2 DISTINCT REGIONS OF DELETION ON THE LONG ARM OF CHROMOSOME-5 IN DIFFERENTIATED ADENOCARCINOMAS OF THE STOMACH

Frequent loss of heterozygosity (LOH) on the long arm of chromosome 5 (5q) has been reported in many types of human malignancies, including gastric carcinoma. One of the targets of 5q-LOH in colorectal carcinom a is certainly the adenomatous polyposis coli (APC) gene on 5q21. Howe ver, other evidence has suggested the presence of another tumor suppre ssor gene in this region which may be inactivated in gastric carcinoma . In the present study, to determine the location of the putative tumo r suppressor gene on 5q, LOH at nine microsatellite loci on 5q were in vestigated in 38 differentiated adenocarcinomas of the stomach that pr obably did not carry APC mutations. LOH at any locus on 5q occurred in 37% (14 of 38) of the tumors. Although many tumors exhibited large in terstitial deletions on 5q that included the APC locus (5q21), we have identified minimum regions of deletion as the D5S428 locus and the in terferon regulatory factor-1 (IRF-1) locus, Thus, at least two putativ e tumor suppressor genes, which play a crucial role in the genesis of differentiated adenocarcinoma of the stomach and are distinct from the APC gene, lie on 5q.