Analysis of 99 microdissected prostate carcinomas reveals a high frequency of allelic loss on chromosome 8p12-21

To investigate the possible involvement of a tumor suppressor gene(s) on chromosome 8 in prostatic neoplasms, we performed a comprehensive loss of heterozygosity (LOH) study on 99 tumors from 97 prostate cancer patients. One of the carcinomas was a lymph node metastasis; the other 98 were primary carcinomas. Pure populations of carcinoma cells and normal epithelia were procured by tissue microdissection. Two separate tumor foci were obtained from each of two patients. Microsatellite markers from 25 loci on the short arm and one locus on the long arm of chromosome 8 were used for PCR-based LOH analysis on matched normal and tumor DNA samples. The overall LOH on 8p in this study was 85.9% (85 of 99) of carcinomas. The loss was highest at markers D8S133, D8S136, NEFL, and D8S137 (62,72, 64, and 75%, respectively), which are located at 8p12-21. Seventy-nine of 99 tumors exhibited loss in at least one of these four loci. In contrast, LOH at 8p22 was much lower: 17,18,18, and 19% at D8S549, D8S602, D8S254, and D8S261, respectively, with 25 of 99 tumors showing deletion in one or more of the four loci. All but 5 tumors with deletions in this more distal region had at least one retained locus between the 8p22 deletion and a more proximal region of loss at 8p12-21; 1 tumor had loss at 8p22 but not 8p12-21. This suggests there may be two distinct regions of loss and, therefore, two tumor suppressor genes on this chromosomal arm. The loss on 8p12-21 showed little or no correlation with grade or stage of disease.