Abstract

Phospholipase C-rl(PLC-rl) plays a significant role in signal transduction for cellular activity, such as proliferation and differentiation. The concept that PLC-rl may be involved in carcinogenesis is supported by recent observations: its expression is highly increased in breast and colon cancer, but decreased in hepatocellular carcinoma(HCC). The aim of present study was to analyze the role of PLC-rl in hepatic carcinogenesis. PLC-rl expression was studied chronologically in cirrhotic and neoplastic lesion and the preventive effect of vitamin A in HCC was examined. Seventy five Sprague-Dawley rats were treated with NNM in drinking water(20 mg/100 ml) and were divided into four groups: group I received NNM alone, group II, NNM+vitamin A. group III, vitamin A alone, and group IV received no treatment. The liver tissue obtained was investigated by gross and microscopic examination, and expression of PLC-rl was studied with immunohistochemistry, immunoprecipitation and immunoblot. Results are as follows: l) The first identifiable pathologic lesion could be found at 4 months in the group I and at 5 months in the group II. 2) The overexpression of FLC-rl was detectable in cirrohtic lesion but, negative expression in HCC, in immunohistochemical study. 3) More expression of PLC-rl was detectable in cirrhotic lesion, but, less in HCC, in immunoprecipitation and immunoblot study. 4) The development of HCC was so eignificantly low(P<0.00l) in group II comparing to group I that preventive effect of vitamin A in the development of HCC could be suggested. In conclusion, an important role of FLC-rl in hepatic carcinogenesis could be suggested as demonstration of the alternation of PLC-rl expression in preneoplastic and neoplastic lesion.

• Keywords: PLC-rl, Carcinogenesis, Liver