中文摘要：

目的：研究沉默乳腺癌相关抗原1（breast cancer—associated antigen1，BRCAA1）基因对胃癌细胞株MGC-803的抑制作用及其可能的机制。方法：构建BRCAA1基因shRNA载体，将构建的shRNA—BRCAAI质粒与阴性对照质粒shRNA—N转染胃癌MGC-803细胞，24h后用荧光显微镜观察转染效率，实时定量PCR检测BRCAA1和GAPDH基因mRNA表达水平。MTT法检测转染后24、48与72h的细胞增殖水平，Annxin—VPE／7AAD检测转染24h后的细胞凋亡水平，Westernblotting检测转染48h后细胞的凋亡相关蛋白表达水平。结果：BRCAA1siRNA表达质粒转染MGC-803细胞24h的转染效率为（81．2±2．6）％。转染后48hMGC．803细胞的BRCAA1mRNA水平下降了61．4％，MGC-803细胞增殖的抑制率达45．0％，转染siRNA细胞的凋亡率明显高于未转染细胞和对照质粒转染细胞[（14．4±1．6）％vs（5．4±2．0）％，（4．4±2．5）％，P〈0．05]。转染siRNA细胞的凋亡相关蛋白Rb与Bax的表达量显著增加（P〈0．05），Bcl-2的表达量显著减少（P〈0．05）。结论：BRCAAI基因的沉默可有效抑制人胃癌MGC．803细胞的增殖和诱导细胞凋亡，其机制与其促进Rb和Bax蛋白表达、抑制Bcl-2蛋白表达有关，

英文摘要：

Objective ： To investigate the inhibitoR, effect of breast cancer-associated antigen 1 （ BRCAA1 ） gene silencing on gastric cancer MGC-803 ceils and the related mechanism. Methods： Plasmid shRNA-BRCAA1 and shRNA-N were constructed and transfected with FuGene HD into gastric cancer cell line MGC-803. The transfection efficiency was examined using fluorescent microscope 24 h later. The total RNAs was extracted 48 h after transfection and the expression of BRCAAI and GAPDH gene were analyzed by real-time PCR. The cell proliferation was assessed by MTT assay 24 h, 48 h, and 72 h after transfection. The cell apoptosis was determined by Annexin V-PE/7AAD. The expression of Rb, Bax, Bcl-2 and BRCAA1 proteins was analyzed by Western blotting 48 h after transfection. Results： We found that the transfection efficiency of shRNA-BRCAA1 was （81.2 ± 2.6） % 24 h after transfection. Forty-eight hours after transfection with shRNA-BRCAA1 the expression of BRCAA1 mRNA decreased by 61.4% ; the inhibition rate of MGC-803 cells growth was 45.0%. The cell apoptosis rate of shRNA-BRCAA1 transfection group was significantly higher than those of untransfected group and mock plasmid transfected group （ [ 14.4 ±1.6 ] % vs [ 5.4±2.0 ] %, [ 4.4 ± 2.5 ] % ,P 〈 0.05 ]. Cells transfected with shRNA-BRCAA1 had significantly increased expression of Rb and Bax proteins （ P 〈 0.05） , and decreased expression of Bcl-2 protein（P 〈0.05）. Conclusion： BRCAAI gene silencing can effectively inhibit the proliferation of MGC-803 cells and induce apoptosis, which might be related to the promotion of Rb and Bax proteins, and suppression of Bcl-2 protein.