Abnormal expression of insulin-like growth factor-II and intervening of its mRNA transcription in the promotion of HepG2 cell apoptosis

Abstract

To explore the expression and pathological features of insulin-like growth factor-II (IGF-II) in tissues and sera of hepatocellular carcinoma (HCC) patients and the siRNA-mediated inhibition of IGF-II mRNA transcription in human HepG2 cells. From December 2009 to August 2010, the self-control HCC, paracancerous and distal cancerous tissues were collected to analyze the expression of IGF-II. The serum levels of IGF-II expression were detected for pathological features. IGF-II expression in HepG2 cells was intervened by siRNA. IGF-II mRNA or IGF-II level and analyzed by reverse transcription-polymerase chain reaction (RT-PCR), real-time PCR or enzyme-linked immunosorbent assay (ELISA). And the ratio of cell apoptosis was analyzed by EdU/Hoechst33342. The levels of IGF-II expression in HCC tissues at mRNA (100%, 30/30) or protein (83.3%, 25/30) were significantly higher (P < 0.01) than those in para-cancerous (46.7%, 53.3%) or distal cancerous tissues (0, 0). The serum level of IGF-II was significantly higher in HCC patients (3.74 ± 0.67) ng/L than that in cases with benign liver diseases (1.93 ± 0.17) ng/L and controls (1.14 ± 0.14) ng/L (P < 0.001). The expression of IGF-II in the HCC group was associated with HBV infection (t = 5.390, P < 0.001). After siRNA transfection, the expression of IGF-II decreased significantly in HepG2 cells at mRNA or protein levels. The down-regulated expression of IGF-II was dependent on the dose and time of IGF-II siRNA. And the apoptotic index of HepG2 cells and the sensitivity to adriamycin both increased. The expression of IGF-II is closely associated with the progression of HCC. And the intervening of its transcription may promote apoptosis and sensitize to adriamycin.