目的： 探讨干扰B7-H4表达对乳腺癌细胞增殖、凋亡、周期以及相关下游分子表达的影响。 方法： 利用脂质体转染技术分别将特异性靶向B7-H4的siRNA（siB7-H4）及其阴性对照（siNC）转染至对数生长期的乳腺癌T47D和MCF-7细胞，分别命名为T47D-siB7-H4、T47D-siNC、MCF-7-siB7-H4和MCF-7-siNC组。用qPCR法和WB法验证siRNA干扰效果及其对细胞周期分子cyclin D1表达的影响，CCK-8法和FCM分别检测干扰B7-H4表达对T47D和MCF-7细胞增殖、周期和凋亡的影响，qPCR法检测B7-H4干扰对E2F家族相关转录因子表达的影响。 结果： 成功构建干扰 B7-H4 表达的乳腺癌T47D和MCF-7细胞。与T47D-siNC和MCF-7-siNC组相比，T47D-siB7-H4和MCF-7-siB7-H4组细胞中B7-H4 mRNA和蛋白表达水平均显著降低、细胞增殖能力显著降低（均P<0.01），并伴有G1/S期细胞周期阻滞以及cyclin D1表达下调（均P<0.01），但细胞凋亡率差异无统计学意义（均P>0.05）。与T47D-siNC相比，干扰 B7-H4 后 T47D 细胞中 E2F1、E2F2、E2F7 和 E2F8 mRNA 水平有不同程度的降低（均P<0.01）；与MCF-7-siNC 相比，干扰 B7-H4后MCF-7细胞中E2F1、E2F2、E2F3、E2F7和E2F8 mRNA水平均有不同程度的降低（P<0.05或P<0.01）。 结论： 干扰乳腺癌细胞B7-H4表达可下调cyclin D1和E2F家族相关转录因子的表达，导致细胞周期阻滞并抑制细胞增殖。

Objective: To investigate the effects of interfering with B7-H4 expression on proliferation, apoptosis, cell cycle and expression of downstream molecules in breast cancer cells. Methods: Breast cancer T47D and MCF-7 cells at logarithmic phase were transfected with siRNA specifically targeting B7-H4 (siB7-H4) or its negative control (siNC) by using Lipofectamine TM 2000, namely T47D siNC, T47D-siB7-H4, MCF-7-siNC, and MCF-7-siB7-H4 group, respectively. The efficacy of siRNA interference and its effect on the expression of cyclin D1 were verified by quantitative PCR (qPCR) and Western blotting (WB). The effects of interfering with B7-H4 on cell proliferation, cell cycle and apoptosis of breast cancer cell lines T47D and MCF-7 were detected by CCK-8 assays and flow cytometry, respectively. The effects of interfering with B7-H4 on the expression of E2F family related transcription factors were examined by qPCR. Results: The T47D and MCF-7 cell lines with B7-H4 knockdown were successfully constructed. Compared with the cells in T47D-siNC and MCF-7-siNC groups, the mRNA and protein levels of B7-H4 were significantly decreased, and the proliferation was significantly inhibited in the cells of T47D-siB7-H4 or MCF-7-siB7-H4 groups, accompanied with G1/S cell cycle arrest as well as downregulation of cyclin D1 (all P<0.01); however, there were no statistically significant differences in apoptotic rates (all P>0.05). Compared with the cells in T47D-siNC group, the mRNA levels of E2F1, E2F2, E2F7 and E2F8 in T47D cells decreased in varying degrees after interfering with B7-H4 (all P<0.01); compared with cells in MCF-7-siNC group, the mRNA levels of E2F1, E2F2, E2F3, E2f7 and E2F8 in MCF-7 cells also decreased in varying degrees after interfering with B7-H4 (P<0.05 or P<0.01). Conclusion: Interfering with B7-H4 in breast cancer cells can down-regulate the expression of cyclin D1 and E2F family related transcription factors, leading to cell cycle arrest and inhibition of cell proliferation.

R739.7; R730.2

国家自然科学基金资助项目（No.81772485）