P53 AND C-ERBB-2 EXPRESSION IN SCHISTOSOMAL URINARY-BLADDER CARCINOMAS AND SCHISTOSOMAL CYSTITIS WITH PREMALIGNANT LESIONS

Immunoreactivity for p53 and c-erbB-2 proteins was studied in 31 schis tosomal urinary bladder carcinomas and 21 cases of schistosomal cystit is with hyperplastic, metaplastic and/or dysplastic (premaligant) lesi ons. The results were compared with 30 carcinomas and 21 premalignant lesions of the urinary bladder without schistosomiasis. Abnormal nucle ar p53 protein accumulation was found in 17/31 schistosomal and in 15/ 30 non-schistosomal carcinomas and in 8/21 schistosomal cystitis with premalignant lesions of which five showed hyperplasia. No case of non- schistosomal hyperplasia or squamous metaplasia examined showed p53-po sitivity. In non-schistosomal carcinomas p53 positivity was significan tly associated with tumour grade (grade I-II vs grade III tumours: P = 0.021) and greater age (P = 0.004) while in schistosomal carcinomas n o such associations were found. Cytoplasmic membrane-bound positivity for c-erbB-2 oncoprotein was found in comparable percentages in schist osomal and non-schistosomal bladder carcinomas (10%), and in both grou ps was co-expressed with p53. p53 gene alteration is an important even t in the development of both schistosomal and non-schistosomal bladder carcinoma.