NOVEL SPLICING OF AN IGF2 POLYMORPHIC REGION IN HUMAN ADRENOCORTICAL CARCINOMAS

The human IGF2 gene lies on chromosome 11p15.5 ansi encodes for a mito genic peptide. IGF2 is often overexpressed in many tumours including a drenal carcinomas. In this study while screening 12 adrenoccortical ca rcinomas for heterozygosity at the Apa I and (CA), repeat polymorphism s we observed a novel splicing event in two samples which showed both an allelic expression imbalance and preferential splicing for one of t he alleles. Further examination revealed that the splicing was not con fined to one particular site. Three of such splice products were isola ted and cloned, Using RNase protection analysis the presence of this s plicing event was demonstrated for both adrenocortical carcinoma sampl es and also in a Hep3B cell line. This suggested that the event may be occurring in all the samples, The presence of this splicing was then confirmed in all 12 adrenocortical carcinoma samples by PCR. These dat a suggest that the splicing event may be a general feature for IGF2 tr anscripts. (C) 1997 Academic Press.