Expression of ras Oncogene p21 Product in Malignant and Benign Lesions and Normal Mucosae of the Stomach in China

Expression of c-ras oncogene was analyzed in 75 cases of carcinomas, 38 benign lesions and 22 normal mucosae of the stomach in Chinese subjects by use of the monoclonal antibody rp28, which reacts to the c-Ha-ras and c-Ki-ras p21 products. The incidence of p21 positive cases (more than 20% of total cells stained by rp28) was 90.7% in gastric carcinomas, 10.5% in benign gastric lesions and 4.5% in normal mucosae. While 34/75 gastric carcinomas contained strongly rp28-reactive (+ +) cells, none of the benign lesions or normal mucosae did. The mean percentage of rp28 reactive (+ or ++) cells in each group was 52.2% in gastric carcinomas, 6.3% in benign lesions and 2.3% in normal mucosae. These indicate that ras p21 expression is significantly high in the gas-tric carcinomas compared to the benign lesions and normal mucosae of the stom-ach. Tests of tubular adenocarcinomas with different degrees of differentiation showed significantly higher amounts of p21 product in well differentiated (71.7%) and moderately differentiated (67.3%) samples than in poorly differentiated adenocarcinomas (40.9%), which contained more, in tern, than mucinous adenocarcinomas (39.2%) and undifferentiated carcinomas (27.5%). This sug-gests that Ha- and/or Ki-ras p21 expression may have some roles in the mainte-nance of the glandular structure in gastric carcinomas