CHARACTERIZATION OF THE APC GENE IN SPORADIC GASTRIC ADENOCARCINOMAS

The prominent role of the APC gene in colorectal tumor development is well established. However, its role in tumorigenesis in other tissues is not clear. Hence, DNA from 30 primary sporadic gastric adenocarcino mas was obtained from patients living in a high risk area of the world (North-Central Italy) in order to further define APC's role in gastri c tumorigenesis. We thoroughly examined that region of APC which is co mmonly mutated in colorectal tumors using proven sensitive methods. Th e IVS protein assay and DNA sequence analysis of APC codons 686 throug h 1693 revealed no intragenic mutations. However, allelic loss of loci near APC was detected in 7 (28%) of 25 informative gastric adenocarci nomas using two 5q dinucleotide repeat markers for LOH analysis. These results suggest that genetic alteration of a region of APC commonly m utated in colorectal cancer is not a common event during sporadic gast ric tumor development, at least in patients from North-Central Italy. Further analysis of chromosome 5q might identify another gene to be si gnificantly altered in these gastric cancers.