目的： 研究siRNA封闭乳腺癌抗原相关基因1(BRCAA1)对乳腺癌细胞MCF-7增殖和Rb基因表达的影响。方法： 采用RNAi技术对乳腺癌细胞MCF-7细胞BRCAA1基因进行特异性抑制，用阳离子脂质体与化学合成的Pre-designed anti-BRCAA1 siRNA构建转染复合体，反转染MCF-7细胞株48h后提取总RNA，分为未处理(NT)组、阴性对照组、阳性对照组和BRCAA1组，经反转录荧光实时PCR检测BRCAA1和Rb基因mRNA表达情况;检测细胞增殖抑制率。结果： 与阴性对照组相比，siRNA转染MCF-7细胞后实验组BRCAA1基因mRNA水平降低了42.3％；Rb基因表达较之阴性对照组上升了11.1％；实验组MCF-7细胞增殖抑制率为（81.9±6.1）％,抑制作用明显强于对照组(P<0.05)。结论： BRCAA1基因的封闭明显抑制了MCF-7细胞的增殖,BRCAA1基因与Rb基因可能存在有某种相互拮抗的作用。

Objective: To investigate the effect of blocking BRCAA1 gene expression with siRNA on the proliferation of tumor cell line MCF-7 and Rb gene expression. Methods: RNAi was employed to specifically knock down BRCAA1 expression. MCF-7 cells were transfected with complexes constructed with lipids and chemically synthesized Pre-designed anti-BRCAA1 siRNAs. The total RNA was isolated and reversely transcribed after 48 h. The expressions of BRCAA1 and Rb mRNA were determined by Real-Time PCR. Results: Compared with negative control, transfected MCF-7 cells had a 42.3% decrease in expression of BRCAA1 mRNA and an 11.1% increase in Rb mRNA expression. The inhibitory rate of MCF-7 cells proliferation was (81.6±61)%. Conclusion: There may be some antagonistic effect between BRCAA1 gene and Rb gene in proliferation of tumor cells, which provides a potential target for anti-tumor gene therapy.

国家重点基础研究发展(973)项目（2005CB724300G）；国家自然科学基金（39900177，30471599）