Roles of EGFR-Stat3 signal pathway in carcinogenesis of experimental hepatoma in rats

The purpose of this study is to investigate if the EGFR-Stat3 signal pathway contributes to the carcinogenesis of hepatoma in rats. Hepatoma was induced in rats by 3'Me-DAB as a model. EGFR, TGF alpha, Stat3, p-Stat3 in different stages of carcinogenesis were detected by immunohistochemistry and Western blot. In situ hybridization was applied to investigate the expression of Stat3 mRNA. The expressions of signal molecules were assessed by KS400 Image Analysis system. The data were statistically evaluated. EGFR, TGF alpha, Stat3 were highly expressed in the stages of liver necrosis and repairment. All hepatocellular carcinoma cases revealed elevated expression of EGFR, TGF alpha. Elevation of Stat3 mRNA and protein levels were identified, increase of activation of Stat3 was also observed. In HCC, there was positive correlation between p-Stat3 level and the expression of TGF alpha and PCNA. Increased expression of Bcl-2 (P < 0.05) coincided with elevated level of p-Stat3. Therefore, the EGFR-Stat3 signal pathway was related to the development of hepatoma in rats. TGF alpha-EGFR autocrine ring formation may lead to the activation of Stat3 and in turn, promote proliferation and regulate the transcription of genes regulating cell apoptosis and cell cycle.