Microsatellite alterations on chromosome 9p21-22 in sporadic colorectal cancer

OBJECTIVE: To study whether alteration of p16 plays an important role in the development of colorectal carcinomas and the relationship between the molecular changes of 9p21-22 chromosome subregion in sporadic colorectal cancers. METHODS: To detect microsatellite instability (MSI) and loss of heterozygosity (LOH) by PCR, denatured-polyacrylamide gel-electrophoresis and silver staining (microsatellite DNA-PCR-silver staining method) and to compare the results with the clinopathological parameters. RESULTS: Between MSI positive and negative cases and the clinopathological findings, some evidences found in the MSI positive group were as follows: (1) tendency towards younger patients (usually < 50 years in age, P < 0.05); (2) more frequently seen in mucoid carcinomas (P < 0.01). CONCLUSIONS: Microsatellite DNA-PCR-silver staining method is very sensitive in detecting even a tiny change of a single base. MSI occured in the selected microsatellite loci of different subregions and different chromosomes might be different in significance, therefore, a right choice of the suitable loci for studying the microsatellite changes is important. Since the frequency of loss of heterozygosity at 9p21-22 is low (merely 8.42%), it is considered that p16 is not closely associated with the development of sporadic colorectal cancer.