Glycogen synthase kinase 3 beta inhibits microRNA-183-96-182 cluster via the β-Catenin/TCF/LEF-1 pathway in gastric cancer cells

Glycogen synthase kinase 3 beta (GSK3 beta) is a critical protein kinase that phosphorylates numerous proteins in cells and thereby impacts multiple pathways including the beta-Catenin/TCF/LEF-1 pathway. MicroRNAs (miRs) are a class of noncoding small RNAs of similar to 22 nucleotides in length. Both GSK3b and miR play myriad roles in cell functions including stem cell development, apoptosis, embryogenesis and tumorigenesis. Here we show that GSK3 beta inhibits the expression of miR-96, miR-182 and miR-183 through the beta-Catenin/TCF/LEF-1 pathway. Knockout of GSK3b in mouse embryonic fibroblast cells increases expression of miR-96, miR-182 and miR-183, coinciding with increases in the protein level and nuclear translocation of beta-Catenin. In addition, overexpression of beta-Catenin enhances the expression of miR-96, miR-182 and miR-183 in human gastric cancer AGS cells. GSK3 beta protein levels are decreased in human gastric cancer tissue compared with surrounding normal gastric tissue, coinciding with increases of beta-Catenin protein, miR-96, miR-182, miR-183 and primary miR-18396- 182 cluster (pri-miR-183). Furthermore, suppression of miR-183-96-182 cluster with miRCURY LNA miR inhibitors decreases the proliferation and migration of AGS cells. Knockdown of GSK3 beta with siRNA increases the proliferation of AGS cells. Mechanistically, we show that beta-Catenin/TCF/LEF-1 binds to the promoter of miR-183-96-182 cluster gene and thereby activates the transcription of the cluster. In summary, our findings identify a novel role for GSK3 beta in the regulation of miR-183-96-182 biogenesis through beta-Catenin/TCF/LEF-1 pathway in gastric cancer cells.