *
DATABASE MEDLINE ON STN, No. 95405860, KEYOMARSI et al., "Deregulation of Cyclin E in Breast Cancer"; & ONCOGENE, 7 September 1995, Vol. 11, No. 5, pages 941-950. *
J. MOL. BIOL., April 1993, Vol. 230, ROSENBLATT et al., "Purification and Crystallization of Human Cyclin-Dependent Kinase 2", pages 1317-1319. *
NATURE GENET., July 1996, Vol. 13, WILSON et al., "BRCA1 Protein Products: Antibody Specificity...", pages 264-265. *

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