Progression in transitional cell carcinoma of the urinary bladder--analysis of Tp53 gene mutations by temperature gradients and sequence in tumor tissues and in cellular urine sediments.

The relationship between expression of p53 protein in bladder cancer and tumor progression is known. In this paper, we attempt to study this phenomenon by molecular-genetic techniques. One hundred thirty-seven bladder tumor tissues were obtained from transurethral resection (TURB). Urine sediments were collected from 72 patients suffering from transitional cell carcinoma and tumor recurrence. These patients were followed up for at least three months. Separate polymerase chain reactions (PCR) were carried out for exons 5, 6, 7, and 8 of the Tp53 gene. Temperature gradient gel electrophoresis (TGGE) was used to screen mutations in the PCR products. Sequencing from reamplified mutant and wildtype bands was excised from the TGGE. Tp53 mutation frequency is 43.1% in 137 bladder cancer specimens, but already 32.7% of Ta-tumors (16/49) were Tp53 mutated. Four of 25 patients with Tp53 wild-type tumors suffered from progression. In the group of patients with Tp53 mutated cancer, seven of 12 had a tumor progression. In 11 of 14 patients with Tp53 mutation in cancer tissue, the same mutation was also found in urine sediments. In such patients, successful tumor treatment by TURB results in loss of their Tp53 mutation in urine sediment, and tumor recurrency resulted in reappearance.

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.