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Novel BRCA1 deleterious mutation (c.1949_1950delTA) in a woman of Senegalese descent with triple-negative early-onset breast cancer.

ABSTRACT: Limited information exists regarding BRCA1 and BRCA2 genetic testing and genetic diversity in BRCA1 and BRCA2 in sub-Saharan African populations. We report a novel mutation that consists of a deletion of 2 bp (c.1949_1950delTA) in the exon 11 of the BRCA1 gene. This is a frameshift mutation that causes the disruption of the translational reading frame resulting in a premature stop codon downstream in the BRCA1 protein. The mutation was present in a Senegalese woman with a triple-negative breast tumor and a family history of breast cancer.

SUBMITTER: Diez O

PROVIDER: S-EPMC3406549 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature

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Novel BRCA1 deleterious mutation (c.1949_1950delTA) in a woman of Senegalese descent with triple-negative early-onset breast cancer.

Diez Orland O Pelegrí Amadeu A Gadea Neus N Gutiérrez-Enríquez Sara S Masas Miriam M Tenés Anna A Bosch Nina N Balmaña Judith J Graña Begoña B

Oncology letters 20110819 6

Limited information exists regarding BRCA1 and BRCA2 genetic testing and genetic diversity in BRCA1 and BRCA2 in sub-Saharan African populations. We report a novel mutation that consists of a deletion of 2 bp (c.1949_1950delTA) in the exon 11 of the BRCA1 gene. This is a frameshift mutation that causes the disruption of the translational reading frame resulting in a premature stop codon downstream in the BRCA1 protein. The mutation was present in a Senegalese woman with a triple-negative breast ...[more]

PMID: 22848303

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Project description:Mutations in BRCA1/2 increase the risk of developing breast and ovarian cancer. Germline BRCA1/2 mutations occur in 8.6-13.7% of unselected epithelial ovarian cancers, somatic mutations are also frequent. BRCA1/2 mutated or dysfunctional cells may be sensitive to PARP inhibition by synthetic lethality. The aim of this study is to comprehensively characterise the BRCA1/2 status of a large panel of ovarian cancer cell lines available to the research community to assist in biomarker studies of novel drugs and in particular of PARP inhibitors. The BRCA1/2 genes were sequenced in 41 ovarian cell lines, mRNA expression of BRCA1/2 and gene methylation status of BRCA1 was also examined. The cytotoxicity of PARP inhibitors olaparib and veliparib was examined in 20 cell lines. The cell line SNU-251 has a deleterious BRCA1 mutation at 5564G > A, and is the only deleterious BRCA1/2 mutant in the panel. Two cell lines (UPN-251 and PEO1) had deleterious mutations as well as additional reversion mutations that restored the protein functionality. Heterozygous mutations in BRCA1/2 were relatively common, found in 14.6% of cell lines. BRCA1 was methylated in two cell lines (OVCAR8, A1847) and there was a corresponding decrease in gene expression. The BRCA1 methylated cell lines were more sensitive to PARP inhibition than wild-type cells. The SNU-251 deleterious mutant was more sensitive to PARP inhibition, but only in a long-term exposure to correct for its slow growth rate. Cell lines derived from metastatic disease are significantly more resistant to veliparib (2.0 fold p = 0.03) compared to those derived from primary tumours. Resistance to olaparib and veliparib was correlated Pearsons-R 0.5393, p = 0.0311. The incidence of BRCA1/2 deleterious mutations 1/41 cell lines derived from 33 different patients (3.0%) is much lower than the population incidence. The reversion mutations and high frequency of heterozygous mutations suggest that there is a selective pressure against BRCA1/2 in cell culture similar to the selective pressure seen in the clinic after treatment with chemotherapy. PARP inhibitors may be useful in patients with BRCA1 deleterious mutations or gene methylation.

Project description:BackgroundAn early age at Breast Cancer (BC) onset may be a hallmark of inherited predisposition, but BRCA1/2 mutations are only found in a minority of younger BC patients. Among the others, a fraction may carry mutations in rarer BC genes, such as TP53, STK11, CDH1 and PTEN. As the identification of women harboring such mutations allows for targeted risk-management, the knowledge of associated manifestations and an accurate clinical and family history evaluation are warranted.Case presentationWe describe the case of a woman who developed an infiltrating ductal carcinoma of the right breast at the age of 32, a contralateral BC at age 36 and another BC of the right breast at 40. When she was 39 years-old, during a dermatological examination, mucocutaneous features suggestive of Cowden Syndrome, a disorder associated to germ-line PTEN mutations, were noticed. PTEN genetic testing revealed the novel c.71A > T (p.Asp24Val) mutation, whose deleterious effect, suggested by conservation data and in silico tools, was definitely demonstrated by the incapacity of mutant PTEN to inhibit Akt phosphorylation when used to complement PTEN-null cells. In BC tissue, despite the absence of LOH or somatic mutations of PTEN, Akt phosphorylation was markedly increased in comparison to normal tissue, thus implying additional somatic events into the deregulation of the PI3K/Akt/mTOR pathway and, presumably, into carcinogenesis. Hence, known oncogenic mutations in PIK3CA (exons 10 and 21) and AKT1 (exon 2) were screened in tumor DNA with negative results, which suggests that the responsible somatic event(s) is a different, uncommon one.ConclusionThis case stresses the importance of clinical/genetic assessment of early-onset BC patients in order to identify mutation carriers, who are at high risk of new events, so requiring tailored management. Moreover, it revealed a novel PTEN mutation with pathogenic effect, pointing out, however, the need for further efforts to elucidate the molecular steps of PTEN-associated carcinogenesis.

Dataset Information

Novel BRCA1 deleterious mutation (c.1949_1950delTA) in a woman of Senegalese descent with triple-negative early-onset breast cancer.

Publications

Novel BRCA1 deleterious mutation (c.1949_1950delTA) in a woman of Senegalese descent with triple-negative early-onset breast cancer.

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