IMMUNOHISTOCHEMICAL EXPRESSION OF THE C-FOS PROTEIN IN PRENEOPLASTIC AND NEOPLASTIC LESIONS DURING HEPATOCARCINOGENESIS IN RATS

We performed an immunohistochemical study of the c-FOS protein, in the preneoplastic and neoplastic liver lesions in rats. The majority of t he lesions at all stages contained an average of 50 to 60 percent of c -FOS immunopositive nuclei: This contrasted with the non-involved pare nchyma, which exhibited a low incidence of positivity (less than 10 pe rcent). No relation with proliferation or apoptosis was observed in th e lesions, whereas the c-FOS protein was overexpressed within a few ho urs of partial hepatectomy. Moreover, our results indicate that increa sed c-FOS protein content is insufficient to elicit full malignancy.