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 for the detection of p53 mutations in prostate and bladder cancers.

MATERIALS AND METHODS

Tumor tissue from 24 prostate cancers and 27 bladder cancers were evaluated. DNA of the critical p53 exons 5-8 were amplified and run on horizontal polyacrylamide gels under defined temperature conditions (TGGE) to yield specific gel shifts and sets of homo- and heteroduplexes in case of mutation. Sequencing with a laser-fluorescent electrophoresis unit was done directly from polymerase chain reaction (PCR) products and/or from reamplified mutant and wild type bands excised from the gels.

RESULTS

The p53 genotype predicted from the TGGE analysis was always confirmed on the excised DNA fragments, in contrast to only 50% of cases tested by direct sequencing from mixed wild type and mutant DNA present in PCR products. With this screening protocol, 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 41.2% of bladder cancers contained mutant p53. At higher stages (> or = T2), 30.0% of prostate cancer and 50.0% of bladder cancers were mutated. Histological tumor grading was > G1 in all but two prostate/bladder cancers with mutant p53. It appears that p53 mutations can occur early in bladder carcinogenesis.

CONCLUSION

TGGE fulfills the clinical need of a rapid and specific screening method, and, at the molecular level, has the advantage of sorting out the wild type and mutant alleles for consecutive sequencing.