pp60c-src Activation in gastric carcinoma: a preliminary study

TO THE EDITOR: Gastric carcinoma is the most common malignancy in Japan. Although some genes such as the protooncoge c-erbB2, K-sam, K-ras, and c-met are overexpressed in gastric carcinoma (1), little is known about molecular events leading to malignant transformation of gastric epithelia. The protooncogene product pp60c-src is the cellular homolog of the Rous sarcoma transforming gene, v-src (2). Both c-src and v-src encode 60 kDa membrane–associated protein tyrosine kinases. For pp60c-src, a close correlation exists between elevated activity of tyrosine kinase and cell transformation (3). To be sure, we know that pp60c-src expression and its activity are increased in a limited number of cases in human cancers (4), including our cases (5). However, the role of pp60c-src in gastric cancer has not been investigated. In the present study, we determined the activity of pp60c-src in gastric carcinoma by measuring the in vitro protein kinase activity of pp60c-src using gastric tissues of tumorous (T) and adjacent normal mucosa (N) obtained from surgery of 12 patients (mean age 65.0 11.5 yr, range 42–78 yr). The samples used in this study came from 12 cases, including six well differentiated, four moderately differentiated, and two poorly differentiated gastric carcinomas.