Abstract 190: Modulation of MiR-21 signaling by MPS1 in human glioblastoma

Abstract

Abstract Monopolar spindle 1 (MPS1) is an essential spindle assembly checkpoint (SAC) kinase involved in determining spindle integrity. Beyond its mitotic functions, it has been implicated in several other signaling pathways. Its overexpression in cancer cells is known to contribute to genomic instability and tumorigenesis. Our earlier studies have elaborated on role of MPS1 in glioblastoma (GBM) radiosensitization. In this study using reverse phase protein arrays (RPPA), we assessed MPS1 mediated cell signaling pathways and demonstrated that inhibiting MPS1 could upregulate the expression of the tumor suppressor genes PDCD4 and MSH2 by downregulating micro RNA-21 (MiR-21). In GBMs MiR-21 expression is significantly elevated and is associated with chemo and radioresistance. Here, we show that MPS1 inhibition significantly repressed MiR-21 levels and elevated PDCD4 and MSH2 expression in GBM cells both in vitro and in vivo. Both MPS1 and MiR-21 depletion suppressed GBM cell proliferation, whereas, ectopic expression of MiR-21 rescued GBM cell growth from MPS1 inhibition. Further, we demonstrate that MPS1 mediates phosphorylation of SMAD3 but not SMAD2 in GBM cells; A possible mechanism behind MiR-21 modulation by MPS1. Collectively, our results shed light onto an important role of MPS1 in TGF-β/SMAD signaling via MiR-21 regulation. We also, evaluated the prognostic effect of MiR-21, PDCD4 and MSH2 expression on survival in GBM patients of different molecular subtypes from The Cancer Genome Atlas (TCGA) database, showing tumors with high MiR-21 expression and low PDCD4 and MSH2 expression were associated with significantly shorter survival times. To our knowledge this is the first report to demonstrate the role of MPS1 in MiR-21 modulation. This scenario in which MiR-21 is modulated by MPS1 inhibition may be exploited as a potential target for effective GBM therapy. Citation Format: Uday Bhanu Maachani, Anita Tandle, Uma Shankavaram, Tamalee Kramp, Kevin A. Camphausen. Modulation of MiR-21 signaling by MPS1 in human glioblastoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 190. doi:10.1158/1538-7445.AM2015-190