Project description:Purpose: As estrogen receptor (ER)-positive breast cancer in BRCA1 mutation carriers arises at an older age with less aggressive tumor characteristics than ER negative BRCA1 mutated breast cancer, it has been suggested that these tumors are ?sporadic? and not BRCA1-driven. With the introduction of targeted treatments specific for tumors with a non-functioning BRCA1 or BRCA2 gene, the question whether the BRCA genes are impaired in the tumor, is highly relevant. Therefore, we performed genomic profiling of BRCA1-mutated ER+ tumors. Experimental design: Genomic profiling, BRCA1 promoter methylation assessment, and loss of heterozygosity analysis were done on 16 BRCA1-mutated ER+ tumors. Results were compared with 57 BRCA1-mutated ER- tumors, 36 BRCA2-mutated ER+ associated tumors, and 182 sporadic ER+ tumors [GSE9021, GSE9114, GSE16511, GSE50407] Results: The genomic profile of BRCA1-mutated ER+ tumors was different from BRCA1-mutated ER- breast tumors, but highly similar to BRCA2-mutated ER+ tumors. In 83% of the BRCA1-mutated ER+ tumors, loss of the wildtype BRCA1 allele was observed. In addition, clinico-pathological variables in BRCA1-mutated ER+ cancer were also more similar to BRCA2-mutated ER+ and sporadic ER+ breast cancer than to BRCA1 mutated ER- cancers. Conclusions: As BRCA1-mutated ER+ tumors show a BRCAness copy number profile and LOH, it is likely that the loss of a functional BRCA1 protein plays a role in tumorigenesis in BRCA1-mutated ER+ tumors. Therefore, we hypothesize that these tumors are sensitive to drugs targeting the BRCA1 gene defect, providing new targeted treatment modalities for advanced BRCA-deficient, ER-positive breast cancer.
Project description:Purpose: As estrogen receptor (ER)-positive breast cancer in BRCA1 mutation carriers arises at an older age with less aggressive tumor characteristics than ER negative BRCA1 mutated breast cancer, it has been suggested that these tumors are ?sporadic? and not BRCA1-driven. With the introduction of targeted treatments specific for tumors with a non-functioning BRCA1 or BRCA2 gene, the question whether the BRCA genes are impaired in the tumor, is highly relevant. Therefore, we performed genomic profiling of BRCA1-mutated ER+ tumors. Experimental design: Genomic profiling, BRCA1 promoter methylation assessment, and loss of heterozygosity analysis were done on 16 BRCA1-mutated ER+ tumors. Results were compared with 57 BRCA1-mutated ER- tumors, 36 BRCA2-mutated ER+ associated tumors, and 182 sporadic ER+ tumors [GSE9021, GSE9114, GSE16511, GSE50407]. Results: The genomic profile of BRCA1-mutated ER+ tumors was different from BRCA1-mutated ER- breast tumors, but highly similar to BRCA2-mutated ER+ tumors. In 83% of the BRCA1-mutated ER+ tumors, loss of the wildtype BRCA1 allele was observed. In addition, clinico-pathological variables in BRCA1-mutated ER+ cancer were also more similar to BRCA2-mutated ER+ and sporadic ER+ breast cancer than to BRCA1 mutated ER- cancers. Conclusions: As BRCA1-mutated ER+ tumors show a BRCAness copy number profile and LOH, it is likely that the loss of a functional BRCA1 protein plays a role in tumorigenesis in BRCA1-mutated ER+ tumors. Therefore, we hypothesize that these tumors are sensitive to drugs targeting the BRCA1 gene defect, providing new targeted treatment modalities for advanced BRCA-deficient, ER-positive breast cancer.
Project description:To find BRCA1-associated copy number abberations, the copy number profiles of Familial Basal-like BRCA1-mutated breast carcinomas were compared to Familial Basal-like carcinomas with no pathgogenic BRCA1/2 mutation. This led to the observation of unanticipated heterogeneity of the BRCA1 associated copy number profiles. Gene expression analysis on the same samples identified tumor infiltrating lymphocytes to be responsible for this observation. High number of infiltrating lymphocytes proved to be detrimental for copy number profiling efforts. After optimal sample selection, BRCA1-associated copy number abberations could be detected.
Project description:Comparison between Estrogen receptor positive and Estrogen receptor negative breast cancer samples Keywords: breast cancer type comparison
Project description:Background: Breast cancer is a complex disease, encompassed by different clinically and molecularly stratified entities. In 2000, Perou and colleagues demonstrated that tumor phenotypic diversity correlates with differences in global gene expression patterns, which in turn reflect aspects of the biological behavior of the tumors. Gene expression profiling has distinguished sporadic breast tumor sub-classes with genetic, histopathological and clinical differences, however, little is known about the molecular classification of hereditary breast tumors. It has been recently suggested that most tumors arising in BRCA1 mutation carriers display a basal-like phenotype, with the percentages reported in different studies ranging from 44 to almost 100%. In the present study we used expression profiling to produce a molecular classification of BRCA1-associated breast tumors and applied an integrative approach to examine biological dependencies or differences. Methods and Findings: We used frozen tumor tissue from fourteen patients all of which harbored germline pathological mutations in BRCA1. Total RNA extraction, amplification and labeling with Cy5 were performed using standard protocols. Universal Human Reference RNA (Stratagene) was used as a reference and labeled with Cy3. Each pair of Cy3/Cy5 samples was hybridized onto the CNIO human OncoChip V2, which consists of a spotted microarray with 11,675 cDNA clones from the I.M.A.G.E. Consortium. Two channel ratios (Cy5/Cy3) for each spot were generated and quantified using GenePix Pro 5.1 (Axon Instruments, Inc., Union City, CA, USA). Data were normalized and filtered and multiple statistical analyses were performed. The data are deposited in the GEO database under the accession number GSE12350. A tissue microarray (TMA) containing an independent series of 15 BRCA1 tumors was used to validate some of the results obtained. We have described molecular signatures that define BRCA1 subclasses depending on the expression of the gene encoding for Estrogen Receptor, ESR1. Signatures were found to be molecularly associated with different biological processes and transcriptional regulatory programs. The signature of ESR1-positive tumors was mainly linked to cell proliferation-related processes and, therefore, regulated by the estrogen receptor, while the signature of ESR1-negative tumors was mainly linked to the immune response and possibly regulated by transcription factors of the REL/NF?B family. These signatures were then verified in an independent series of hereditary and sporadic breast tumors, which revealed a possible prognostic value for each subclass. Over-expression of immune response genes appears to be a common feature of ER-negative sporadic and hereditary breast cancer and is associated with good prognosis. Interestingly, the ESR1-negative tumors were sub-stratified into two groups presenting light differences in the magnitude of the expression of immune response transcripts and REL/NF?B transcription factors, and this could be dependent on the type of germline alteration. In addition, analysis of the human protein-protein interaction network provides the wiring diagram of critical molecular associations in BRCA1 tumorigenesis and identifies close relationships between the different signatures. Conclusions: In summary, in the present study we have established the gene expression profiling of a series of BRCA1 tumors and found that there is a further degree of heterogeneity beyond the main classification by the expression of ESR1 and the presence or absence of a basal-like phenotype. We have identified specific signatures for ESR1-positive and ESR1-negative BRCA1 tumors, the latter characterized by the enrichment of immune response and cell cycle genes, and have found that slight differences in the level of expression of the immune response stratify the ESR1-negative BRCA1 tumors into two additional sub-groups (A and B) with possible prognostic differences. NFkB could be a major driver responsible for the levels of both immune response and apoptotic genes in this group of tumors, which could in turn be related to the type of germline mutation in BRCA1. This study reveals the molecular complexity of BRCA1 breast tumors, which are found to display similarities to sporadic tumors, and suggests possible prognostic implications. 14 samples (primary breast tumors containing a BRCA1 mutation) were hybridized to a cDNA microarray in order to investigate the possible heterogeneity within the BRCA1 group.
Project description:Comparison between Estrogen receptor positive and Estrogen receptor negative breast cancer samples Keywords: breast cancer type comparison 152 unique breast cancer tissue sample are included in the analysis. The total mRNA has been labeled with Cy5 and then hybridized on a two color arrays against the stratagen Human common reference that was previously labelled with Cy3.
Project description:Background: Breast cancer is a complex disease, encompassed by different clinically and molecularly stratified entities. In 2000, Perou and colleagues demonstrated that tumor phenotypic diversity correlates with differences in global gene expression patterns, which in turn reflect aspects of the biological behavior of the tumors. Gene expression profiling has distinguished sporadic breast tumor sub-classes with genetic, histopathological and clinical differences, however, little is known about the molecular classification of hereditary breast tumors. It has been recently suggested that most tumors arising in BRCA1 mutation carriers display a basal-like phenotype, with the percentages reported in different studies ranging from 44 to almost 100%. In the present study we used expression profiling to produce a molecular classification of BRCA1-associated breast tumors and applied an integrative approach to examine biological dependencies or differences. Methods and Findings: We used frozen tumor tissue from fourteen patients all of which harbored germline pathological mutations in BRCA1. Total RNA extraction, amplification and labeling with Cy5 were performed using standard protocols. Universal Human Reference RNA (Stratagene) was used as a reference and labeled with Cy3. Each pair of Cy3/Cy5 samples was hybridized onto the CNIO human OncoChip V2, which consists of a spotted microarray with 11,675 cDNA clones from the I.M.A.G.E. Consortium. Two channel ratios (Cy5/Cy3) for each spot were generated and quantified using GenePix Pro 5.1 (Axon Instruments, Inc., Union City, CA, USA). Data were normalized and filtered and multiple statistical analyses were performed. The data are deposited in the GEO database under the accession number GSE12350. A tissue microarray (TMA) containing an independent series of 15 BRCA1 tumors was used to validate some of the results obtained. We have described molecular signatures that define BRCA1 subclasses depending on the expression of the gene encoding for Estrogen Receptor, ESR1. Signatures were found to be molecularly associated with different biological processes and transcriptional regulatory programs. The signature of ESR1-positive tumors was mainly linked to cell proliferation-related processes and, therefore, regulated by the estrogen receptor, while the signature of ESR1-negative tumors was mainly linked to the immune response and possibly regulated by transcription factors of the REL/NFκB family. These signatures were then verified in an independent series of hereditary and sporadic breast tumors, which revealed a possible prognostic value for each subclass. Over-expression of immune response genes appears to be a common feature of ER-negative sporadic and hereditary breast cancer and is associated with good prognosis. Interestingly, the ESR1-negative tumors were sub-stratified into two groups presenting light differences in the magnitude of the expression of immune response transcripts and REL/NFκB transcription factors, and this could be dependent on the type of germline alteration. In addition, analysis of the human protein-protein interaction network provides the wiring diagram of critical molecular associations in BRCA1 tumorigenesis and identifies close relationships between the different signatures. Conclusions: In summary, in the present study we have established the gene expression profiling of a series of BRCA1 tumors and found that there is a further degree of heterogeneity beyond the main classification by the expression of ESR1 and the presence or absence of a basal-like phenotype. We have identified specific signatures for ESR1-positive and ESR1-negative BRCA1 tumors, the latter characterized by the enrichment of immune response and cell cycle genes, and have found that slight differences in the level of expression of the immune response stratify the ESR1-negative BRCA1 tumors into two additional sub-groups (A and B) with possible prognostic differences. NFkB could be a major driver responsible for the levels of both immune response and apoptotic genes in this group of tumors, which could in turn be related to the type of germline mutation in BRCA1. This study reveals the molecular complexity of BRCA1 breast tumors, which are found to display similarities to sporadic tumors, and suggests possible prognostic implications.
Project description:Hormone therapy targeting estrogen receptor (ER) is the principal treatment for ER-positive breast cancers but many cancers develop resistance to anti-estrogens. Cyclin-dependent kinase 8 (CDK8) is a transcriptional regulator of several oncogenic pathways. Expression levels of CDK8 and ERα are inversely correlated in breast cancers suggesting a functional association between CDK8 and ER. CDK8 inhibition by selective small-molecule inhibitors, by shRNA knockdown or by CRISPR-Cas9 knockout suppressed estrogen-induced transcription, with no significant effects on ERα protein expression or phosphorylation. CDK8 inhibition also abrogated the mitogenic effect of estrogen on ER-positive breast cancer cells and potentiated growth inhibition by the ER antagonist fulvestrant. In vivo, administration of a CDK8 inhibitor suppressed ER-positive breast cancer xenograft growth and augmented the effects of fulvestrant with no apparent toxicity. CDK8 inhibitors also suppressed the development of estrogen independence in ER-positive breast cancer cells. These results identify CDK8 as a novel drug target for breast cancer therapy.