Evidence for the presence of two tumor suppressor genes on chromosome 8p for colorectal carcinoma.

We have examined loss of heterozygosity on the short arm of chromosome 8 in 133 colorectal carcinomas, using 20 restriction fragment length polymorphism markers. Loss of heterozygosity was observed in 58 (44%) of 131 tumors that were informative with at least one locus. Among these 58, 32 revealed a partial or interstitial deletion of chromosome 8p. Detailed deletion mapping of chromosome 8p in these tumors identified two distinct, commonly deleted regions. One was located between markers C18-266 and pSVL-LPL at 8p23.2-8p22, and the other between CI8-319 and CI8-494 at 8p21.3-8p11.22. The genetic lengths of these two intervals were estimated to be 28 and 18 cM, respectively. The results suggest that at least two tumor suppressor genes associated with colorectal carcinomas are present on chromosome 8p. Correlation of loss of heterozygosity on 8p to the clinicopathological stage was also detected, suggesting that inactivation of a tumor suppressor gene(s) on 8p plays a role in progression of colorectal carcinomas.