Abstract 4067: TRPM7 channels regulate glioma stem cell through STAT3 and Notch signaling pathways

Abstract

Abstract A small fraction of cancer stem cells (CSC) initiate and maintain tumors thus driving glioma tumorigenesis and are responsible for resistance to classical chemo- and radio-therapies. It is desirable to identify signaling pathways related to CSC to develop novel therapies to selectively target them. TRPM7 is a ubiquitous Ca2+ and Mg2+ permeable ion channel which contains a serine/threonine kinase. Recent studies have demonstrated that TRPM7 plays an important role in the growth and proliferation of various tumor cells. To determine the possibility of an interaction among TRPM7, Notch, STAT3 and the ALDH1 signaling in the context of brain tumors, we investigated the effects of TRPM7 pathway activation on glioma cells and stem-like cells derived from them. Methods: 1) We analyzed human stem cell signaling pathways using real time RT2 Profile PCR arrays in the A172 glioma cells upon TRPM7 gene silencing. 2) We then examined Notch and STAT3 pathway activation, Aldehyde dehydrogenase 2 family, mitochondrial (ALDH1) and CD133 expressions in parental and glioma stem cell (GSC) populations using quantitative real time-PCR, Western blot, and immunofluorence images. 3) We conducted a ChIP analysis to examine the effects of STAT3 on ALDH1 promoter by introducing constitutive STAT3 (caSTAT3) and dominant STAT3 (dnSTAT3) into A172 cells. 4) Finally, we examined the role of TRPM7 in glioma cell migration and invasion using transwell invasion assay and wound healing assay. Results: 1) RT2 Profile PCR arrays showed that TRPM7 gene silencing down-regulated genes (≥2 fold-change) involved in Notch pathway [Notch1, Jagged 1(JAG1) and Delta-like 1, Drosophila (DLL1)], Wnt pathway, Wingless-type MMTV integration site family, member 1(WNT1) and ALDH1. 2) STAT3 activation and Notch1 expression were decreased in response to TRPM7 silencing. 3) Notch-regulated genes including Notch1, Hey2, JAG1, and Survivin as well as ALDH1 were significantly expressed higher in spheroid glioma CSCs when compared with monolayer cultures. 4) ALDH1 promoter activity was activated by STAT3 in A172 cells. 5) Knockdown of TRPM7 inhibited migration and invasion of A172 cells. Conclusions: TRPM7 activates JAK2/STAT3 and/or Notch signaling pathways and leads to increased cell proliferation and migration. These findings for the first time demonstrate that TRPM7 (1) activates a previously unrecognized STAT3→ALDH1 pathway, and (2) promotes the induction of ALDH1 activity in glioma cells. (This work was supported by the National Institutes of Health grant numbers NIH R01NS047506, R01NS066027, UL1 RR025008, U54 RR026137, AHA 0840132N, and ALZ IIRG-10-173350.) Citation Format: Mingli Liu, Koichi Inoue, Tiandong Leng, Shanchun Guo, Zhigang Xiong. TRPM7 channels regulate glioma stem cell through STAT3 and Notch signaling pathways. [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 4067. doi:10.1158/1538-7445.AM2014-4067