Loss of heterozygosity (LOH) in the 8p22 region in prostate cancer

Forty-six prostate tumor samples from patients who underwent radical prostatectomy were analyzed by polymerase chain reaction (PCR) for loss of heterozygosity at three highly polymorphic loci (D8S258, LPL, D8S261) of the chromosomal region 8p22. The presence of genetic alterations was evaluated by comparing each tumor sample with the normal tissue (peripheral blood) obtained preoperatively from the same patient. All the analyzed loci, even if with different informative values, showed loss of heterozygosity (LOH) with a frequency of 22% at D8S258 locus (6/28 informative samples), 18% at LPL locus (6/33 informative samples) and 11.5% at D8S261 locus (3/26 informative samples). Therefore, LOH is more frequent in the D8S258-LPL region. The total number of tumors showing a LOH in one or more analyzed loci was 9, corresponding to a frequency of about 20% of all analyzed tumors. Moreover, this percentage rose to 25% and 36% respectively, considering patients with Gleason scores < 8 and > 8. Loss of heterozygosity, unlike high Gleason scores, showed no correlation with either cancer progression or relapse. The results confirm one or more onco-suppressor genes are localized in the D8S261D8S258 region and seem prevalently associated with initial steps of prostatic cancerogenesis. LOH, even if at low frequency, in tumors with a Gleason score below 8, supports this interpretation. Further studies are necessary to correlate the instability of the 8p22 region with clinical- pathological parameters.