Immunohistochemical study of the ras oncogene expression in human bladder endoscopy specimens.

We have used the monoclonal antibody Y13 259 to the ras oncogene p21 protein product in 42 endoscopy specimens from the bladder of 37 patients, in order to determine the ras oncogene expression in different conditions of the urothelium. The examined material included: 27 normal and hyperplastic or dysplastic mucosae and 13 papillomas and transitional cell carcinomas, graded according to Mostofi's classification. Our results showed the following: the normal urothelium sections tended to be negative, while the umbrella cells from the superficial layer always expressed a higher degree of positivity. The majority of the hyperplastic lesions and the papillomas were weakly positive or negative. In contrast, all the dysplastic lesions and the carcinomas of different grades were strongly positive. Our results suggest that elevated expression of ras oncogene may serve as an early marker in the pathogenesis of bladder lesions.