Proteins related to early changes in carcinogenesis of hepatic oval cells after treatment with methylnitronitrosoguanidine

Hepatic oval cells are considered as facultative progenitor/stem cells of liver and able to differentiate into either hepatocytes or biliary epithelial cells. The transformed oval cells by carcinogen possess potential to develop carcinomas in animal models. In order to better understand the molecular mechanism in carcinogenetic process, we used a proteomic approach to assess the early changes in protein expression of oval cells (OC3W3-15) initiated by methylnitronitrosoguanidine (MNNG). Meanwhile, we compared cell biologic characteristics of the MNNG treated OC3W3-15 cells and control oval cells by electron microscopy, flow cytometry, karyotype and soft agar assay. The mRNA levels of GGT and GSTP1 determined by real-time PCR were also detected in both cell lines. Our results showed that MNNG-treated OC3W3-15 cells exhibited characteristics of malignant transformation, including growth rate, chromosomal aberrations, abnormal DNA content, and the ability to form colonies. The cells expressed higher levels of the tumor marker AFP, GGT and GSTP1 mRNA than that of control cells. Significant changes of several proteins involved in the malignant transformation process, including cell cycle related proteins, proteins involved in organism development and cell differentiation, are found in OC3W3-15 cells. The proteins may provide early affection in malignant transformation of hepatic oval cells, and yield further insight into mechanism of carcinogenesis of hepatocellular carcinoma.