Correlation between epigenetic alterations in the insulin growth factor-II gene and hepatocellular carcinoma

Abstract

To investigate whether epigenetic alterations in the insulin-like growth factor-II (IGF-II) gene that cause differential transcription or expression are correlated with onset and severity of hepatocellular carcinoma (HCC). Patient-matched specimens of HCC, paracancerous, and non-cancerous tissues were collected from 40 primary liver cancer patients. Epigenetic alterations in the promoter (P3) sequence of the IGF-II gene were analyzed by methylation-specific PCR (MSP) and IGF-II transcription was measured by RT-PCR. IGF-II protein expression and clinicopathological features were assessed by immunohistochemistry and microscopic observation. The rate of IGF-II P3 methylation was significantly lower in HCC tissues (0%) than in paracancerous tissues (vs. 47.5%; x2 = 24.918, P less than 0.001) and non-cancerous tissues (vs. 100%; x2 = 80.000, P less than 0.001). IGF-II mRNA expression was significantly higher in HCC tissues (100%) than in paracancerous tissues (vs. 52.5%; x2 = 24.918, P less than 0.001) and non-cancerous tissues (vs. 0%; x2 = 80.000, P less than 0.001). IGF-II protein expression was significantly higher in HCC tissues (82.5%) than in paracancerous tissues (vs. 45.0%; x2 = 12.170, P less than 0.001) and non-cancerous tissues (vs. 0%; x2 = 56.170, P less than 0.001). IGF-II overexpression in HCC was significantly associated with degree of differentiation, extent of infiltrated serosa, size of tumor, and HBV-positive infection status. Epigenetic alterations in the IGF-II gene regulate its transcription and expression and are closely associated with HCC development and progression.