open access: Interrelationship between microsatellite instability and microRNA in gastrointestinal cancer

Interrelationship between microsatellite instability and microRNA in gastrointestinal cancer

Abstract

There is an increasing understanding of the roles that microsatellite instability (MSI) plays in Lynch syndrome (by mutations) and sporadic (by mainly epigenetic changes) gastrointestinal (GI) and other cancers. Deficient DNA mismatch repair (MMR) results in the strong mutator phenotype known as MSI, which is the hallmark of cancers arising within Lynch syndrome. MSI is characterized by length alterations within simple repeated sequences called microsatellites. Lynch syndrome occurs primarily because of germline mutations in one of the MMR genes, mainly MLH1 or MSH2, less frequently MSH6, and rarely PMS2. MSI is also observed in about 15% of sporadic colorectal, gastric, and endometrial cancers and in lower frequencies in a minority of other cancers where it is often associated with the hypermethylation of the MLH1 gene. miRNAs are small noncoding RNAs that regulate gene expression at the posttranscriptional level and are critical in many biological processes and cellular pathways....