Expression of ras and myc oncogenes in human hepatocellular carcinoma and non-neoplastic liver tissues.

An immunohistochemical assay was used to assess expression of ras p21 and myc p62 oncogene products in human hepatocellular carcinoma (HCC) and non-neoplastic liver tissues. The monoclonal antibodies Y13 259 and Myc1-9E10, specific for ras p21 and myc p62 oncoproteins, were employed on paraffin-embedded sections. Most HCCs showed enhanced ras p21 and myc p62 expression, as indicated by staining intensity. Cirrhotic livers revealed increased myc p62 and occasionally increased ras p21 expression. HBsAg+ hepatocytes showed intense immunostaining for ras p21. Fibrotic, cholestatic, fetal and normal adult liver did not present enhancement of oncoprotein production. We suggest that combined over-expression of ras and myc oncoproteins may be important for the malignant phenotypic alteration in human HCC.