MICROSATELLITE ALTERATIONS IN HUMAN AND RAT ESOPHAGEAL TUMORS AT SELECTIVE LOCI

(CA)n simple repeats in DNA were examined at 17 loci in 18 human squam ous cell carcinomas of the esophagus and compared with those in normal esophageal tissue from the same patients. Six loci were examined in 3 2 esophageal papillomas that had been induced by N-nitrosomethylbenzyl amine in BD VI rats. Length-altered CA repeats were found in two human tumors and four rat papillomas. Loss of heterozygosity was observed i n three human tumors; two rat papillomas had lost microsatellite bands that are common in inbred BD Vi rats. Both (CA)n microsatellite lengt h alteration and loss of heterozygosity were clustered at certain loci in the human tumor samples and in the chemically induced rat esophage al tumors. Our findings indicate that genomic instability that results in alteration of repeated sequences not only occurs in human tumors b ut may also be a consequence of chemical carcinogenesis in rodents. (C ) 1995 Wiley-Liss, Inc.