Mutations of ras genes are relatively frequent in Japanese prostate cancers: pointing to genetic differences between populations.

Point mutations of the ras gene family are thought to be involved in the development of a variety of human tumors. However, it remains unknown whether the ras gene might play a key role in prostate carcinogenesis. We therefore analysed Ki-,N- and H-ras gene mutations in a series of 81 Japanese prostate cancers using PCR-SSCP analysis and Mutant-Allele-Specific Amplification (MASA) method. Mutated as genes were detected in 20 of the 81 samples (24%); three of 22 latent, one of five stage B, four of 14 stage C and 12 of 40 stage D cancers. Of the twenty as gene mutations, 13 were in Ki-ras (codon 12), five in H-ras codon 61 and two H-ras codon 13. The observed frequency of ras gene mutations was higher than that reported in the literature for some non-Japanese prostate cancers, suggesting the possibility of genetic differences between populations.