RESUMO
The localization of BRCA1 protein was studied in 49 sporadic breast carcinomas for which allelic losses of BRCA1 have been investigated. One group consisted of 15 breast carcinomas having one allelic loss of BRCA1 and the other group of 34 breast carcinomas with no allelic loss of BRCA1. The localization of BRCA1 in the 2 groups was performed using polyclonal antibodies (K-18; C-20; D-20; I-20) raised against BRCA1 and by comparing frozen and paraffin-embedded tissues. We show that no correlation was found between the expression of BRCA1 protein and allelic loss of BRCA1. But, the nuclear detection of BRCA1 in frozen samples was improved when compared to paraffinized ones.
Assuntos
Proteína BRCA1/metabolismo , Neoplasias da Mama/metabolismo , Anticorpos , Proteína BRCA1/genética , Proteína BRCA1/imunologia , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Feminino , Humanos , Imunoensaio , Perda de Heterozigosidade , Metástase Neoplásica , Frações Subcelulares/metabolismo , Células Tumorais CultivadasRESUMO
The present study was undertaken to analyse the loss of heterozygosity (LOH) of the three genes, BRCA1, BRCA2 and ATM, and their correlation to clinicopathological parameters in sporadic breast cancer. We studied 59 sets of invasive ductal carcinoma, compared to matched normal control DNA. Microsatellite markers intragenic to BRCA1 (D17S1323, D17S1322, D17S855), BRCA2 (D13S1699, D13S1701, D13S1695) and ATM (D11S2179) were simultaneously used. In addition, one marker telomeric to BRCA2 (D13S1694) and four markers flanking ATM were analysed (D11S1816, D11S1819, D11S1294, D11S1818). Thirty-one per cent of the informative cases showed loss of heterozygosity for the BRCA1 gene, 22.8% for BRCA2 gene and 40% for ATM. LOH of BRCA1 correlated with high grade tumors (p=0.0005) and negative hormone receptors (p=0.01). LOH of ATM correlated with higher grade (p=0.03) and a younger age at diagnosis (p=0.03) in our set of tumors. No correlations were detected between BRCA2 LOH and any of the analysed clinicopathological parameters. However, a correlation was detected between allelic loss of the D13S1694 marker, telomeric to BRCA2, and larger tumor sizes and negative estrogen receptors, favoring the hypothesis of the presence of another putative tumor suppressor gene, telomeric to BRCA2, in the 13q12-q14 region. Only 11 tumors had LOH at more than one of the three genes, most of them (6/11) associated LOH of BRCA1 and ATM. One tumor only combined loss of the three genes BRCA1, BRCA2 and ATM.
Assuntos
Proteína BRCA1/genética , Neoplasias da Mama/genética , Carcinoma Ductal de Mama/genética , Genes/genética , Proteínas de Neoplasias/genética , Proteínas Serina-Treonina Quinases , Proteínas/genética , Fatores de Transcrição/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Proteínas Mutadas de Ataxia Telangiectasia , Proteína BRCA2 , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/patologia , Proteínas de Ciclo Celular , Proteínas de Ligação a DNA , Interpretação Estatística de Dados , Feminino , Humanos , Perda de Heterozigosidade/genética , Repetições de Microssatélites/genética , Pessoa de Meia-Idade , Proteínas Supressoras de TumorRESUMO
BACKGROUND: Previously, we reported experimental evidence that BRCA1, breast and ovarian cancer susceptibility gene is up-regulated in response to Prolactin stimulation. In this work, we studied the effects of Cyclosporine A and the competition with Prolactin on BRCA1 protein expression in vitro. METHODS: The expression of BRCA1 was monitored in a human breast cancer cell line (MCF7) by comparison with a normal breast epithelial one (MCF10a) treated with Cyclosporine A and ovine Prolactin. The amount of BRCA1 protein expression was quantified using a strategy of two successive affinity perfusion chromatographies. RESULTS AND CONCLUSION: We showed that Prolactin in presence of Cyclosporine A has no effect on BRCA1 protein expression in human breast cell lines. This emphasized the hypothesis that BRCA1 may be stimulated by Prolactin.
Assuntos
Proteína BRCA1/biossíntese , Neoplasias da Mama/genética , Ciclosporina/farmacologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Prolactina/farmacologia , Proteína BRCA1/genética , Neoplasias da Mama/metabolismo , Feminino , Humanos , Imunossupressores/farmacologia , Prolactina/antagonistas & inibidores , Células Tumorais Cultivadas , Regulação para Cima/efeitos dos fármacosAssuntos
Proteína BRCA1/biossíntese , Neoplasias da Mama/patologia , Mama/efeitos dos fármacos , Estrogênios não Esteroides/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Genes BRCA1 , Genisteína/farmacologia , Isoflavonas/farmacologia , Adenocarcinoma/química , Adenocarcinoma/metabolismo , Adenocarcinoma/patologia , Mama/metabolismo , Neoplasias da Mama/química , Neoplasias da Mama/metabolismo , Células Cultivadas , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Estrogênios , Feminino , Humanos , Proteínas de Neoplasias/análise , Neoplasias Hormônio-Dependentes/química , Neoplasias Hormônio-Dependentes/metabolismo , Neoplasias Hormônio-Dependentes/patologia , Fitoestrógenos , Preparações de Plantas , Receptores de Estrogênio/análise , Receptores de Estrogênio/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Células Tumorais CultivadasAssuntos
Proteína BRCA1/efeitos dos fármacos , Neoplasias da Mama/metabolismo , Mama/metabolismo , Gorduras Insaturadas na Dieta/farmacologia , Ácidos Graxos Ômega-3/farmacologia , Ácidos Graxos Insaturados/farmacologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Proteína BRCA1/genética , Mama/citologia , Neoplasias da Mama/genética , Divisão Celular/efeitos dos fármacos , Linhagem Celular , Relação Dose-Resposta a Droga , Ácidos Graxos Ômega-6 , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , HumanosRESUMO
In sporadic breast cancer, no mutations of the BRCA1 gene have been reported so far, whereas BRCA1 mRNA is markedly decreased in invasive breast cancer. To elucidate the contribution of the BRCA1 gene in sporadic breast cancer, we quantified the BRCA1 protein, using [125I] labeling of whole-cell proteins, lentil-lectin affinity chromatography, immunoprecipitation by anti-BRCA1 antibodies (C-20, D-20, I-20 and K-18), purification of the immune complex by protein A affinity chromatography and chromato-focusing. As loss of 1 allele may lead to a decreased expression of the gene, 10 tumors were previously checked for loss of heterozygosity (LOH) of the BRCA1 gene, using 3 intragenic microsatellite markers. Our results indicated that the BRCA1 gene product was decreased in the 4 tumors with LOH compared with matched normal breast tissues. Reduced amounts of BRCA1 protein were also detected in 3 of 6 tumors without LOH. Our quantitative method allowed us to demonstrate that the BRCA1 protein level was decreased in sporadic invasive breast carcinomas with or without LOH of the BRCA1 gene, implying multiple mechanisms of BRCA1 expression down-regulation in these tumors. Our data suggest that the amount of BRCA1 protein present may play an important role in human sporadic breast carcinoma.