OVER-EXPRESSION OF THE C-MYC PROTOONCOGENE IN COLORECTAL-CARCINOMA

Alterations in the c-myc proto-oncogene in colorectal cancer were stud ied at the level of RNA expression, gene amplification and rearrangeme nts. One hundred cases of colorectal cancer, stratified by Dukes' stag e were examined. The level of messenger RNA expression was measured in tumours and matched normal mucosa from the same patient. Between 5 an d 400 fold over-expression was found in 66% of tumours. Neither the pr esence nor the level of over-expression correlated with tumour staging . A significant correlation (P < 0.01) was found between over-expressi on of c-myc in tumours and the presence of synchronous adenomas elsewh ere in the colon. In contrast to other tumours, no rearrangements of t he gene were found on Southern analysis of colorectal cancers. Similar ly, amplification of the gene was not found in the cancers examined.