Abstract 3437: Targeting microRNA-143 in glioblastoma in vivo increases tumor growth

Abstract

Abstract The purpose of this study is to assess the biological role of the microRNA-143 (miR-143) in Glioblastoma multiforme (GBM). GBM is the most common and lethal of all brain tumors. In the United States, the incidence of GBM is about 17% of all primary brain tumors and about 60-75% of all Astrocytomas (American Brain Tumor Association, 2014). The standard therapy is surgical tumor removal followed by chemotherapy and radiotherapy. However, many patients recur after treatment and the median survival rate for GBM has remained 15 months for the past 20 years. Thus, novel therapies for GBM treatment are urgently necessary. MicroRNAs (miRNAs) are a class of small non-coding RNAs (18-22 nucleotides in length) that regulate gene expression at the post-transcriptional level. MiRNAs bind to the 3’-untranslate region (UTR) of messenger RNAs (mRNAs) and regulate protein synthesis. Several deregulated miRNAs have been identified in all cancer types including GBM. In this study we aim to thoroughly uncover the role of miR-143 by using GBM cell lines, mouse models and patient samples. Total RNA was isolated from FFPE samples from brain tumor patients. TaqMan-based Real-time PCR showed that the relative expression of miR-143 was higher in GBM patients compared to control individuals, and with paired surrounding non-cancerous tissue. Furthermore, GBM cells transiently transfected with a miR-143 oligonucleotide inhibitor showed reduced cell proliferation (68.5%) (clonogenicity assay), increased apoptosis and cell cycle arrest of GBM cells in the S phase (Flow cytometry and Western blots). In vivo studies using primary GBM cells injected in the flank of nude mice showed that repeated doses of miR-143-inhibitor liposomal formulation increased the tumor size compared with control mice. These contradictory results could be due to effects of the microenvironment where the tumor is growing. Further studies will be made using intracranial injections in an orthotopic xenograft mouse model to confirm this hypothesis. Western blot analysis and luciferase reporter assays are also underway to identify novel miR-143 target genes in GBM cells. This research project is being supported by: PRCTRC: NCRR (U54 RR 026139-01A1), NIMHD (8U54 MD 007587-03), and RCMI: MBRS-RISE, NCRR (2G12-RR003051) and NIMHD (8G12-MD007600) from the NIH. Citation Format: Eunice Lozada-Delgado, Fatma Valiyeva, Maria Marcos, Pablo Vivas. Targeting microRNA-143 in glioblastoma in vivo increases tumor growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3437. doi:10.1158/1538-7445.AM2017-3437