INTERNATIONAL COMPARISON ON RAS GENE-MUTATIONS IN LATENT PROSTATE CARCINOMA

Latent carcinomas of the prostate, discovered at autopsy in men with n o prior treatment for prostatic disease, were studied for ras proto-on cogene mutations. Subjects included 21 Japanese, 15 U.S. whites, 15 U. S. blacks, 20 Hawaiian Japanese and 10 Colombians. PCR and sequence-sp ecific oligonucleotide hybridization identified mutations in 5 Japanes e, in 1 Hawaiian Japanese, in 1 U.S. black, in 1 U.S. white and in 3 C olombians. The 5 Japanese tumor samples contained 3 point mutations in codon 12 of K-ras and 2 mutations in codon 12 of N-ras respectively. One tumor in a Hawaiian Japanese man also showed a K-ras point mutatio n at codon 12. Two Colombians and one U.S. black man had tumors with m utations at codon 61 of H-ras, while 1 Colombian showed an N-ras mutat ion at this codon. The overall frequency of ras gene mutations was low , but point mutations in codon 12 were most common in latent tumors of Japanese, who experienced the lowest incidence and mortality from thi s tumor. Latent tumors in men from ethnic groups with high mortality a nd incidence rates showed fewer ras mutations than the Japanese, and t hese were more likely to involve codon 61. This finding is consistent with prior studies of more aggressive clinical cancers in Japanese men that indicated a higher frequency of mutations at codon 61.