摘要：
目的通过比较DNA损伤修复基因乳腺癌易感基因1(breast cancer susceptibility gene 1，BRCA1)和抑癌基因p53在HCC1937和MCF7两种乳腺癌细胞系中的功能状态及对DNA损伤修复反应的应答特性，研究两种细胞系在功能上的差异。方法应用westernblotting法检测两种乳腺癌细胞系中BRCA1和p53蛋白的表达,并检测了经过10 Gy电离辐射下1、4、8 h后BRCA1蛋白在MCF7、HCC1937和HCC1937野生型BRCA1（HCC1937 wtBRCA1）细胞系中的表达水平。同时用免疫荧光法观察BRCA1蛋白在MCF7和HCC1937细胞系细胞内的分布和焦点形成情况，并对电离辐射下的BRCA1、Rad51蛋白的焦点形成百分比进行计算。进一步用流式细胞仪检测两种细胞系的细胞周期变化。结果MCF7细胞中野生型的BRCA1和p53主要分布于细胞核内，这两种蛋白对DNA损伤反应有应答。10 Gy 8 h照射条件下,MCF7细胞系中BRCA1蛋白焦点形成百分比较无电离辐射高［(5940±366)%比(1180±351)%，t=1626，P<005］；MCF7细胞系照射组中Rad51蛋白焦点形成百分比较无电离辐射高［（7390±866）%比（1670±376）%，t=1049,P<005］，照射组p53蛋白［(8254±104)比(2375±051)，t=8790,P<005］和p21蛋白［(9095±113)比(5019±089)，t= 4911,P<005］表达水平均较无电离辐射高,细胞在G1期蓄积。与MCF7细胞相比，在HCC1937细胞中的BRCA1和p53都产生了变异，在细胞核内两种蛋白较少。10 Gy 8 h照射条件下HCC1937细胞中无BRCA1蛋白焦点形成、p53和p21几乎无诱导表达以及细胞在G1和G2M期无明显的蓄积。当恢复野生型BRCA1在HCC1937细胞内表达后，10 Gy 8 h照射条件下Rad51蛋白焦点形成百分比较无电离辐射高［（6170±403）%比（622±227）%，t=2078，P<005］，细胞在G2M期的蓄积增多。结论乳腺癌细胞系HCC1937和MCF7在应答DNA损伤修复反应时具有不同的功能特性。
关键词：乳腺肿瘤;BRCA1蛋白质；DNA损伤；HCC1937;MCF7
Abstract:
ObjectiveThe functional characters of MCF7 and HCC1937 cell lines were compared through the activity of BRCA1 and p53 following DNA damage in order to provide more research evidence for the related studies in both breast cancer cell linesMethodsThe protein level of BRCA1 and p53 in two breast cancer cell lines and the protein level of BRCA1 in MCF7,HCC1937 and HCC1937 wtBRCA1 breast cancer cell lines treated with 10Gy after 1 h,4 h or 8 h were detected by western blotting analysis The distribution and foci formation of BRCA1 in the cells were observed through immunostaining assay and the percentage of BRCA1 or Rad51 foci formation after ionizing radiation was calculated Cell cycle profiling was analyzed using flow cytometry ResultsMost of BRCA1 and p53 localized in nucleus, and both proteins responded to DNA damage in MCF7 cells In MCF7 cells，BRCA1 and Rad51 foci formation respectively increased to (5940±366)% from(1180±351)% (t=1626,P<005)and (7390±866）% from(1670±376）% (t=1049,P<005) after 10 Gy 8 h ; p53 and p21 protein level was further separately induced and enhanced to (8254±104) from (2375±051) (t=8790,P<005) and (9095±113) from (5019±089)( t=4911,P<005) after 10 Gy 8 h; and the cells were accumulated in G1 phase In contrast to MCF7, in HCC1937 cell line, both of BRCA1 and p53 were defective in nucleus since both proteins were mutated; in response to DNA damage, BRCA1 foci formation was not found， p53 and p21 was not induced; there was no cell accumulation in both of G1S and G2M phases However, after complementation of wildtype BRCA1 in HCC1937 cells, DNA damageinduced Rad51 foci formation increased to (6170±403）% from (622±227）% (t=2078,P<005) and accumulation of cells in G2M phase was also restored after 10 Gy 8h , which was similar to that of in MCF7 cells ConclusionsWe have identified that BRCA1 and p53 have dramatically different functions in MCF7 and HCC1937 cell lines in response to DNA damage
Key words: Breast neoplasms;BRCA1 protein;DNA damage；HCC1937;MCF7
发表日期：2014/9
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