Immunohistochemical and Immunoblot Analyses of ras‐p21 Expression in Lung Carcinomas

Immunohistochemical and immunoblot analyses were performed on 49 cases of surgically resected primary lung carcinoma to examine the expression of ras oncogene product using monoclonal antibodies to ras-p21. Two different monoclonal antibodies, NCC-RAS-001 and RAP-5 were used for immunohistochemical study. Cancer cells of 16 cases (33%) and 15 cases (31%) were strongly positive for NCC-RAS-001 and RAP-5, respectively. The staining pattern of antibodies was heterogenous among cancer cells, even in the same case. Among various histologic type of lung cancers, squamous cell carcinomas and well-differentiated adenocarcinomas had a tendency to react more intensively than other histologic types of carcinoma. Immunoblot analysis using monoclonal antibody NCC-RAS-004 revealed the presence of ras-p21 not only in cancer tissues but also in non-cancerous tissues in all cases analysed. In 13 cases (27%), cancer tissue expressed more than twice as much ras-p21 as non-cancerous tissues. Our study showed that the over-expression of ras-p21 in lung carcinomas compared with non-cancerous tissues was a relatively common phenomenon, especially in squamous cell carcinomas and adenocarcinomas.