ALLELIC IMBALANCE IN GASTRIC-CANCER - AN AFFECTED SITE ON CHROMOSOME ARM 3P

In order to detect regions of DNA containing tumor suppressor genes in volved in the development of gastric cancer, we performed an allelotyp e study on 78 gastric adenocarcinomas from a population composed large ly of Texan Hispanics and Angles, two ethnic groups that have a ratio of incidence rates of gastric cancer of approximately 2:1. In total, 4 2 microsatellite markers were employed, which detected at least one si te per arm of each autosome in the human genome. These included severa l markers linked to known tumor suppressor genes (TP53, APC, DCC, RB1, and BRCA1). Sites showing quantitative allelic imbalance (AI) greater than 30% were located on 3p (36%), 11q (31%), 12q (38%), 13q (33%), 1 7p near TP53 (74%), and 17q near BRCA1 (32%). Among the 22% of cases s howing microsatellite instability (MI), a subset (4 of 17) showed inst ability at 59% or more of sites tested. No ethnic bias was detected in cases showing MI or in cases with Al at sites with rates of AI above 30%, Tumors of the intestinal subtype were significantly more likely t han diffuse tumors to show AI at D 13S 170 (P = 0.01). A deletion map of chromosome arm 3p was prepared for tumors with Al at D3S 1478. Thes e data indicate that a tumor suppressor gene on chromosome arm 3p is i nvolved in the development of a subset of gastric cancers. (C) 1995 Wi ley-Liss, Inc.