MiR-522 contributes to cell proliferation of human glioblastoma cells by suppressing PHLPP1 expression.

Previous studies have shown that microRNAs play essential roles in cancer growth and progression. Although a number of microRNAs were differentially expressed in glioblastoma (GBM). In this study, we evaluated the miR-522s role in cell proliferation in GBM. Expression of miR-522 is markedly upregulated in GBM tissues and GBM cells compared with the matched non-tumor adjacent brain tissues (TAT) and normal human astrocytes (NHAs). In functional assays, miR-522 promoted GBM cell proliferation, which could be reversed by inhibitor of miR-522. We further identified PH domain leucine-rich repeats protein phosphatase-1 (PHLPP1) as a putative target of miR-522, which is likely a main contributor to the promotion of tumor cell growth observed in our assays. Our results demonstrated that miR-522 promoted tumor cell proliferation and hence may represent a novel therapeutically relevant cellular target to treatment of GBM patients.