miRNA-99b-3p functions as a potential tumor suppressor by targeting glycogen synthase kinase-3β in oral squamous cell carcinoma Tca-8113 cells

Dysregulation of microRNAs (miRNAs) has been associated with carcinogenesis in oral squamous cell carcinoma (OSCC). In the present study, we investigated the expression and function of miR-99b-3p in human OSCC. We found that the expression levels of miR-99b-3p decreased in 21 clinical OSCC samples (84%). Furthermore, ectopic expression of miR-99b-3p inhibited OSCC cell proliferation by downregulating glycogen synthase kinase-3 beta (GSK3 beta), an miR-99b-3p' target gene, at the mRNA and protein levels, both in vitro and in vivo. Moreover, the silencing of GSK3 beta recapitulated the cellular and molecular effects in a similar manner to the overexpression of miR-99b-3p, which included inhibition of OSCC cell proliferation and suppression of p65 (RelA) and G(1) regulators (cyclin D-1, CDK4 and CDK6) in vitro. Our data suggest that miR-99b-3p functions as a tumor suppressor in OSCC via GSK3 beta downregulation.