Abstract: Background and purpose: Insulin-like growth factor-1 (IGF-1) is a peptide that participates in many biological processes by stimulating the downstream signaling pathways through their interaction with IGF-1 receptor (IGF-1R) and insulin receptor (IR). Bone morphogenetic proteins (BMPs) are a group of functional proteins which participate in the biological processes of proliferation and migration in many kinds of cancers and have become a hot area of cancer research. The study aimed to investigate the effects of silencing IGF-1R gene on the expression level of BMP2 gene, and the cell proliferation and apoptosis of SMMC7721 cells. Methods: The RNAi plasmid targeting IGF-1R gene was constructed and transfected into SMMC7721 cells. Then the inhibition effect on the expression level of IGF-1R and BMP2 gene was detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. The SMMC7721 growth curve and cell apoptosis were detected by MTT assay and flow cytometry after they were transfected with RNAi plasmid. Results: The RNAi plasmid targeting IGF-1R gene was constructed successfully. The inhibition efficiencies at mRNA expression levels were 68.9% and 80.7% (IGF-1R gene), 79.5% and 83.3% (BMP2 gene), respectively, after transfection with IGF-1R-siRNA-1 and IGF-1R-siRNA-2 plasmid (P<0.05). The inhibition efficiencies at protein levels were 46.1% and 62.1% (IGF-1R gene, P<0.05), 42.5% and 60.9% (BMP2 gene, P<0.05), respectively. The results of MTT growth curve showed that the proliferation rate in the transfected SMMC7721 cells was significantly slower than that in the control group (P<0.05). The proportion of apoptotic cells in transfected groups was significantly higher than that in the control group (P<0.05). Conclusion: Silencing IGF-1R gene can downregulate the expression of BMP2 gene at different levels that results in inhibition of cell proliferation and promotion of apoptosis in SMMC7721 cells.

Key words: IGF-1R gene, BMP-2 gene, Hepatocellular carcinoma SMMC7721 cell, Cell proliferation, Cell apoptosis