Transactivation of the p21 promoter by BRCA1 splice variants in mammary epithelial cells: evidence for both common and distinct activities of wildtype and mutant forms
Transactivation of the p21 promoter by BRCA1 splice variants in mammary epithelial cells: evidence for both common and distinct activities of wildtype and mutant forms
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DOI：
10.1038/sj.onc.1204025
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发表时间：
2000-12-14
期刊：
影响因子：
8
通讯作者：
Arrick, BA
中科院分区：
文献类型：
--
作者：
Lu, ML;Arrick, BA
我们已经评估了转录激活的人p21启动子报告构建体转染BRCA 1表达构建体成肿瘤和nontumorigenic人乳腺细胞系。两个具有野生型p53的细胞系（MCF-7和MCF 10A）证实：p21启动子被全长BRCA 1（BRCA 1（L））以及两个缺少大部分外显子11的剪接变体（BRCA 1（S）和BRCA 1（S-9，10））转录激活。与此相反，两个细胞系突变p53（MDA-231和HCC 1937）是无活性的。BRCA 1 L与BRCA 1（S）或BRCA 1（S-9，10）的共转染表现出协同的p21启动子激活，这是由于基于巨细胞病毒启动子的BRCA 1表达构建体的表达增强。我们研究了BRCA 1中两个已知序列改变的转录活性，一个导致BRCA 1的羧基末端截短，并且明显具有致病性，另一个是怀疑易患癌症的错义突变。虽然这两种突变在一些反式激活试验中显示出缺陷，但我们观察到当掺入全长BRCA 1（L）中时，这两种突变在p21启动子的激活中完全活跃。相反，这些突变使BRCA 1（S）失活。这些观察结果表明，这样的转录检测不能作为基础的BRCA 1序列的功能评价过程中遇到的基因检测。
We have evaluated the transcriptional activation of a human p21 promoter reporter construct by transfection of BRCA1 expression constructs into tumorigenic and nontumorigenic human breast cell lines. Two cell lines with wildtype p53 (MCF-7 and MCF10A) demonstrated: transcriptional activation of the p21 promoter by full-length BRCA1 (BRCA1(L)) as well as by two splice variants that lack most of exon 11 (BRCA1(S) and BRCA1(S-9,10)). In contrast, two cell lines with mutant p53 (MDA-231 and HCC1937) were inactive. Co-transfection of BRCA1L with BRCA1(S) or BRCA1(S-9,10) exhibited synergistic p21 promoter activation, due to augmented expression of the cytomegalovirus promoter-based BRCA1 expression constructs. We examined the transcriptional activity of two known sequence alterations in BRCA1, one that results in a carboxy-terminal truncation of BRCA1 and is clearly pathogenic, and the other a missense mutation that is suspected of predisposing to cancer. Although both mutations have been shown to be defective in some assays of transactivation, we observed both mutations to be fully active in activation of the p21 promoter when incorporated in the full-length BRCA1(L). In contrast, these mutations rendered BRCA1(S) inactive. These observations indicate that such transcriptional assays cannot serve as the basis for a functional appraisal of BRCA1 sequence alterations encountered in the course of genetic testing.