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.