title: Epigenetic regulation of miRNA-211 by MMP-9 governs glioma cell apoptosis, chemosensitivity and radiosensitivity.
abstract: Glioblastoma multiforme (GBM) is the most aggressive brain cancer, and to date, no curative treatment has been developed. In this study, we report that miR-211, a microRNA predicted to target MMP-9, is suppressed in grade IV GBM specimens. Furthermore, we found that miR-211 suppression in GBM involves aberrant methylation-mediated epigenetic silencing of the miR-211 promoter. Indeed, we observed a highly significant inverse correlation between miR-211 expression and MMP-9 protein levels, which is indicative of post-transcriptional control of gene expression. Additionally, shRNA specific for MMP-9 (pM) promoted miR-211 expression via demethylation of miR-211 promoter-associated CpG islands (-140 to +56). In independent experiments, we confirmed that miR-211 overexpression and pM treatments led to the activation of the intrinsic mitochondrial/Caspase-9/3-mediated apoptotic pathway in both glioma cells and cancer stem cells (CSC). We also investigated whether miR-211 is involved in the regulation of MMP-9 and thus plays a functional role in GBM. We found an acute inhibitory effect of miR-211 on glioma cell invasion and migration via suppression of MMP-9. Given the insensitivity of some GBMs to radiation and chemotherapy (temozolomide) along with the hypothesis that glioma CSC cause resistance to therapy, our study indicates that miR-211 or pM in combination with ionizing radiation (IR) and temozolomide significantly induces apoptosis and DNA fragmentation. Of note, miR-211- and pM-treated CSC demonstrated increased drug retention capacity, as observed by MDR1/P-gp mediated-Rhodamine 123 drug efflux activity assay. These results suggest that either rescuing miR-211 expression or downregulation of MMP-9 may have a new therapeutic application for GBM patients in the future.
authors.affiliation: Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine, Peoria, IL, USA.
authors.forename: Swapna
authors.initials: S
authors.lastname: Asuthkar
authors.forename: Kiran Kumar
authors.initials: KK
authors.lastname: Velpula
authors.forename: Chandramu
authors.initials: C
authors.lastname: Chetty
authors.forename: Bharathi
authors.initials: B
authors.lastname: Gorantla
authors.forename: Jasti S
authors.initials: JS
authors.lastname: Rao
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001932:Brain Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics* / Q000532:radiotherapy; D002465:Cell Movement / Q000235:genetics; D018899:CpG Islands; D019175:DNA Methylation; D015536:Down-Regulation; D057890:Epigenomics; D005909:Glioblastoma / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics* / Q000532:radiotherapy; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D035683:MicroRNAs / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011836:Radiation Tolerance / Q000235:genetics; D051898:Smad1 Protein / Q000378:metabolism; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: C549405:MIRN211 microRNA, human; D035683:MicroRNAs; C497399:SMAD1 protein, human; D051898:Smad1 Protein; D016212:Transforming Growth Factor beta; D020780:Matrix Metalloproteinase 9