Allelic loss on chromosome 6Q in primary prostate cancer

Molecular genetic analyses of human prostate cancer (CaP) has revealed frequent loss of specific chromosome regions suggesting the presence of putative tumor suppressor gene(s) (TSG) on these chromosome loci whose inactivation may play a role in prostate tumorigenesis. To understand the role of 6q alterations in CaP, we have undertaken a comprehensive analysis of proximal 6q. Genomic DNA from tumor and normal prostate tissues from radical prostatectomy specimens of 38 patients were analyzed by polymerase chain reaction (PCR) for 13 polymorphic microsatellite loci on 6q. Allelic losses of 1 or more polymorphic loci were detected in 11 of 38 patients (29%). Six of 11 tumors showing any 6q deletion were found to have allelic losses at D6S1056 and D6S300 loci. Our results revealed a 1.5 megabase interval between D6S1056 and D6S300 at 6q16.3-21 as the minimal region of deletion, which may contain the putative TSG involved in prostate tumorigenesis. One of the tumor samples demonstrated homozygous deletion at a distal location D6S314 (6q23-24), suggesting another locus potentially associated with CaP. Although the relationship of 6q loss of heterozygosity (LOH) with various clinico-pathologic variables, i.e., cancer recurrence or pathologic stage, did not reveal a statistically significant association, the risk for 6q LOH to non-organ confined (pT3) disease was 5-fold higher than for organ confined disease.