Focal distribution of p16/CDKN2 gene mutations within individual prostate carcinomas

To examine the potential role of pl6/CDKN2 gene mutations in prostate tumorigenesis, focal areas within individual tumors were investigated. Eleven cases of histologically heterogeneous prostate carcinomas obtained by radical prostatectomy were subjected to analysis of p16/CDKN2 gene mutations. DNA was extracted from 5 to 10 separate areas of each tumor with different growth or histological patterns. Exons 1 through 3 of the p16/CDKN2 gene were amplified using the polymerase chain reaction (PCR) and screened for homozygous deletions and mutations of this gene by single-strand conformation polymorphism (SSCP) analysis. No homozygous deletions were observed in any of the prostate carcinomas, but two of the eleven tumors demonstrated mutations in exon 2 of p16/CDKN2 gene. Missense mutations were detected in only one and two foci, respectively, out of six ana ten selected tumor areas. The present results suggest that p16/CDKN2 gene mutations, although they occur at a low incidence, are involved in prostate tumorigenesis, indicating a mutational heterogeneity in addition to morphological heterogeneity.