Abstract 4354: miR-603 targets WIF1 to promote glioma tumorigenesis via Wnt/β-catenin pathway

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Glioma is the most common and deadly brain tumor. In spite of progressive treatments, which include surgery, chemotherapy and radiotherapy, patient prognosis has not improved significantly. Thus emerges the urgent need to discover novel targets that effectively control glioma. The aim of our work is to investigate the possible roles of miR-603 in glioma tumorigenesis. We first examined miR-603 expression in glioma patient samples and cell lines using RT-PCR. Then, the effect of miR-603 on glioma cells was determined by MTS assay, neurosphere formation assay, EdU assay and cell cycle analysis. Western blot, immunofluorescence staining and luciferase assay were conducted to analyze the regulation of Wnt/β-catenin signaling pathway by miR-603. Lastly, nude mice were subject to intracranial xenograft of U87 cells to determine miR-603's function on glioma oncogenesis in vivo. Herein, we report, for the first time, that miR-603 is highly expressed in glioma tissue and cell lines (U87vlll, U87, T98G, LN229, U373 and U251), suggesting its prominence in glioma tumorigenesis (p < 0.01). Transfection of miR-603 inhibitor into U87 and U373 glioma cells revealed a significant inhibition of cell proliferation, cell cycle progression and neurosphere formation. Conversely, overexpression of miR-603 remarkably promoted these effects. From publicly available algorithms, we identified WIF1 as a potential target of miR-603. WIF1 is known to be a Wnt/β-catenin pathway inhibitor that impedes cancer cell proliferation. As expected, western blot analysis showed that WIF1 expression was markedly decreased in U87 and U373 cells transfected with miR-603, and increased in cells transfected with miR-603-inhibitor. Moreover, we confirmed WIF1 is a bona fide target of miR-603 by 3′UTR luciferase reporter assay. The negative correlation between WIF1 and miR-603 expression was shown by Pearson correlation in four normal brain tissue samples and 43 primary glioma tissue samples. Next, we found that overexpression of miR-603 could attenuate nuclear β-catenin levels and TOPflash luciferase activity, indicating that miR-603 inhibits Wnt/β-catenin signaling pathway. In accordance with our results, WIF1 and TCF4 depletion using specific siRNA dramatically suppressed the cell proliferation, cell cycle progression and neurosphere formation induced by miR-603, thus confirming that WIF1 and Wnt/β-catenin signaling pathway are functionally involved in miR-603 regulation of glioma cancer cell growth. Furthermore, nude mice stereotactically implanted with Lentivirus-miR-603-U87 cells in the right cerebral hemisphere displayed significant inhibition of WIF1 expression, shortened survival time and increased tumor size when compared with mice implanted with Lentivirus-miR-control-U87 cells. Collectively, miR-603 regulates glioma development via target WIF1, and could potentially be used in therapeutic applications for glioma treatment. Note: This abstract was not presented at the meeting. Citation Format: Mian Guo, Guangzhi Wang, Kevork Khadarian, Yongri Zheng, Albert D. Ha, Jia Shen. miR-603 targets WIF1 to promote glioma tumorigenesis via Wnt/β-catenin pathway. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4354. doi:10.1158/1538-7445.AM2014-4354