Studies of a novel BRCA1 tricomplex in breast cancer

乳腺癌中新型 BRCA1 三复合物的研究

基本信息

批准号：
7229493
负责人：
HAVA Karsenty AVRAHAM
金额：
$ 35.86万
依托单位：
BETH ISRAEL DEACONESS MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2003
资助国家：
美国
起止时间：
2003-05-01 至 2010-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7229493
关键词：
Address Affect Amino Acids Apoptosis Appendix BRCA1 Protein BRCA1 gene Behavior Binding Binding Proteins Biology Breast Breast Cancer Cell Cancer-Predisposing Gene Cell Cycle Cells Complex DNA Damage DNA Repair Development Enzymes Epithelial Cells Genes Genetic Transcription Genome Stability Hereditary Breast Carcinoma Human In Vitro Inherited Lead Link Maintenance Malignant neoplasm of ovary Mammary gland Mediating Molecular Mutate Mutation N-Myc Protein Neoplastic Cell Transformation Phenotype Play Proteins Proto-Oncogene Proteins c-myc Recruitment Activity Reporting Risk Role T47D Telomerase Transcriptional Regulation Tumor Suppressor Proteins Tumorigenicity c-myc Genes c-myc Proto-Oncogenes carcinogenesis cell growth human TERT protein in vivo insight malignant breast neoplasm neoplastic cell novel outcome forecast promoter protein function response transcription factor tumor tumor growth

项目摘要

DESCRIPTION (provided by applicant): Inherited mutations in the breast and ovarian cancer susceptibility gene, BRCA1, are associated with a high risk for developing breast and ovarian cancers. Amplification of the proto-oncogene, c-Myc, occurs in 10- 30% of human breast cancers and is associated with aggressive tumor behavior and poor prognosis. We observed a novel endogenous association of BRCA1 with Nmi (N-Myc-interacting protein) in breast cancer cells (Li et al., J Biol Chem, 2002, 277(23):20985-73). Nmi was found to interact specifically with BRCA1, both in-vitro and in-vivo, by binding to two major domains in BRCA1, amino acid residues 209-683 and 1301-1863. Nmi also functioned as an adaptor molecule to recruit c-Myc to a complex containing Nmi/c-Myc/BRCA1. The endogenous complex of Nmi/c-Myc/BRCA1 was observed in T47D breast cancer cells and MCF-10A normal breast epithelial cells. Since c-Myc can activate transcription of the human telomerase reverse transcriptase gene (hTERT), we addressed the role of BRCA1 and Nmi in modulating c-Myc induced hTERT promoter activity. While Nmi or BRCA1 alone had no effect on c-Myc induced hTERT promoter activity and telomerase activity, BRCA1 together with Nmi significantly inhibited c-Myc induced hTERT promoter activity (approximately 75% inhibition) in breast cancer cells. Two mutated forms of BRCA1, a missense (A1708E) and a nonsense (Y1853X) that have been identified in familial breast cancers, associated with Nmi and c-Myc but failed to suppress c-Myc induced hTERT promoter activity. These results suggest a novel pathogenetic mechanism whereby mutations in BRCA1, via a novel transcription factor complex containing BRCAI/c-Myc/Nmi, impair inhibition of c-Myc induced hTERT promoter activity and telomerase activity and allow sustained activation of telomerase, a key enzyme in carcinogenesis. We aim to further characterize the association of Nmi with BRCA1 and the role of the Nmi-BRCA1 complex in the transcriptional regulation and transformation of c-Myc. In addition, we will investigate the function of Nmi in mammary epithelial cells and determine the role of the novel tricomplex of BRCA1/Nmi/c-Myc in breast epithelial cells and in c-Myc induced hTERT promoter activity and telomerase activity in breast cancer cells. These studies should lead to new insights into the biology of BRCA1, and will further elucidate the molecular mechanisms that regulate the transformation of breast cancer cells.

描述（由申请人提供）：乳腺癌和卵巢癌敏感性基因BRCA1的遗传突变与患乳腺癌和卵巢癌的高风险有关。原始癌基因C-MYC的扩增发生在10-30％的人乳腺癌中，与侵袭性肿瘤行为和预后不良有关。我们观察到BRCA1与NMI（N-Myc相互作用蛋白）在乳腺癌细胞中的新内源性相关性（Li等，J Biol Chem，2002，277（23）：20985-73）。发现NMI通过与BRCA1中的两个主要结构域，氨基酸残基209-683和1301-1863结合，与BRCA1与BRCA1特别相互作用。 NMI还充当衔接子分子，可将C-MYC募集到包含NMI/C-MYC/BRCA1的复合物。在T47D乳腺癌细胞和MCF-10A正常乳腺上皮细胞中观察到NMI/C-MYC/BRCA1的内源性复合物。由于C-MYC可以激活人端粒酶逆转录酶基因（HTERT）的转录，因此我们解决了BRCA1和NMI在调节C-MYC诱导的HTERT启动子活性中的作用。虽然单独的NMI或BRCA1对C-MYC诱导的HTERT启动子活性和端粒酶活性没有影响，但BRCA1与NMI一起显着抑制了C-MYC诱导的HTERT启动子活性（约75％抑制）在乳腺癌细胞中。两种突变形式的BRCA1，一个错义（A1708E）和一个与NMI和C-MYC相关的家族性乳腺癌中已经鉴定出的，但未能抑制C-Myc诱导的HTERT HTERT促进蛋白活性。这些结果表明了一种新型的致病机制，通过含有BRCAI/C-MYC/NMI的新型转录因子复合物，BRCA1中的突变损害了C-MYC诱导的HTERT启动子活性和端粒酶活性，并允许持续激活端粒，端粒酶，一种关键的酶（一种致癌物中的关键酶）。我们的目的是进一步表征NMI与BRCA1的关联以及NMI-BRCA1复合物在C-MYC的转录调控和转化中的作用。此外，我们将研究NMI在乳腺上皮细胞中的功能，并确定BRCA1/NMI/C-MYC的新型三脑复合物在乳腺上皮细胞中以及C-MYC诱导的HTERT启动子启动子活性和端粒酶活性中的作用。这些研究应导致对BRCA1生物学的新见解，并将进一步阐明调节乳腺癌细胞转化的分子机制。