[Localization of oncoprotein P21ras in the human liver cancer]

Using the human liver cancer DNA transfected NIH/3T3 cell line, the human N-ras oncogene and the over expression of the oncoprotein P21ras was demonstrated, BALB/C mice were immunized. The spleen cells from the immunized mice were fused with SP2/0 myeloma cells. After the HAT medium selection and screening, two hybridoma cell lines, SCI-Oncogema 1 and 2, were established. In the immunoprecipitation test, the molecular weight of the protein reacting to Oncogema 1 was 21,000. This M.W 21,000 protein possessed the capability to bind with GTP, i.e. the character of P21ras. These data indicate that the Oncogema 1 is the monoclonal antibody against P21ras. Using Oncogema 1, specimens from 6 liver cancer patients were studied by immunopathology. With ABC stain, it was observed that the malignant cells in all the samples showed dark staining; the P21ras revealed over expression. Although the staining was heterogeneous, it implied that the ras oncogene was involved in the carcinogenesis of these six samples. No over expression was seen in the normal liver cells even in those around the cancerous lesion. However, dysplastic cells were moderately stained which means that the ras oncogene was activated and P21ras over expressed in these cells. The results suggest that the ras oncogene and P21ras play an important role in the early stage of liver cancer carcinogenesis.