LOSS OF HETEROZYGOSITY AT 5Q21 IN NONSMALL CELL LUNG-CANCER - A FREQUENT EVENT BUT WITHOUT EVIDENCE OF APC MUTATION

Four genetic polymorphisms in the APC and MCC genes at chromosome 5q21 were analysed for loss of heterozygosity (LOH) in 97 primary squamous carcinomas and adenocarcinomas of the lung, LOH was identified in at least two polymorphic loci in 41 percent of informative cases, There w as no significant difference in the frequency of LOH between squamous carcinomas and adenocarcinomas, Within the adenocarcinoma group, howev er, LOH appeared to be more common in tumours having a bronchial origi n (5/9; 56 per cent) than in parenchymal adenocarcinoma (6/21; 29 per cent). All 32 tumours showing LOH at one or more polymorphic sites wer e examined for mutations in the mutation cluster region (MCR) of A PC by single-strand conformational polymorphism (SSCP) analysis, Mutation s were not detected in any of these cases, We therefore propose that i t is likely that a tumour suppressor gene on 5q other than APC is invo lved in the pathogenesis of lung cancer.