Screening of human bladder tumors and urine sediments for the presence of H‐ras mutations

A series of 111 human bladder tumors were screened using oligonucleotide mutant specific probes, restriction enzyme analysis and single‐stranded confirmation polymorphism (SSCP) for the presence of H‐ras activation events. Thirty‐three tumors were found to harbor H‐ras mutations where a glycine to valine (G→ T) change in codon 12 was the most common point mutation recorded (26 tumors). Additional mutations involved glycine to cysteine at codon 13 (2 tumors) and glutamine to arginine/lysine/leucine at codon 61 (3/1/1 tumors, respectively). Ambiguous signals recorded with oligonucleotide probes were further analyzed using SSCP analysis revealing the presence of H‐ras mutations in restricted regions of some tumors. The apparent sensitivity of SSCP enabled us to extend this study to DNA isolated from urine sediments where 4 of the 9 patients studied showed representation of mutant H‐ras. Our study demonstrates a sensitive, non‐invasive assay for the screening of urine‐borne cells, with no requirement for prior knowledge of the mutational change at the H‐ras locus.