MICROSATELLITE INSTABILITY IN CERVICAL AND ENDOMETRIAL CARCINOMAS

Microsatellite instability has been found preferentially in tumours as sociated with the hereditary non-polyposis-colorectal cancer (HNPCC) s yndrome, This phenotype, manifested as new alleles at microsatellite l oci, and often the result of a defective mismatch-repair gene, is seen as allelic mobility shifts during electrophoretic runs. We examined p ossible alterations at 8 dinucleotide loci mapping to 6 different chro mosomes in endometrial cancers (n = 20) and cervical cancers (n = 82). Overall instability was found in 30% of the endometrial cancers and i n 6% of the cervical cancers, including 3 (15%) and 2 (2%) tumours, re spectively, unstable at more than one locus. In contrast to the endome trial cancer sub-group, the affected cervical cancers were characteriz ed by one or two new alleles at one or few loci, By DNA ploidy measure ments 5 diploid endometrial cancers were microsatellite-unstable vs. o ne diploid of 6 unaltered cases (p = 0.015; Fisher's exact test). Our data confirm that a sub-set of diploid sporadic endometrial cancers ar e characterized by a mutator phenotype similar to that found in colore ctal cancer, In contrast, among cervical cancers, not characterized by the HNPCC-tumour spectrum, this mutator phenotype is seen infrequentl y, and positive cases appear to display only minor alterations. (C) 19 97 Wiley-Liss, inc.