RNA干扰靶向抑制磷脂酰肌醇3-激酶P85α蛋白表达对结直肠癌细胞周期和细胞凋亡的影响

目的探讨RNA干扰靶向抑制磷脂酰肌醇3-激酶（P13K）P85α蛋白表达对结直肠癌细胞周期与细胞凋亡的影响。方法设计4条shRNA干扰载体及1条阴性对照载体．分别稳定转染结直肠癌SW480细胞。采用Western blot筛选出对P13K P85α蛋白抑制效率最高的shRNA干扰片段．然后通过PI标记法和Annexin V—FITC标记法分别检测干扰后SW480细胞周期和细胞凋亡情况。结果转染shRNA／324后．SW480细胞P13K P85α蛋白降低最为显著．抑制率为90％。选择该干扰片段进行后续实验。干扰组与对照组SW480细胞的G1期细胞数量分别占（62．4±2．7）％和（51．2±3．5）％；S期细胞数量占（23．9±1．7）％和（34．1±3．4）％；氟尿嘧啶所诱导的细胞凋亡率为（11．1±3．7）％和（1．4±0．6）％；上述差异均有统计学意义（P〈0．05）。结论P13K P85α蛋白表达下降可引起结直肠癌SW480细胞周期阻滞，细胞凋亡增加：PI3K P85α可能成为结直肠癌基因治疗的新靶点。

Influence of phosphatidylinositol-3-kinases P85α silence by RNA interference on cell cycle and apoptosis of colorectal cancer cells in vitro

Objective To investigate the effect of phosphatidylinositol-3-kinases (PI3K) P85α silence on cell cycle and apoptosis of colorectal cancer cells. Methods Four shRNA vectors(shRNA/89,324, 1073 and 1123) and one negative control vector were designed and stably transfected into SW480 cells. Western blotting was used to determine the expression level of P85α. Flow cytometry was used to determine the PI-labeled cycle after stable transfection. Annexin V-FITC kit was used to determine the apoptosis. Results Western blotting analysis showed that the expression level of PI3K P85α protein was significantly decreased in cells transfected with shRNA/324 vector. The inhibition rate was 90%. The group was selected for the following experiments. G1 phase cells in the interference group and the control group were (62.4±2.7)% and (51.2±3.5)%, respectively. S phase cells in the interference group and the control group were (23.9±1.7)% and (34.1±3.4)%, respectively. Apoptosis cells induced by 5-FU of interference group and control group were (11.1±3.7)% and (1.4±0.6)%, respectively. The differences were all significant(P＜0.05). Conclusions Depletion of PI3K P85α can significantly induce SW480 cell cycle arrest and sensitize SW480 cells to 5-FU induced apoptosis. PI3K P85α may be a new therapeutic target for colorectal cancer cells.