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Signatures of ER status in breast cancer

Abstrict

The invention relates to the identification and use of gene expression profiles, or patterns, suitable for identification of populations that are positive and negative for estrogen receptor expression. The gene expression profiles may be embodied in nucleic acid expression, protein expression, or other expression formats, and may be used in the study and/or diagnosis of cells and tissue in breast cancer as well as for the study and/or determination of prognosis of a patient, including breast cancer survival.

Claims

We claim:

1. An array comprising polynucleotide probes capable of hybridizing to nucleic acid molecules of one or more of the genes listed in Table 1, 2, 3, or 4 and comprising sequences within 350 nucleotides of the polyadenylation site of said genes, said probes hybridized to nucleic acids derived from a cell of a subject afflicted with, or suspected of having, breast cancer

2. The array of claim 1 comprising 11 or more of the genes in Table 1, 2, 3, or 4.

3. The array of claim 2 comprising all the genes in Table 1, 2, 3, or 4.

4. The array of claim 1 wherein said cell is from a human subject or such a subject afflicted with breast cancer.

5. The array of claim 1 wherein said nucleic acids derived from one or more breast cancer cells are prepared by mRNA amplification.

6. The array of claim 1 wherein said nucleic acids derived from one or more breast cancer cells are cDNA.

7. The array of claim 1 wherein said cell is in a section of tissue from a subject or is microdissected from said section.

8. A method to determine the ER status of breast cancer cells in a sample from a subject comprising assaying said sample for expression of one or more genes in Table 1 or 3 and/or one or more genes in Table 2 or 4.

9. The method of claim 8 wherein said assaying comprises preparing RNA, optionally labeled, from said sample and optionally converting said RNA into cDNA, optionally labeled.

10. The method of claim 9 wherein said RNA is not labeled and used for quantitative PCR.

11. The method of claim 9 wherein said assaying comprises using an array.

12. The method of claim 8 wherein said sample is a ductal lavage or fine needle aspiration or FFPE breast tissue sample.

13. The method of claim 12 wherein said sample is microdissected to isolate one or more cells that are breast cancer cells or suspected of being breast cancer cells.

14. The method of claim 10 further comprising determination of the ratio of the expression of a gene in Table 1 or 3 to the expression of a gene in Table 2 or 4 as an indicator of ER status.

15. A method to determine therapeutic treatment for a patient having breast cancer comprising identifying said patient as being ER positive or ER negative after assaying breast cancer cells of said patient for expression of one or more genes listed in Table 1, 2, 3, and/or 4 and selecting the appropriate treatment for a patient having cells of such ER status.

16. The method of claim 15 wherein said assaying comprises preparing RNA, optionally labeled, from said sample and optionally converting said RNA into cDNA, optionally labeled.

17. The method of claim 16 wherein said RNA is not labeled and used for quantitative PCR.

18. The method of claim 16 wherein said assaying comprises using an array.

19. The method of claim 16 wherein said sample is a ductal lavage or fine needle aspiration or FFPE breast tissue sample.

20. The method of claim 19 wherein said sample is microdissected to isolate one or more cells that are breast cancer cells or suspected of being breast cancer cells.

21. The method of claim 16 wherein said assaying comprises determination of the ratio of the expression of a gene in Table 1 or 3 to the expression of a gene in Table 2 or 4 as an indicator of ER status.

Description


RELATED APPLICATIONS

[0001] This application claims benefit of priority from U.S. Provisional Patent application 60/451,942, filed Mar. 4, 2003, which is hereby incorporated by reference in its entirety as if fully set forth.

FIELD OF THE INVENTION

[0002] The invention relates to the identification and use of gene expression profiles, or patterns, involved in breast cancer survival. In particular, the invention provides the identities of genes that may be used to identify populations that are positive and negative for estrogen receptor expression. The gene expression profiles, whether embodied in nucleic acid expression, protein expression, or other expression formats, are used in the study and/or diagnosis of cells and tissue in breast cancer as well as for the study and/or determination of prognosis of a patient. The profiles may also be used in methods of diagnosis or prognosis.

BACKGROUND OF THE INVENTION

[0003] Breast cancer is by far the most common cancer among women. Each year, more than 180,000 and 1 million women in the U.S. and worldwide, respectively, are diagnosed with breast cancer. Breast cancer is the leading cause of death for women between ages 50-55, and is the most common non-preventable malignancy in women in the Western Hemisphere. An estimated 2,167,000 women in the United States are currently living with the disease (National Cancer Institute, Surveillance Epidemiology and End Results (NCI SEER) program, Cancer Statistics Review (CSR), www-seer.ims.nci.nih.gov/Publications/CSR1973 (1998)). Based on cancer rates from 1995 through 1997, a report from the National Cancer Institute (NCI) estimates that about 1 in 8 women in the United States (approximately 12.8 percent) will develop breast cancer during her lifetime (NCI's Surveillance, Epidemiology, and End Results Program (SEER) publication SEER Cancer Statistics Review 1973-1997). Breast cancer is the second most common form of cancer, after skin cancer, among women in the United States. An estimated 250,100 new cases of breast cancer are expected to be diagnosed in the United States in 2001. Of these, 192,200 new cases of more advanced (invasive) breast cancer are expected to occur among women (an increase of 5% over last year), 46,400 new cases of early stage (in situ) breast cancer are expected to occur among women (up 9% from last year), and about 1,500 new cases of breast cancer are expected to be diagnosed in men (Cancer Facts & Figures 2001 American Cancer Society). An estimated 40,600 deaths (40,300 women, 400 men) from breast cancer are expected in 2001. Breast cancer ranks second only to lung cancer among causes of cancer deaths in women. Nearly 86% of women who are diagnosed with breast cancer are likely to still be alive five years later, though 24% of them will die of breast cancer after 10 years, and nearly half (47%) will die of breast cancer after 20 years.

[0004] Every woman is at risk for breast cancer. Over 70 percent of breast cancers occur in women who have no identifiable risk factors other than age (U.S. General Accounting Office. Breast Cancer, 1971-1991: Prevention, Treatment and Research. GAO/PEMD-92-12; 1991). Only 5 to 10% of breast cancers are linked to a family history of breast cancer (Henderson I C, Breast Cancer. In: Murphy G P, Lawrence W L, Lenhard R E (eds). Clinical Oncology. Atlanta, Ga.: American Cancer Society; 1995:198-219).

[0005] Each breast has 15 to 20 sections called lobes. Within each lobe are many smaller lobules. Lobules end in dozens of tiny bulbs that can produce milk. The lobes, lobules, and bulbs are all linked by thin tubes called ducts. These ducts lead to the nipple in the center of a dark area of skin called the areola. Fat surrounds the lobules and ducts. There are no muscles in the breast, but muscles lie under each breast and cover the ribs. Each breast also contains blood vessels and lymph vessels. The lymph vessels carry colorless fluid called lymph, and lead to the lymph nodes. Clusters of lymph nodes are found near the breast in the axilla (under the arm), above the collarbone, and in the chest.

[0006] Breast tumors can be either benign or malignant. Benign tumors are not cancerous, they do not spread to other parts of the body, and are not a threat to life. They can usually be removed, and in most cases, do not come back. Malignant tumors are cancerous, and can invade and damage nearby tissues and organs. Malignant tumor cells may metastasize, entering the bloodstream or lymphatic system. When breast cancer cells metastasize outside the breast, they are often found in the lymph nodes under the arm (axillary lymph nodes). If the cancer has reached these nodes, it means that cancer cells may have spread to other lymph nodes or other organs, such as bones, liver, or lungs.

[0007] Major and intensive research has been focused on early detection, treatment and prevention. This has included an emphasis on determining the presence of precancerous or cancerous ductal epithelial cells. These cells are analyzed, for example, for cell morphology, for protein markers, for nucleic acid markers, for chromosomal abnormalities, for biochemical markers, and for other characteristic changes that would signal the presence of cancerous or precancerous cells. This has led to various molecular alterations that have been reported in breast cancer, few of which have been well characterized in human clinical breast specimens. Molecular alterations include presence/absence of estrogen and progesterone steroid receptors, HER-2 expression/amplification (Mark H F, et al. HER-2/neu gene amplification in stages I-IV breast cancer detected by fluorescent in situ hybridization. Genet Med; 1(3):98-103 1999), Ki-67 (an antigen that is present in all stages of the cell cycle except G0 and used as a marker for tumor cell proliferation, and prognostic markers (including oncogenes, tumor suppressor genes, and angiogenesis markers) like p53, p27, Cathepsin D, pS2, multi-drug resistance (MDR) gene, and CD31.

[0008] Estrogen receptor (ER) status has been of particular interest because it has been correlated with prognosis and treatment regimens. Generally speaking, patients identified as having ER positive breast cancer biopsies have a better overall survival expectation while patients with ER negative biopsies are treated more aggressively, such as with immediate chemotherapy after surgical intervention, because of a poor prognosis.

[0009] Citation of documents herein is not intended as an admission that any is pertinent prior art. All statements as to the date or representation as to the contents of documents is based on the information available to the applicant and does not constitute any admission as to the correctness of the dates or contents of the documents.

SUMMARY OF THE INVENTION

[0010] The present invention relates to the identification and use of gene expression patterns (or profiles or "signatures") which are correlated with (and thus able to discriminate between) cells that are positive or negative for estrogen receptor (ER) expression in breast cancer specimens. The patterns may thus serve as a supplement to assays for ER status in breast cancer samples or used as a substitute for known assays for ER status. The patterns may thus be used in diagnostic or prognostic methods or assays in the clinic to determine the course of treatment following identification of the presence of breast cancer or subsequent surgical removal thereof.

[0011] The patterns also provide the identity of genes that may be the focus of therapeutic efforts to identify agents and treatment methods to alleviate the severity of breast cancer, improve the chances for surviving breast cancer, and/or decrease the chances of breast cancer recurrence or metastases. Such agents and methods may be used to increase or decrease the expression of one or more genes of the patterns to restore cells to a less cancerous state or a state with a better prognosis for the patient. The patterns may also be used to identify cellular mechanisms or pathways, as well as the components of such mechanisms or pathways, to be altered or modulated in the treatment of breast cancer.

[0012] The present invention provides a non-subjective means for the identification of ER status in breast cancer samples by assaying for the expression patterns associated with ER status. Thus subjective interpretation is necessary and a more accurate assessment of ER status, and breast cancer status and prognosis, is provided. Furthermore, the expression patterns can also be used as a means to assay small, node negative tumors that are not readily assayed by other means.

[0013] The gene expression patterns comprise one or more than one gene capable of discriminating between breast cancer that is ER positive or ER negative with significant accuracy. The gene(s) are identified as correlated with ER expression status in breast cancer such that the levels of their expression are relevant to a determination of ER status in breast cancer of a cell. Thus in one aspect, the invention provides a method to determine the ER status of breast cancer of a subject afflicted with, or suspected of having, breast cancer by assaying a cell containing sample from said subject for expression of one or more than one gene disclosed herein as correlated with ER status in breast cancer.

[0014] Gene expression patterns of the invention are identified by analysis of gene expression in multiple samples of ER positive and ER negative samples from breast cancer biopsies. The overall gene expression profile of a sample is obtained through quantifying the expression levels of mRNA corresponding to multiple genes to identify genes that are positively, or negatively, correlated, with ER positive and ER negative sample.

[0015] A profile of genes that are highly correlated with ER status may be used to assay an sample from a subject afflicted with, or suspected of having, breast cancer to identify the ER status of breast cancer to which the sample belongs. This may be done in combination with, or separate from a direct assay for ER expression. Such assays may be used as part of a method to determine the therapeutic treatment for said subject based upon the ER status identified. The present invention also provides for the advantageous ability to determine ER status in combination with other information to provide more detailed information in diagnosing and treating breast cancer.

[0016] The correlated genes may be used singly with significant accuracy or in combination to increase the ability to accurately identify ER status. The present invention thus provides means for correlating a molecular expression phenotype with ER expression and thus a physiological (cellular) state. This correlation also provides a way to molecularly diagnose and/or monitor a cell's status. Additional uses of the correlated gene(s) are in the classification of cells and tissues; determination of diagnosis and/or prognosis; and determination and/or alteration of therapy.

[0017] An assay of the invention may utilize a means related to the expression level of the sequences disclosed herein as long as the assay reflects, quantitatively or qualitatively, expression of the sequence. Preferably, however, a quantitative assay means is preferred. The ability to discriminate is conferred by the identification of expression of the individual genes as relevant and not by the form of the assay used to determine the actual level of expression. An assay may utilize any identifying feature of an identified individual gene as disclosed herein as long as the assay reflects, quantitatively or qualitatively, expression of the gene. Identifying features include, but are not limited to, unique nucleic acid sequences used to encode (DNA), or express (RNA), said gene or epitopes specific to, or activities of, a protein encoded by said gene. Alternative means include detection of nucleic acid amplification as indicative of increased expression levels and nucleic acid inactivation, deletion, or methylation, as indicative of decreased expression levels. Stated differently, the invention may be practiced by assaying one or more aspect of the DNA template(s) underlying the expression of the disclosed sequence(s), of the RNA used as an intermediate to express the sequence(s), or of the proteinaceous product expressed by the sequence(s), as well as proteolytic fragments of such products. As such, the detection of the presence of, amount of, stability of, or degradation (including rate) of, such DNA, RNA and proteinaceous molecules may be used in the practice of the invention. As such, all that is required is the identity of the gene(s) necessary to discriminate between ER positive and negative samples and an appropriate cell containing sample for use in an expression assay.

[0018] In one aspect, the invention provides for the identification of the gene expression patterns by analyzing global, or near global, gene expression from single cells or homogenous cell populations which have been dissected away from, or otherwise isolated or purified from, contaminating cells beyond that possible by a simple biopsy. Because the expression of numerous genes fluctuate between cells from different patients as well as between cells from the same patient sample, the expression of multiple individual genes may be analyzed to for the best the ability to discriminate ER positive and negative samples.

[0019] In a further aspect, the gene(s) capable of discriminating between ER positive and negative samples may be used to identify ER status of an unknown sample of cell(s) from the breast. Preferably, the sample is isolated via non-invasive means. The expression of said gene(s) in said unknown sample may be determined and compared to the expression of said gene(s) in reference data of gene expression patterns from ER positive and/or negative samples. Alternatively, the expression level may be compared to expression levels in normal or non-cancerous cells, preferably from the same sample or subject. In embodiments of the invention utilizing quantitative PCR, the expression level may be compared to expression levels of reference genes in the same sample or a ratio of expression levels may be used. The invention provides for ratios of the expression level of a sequence that is under expressed to the expression level of a sequence that is over expressed as a indicator of ER positive or ER negative status. The use of a ratio can reduce comparisons with normal or non-cancerous cells.

[0020] One advantage provided by the present invention is that contaminating, non-breast cells (such as infiltrating lymphocytes or other immune system cells) are not present to possibly affect the genes identified or the subsequent analysis of gene expression to identify the status of suspected breast cancer cells. Such contamination is present where a biopsy is used to generate gene expression profiles.

[0021] While the present invention has been described mainly in the context of human breast cancer, it may be practiced in the context of breast cancer of any animal known to be potentially afflicted by breast cancer. Preferred animals for the application of the present invention are mammals, particularly those important to agricultural applications (such as, but not limited to, cattle, sheep, horses, and other "farm animals") and for human companionship (such as, but not limited to, dogs and cats).

DETAILED DESCRIPTION OF THE SPECIFIC EMBODIMENTS

[0022] Definitions of Terms as Used Herein:

[0023] A gene expression "pattern" or "profile" or "signature" refers to the relative expression of a gene between ER positive and negative cells which expression is correlated with being able to distinguish between ER positive and negative cells.

[0024] A "gene" is a polynucleotide that encodes a discrete product, whether RNA or proteinaceous in nature. It is appreciated that more than one polynucleotide may be capable of encoding a discrete product. The term includes alleles and polymorphisms of a gene that encodes the same product, or a functionally associated (including gain, loss, or modulation of function) analog thereof, based upon chromosomal location and ability to recombine during normal mitosis.

[0025] A "sequence" or "gene sequence" as used herein is a nucleic acid molecule or polynucleotide composed of a discrete order of nucleotide bases. The term includes the ordering of bases that encodes a discrete product (i.e. "coding region"), whether RNA or proteinaceous in nature, as well as the ordered bases that precede or follow a "coding region". Non-limiting examples of the latter include 5' and 3' untranslated regions of a gene. It is appreciated that more than one polynucleotide may be capable of encoding a discrete product. It is also appreciated that alleles and polymorphisms of the disclosed sequences may exist and may be used in the practice of the invention to identify the expression level(s) of the disclosed sequences or the allele or polymorphism. Identification of an allele or polymorphism depends in part upon chromosomal location and ability to recombine during mitosis.

[0026] The terms "correlate" or "correlation" or equivalents thereof refer to an association between expression of one or more genes and the ER status of a breast cancer cell and/or a breast cancer patient. A gene may be expressed at higher or lower levels and still be correlated with ER status and thus breast cancer survival or outcome. The invention provides for the correlation between increases, as well as decreases, in expression of gene sequences and ER positive or negative status. Increases and decreases may be readily expressed in the form of a ratio between expression in a non-normal cell and a normal cell such that a ratio of one (1) indicates no difference while ratios of two (2) and one-half indicate twice as much, and half as much, expression in the non-normal cell versus the normal cell, respectively. Expression levels can be readily determined by quantitative methods as described below.

[0027] For example, increases in gene expression can be indicated by ratios of or about 1.1, of or about 1.2, of or about 1.3, of or about 1.4, of or about 1.5, of or about 1.6, of or about 1.7, of or about 1.8, of or about 1.9, of or about 2, of or about 2.5, of or about 3, of or about 3.5, of or about 4, of or about 4.5, of or about 5, of or about 5.5, of or about 6, of or about 6.5, of or about 7, of or about 7.5, of or about 8, of or about 8.5, of or about 9, of or about 9.5, of or about 10, of or about 15, of or about 20, of or about 30, of or about 40, of or about 50, of or about 60, of or about 70, of or about 80, of or about 90, of or about 100, of or about 150, of or about 200, of or about 300, of or about 400, of or about 500, of or about 600, of or about 700, of or about 800, of or about 900, or of or about 1000. A ratio of 2 is a 100% (or a two-fold) increase in expression. Decreases in gene expression can be indicated by ratios of or about 0.9, of or about 0.8, of or about 0.7, of or about 0.6, of or about 0.5, of or about 0.4, of or about 0.3, of or about 0.2, of or about 0.1, of or about 0.05, of or about 0.01, of or about 0.005, of or about 0.001, of or about 0.0005, of or about 0.0001, of or about 0.00005, of or about 0.00001, of or about 0.000005, or of or about 0.000001.

[0028] For a given phenotype, a ratio of the expression of a gene sequence expressed at increased levels in correlation with an ER status to the expression of a gene sequence expressed at decreased levels in correlation with the ER status may also be used as an indicator of the phenotype. As a non-limiting example, the ER positive status may be correlated with increased expression of a gene sequence over expressed in ER positive cells as well as decreased expression of a gene sequence under expressed in ER positive cells. Therefore, a ratio of the expression levels of the under expressed sequence to the expression levels of the over expressed sequence may be used as an indicator of ER status. Ratios comprising gene sequences that are differentially expressed in ER negative cells may also be used.

[0029] A "polynucleotide" is a polymeric form of nucleotides of any length, either ribonucleotides or deoxyribonucleotides. This term refers only to the primary structure of the molecule. Thus, this term includes double- and single-stranded DNA and RNA. It also includes known types of modifications including labels known in the art, methylation, "caps", substitution of one or more of the naturally occurring nucleotides with an analog, and internucleotide modifications such as uncharged linkages (e.g., phosphorothioates, phosphorodithioates, etc.), as well as unmodified forms of the polynucleotide.

[0030] The term "amplify" is used in the broad sense to mean creating an amplification product can be made enzymatically with DNA or RNA polymerases. "Amplification," as used herein, generally refers to the process of producing multiple copies of a desired sequence, particularly those of a sample. "Multiple copies" mean at least 2 copies. A "copy" does not necessarily mean perfect sequence complementarity or identity to the template sequence.

[0031] By corresponding is meant that a nucleic acid molecule shares a substantial amount of sequence identity with another nucleic acid molecule. Substantial amount means at least 95%, usually at least 98% and more usually at least 99%, and sequence identity is determined using the BLAST algorithm, as described in Altschul et al. (1990), J. Mol. Biol. 215:403-410 (using the published default setting, i.e. parameters w=4, t=17). Methods for amplifying mRNA are generally known in the art, and include reverse transcription PCR (RT-PCR) and those described in U.S. patent application Ser. No. 10/062,857 (filed on Oct. 25, 2001), as well as U.S. Provisional Patent Applications 60/298,847 (filed Jun. 15, 2001) and 60/257,801 (filed Dec. 22, 2000), all of which are hereby incorporated by reference in their entireties as if fully set forth. Another method which may be used is quantitative PCR (or Q-PCR). Alternatively, RNA may be directly labeled as the corresponding cDNA by methods known in the art.

[0032] A "microarray" is a linear or two-dimensional array of preferably discrete regions, each having a defined area, formed on the surface of a solid support such as, but not limited to, glass, plastic, or synthetic membrane. The density of the discrete regions on a microarray is determined by the total numbers of immobilized polynucleotides to be detected on the surface of a single solid phase support, preferably at least about 50/cm.sup.2, more preferably at least about 100/cm.sup.2, even more preferably at least about 500/cm.sup.2, but preferably below about 1,000/cm.sup.2. Preferably, the arrays contain less than about 500, about 1000, about 1500, about 2000, about 2500, or about 3000 immobilized polynucleotides in total. As used herein, a DNA microarray is an array of oligonucleotides or polynucleotides placed on a chip or other surfaces used to hybridize to amplified or cloned polynucleotides from a sample. Since the position of each particular group of primers in the array is known, the identities of a sample polynucleotides can be determined based on their binding to a particular position in the microarray.

[0033] Because the invention relies upon the identification of genes that are over- or under-expressed, one embodiment of the invention involves determining expression by hybridization of mRNA, or an amplified or cloned version thereof, of a sample cell to a polynucleotide that is unique to a particular gene sequence. Preferred polynucleotides of this type contain at least about 20, at least about 22, at least about 24, at least about 26, at least about 28, at least about 30, or at least about 32 consecutive base pairs of a gene sequence that is not found in other gene sequences. The term "about" as used in the previous sentence refers to an increase or decrease of 1 from the stated numerical value. Even more preferred are polynucleotides of at least or about 50, at least or about 100, at least about or 150, at least or about 200, at least or about 250, at least or about 300, at least or about 350, or at least or about 400 base pairs of a gene sequence that is not found in other gene sequences. The term "about" as used in the preceding sentence refers to an increase or decrease of 10% from the stated numerical value. Such polynucleotides may also be referred to as polynucleotide probes that are capable of hybridizing to sequences of the genes, or unique portions thereof, described herein. Preferably, the sequences are those of mRNA encoded by the genes, the corresponding cDNA to such mRNAs, and/or amplified versions of such sequences. In preferred embodiments of the invention, the polynucleotide probes are immobilized on an array, other devices, or in individual spots that localize the probes.

[0034] In another embodiment of the invention, all or part of a disclosed sequence may be amplified and detected by methods such as the polymerase chain reaction (PCR) and variations thereof, such as, but not limited to, quantitative PCR (Q-PCR), reverse transcription PCR (RT-PCR), and real-time PCR (including as a means of measuring the initial amounts of mRNA copies for each sequence in a sample), optionally real-time RT-PCR or real-time Q-PCR. Such methods would utilize one or two primers that are complementary to portions of a disclosed sequence, where the primers are used to prime nucleic acid synthesis. The newly synthesized nucleic acids are optionally labeled and may be detected directly or by hybridization to a polynucleotide of the invention. The newly synthesized nucleic acids may be contacted with polynucleotides (containing sequences) of the invention under conditions which allow for their hybridization. Additional methods to detect the expression of expressed nucleic acids include RNAse protection assays, including liquid phase hybridizations, and in situ hybridization of cells.

[0035] Alternatively, and in yet another embodiment of the invention, gene expression may be determined by analysis of expressed protein in a cell sample of interest by use of one or more antibodies specific for one or more epitopes of individual gene products (proteins), or proteolytic fragments thereof, in said cell sample or in a bodily fluid of a subject. The cell sample may be one of breast cancer epithelial cells enriched from the blood of a subject, such as by use of labeled antibodies against cell surface markers followed by fluorescence activated cell sorting (FACS). Such antibodies are preferably labeled to permit their easy detection after binding to the gene product. Detection methodologies suitable for use in the practice of the invention include, but are not limited to, immunohistochemistry of cell containing samples or tissue, enzyme linked immunosorbent assays (ELISAs) including antibody sandwich assays of cell containing tissues or blood samples, mass spectroscopy, and immuno-PCR.

[0036] The term "label" refers to a composition capable of producing a detectable signal indicative of the presence of the labeled molecule. Suitable labels include radioisotopes, nucleotide chromophores, enzymes, substrates, fluorescent molecules, chemiluminescent moieties, magnetic particles, bioluminescent moieties, and the like. As such, a label is any composition detectable by spectroscopic, photochemical, biochemical, immunochemical, electrical, optical or chemical means.

[0037] The term "support" refers to conventional supports such as beads, particles, dipsticks, fibers, filters, membranes and silane or silicate supports such as glass slides.

[0038] As used herein, a "breast tissue sample" or "breast cell sample" refers to a sample of breast tissue or fluid isolated from an individual suspected of being afflicted with, or at risk of developing, breast cancer. Such samples are primary isolates (in contrast to cultured cells) and may be collected by any non-invasive means, including, but not limited to, ductal lavage, fine needle aspiration, needle biopsy, the devices and methods described in U.S. Pat. No. 6,328,709, or any other suitable means recognized in the art. Alternatively, the "sample" may be collected by an invasive method, including, but not limited to, surgical biopsy. A sample of the invention may also be one that has been formalin fixed and paraffin embedded (FFPE).

[0039] "Expression" and "gene expression" include transcription and/or translation of nucleic acid material.

[0040] As used herein, the term "comprising" and its cognates are used in their inclusive sense; that is, equivalent to the term "including" and its corresponding cognates.

[0041] Conditions that "allow" an event to occur or conditions that are "suitable" for an event to occur, such as hybridization, strand extension, and the like, or "suitable" conditions are conditions that do not prevent such events from occurring. Thus, these conditions permit, enhance, facilitate, and/or are conducive to the event. Such conditions, known in the art and described herein, depend upon, for example, the nature of the nucleotide sequence, temperature, and buffer conditions. These conditions also depend on what event is desired, such as hybridization, cleavage, strand extension or transcription.

[0042] Sequence "mutation," as used herein, refers to any sequence alteration in the sequence of a gene disclosed herein interest in comparison to a reference sequence. A sequence mutation includes single nucleotide changes, or alterations of more than one nucleotide in a sequence, due to mechanisms such as substitution, deletion or insertion. Single nucleotide polymorphism (SNP) is also a sequence mutation as used herein. Because the present invention is based on the relative level of gene expression, mutations in non-coding regions of genes as disclosed herein may also be assayed in the practice of the invention.

[0043] "Detection" includes any means of detecting, including direct and indirect detection of gene expression and changes therein. For example, "detectably less" products may be observed directly or indirectly, and the term indicates any reduction (including the absence of detectable signal). Similarly, "detectably more" product means any increase, whether observed directly or indirectly.

[0044] Increases and decreases in expression of the disclosed sequences are defined in the following terms based upon percent or fold changes over expression in normal cells. Increases may be of 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, or 200% relative to expression levels in normal cells. Alternatively, fold increases may be of 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, or 10 fold over expression levels in normal cells. Decreases may be of 10, 20, 30, 40, 50, 55, 60, 65, 70, 75, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 99 or 100% relative to expression levels in normal cells.

[0045] Unless defined otherwise all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs.

SPECIFIC EMBODIMENTS

[0046] The present invention relates to the identification and use of gene expression patterns (or profiles or "signatures") which discriminate between (or are correlated with) breast cancer cells that are ER positive or negative, preferably ER.alpha. positive or negative. Because the overall gene expression profile differs from person to person, cancer to cancer, and cancer cell to cancer cell, correlations between genes expressed or under expressed in ER positive and negative cells are capable of identifying ER status. ER status has been used as a factor in determinations of therapeutic treatment of patients with breast cancer. For example, ER positive status has been used as an indicator of responsiveness to treatment with tamoxifen and other selective estrogen receptor modulators (SERMs).

[0047] The present invention may be practiced with any subset of the genes disclosed herein. Gene expression in cells of breast cancer biopsies were used to identify thousands of genes capable of discriminating between ER positive and negative breast cancer cells as described in the following Example. The identification may be made by using expression profiles of various homogenous breast cancer cell populations, which are optionally isolated by microdissection, such as, but not limited to, laser capture microdissection (LCM) of 100-1000 cells.

[0048] Genes that are identified as being expressed differently between ER positive and ER negative cells may be analyzed by standard statistical analysis, such as the t-test, to assign a value for the significance of the difference. Genes with a significance above a particular threshold may be included in a pattern that segregates breast cancer based on ER status.

[0049] The expression of other genes in a breast cancer cell would be relatively unable to provide information concerning, and thus assist in the discrimination of ER status in breast cancer.

[0050] To determine the (increased or decreased) expression levels of genes in the practice of the present invention, any method known in the art may be utilized. In one preferred embodiment of the invention, expression based on detection of RNA which hybridizes to the genes identified and disclosed herein is used. This is readily performed by any RNA detection or amplification+detection method known or recognized as equivalent in the art such as, but not limited to, reverse transcription-PCR, the methods disclosed in U.S. patent application Ser. No. 10/062,857 (filed on Oct. 25, 2001) as well as U.S. Provisional Patent Applications 60/298,847 (filed Jun. 15, 2001) and 60/257,801 (filed Dec. 22, 2000), and methods to detect the presence, or absence, of RNA stabilizing or destabilizing sequences.

[0051] Alternatively, expression based on detection of DNA status may be used. Detection of the DNA of an identified gene as methylated or deleted may be used for genes that have decreased expression in correlation with ER status. This may be readily performed by PCR based methods known in the art, including, but not limited to, quantitative PCR (Q-PCR). Conversely, detection of the DNA of an identified gene as amplified may be used for genes that have increased expression in correlation with ER status. This may be readily performed by PCR based, fluorescent in situ hybridization (FISH) and chromosome in situ hybridization (CISH) methods known in the art.

[0052] Expression based on detection of a presence, increase, or decrease in protein levels or activity may also be used. Detection may be performed by any immunohistochemistry (IHC) based, blood based (especially for secreted proteins), antibody (including autoantibodies against the protein) based, ex foliate cell (from the cancer) based, mass spectroscopy based, and image (including used of labeled ligand) based method known in the art and recognized as appropriate for the detection of the protein. Antibody and image based methods are additionally useful for the localization of tumors after determination of cancer by use of cells obtained by a non-invasive procedure (such as ductal lavage or fine needle aspiration), where the source of the cancerous cells is not known. A labeled antibody or ligand may be used to localize the carcinoma(s) within a patient.

[0053] A preferred embodiment using a nucleic acid based assay to determine expression is by immobilization of one or more sequences of the genes identified herein on a solid support, including, but not limited to, a solid substrate as an array or to beads or bead based technology as known in the art. Alternatively, solution based expression assays known in the art may also be used. The immobilized gene(s) may be in the form of polynucleotides that are unique or otherwise specific to the gene(s) such that the polynucleotide would be capable of hybridizing to a DNA or RNA corresponding to the gene(s). These polynucleotides may be the full length of the gene(s) or be short sequences of the genes (up to one nucleotide shorter than the full length sequence known in the art by deletion from the 5' or 3' end of the sequence) that are optionally minimally interrupted (such as by mismatches or inserted non-complementary base pairs) such that hybridization with a DNA or RNA corresponding to the gene(s) is not affected. Preferably, the polynucleotides used are from the 3' end of the gene, such as within about 350, about 300, about 250, about 200, about 150, about 100, or about 50 nucleotides from the polyadenylation signal or polyadenylation site of a gene or expressed sequence. Polynucleotides containing mutations relative to the sequences of the disclosed genes may also be used so long as the presence of the mutations still allows hybridization to produce a detectable signal.

[0054] Alternatively, amplification of such sequences from the 3' end of genes by methods such as quantitative PCR may be used to determine the expression levels of the sequences. The Ct values generated by such methods may be used to generate the ratios of expression levels as described herein.

[0055] The immobilized gene(s) may be used to determine the state of nucleic acid samples prepared from sample breast cell(s) for which the ER status is not known or for confirmation of a status that is already assigned to the sample breast cell(s). Without limiting the invention, such a cell may be from a patient suspected of being afflicted with, or at risk of developing, breast cancer. The immobilized polynucleotide(s) need only be sufficient to specifically hybridize, optionally under stringent conditions, to the corresponding nucleic acid molecules derived from the sample. While even a single correlated gene sequence may to able to provide adequate accuracy in discriminating between ER status, two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, ten or more, or eleven or more of the genes identified herein may be used as a subset capable of discriminating may be used in combination to increase the accuracy of the method. The invention specifically contemplates the selection of more than one, two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, ten or more, or eleven or more of the genes disclosed in the tables and figures herein for use as a subset in the identification of whether a breast cancer sample is ER positive or negative.

[0056] Of course 15 or more, 20 or more, 30 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, 90 or more, 100 or more, 150 or more, 200 or more, 250 or more, 300 or more, 350 or more, 400 or more, 450 or more, 500 or more, 600 or more, 700 or more, 800 or more, 900 or more, 1000 or more, or all the genes provided in Table 1 or 2 below may be used. Additionally, genes that identify ER positive and ER negative may be used together to permit differential identification of a test sample as being ER positive or ER negative.

[0057] In embodiments where only one or a few genes are to be analyzed, the nucleic acid derived from the sample breast cancer cell(s) may be preferentially amplified by use of appropriate primers such that only the genes to be analyzed are amplified to reduce contaminating background signals from other genes expressed in the breast cell. Alternatively, and where multiple genes are to be analyzed or where very few cells (or one cell) is used, the nucleic acid from the sample may be globally amplified before hybridization to the immobilized polynucleotides. Of course RNA, or the cDNA counterpart thereof may be directly labeled and used, without amplification, by methods known in the art.

[0058] The invention is preferably practiced with unique sequences present within the gene sequences disclosed herein. The uniqueness of a disclosed gene sequence refers to the portions or entireties of the sequences which are found in each gene to the exclusion of other genes. Such unique sequences include those found at the 3' untranslated portion of the genes. Preferred unique sequences for the practice of the invention are those which contribute to the consensus sequences for each gene such that the unique sequences will be useful in detecting expression in a variety of individuals rather than being specific for a polymorphism present in some individuals. Alternatively, sequences unique to an individual or a subpopulation may be used. The preferred unique sequences are preferably of the lengths of polynucleotides of the invention as discussed herein.

[0059] In particularly preferred embodiments of the invention, polynucleotides having sequences present in the 3' untranslated and/or non-coding regions of the disclosed gene sequences are used to detect expression levels in breast cells. Such polynucleotides may optionally contain sequences found in the 3' portions of the coding regions of the disclosed sequences. Polynucleotides containing a combination of sequences from the coding and 3' non-coding regions preferably have the sequences arranged contiguously, with no intervening heterologous sequence(s).

[0060] Alternatively, the invention may be practiced with polynucleotides having sequences present in the 5' untranslated and/or non-coding regions of gene sequences in breast cells to detect their levels of expression. Such polynucleotides may optionally contain sequences found in the 5' portions of the coding regions. Polynucleotides containing a combination of sequences from the coding and 5' non-coding regions preferably have the sequences arranged contiguously, with no intervening heterologous sequence(s). The invention may also be practiced with sequences present in the coding regions of disclosed sequences.

[0061] Preferred polynucleotides contain sequences from 3' or 5' untranslated and/or non-coding regions of at least about 16, at least about 18, at least about 20, at least about 22, at least about 24, at least about 26, at least about 28, at least about 30, at least about 32, at least about 34, at least about 36, at least about 38, at least about 40, at least about 42, at least about 44, or at least about 46 consecutive nucleotides. The term "about" as used in the previous sentence refers to an increase or decrease of 1 from the stated numerical value. Even more preferred are polynucleotides containing sequences of at least or about 50, at least or about 100, at least about or 150, at least or about 200, at least or about 250, at least or about 300, at least or about 350, or at least or about 400 consecutive nucleotides. The term "about" as used in the preceding sentence refers to an increase or decrease of 10% from the stated numerical value.

[0062] Sequences from the 3' or 5' end of the above described coding regions as found in polynucleotides of the invention are of the same lengths as those described above, except that they would naturally be limited by the length of the coding region. The 3' end of a coding region may include sequences up to the 3' half of the coding region. Conversely, the 5' end of a coding region may include sequences up the 5' half of the coding region. Of course the above described sequences, or the coding regions and polynucleotides containing portions thereof, may be used in their entireties.

[0063] Polynucleotides combining the sequences from a 3' untranslated and/or non-coding region and the associated 3' end of the coding region are preferably at least or about 100, at least about or 150, at least or about 200, at least or about 250, at least or about 300, at least or about 350, or at least or about 400 consecutive nucleotides. Preferably, the polynucleotides used are from the 3' end of the gene, such as within about 350, about 300, about 250, about 200, about 150, about 100, or about 50 nucleotides from the polyadenylation signal or polyadenylation site of a gene or expressed sequence. Polynucleotides containing mutations relative to the sequences of the disclosed genes may also be used so long as the presence of the mutations still allows hybridization to produce a detectable signal.

[0064] In another embodiment of the invention, polynucleotides containing deletions of nucleotides from the 5' and/or 3' end of the above disclosed sequences may be used. The deletions are preferably of 1-5, 5-10, 10-15, 15-20, 20-25, 25-30, 30-35, 35-40, 40-45, 45-50, 50-60, 60-70, 70-80, 80-90, 90-100, 100-125, 125-150, 150-175, or 175-200 nucleotides from the 5' and/or 3' end, although the extent of the deletions would naturally be limited by the length of the disclosed sequences and the need to be able to use the polynucleotides for the detection of expression levels.

[0065] Other polynucleotides of the invention from the 3' end of the above disclosed sequences include those of primers and optional probes for quantitative PCR. Preferably, the primers and probes are those which amplify a region less than about 350, less than about 300, less than about 250, less than about 200, less than about 150, less than about 100, or less than about 50 nucleotides from the from the polyadenylation signal or polyadenylation site of a gene or expressed sequence.

[0066] In yet another embodiment of the invention, polynucleotides containing portions of the above disclosed sequences including the 3' end may be used in the practice of the invention. Such polynucleotides would contain at least or about 50, at least or about 100, at least about or 150, at least or about 200, at least or about 250, at least or about 300, at least or about 350, or at least or about 400 consecutive nucleotides from the 3' end of the disclosed sequences.

[0067] The above assay embodiments may be used in a number of different ways to identify or detect ER status in a breast cancer cell sample from a patient. In many cases, this may reflect a secondary screen for the patient, who may have already undergone mammography or physical exam as a primary screen. If positive, the subsequent needle biopsy, ductal lavage, fine needle aspiration, or other analogous methods may provide the sample for use in the above assay embodiments. The present invention is particularly useful in combination with non-invasive protocols, such as ductal lavage or fine needle aspiration, to prepare a breast cell sample.

[0068] The present invention provides an objective set of criteria, in the form of gene expression profiles of a discrete set of genes, to discriminate (or delineate) between ER positive and negative breast cancer cells.

[0069] In one embodiment of the invention, the isolation and analysis of a breast cancer cell sample may be performed as follows:

[0070] (1) Ductal lavage or other non-invasive procedure is performed on a patient to obtain a sample.

[0071] (2) Sample is prepared and coated onto a microscope slide. Note that ductal lavage results in clusters of cells that are cytologically examined as stated above.

[0072] (3) Pathologist or image analysis software scans the sample for the presence of non-normal and/or atypical cells.

[0073] (4) If non-normal and/or atypical cells are observed, those cells are harvested (e.g. by microdissection such as LCM).

[0074] (5) RNA is extracted from the harvested cells.

[0075] (6) RNA is purified, amplified, and labeled.

[0076] (7) Labeled nucleic acid is contacted with a microarray containing polynucleotides of the genes identified herein as correlated to discriminations between ER status under hybridization conditions to allow hybridization to occur, then processed and scanned to obtain a pattern of intensities of each spot (relative to a control for general gene expression in cells) which determine the level of expression of the gene(s) in the cells.

[0077] (8) The pattern of intensities is analyzed by comparison to the expression patterns of the genes in known samples of ER positive and negative breast cancer cells (relative to the same control).

[0078] A specific example of the above method would be performing ductal lavage following a primary screen, observing and collecting non-normal and/or atypical cells for analysis. The comparison to known expression patterns, such as that made possible by a model based on the disclosed genes and patterns, identifies the cells as being ER positive or negative.

[0079] Alternatively, the sample may permit the collection of both normal as well as non-normal and/or atypical cells for analysis. The gene expression patterns for each of these two samples will be compared to each other as well as the model and the normal versus individual abnormal comparisons therein based upon the reference data set. This approach can be significantly more powerful that the non-normal and/or atypical cells only approach because it utilizes significantly more information from the normal cells and the differences between normal and non-normal/atypical cells (in both the sample and reference data sets) to determine the status of the non-normal and/or atypical cells from the sample.

[0080] With use of the present invention, skilled physicians may prescribe treatments based on non-invasive samples that they would have prescribed for a patient which had previously received a diagnosis via a solid tissue biopsy.

[0081] The above discussion is also applicable where a palpable lesion is detected followed by fine needle aspiration or needle biopsy of cells from the breast. The cells are plated and reviewed by a pathologist or automated imaging system which selects cells for analysis as described above.

[0082] The present invention may also be used, however, with solid tissue biopsies. For example, a solid biopsy may be collected and prepared for visualization followed by determination of expression of one or more genes identified herein to determine ER status in breast cancer. One preferred means is by use of in situ hybridization with polynucleotide or protein identifying probe(s) for assaying expression of said gene(s).

[0083] In an alternative method, the solid tissue biopsy may be used to extract molecules followed by analysis for expression of one or more gene(s). This provides the ability to leave out the need for visualization and collection of only those cells suspected of being non-normal and/or atypical. This method may of course be modified such that only cells suspected of being non-normal and/or atypical are collected and used to extract molecules for analysis. This would require visualization and selection as an prerequisite to gene expression analysis.

[0084] In a further modification of the above, both normal cells and cells suspected of being non-normal and/or atypical are collected and used to extract molecules for analysis of gene expression. The approach, benefits and results are as described above using non-invasive sampling.

[0085] The genes identified herein may be used to generate a model capable of predicting the breast cancer ER statis of an unknown breast cell sample based on the expression of the identified genes in the sample.

[0086] The detection of gene expression from the samples may be by use of a single microarray able to assay gene expression of the genes disclosed herein, whether correlated with ER positive or negative status.

[0087] Other uses of the present invention include providing the ability to identify breast cancer cell samples as being those of ER positive or negative for further research or study. This provides a particular advantage in many contexts requiring the identification of breast cancer ER status based on objective genetic or molecular criteria.

[0088] The materials for use in the methods of the present invention are ideally suited for preparation of kits produced in accordance with well known procedures. The invention thus provides kits comprising agents for the detection of expression of the disclosed genes for identifying breast cancer ER status. Such kits optionally comprising the agent with an identifying description or label or instructions relating to their use in the methods of the present invention, is provided. Such a kit may comprise containers, each with one or more of the various reagents (typically in concentrated form) utilized in the methods, including, for example, pre-fabricated microarrays, buffers, the appropriate nucleotide triphosphates (e.g., dATP, dCTP, dGTP and dTTP; or rATP, rCTP, rGTP and UTP), reverse transcriptase, DNA polymerase, RNA polymerase, and one or more primer complexes of the present invention (e.g., appropriate length poly(T) or random primers linked to a promoter reactive with the RNA polymerase). A set of instructions will also typically be included.

[0089] The methods provided by the present invention may also be automated in whole or in part. All aspects of the present invention may also be practiced such that they consist essentially of a subset of the disclosed genes to the exclusion of material irrelevant to the identification of ER status.

[0090] The present invention also provides for the use of the gene product of one or more of the disclosed gene in the identification of agents that increase or decrease the expression of, or the activity of, said gene product. Methods of identifying such agents are preferably used to identify agents that will return the expression of, or the activity of, a gene product to a more normal level as opposed to the level seen in ER positive or negative cell. Most preferred is the return of an ER negative cell to normalcy in light of the poor prognosis for patients with ER negative status.

[0091] Such methods may be used to identify agents that decrease the expression of, or the activity of, a gene product encoded by a gene that is over expressed in ER positive or ER negative cells. Alternatively, such methods may be used to identify agents that increase the expression of, or the activity of, a gene product encoded by a gene that is under expressed in ER positive or ER negative cells.

[0092] The following tables set forth the genes of the invention. For example, Tables 1 and 3 include the ESR1 (estrogen receptor alpha) gene. "CloneID" as used in the context of the present invention refers to the IMAGE Consortium clone ID number of each gene, the sequences of which are hereby incorporated by reference in their entireties as they are available from the Consortium at image.llnl.gov as accessed on the filing date of the present application. "GeneID" as used in the context of the Tables herein as well as the present invention refers to the GenBank accession number of a sequence of each gene, the sequences of which are hereby incorporated by reference in their entireties as they are available from GenBank as accessed on the filing date of the present application.

[0093] P value refers to values assigned as described in the Example below. The indications of "E-xx" where "xx" is a two digit number refers to alternative notation for exponential figures where "E-xx" is "10.sup.-xx". Thus in combination with the numbers to the left of "E-xx", the value being represented is the numbers to the left times 10.sup..times.xx. Chromosome Location refers to the human chromosome to which the gene has been assigned. Description provides a brief identifier of what the gene encodes/expresses.

[0094] Table 5 provides non-limiting examples of the corresponding GenBank accession number, clone ID number, and Unigene (cluster) ID numbers for exemplary sequences disclosed herein. The sequences of the invention may thus be identified by any of these identifiers. The identification of other corresponding numbers (GenBank accession number, clone ID number, and/or Unigene (cluster) ID numbers) for sequences disclosed herein can be made as a matter of routine from public information sources and without undue experimentation.

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