Abstract A40: MicroRNA-494 inhibits growth of the gastrointesintal stromal tumor by targeting multiple cell cycle regulatory genes

Abstract

Abstract Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms occurring throughout the entire region of the gastrointestinal tract. Two oncogenes of the receptor tyrosine kinase family, KIT and PDGFRA, have gain-of-function mutations in approximately 70% and 15% of GISTs. Mutations of these 2 genes cause sustained activation, resulting in constant stimulation of the downstream signaling pathways of KIT and platelet-derived growth factor receptor, alpha polypeptide. Although KIT mutations are present in approximately 70% of GISTs,KIT overexpression is observed in more than 90% of GISTs. Dysregulation of microRNAs(miRNA)-494 was demonstrated to be a major cause for the overexppression of mutatnt KIT proteins in GISTs. It was also demonstrated that miR-494 treatment inhibits proliferation of GISTs and promotes apoptosis however, no details mechanisms are not known. The purpose of this study was to provide evidence regarding the roles of miR-494 in GIST suppression. To elucidate the specific pathways affected by miRNA-494 treatment on GIST cell lines, transcriptome analysis of GIST430 and GIST882 cells transfected with nontargeting microRNA or with miR-494 was performed and subsequently validated by qRT-PCR. Based on the transcriptome analysis, we found that multiple cell cycle relevant pathways were down-regulated by miR-494 treatment and importantly, core genes such as KIT, CASP2, CDCA2, AURKB, CDCA8, E2F7, BIRC5 and CKS1B involved in the regulation of cell cycle pathways were identified as novel targets by miR-494. Using reporter assays, we further validated that miR-494 directly binds to the 3'UTR regions of BRAC5, CKS1B and E2F7 and induces biological alterations. To demonstrate the perturbation of cell cycle pathways by miR-494, FACS analysis using five GIST cell lines was performed and we found that all of the five GIST cell lines transfected with miR-494 subjected to cell cycle arrest and apoptosis. Colony forming and proliferation assays also demonstrated that miR-494 treatment induced the growth inhibition of GIST cells which was derived from the alterations of cell cycle pathways. Taken together, our findings suggest that the efficient suppression of GISTs by miR-494 is driven not only by targeting KIT, but also multiple genes involved in cell cycle pathways Citation Format: SeongJu Yun, Won Kyu Kim, Hoguen Kim. MicroRNA-494 inhibits growth of the gastrointesintal stromal tumor by targeting multiple cell cycle regulatory genes. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A40.