Loss of Heterozygosity Analysis on the Long Arm of Chromosome 7 in Gastric Carcinoma

OBJECTIVE In order to define the common deleted region related to primary gastric carcinomas in Chinese, the frequency of loss of heterozygosit (LOH) on human chromosome 7q and its clinical significance were investigated.

METHODS A set of 9 microsatellite markers on 7q with an average genetic distance of 10cM were used to identify LOH by multi-PCR amplification of matched tumor and non-tumor DNAs from 70 patients with primary gastric carcinoma. The PCR products were separated by electrophoresis in polyacrylamide geis and analysed for LOH by using Genescan and Genotyper software.

RESULTS The total frequency of LOH at any locus on 7q was 34.3% (24/ 70) in the tumors. Compared to non-tumor DNA, LOH at D7S486 and D7S798 loci were higher, 24.0% (12/50) and 19.2% (5/26), respectively The total frequency of LOH on 7q was markedly higher with an increase in the clinical stage (P<0.05). The frequency of LOH at D7S486 in cases with lymph node metastasis was significantly higher than in cases without lymph node metastasis, P=0 015.

CONCLUSION The higher incidence of LOH at D7S486 and D7S798 in primary gastric carcinoma compared to normal tissue suggests that the potential tumor suppressor genes (TSGs) involved in the progression of gastric carcinoma might be nearby these 2 loci.