Abstract 4180: miRNA-mediated anticancer properties of the PPARα-activator fenofibrate on glioblastoma cell growth and migration.

Abstract

Abstract Background: Glioblastoma is an aggressive tumor which originates from the glial cells and accounts for nearly 50% of adult brain tumors. These tumors are characterized by rapid proliferation, aggressive metastatic potential, and resistance to radio- and chemotherapy. MicroRNAs (miRNAs) are 22-nucleotides long RNAs that regulate gene expression post-transcriptionally. Fenofibrate is a potent agonist of peroxisome proliferator activated receptor alpha (PPARα) that is used for the treatment of cardiovascular disease and various metabolic disorders. In addition, treatment with Fenofibrate results in the proliferation of peroxisomes and a marked reduction in the growth of Glioblastoma cells. Methods: To evaluate the effects of treatment on miRNA expression, we used TaqMan quantitative real-time PCR assays from Life Technologies (Grand Island, NY). miRNAs were cloned into BLOCK-iT Pol II miR RNAi Expression Vectors (Life Technologies). Cell growth was evaluated using Guava ViaCount Reagent (Guava Technologies, Hayward, CA). Migration of miRNA-expressing cells was assessed 24h after plating on 8 μm membranes (BD Biosciences, San Jose, CA). Results: In this study, we utilized the LN229 Glioblastoma cell line and found that among the miRNAs up-regulated by Fenofibrate treatment, miR-634 and miR-136 targeted CYR61, a protein involved in migration and proliferation of cancer cells. We additionally found that miR-136 was up-regulated by Fenofibrate treatment while miR-155, another miRNA previously shown to target CYR61, was down-regulated by Fenofibrate. All three miRNAs were predicted and validated to directly target the 3’-UTR of Cyr61. Over-expression of miR-136 and miR-634 miRNAs negatively affected proliferation, but not migration, of LN229 cells. Forced expression of miR-155 reduced migration and addition of recombinant Cyr61 reversed this impairment in migration. Investigation of the signaling pathways regulated by miR-634, revealed an increased phosphorylation of p70 S6 kinase (Thr389), suggesting an induction of the mammalian target of rapamycin (mTOR) complex 1 pathway. Induction of the mTOR pathway was dependent on Akt and Erk activation. In miR-634 overexpressing cells, TSC2, a negative regulator of mTOR signaling, was found to be decreased. Further studies on the differential roles of miRs-136, -155, and -634 in controlling cell growth, cell size, and migration will provide important information on the molecular mechanisms involved in the anticancer properties of Fenofibrate. Citation Format: Duane Jeansonne, Marco Pacifici, Adam Lassak, Krzysztof Reiss, Francesca Peruzzi. miRNA-mediated anticancer properties of the PPARα-activator fenofibrate on glioblastoma cell growth and migration. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4180. doi:10.1158/1538-7445.AM2013-4180