Microsatellite instability and frameshift mutation in gastric carcinoma

Objective To study the relationship between microsatellite instability (MSI) and frameshift mutations of hMSH6, BAX and TGFβ RⅡ. Methods Eight microsatellite loci and frameshift mutations of hMSH6, BAX and TGFβ RⅡ were analyzed by polymerase chain reaction (PCR) based methods. Results MSI was detected in 25.0% (11/44) of gastric cancer. Six (13.6%) gastric carcinomas were high MSI (Four Loci or morc) and five (11.4%) were low MSI (one to three loci). The frequency of MSI high proved to be significantly higher in intestinal type than in diffuse carcinomas ( P 0.05). Of the 44 gastric carcinomas, frameshift mutations were detected in 4 for TGFβ RⅡ, 1 for BAX and 1 for hMSH6. All frameshift mutations were detected in gastric carcinomas with high MSI, none was detected in those with low MSI or MSI negative. Conclusions Gastric cancers with high MSI exihibits a tendency to accumulate frameshift mutations in simple repeated nucleotide sequence.