胰岛素样生长因子结合蛋白7过表达对人乳腺癌细胞系-7增殖的影响及其机制研究

目的  探究过表达胰岛素样生长因子结合蛋白7（IGFBP7）对人乳腺癌细胞系-7（MCF-7）增殖的影响及其机制。方法  采用LipofectamineTM 2000将pIRES2-ZsGreen1-IGFBP7质粒或pIRES2-ZsGreen1空白质粒转染进MCF-7乳腺癌细胞，并用荧光显微镜鉴定细胞转染；实时荧光定量聚合酶链反应（Real-time PCR）对转染48 h后IGFBP7蛋白进行定量；细胞凋亡实验检测转染24、48和72 h后各组细胞增殖情况；Western bolt检测转染48 h后各组细胞（蛋白激酶B/雷帕霉素靶蛋白）（AKT/mTOR）信号通路相关蛋白的表达。结果  Real-time PCR的检测结果提示经过IGFBP7转染的细胞IGFBP7 mRNA表达水平明显升高；细胞凋亡实验结果发现，与空白处理组和空白质粒转染组比较，IGFBP7过表达组细胞增殖能力明显降低；Western bolt检测结果发现，AKT蛋白的磷酸化水平明显下降，且其下游的mTOR表达明显下降（P <0.05）。结论  IGFBP7过表达对MCF-7乳腺癌细胞的增殖具有抑制效果，可能是通过对AKT/mTOR信号通路的抑制达到对MCF-7的抑制。

Effect of IGFBP7 overexpression on proliferation of breast cancer cell line MCF-7

Objective  To investigate the effect of insulin-like growth factor binding protein 7 (IGFBP7) on prolife- ration of human breast cancer cell line MCF-7 and its mechanism. Methods  Plasmid pIRES2-ZsGreen1-IGFBP7 or empty plasmid pIRES2-ZsGreen1 was transfected into MCF-7 cells using LipofectamineTM 2000 and the cell transfection efficiency was examined by fluorescence microscopy. Real-time fluorescent quantitative PCR (RTFQ-PCR) was used to quantify the expression of IGFBP7. MTT was performed to evaluate the effect of IGFBP7 on prolife- ration and apoptosis of MCF-7 cells at 24, 48 and 72 hours after transfection. The expression of relevant proteins of AKT/mTOR signaling pathway was analyzed by Western blot. Results  The IGFBP7 mRNA level increased significantly after IGFBP7 transfection. Compared with the controls, cell proliferation noticeably decreased in the IGFBP7-transfected group. Western bolt analysis indicated that the AKT phosphorylation was down-regulated, and the mTOR level dropped markedly (P < 0.05). Conclusions  Overexpression of IGFBP7 could down-regulate the proliferation of MCF-7 cells, possibly via inhibiting the AKT/mTOR signaling pathway.