Overexpression of the wild type p73 gene in human bladder cancer

p73, a first p53 relative, was recently identified and shown to be monoalle lically expressed in a number of different human tissues. To determine the potential role of this gene in human bladder cancer, we investigated p73 ex pression levels, allelic expression patterns, and analysed p73 mutations in 23 unselected primary invasive bladder cancers with matched normal tissues and in seven bladder cancer cell lines. In a comparison between normal and turner tissues using quantitative RT-PCR analysis, me found that p73 was o verexpressed in 22/23 bladder cancers, sometimes as great as 20-fold. Allel ic expression analysis using a C/T polymorphism in exon 2 and a newly ident ified T/C polymorphism in exon 5 revealed that p73 was biallelically expres sed in both normal bladder and cancer tissues, suggesting that p73 is not i mprinted in bladder tissue. Mutation screening of the p73 gene in bladder c ancer DNAs using denaturing high-performance liquid chromatography analysis and DNA sequencing revealed no tumor-specific mutations in any coding exon s of the p73 gene, These data suggest that the p73 is unlikely to be a tumo r suppressor gene, but that overexpression of p73 may contribute to tumorig enesis in bladder cancer.