BackgroundMiR-221 and miR-222 (miR-221/222) are frequently up-regulated in various types of human malignancy including glioblastoma. Recent studies have reported that miR-221/222 regulate cell growth and cell cycle progression by targeting p27 and p57. However the underlying mechanism involved in cell survival modulation of miR-221/222 remains elusive.ResultsHere we showed that miR-221/222 inhibited cell apoptosis by targeting pro-apoptotic gene PUMA in human glioma cells. Enforced expression of miR-22/222 induced cell survival whereas knockdown of miR-221/222 rendered cells to apoptosis. Further, miR-221/222 reduced PUMA protein levels by targeting PUMA-3'UTR. Introducing PUMA cDNA without 3'UTR abrogated miR-221/222-induced cell survival. Notably, knockdown of miR-221/222 induces PUMA expression and cell apoptosis and considerably decreases tumor growth in xenograft model. Finally, there was an inverse relationship between PUMA and miR-221/222 expression in glioma tissues.ConclusionTo our knowledge, these data indicate for the first time that miR-221/222 directly regulate apoptosis by targeting PUMA in glioblastoma and that miR-221/222 could be potential therapeutic targets for glioblastoma intervention.

These data provide compelling evidence that β-catenin regulation of miR-21 via STAT3 plays a role in glioma cell invasion and proliferation and indicate that STAT3 is a potential therapeutic target for glioma intervention.

Activation of Akt signaling pathway has been suggested involving in chemoresistance, metastasis and tumorigenesis of gastric cancer. However, the mechanism of Akt regulation in gastric cancer is not fully understood. RUNX3, which was first identified as a transcription factor, suppresses gastric tumorigenesis through regulating expression of target genes. Here, we found that restoration of RUNX3 significantly downregulates the protein and mRNA expression of Akt1 in gastric cancer cell lines, AGS and SNU-1. Knockdown of RUNX3 upregulates protein and mRNA expression of Akt1 in normal gastric epithelial cell line, GES-1. The negative correlation of RUNX3 and Akt expression and downstream b-catenin/cyclin D1 effectors was further confirmed in AGS and GES-1 cell lines, as well as clinical specimens of gastric cancer. We identified two RUNX3-binding sites in Akt1 promoter and the binding of RUNX3 on Akt1 promoter significantly inhibits Akt1 expression. The RUNX3-mediated inhibition of Akt1 caused b-catenin protein degradation and then cyclin D1 downregulation. Restoration of cyclin D1 reverses cell growth inhibition and G1 phase arrest induced by RUNX3 in gastric cancer cells. Our results show that loss of RUNX3 expression can enhance the Akt1-mediated signaling pathway and promote the tumorigenesis process in human gastric cancer.