Abstract: Objective To investigate the implications of miR-33b down-regulation by DNA Methylation in gastric cancer (GC) and the association between miR-33b level and various clinicopathological factors. Methods Expression of miR-33b was detected by Taqman real-time PCR in 42 paired GC samples. The association between miR-33b level and various clinicopathological factors was analyzed. Genomic DNA samples were amplificated by PCR after modified by sodium bisulfite using the EpiTect Bisulfite Kit then the methylation degree of CpG island upstream of miR-33b gene was detected by methylation specific PCR (MSP). Results The lower level expression of miR-33b was not associated with gender, age, venous invasion, position, borrmann typing, pT stage, pN stage, but significantly associated with gastric cancer metastasis (p<0.05) and regulated by CpG island hypermethylation (p<0.05). Conclusion miR-33b may be regulated by DNA methylation and act as a tumor suppressor in gastric cancer.

Key words: miR-33b, gastric cancer, methylation