Mutation analysis of APC gene at fifteen exon in colorectal cancer

Objective To evaluate the role of APC mutation in the development of colorectal carcinomas and to correlate APC mutation with microsatellite instability (MSI).Methods APC mutation was measured with multiplex PCR,denaturing gradient gel electrophoresis and DNA sequencing;MSI was analyzed by PCR-based methods.Results Seventy-six cases of sporadic colorectal carcinoma were studied for APC mutation at exon 15 and MSI.APC mutations were detected in 29(38.2%) colorectal cancers.APC mutations were associated with left side colorectal cancer (P0.05).On the contrary,no association was observed between APC mutation and tumor size,differentiation,depth of invasion,metastasis or clinical stages.By using five microsatellite markers,MSI in at least one locus was detected in 20 of 76(26.3%) of the tumors analyzed.APC mutation were all detected in MSI-Low (only one locus,n=10)or MSS(tumor lacking MSI or stable,n=56),but no mutation was found in MSI-H (≥2 loci,n=10).Conclusions APC mutation is involved in carcinogenesis of left side colorectal cancer and is independent of MSI-H phenotype but related to the LOH pathway in colorectal cancer.