MUTATION OF THE TUMOR-SUPPRESSOR GENE P53 IN HUMAN PROSTATE AND BLADDER CANCERS - INVESTIGATION BY TEMPERATURE-GRADIENT GEL-ELECTROPHORESIS(TGGE)

Purpose: To test the value of a recently developed screening method fo r the detection of p53 mutations in prostate and bladder cancers. Mate rials and Methods: Tumor tissue from 24 prostate cancers and 27 bladde r cancers were evaluated. DNA of the critical p53 exons 5-8 were ampli fied and run on horizontal polyacrylamide gels under defined temperatu re conditions (TGGE) to yield specific gel shifts and sets of homo- an d heteroduplexes in case of mutation. Sequencing with a laser-fluoresc ent electrophoresis unit was done directly from polymerase chain react ion (PCR) products and/or from reamplified mutant and wild type bands excised from the gels. Results: The p53 genotype predicted from the TG GE analysis was always confirmed on the excised DNA fragments, in cont rast to only 50% of cases tested by direct sequencing from mixed wild type and mutant DNA present in PCR products. With this screening proto col, 6 of 24 prostate cancers (25.0%) and 11 of 27 bladder cancers (40 .7%) showed p53 mutations. At stage T1, none of prostate cancers and 4 1.2% of bladder cancers contained mutant p53. At higher stages (greate r than or equal to T2), 30.0% of prostate cancer and 50.0% of bladder cancers were mutated. Histological tumor grading was > G1 in all but t wo prostate/bladder cancers with mutant p53. It appears that p53 mutat ions can occur early in bladder carcinogenesis. Conclusion: TGGE fulfi lls the clinical need of a rapid and specific screening method, and, a t the molecular level, has the advantage of sorting out the wild type and mutant alleles for consecutive sequencing.