Genotype and phenotype in hereditary and sporadic breast cancers

10538 Background: BRCA1 protein is involved in distinct DNA-repair processes. Germline mutations in BRCA1 gene confer cancer susceptibility. A frequent mechanism for epigenetic inactivation is hypermethylation of the CpG island in promoters of tumours suppressor genes. BRCA1 promoter hypermethylation has been found in a variable percentage of breast cancers (15–30%). BRCA1-associated breast cancers are usually high-grade, poorly differentiated and stain negative for HER2/neu, oestrogen and progesterone receptors (ER, PgR). Many studies have shown that hereditary BRCA1 and basal-like sporadic breast tumours have a similar phenotype and gene expression signature. Methods: By clinical criteria, 223 patients were selected and, for each patient, the probability to carry a BRCA1 mutation was calculated using the software BRCAPRO and Manchester Score System. All patients were studied by direct sequencing and MLPA of BRCA1 Open Reading Frames (ORFs). Thirty sporadic breast carcinomas, from women undergone surgery for primary invasive breast carcinoma between 1995 and 2001, were selected on the basis of negative staining for ER, PgR and HER2/neu (“BRCA-like”). In these patients, Methylation Specific-PCR and Bisulfite Sequencing on genomic DNA (obtained from sections of paraffin-embedded tissues and modified with sodium bisulfite) were used to assess the methylation pattern of BRCA1 promoter. BRCA1 immunohystochemical analysis (IHC) was performed in all patients. Results: We identified 17 patients with deleterious germline mutations in BRCA1. In “BRCA-like” patients, 13 methylated and 17 unmethylated cases were found by methylation analysis of BRCA1 promoter. The BRCA1 IHC was performed in all available samples ( table 1 ). Conclusions: Hypermethylation of BRCA1 promoter was found in 43% of “BRCA- like” patients. Expression of BRCA1 seems to correlate with hypermethylation of its promoter. Further studies are in progress to better understand the possible role of BRCA1 promoter hypermethylation in sporadic breast cancers. [Table: see text] No significant financial relationships to disclose.

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High BRCA1 gene expression increases the risk of early distant metastasis in ER+ breast cancers

Scientific Reports ◽

10.1038/s41598-021-03471-w ◽

2022 ◽

Vol 12 (1) ◽

Author(s):

Hui-Ju Chang ◽

Ueng-Cheng Yang ◽

Mei-Yu Lai ◽

Chen-Hsin Chen ◽

Yang-Cheng Fann

Keyword(s):

Gene Expression ◽

Distant Metastasis ◽

Brca1 Gene ◽

Estrogen Signaling ◽

Tamoxifen Treatment ◽

Testable Hypothesis ◽

Marker Genes ◽

Proliferation Marker ◽

Breast Cancers ◽

Brca1 Protein

AbstractAlthough the function of the BRCA1 gene has been extensively studied, the relationship between BRCA1 gene expression and tumor aggressiveness remains controversial in sporadic breast cancers. Because the BRCA1 protein is known to regulate estrogen signaling, we selected microarray data of ER+ breast cancers from the GEO public repository to resolve previous conflicting findings. The BRCA1 gene expression level in highly proliferative luminal B tumors was shown to be higher than that in luminal A tumors. Survival analysis using a cure model indicated that patients of early ER+ breast cancers with high BRCA1 expression developed rapid distant metastasis. In addition, the proliferation marker genes MKI67 and PCNA, which are characteristic of aggressive tumors, were also highly expressed in patients with high BRCA1 expression. The associations among high BRCA1 expression, high proliferation marker expression, and high risk of distant metastasis emerged in independent datasets, regardless of tamoxifen treatment. Tamoxifen therapy could improve the metastasis-free fraction of high BRCA1 expression patients. Our findings link BRCA1 expression with proliferation and possibly distant metastasis via the ER signaling pathway. We propose a testable hypothesis based on these consistent results and offer an interpretation for our reported associations.

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Epigenetic Activation of BRCA1 by Genistein In Vivo and Triple Negative Breast Cancer Cells Linked to Antagonism toward Aryl Hydrocarbon Receptor

Nutrients ◽

10.3390/nu11112559 ◽

2019 ◽

Vol 11 (11) ◽

pp. 2559 ◽

Cited By ~ 11

Author(s):

Donovan ◽

Selmin ◽

Doetschman ◽

Romagnolo

Keyword(s):

Aryl Hydrocarbon Receptor ◽

Triple Negative ◽

Brca1 Gene ◽

Cpg Methylation ◽

Breast Cancers ◽

Mcf7 Cells ◽

Brca1 Protein ◽

Protein Levels ◽

Aryl Hydrocarbon

Triple negative breast cancers (TNBC) are the most aggressive and lethal breast cancers (BC). The aryl hydrocarbon receptor (AHR) is often overexpressed in TNBC, and its activation results in the epigenetic silencing of BRCA1, which is a necessary factor for the transcriptional activation of estrogen receptor (ER)α. The dietary isoflavone genistein (GEN) modulates BRCA1 CpG methylation in BC cells. The purpose of this study was to investigate the effect of GEN on BRCA1 epigenetic regulation and AHR activity in vivo and TNBC cells. Mice were administered a control or GEN-enriched (4 and 10 ppm) diet from gestation through post-natal day 50. Mammary tissue was analyzed for changes in BRCA1 regulation and AhR activity. TNBC cells with constitutively hypermethylated BRCA1 (HCC38) and MCF7 cells were used. Protein levels and mRNA expression were measured by Western blot and real-time PCR, respectively. BRCA1 promoter occupancy and CpG methylation were analyzed by chromatin immunoprecipitation and methylation-specific PCR, respectively. Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. GEN administered in the diet dose-dependently decreased basal Brca1 methylation and AHR activity in the mammary gland of adult mice. HCC38 cells were found to overexpress constitutively active AHR in parallel with BRCA1 hypermethylation. The treatment of HCC38 cells with GEN upregulated BRCA1 protein levels, which was attributable to decreased CpG methylation and AHR binding at BRCA1 exon 1a. In MCF7 cells, GEN prevented the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-dependent localization of AHR at the BRCA1 gene. These effects were consistent with those elicited by control AHR antagonists galangin (GAL), CH-223191, and α-naphthoflavone. The pre-treatment with GEN sensitized HCC38 cells to the antiproliferative effects of 4-hydroxytamoxifen. We conclude that the dietary compound GEN may be effective for the prevention and reversal of AHR-dependent BRCA1 hypermethylation, and the restoration of ERα-mediated response, thus imparting the sensitivity of TNBC to antiestrogen therapy.

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BRCA1 promoter hypermethylation in human placenta: a hidden link with β-hCG expression

Carcinogenesis ◽

10.1093/carcin/bgz117 ◽

2019 ◽

Vol 41 (5) ◽

pp. 611-624 ◽

Cited By ~ 1

Author(s):

Revathy Nadhan ◽

Jayashree Vijaya Vaman ◽

Satheesh Kumar Sengodan ◽

Sreelatha Krishnakumar Hemalatha ◽

Nirmala Chellappan ◽

...

Keyword(s):

Inverse Correlation ◽

Promoter Hypermethylation ◽

Breast Cancers ◽

Brca1 Promoter ◽

Brca1 Promoter Methylation ◽

Brca1 Mrna ◽

Gestational Trophoblastic Diseases ◽

Breast Lumps ◽

Regional Cancer Centre ◽

Β Hcg

AbstractGestational trophoblastic diseases (GTD) are group of pregnancy-related tumors characterized by abnormal levels of ‘β-hCG’ with higher incidence in South-East Asia, especially India. Our laboratory has reported that wild-type BRCA1 transcriptionally regulates β-hCG in triple negative breast cancers (TNBCs). These factors culminated into analysis of BRCA1 status in GTD, which would emanate into elucidation of BRCA1- β-hCG relationship and unraveling etio-pathology of GTD. BRCA1 level in GTD is down-regulated due to the over-expression of DNMT3b and subsequent promoter hypermethylation, when compared to the normal placentae accompanied with its shift in localization. There is an inverse correlation of serum β-hCG levels with BRCA1 mRNA expression. The effects of methotrexate (MTX), which is the first-line chemotherapeutic used for GTD treatment, when analyzed in comparison with plumbagin (PB) revealed that PB alone is efficient than MTX alone or MTX-PB in combination, in showing selective cytotoxicity against GTD. Interestingly, PB increases BRCA1 levels post-treatment, altering DNMT3b levels and resultant BRCA1 promoter methylation. Also, cohort study analyzed the incidence of GTD at Sree Avittom Thirunal (SAT) Hospital, Thiruvananthapuram, which points out that 11.5% of gestational trophoblastic neoplasia (GTN) cases were referred to Regional Cancer Centre, Thiruvananthapuram, for examination of breast lumps. This has lend clues to supervene the risk of GTD patients towards BRCA1-associated diseases and unveil novel therapeutic for GTD, a plant-derived naphthoquinone, PB, already reported as selectively cytotoxic against BRCA1 defective tumors.

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BRCA1 Promoter Hypermethylation is Associated with Good Prognosis and Chemosensitivity in Triple-Negative Breast Cancer

Cancers ◽

10.3390/cancers12040828 ◽

2020 ◽

Vol 12 (4) ◽

pp. 828 ◽

Cited By ~ 1

Author(s):

William Jacot ◽

Evelyne Lopez-Crapez ◽

Caroline Mollevi ◽

Florence Boissière-Michot ◽

Joelle Simony-Lafontaine ◽

...

Keyword(s):

Breast Cancer ◽

Adjuvant Chemotherapy ◽

Protein Expression ◽

Triple Negative ◽

Surrogate Marker ◽

Promoter Hypermethylation ◽

Brca1 Protein ◽

Brca1 Promoter ◽

Basal Marker ◽

N Stage

The aberrant hypermethylation of BRCA1 promoter CpG islands induces the decreased expression of BRCA1 (Breast Cancer 1) protein. It can be detected in sporadic breast cancer without BRCA1 pathogenic variants, particularly in triple-negative breast cancers (TNBC). We investigated BRCA1 hypermethylation status (by methylation-specific polymerase chain reaction (MS-PCR) and MassARRAY® assays), and BRCA1 protein expression using immunohistochemistry (IHC), and their clinicopathological significance in 248 chemotherapy-naïve TNBC samples. Fifty-five tumors (22%) exhibited BRCA1 promoter hypermethylation, with a high concordance rate between MS-PCR and MassARRAY® results. Promoter hypermethylation was associated with reduced IHC BRCA1 protein expression (p = 0.005), and expression of Programmed death-ligand 1 protein (PD-L1) by tumor and immune cells (p = 0.03 and 0.011, respectively). A trend was found between promoter hypermethylation and basal marker staining (p = 0.058), and between BRCA1 expression and a basal-like phenotype. In multivariate analysis, relapse-free survival was significantly associated with N stage, adjuvant chemotherapy, and histological subtype. Overall survival was significantly associated with T and N stage, histology, and adjuvant chemotherapy. In addition, patients with tumors harboring BRCA1 promoter hypermethylation derived the most benefit from adjuvant chemotherapy. In conclusion, BRCA1 promoter hypermethylation is associated with TNBC sensitivity to adjuvant chemotherapy, basal-like features and PD-L1 expression. BRCA1 IHC expression is not a good surrogate marker for promoter hypermethylation and is not independently associated with prognosis. Association between promoter hypermethylation and sensitivity to Poly(ADP-ribose) polymerase PARP inhibitors needs to be evaluated in a specific series of patients.

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BRCA1 in hormonal carcinogenesis: basic and clinical research

Endocrine Related Cancer ◽

10.1677/erc.1.00972 ◽

2005 ◽

Vol 12 (3) ◽

pp. 533-548 ◽

Cited By ~ 50

Author(s):

E M Rosen ◽

S Fan ◽

C Isaacs

Keyword(s):

Hormone Receptors ◽

Cancer Susceptibility ◽

Steroid Hormone ◽

Susceptibility Gene ◽

Suppressor Gene ◽

Steroid Hormone Receptors ◽

Breast Cancers ◽

Hormonal Stimulation ◽

Brca1 Protein ◽

Hormonal Factors

The breast and ovarian cancer susceptibility gene-1 (BRCA1) located on chromosome 17q21 encodes a tumor suppressor gene that functions, in part, as a caretaker gene in preserving chromosomal stability. The observation that most BRCA1 mutant breast cancers are hormone receptor negative has led some to question whether hormonal factors contribute to the etiology of BRCA1-mutant breast cancers. Nevertheless, the caretaker function of BRCA1 is a generic one and does not explain why BRCA1 mutations confer a specific risk for tumor types that are hormone-responsive or that hormonal factors contribute to the etiology, including those of the breast, uterus, cervix, and prostate. An accumulating body of research indicates that in addition to its well-established roles in regulation of the DNA damage response, the BRCA1 protein interacts with steroid hormone receptors (estrogen receptor (ER-α) and androgen receptor (AR)) and regulates their activity, inhibiting ER-α activity and stimulating AR activity. The ability of BRCA1 to regulate steroid hormone action is consistent with clinical-epidemiological research suggesting that: (i) hormonal factors contribute to breast cancer risk in BRCA1 mutation carriers; and (ii) the spectrum of risk-modifying effects of hormonal factors in BRCA1 carriers is not identical to that observed in the general population. These data suggest a model for BRCA1 carcinogenesis in which genomic instability leads to the initiation of cancerous cell clones, while loss of normal restraint on hormonal stimulation of mammary epithelial cell proliferation allows amplification of these pre-existing clones. Further research will be required to substantiate this hypothesis.

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Abnormal promoter DNA hypermethylation of the integrin, nidogen, and dystroglycan genes in breast cancer

Scientific Reports ◽

10.1038/s41598-021-81851-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Vladimir V. Strelnikov ◽

Ekaterina B. Kuznetsova ◽

Alexander S. Tanas ◽

Viktoria V. Rudenko ◽

Alexey I. Kalinkin ◽

...

Keyword(s):

Cpg Island ◽

Strong Association ◽

Cell Activity ◽

Promoter Hypermethylation ◽

Normal Breast ◽

Breast Carcinomas ◽

Her2 Positive ◽

A Genome ◽

Extracellular Matrix Components ◽

Integrin Α4

AbstractCell transmembrane receptors and extracellular matrix components play a pivotal role in regulating cell activity and providing for the concerted integration of cells in the tissue structures. We have assessed DNA methylation in the promoter regions of eight integrin genes, two nidogen genes, and the dystroglycan gene in normal breast tissues and breast carcinomas (BC). The protein products of these genes interact with the basement membrane proteins LAMA1, LAMA2, and LAMB1; abnormal hypermethylation of the LAMA1, LAMA2, and LAMB1 promoters in BC has been described in our previous publications. In the present study, the frequencies of abnormal promoter hypermethylation in BC were 13% for ITGA1, 31% for ITGA4, 4% for ITGA7, 39% for ITGA9, 38% for NID1, and 41% for NID2. ITGA2, ITGA3, ITGA6, ITGB1, and DAG1 promoters were nonmethylated in normal and BC samples. ITGA4, ITGA9, and NID1 promoter hypermethylation was associated with the HER2 positive tumors, and promoter hypermethylation of ITGA1, ITGA9, NID1 and NID2 was associated with a genome-wide CpG island hypermethylated BC subtype. Given that ITGA4 is not expressed in normal breast, one might suggest that its abnormal promoter hypermethylation in cancer is non-functional and is thus merely a passenger epimutation. Yet, this assumption is not supported by our finding that it is not associated with a hypermethylated BC subtype. ITGA4 acquires expression in a subset of breast carcinomas, and methylation of its promoter may be preventive against expression in some tumors. Strong association of abnormal ITGA4 hypermethylation with the HER2 positive tumors (p = 0.0025) suggests that simultaneous presence of both HER2 and integrin α4 receptors is not beneficial for tumor cells. This may imply HER2 and integrin α4 signaling pathways interactions that are yet to be discovered.

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MRCKα Is Dispensable for Breast Cancer Development in the MMTV-PyMT Model

Cells ◽

10.3390/cells10040942 ◽

2021 ◽

Vol 10 (4) ◽

pp. 942

Author(s):

Mei Qi Kwa ◽

Rafael Brandao ◽

Trong H. Phung ◽

Jianfeng Ge ◽

Giuseppe Scieri ◽

...

Keyword(s):

Breast Cancer ◽

Gene Expression Signature ◽

Genomic Analysis ◽

Cancer Development ◽

Breast Cancer Cell Lines ◽

Normal Mammary Gland ◽

Breast Cancers ◽

Human Breast ◽

Breast Cancer Development

MRCKα is a ubiquitously expressed serine/threonine kinase involved in cell contraction and F-actin turnover, which is highly amplified in human breast cancer and part of a gene expression signature for bad prognosis. Nothing is known about the in vivo function of MRCKα. To explore MRCKα function in development and in breast cancer, we generated mice lacking a functional MRCKα gene. Mice were born close to the Mendelian ratio and showed no obvious phenotype including a normal mammary gland formation. Assessing breast cancer development using the transgenic MMTV-PyMT mouse model, loss of MRCKα did not affect tumor onset, tumor growth and metastasis formation. Deleting MRCKα and its related family member MRCKβ in two triple-negative breast cancer cell lines resulted in reduced invasion of MDA-MB-231 cells, but did not affect migration of 4T1 cells. Further genomic analysis of human breast cancers revealed that MRCKα is frequently co-amplified with the oncogenes ARID4B and AKT3 which might contribute to the prognostic value of MRCKα expression. Collectively, these data suggest that MRCKα might be a prognostic marker for breast cancer, but probably of limited functional importance.

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