P53 GENE-MUTATIONS IN HUMAN UROTHELIAL CARCINOMAS - ANALYSIS BY IMMUNOHISTOCHEMISTRY AND SINGLE-STRAND CONFORMATION POLYMORPHISM

We examined 60 cases of human urothelial carcinomas (27 superficial an d 33 deeply invasive) for the frequency of p53 gene mutations. Forty-t wo cases were analyzed by both the immunohistochemical and the single- strand conformation polymorphism (SSCP) methods, and the remaining 18 cases were assayed by SSCP alone. For the latter assay, exons 4 to 8 w ere amplified by polymerase chain reaction, and the amplified nucleoti des were analyzed for the evidence of mutations by gel electrophoresis . When mobility shift was observed, direct nucleotide sequencing was p erformed to determine mutation sequence. Three superficial and eight d eeply invasive carcinomas demonstrated evidence of mutations. Mutation s involved various codons randomly. The fact that all tumors with muta tions of the p53 gene except for one were of high nuclear grade (grade III) suggests that p53 mutation is associated with the progression of bladder cancers. Our results indicate that SSCP is a sensitive screen ing assay for detecting gene mutations. Immunohistochemical analysis i s also a sensitive method but may yield false positive as well as fals e negative results.