Frequent Loss of Heterozygosity at 7q31.1 in Primary Prostate Cancer Is Associated with Tumor Aggressiveness and Progression

Cytogenetic analyses have demonstrated that chromosome region 7q22–32 is commonly altered in prostate adenocarcinomas. In addition, in recent fluorescence in situ hybridization studies, we have observed that aneusomy of chromosome 7 is frequent in prostate cancer and is associated with higher tumor grade, advanced pathological stage, and early prostate cancer death. These findings suggest that genetic alterations of chromosome 7 play a significant role in the development of prostate cancer. To better define the chromosome 7 alterations, PCR analysis of 21 microsatellite loci was performed on 54 paired prostate cancer and control DNAs. Overall, chromosome 7 allelic imbalance was identified in 16 of 54 cases (30%). Allelic imbalances of loci mapped to 7q were observed in 15 of the 16 cases. The allelic imbalances were classified as losses in 15 tumors (28%) and as gains in 1 (2%) by comparative multiplex PCR analysis. The most common site of allelic loss included loci D7S523 and D7S486 at 7q31.1. A comparison with clinicopathological features of the tested tumors revealed that the allelic loss of 7q31.1 correlated with higher tumor grade (P = 0.012) and lymph node metastasis (P = 0.017). These results indicate that 7q31 may be the site of a putative suppressor gene(s) important for the pathogenesis of prostate carcinoma, and that the genetic alterations at 7q31.1 may participate in tumor progression and metastasis.