MR-05 * GLIOMA STEM CELL SPECIFIC microRNA-mRNA INTERACTION NETWORK

Abstract

The role of cancer stem cells in tumor formation and tumor heterogeneity is currently one of the most researched topics in cancer biology. A better understanding of molecular mechanisms regulating the biology of cancer stem cells may ultimately help provide a better management of cancer patients. Various individual or families of microRNAs have been shown to have oncogenic or tumor suppressor function in glioblastoma (GBM). It is postulated that there exists an extensive microRNA mediated RNA-RNA interaction network in GBMs utilizing systems biology approach supporting a competitive endogenous RNA (ce-RNA). MicroRNAs have functional relevance in regulation of critical genes and pathways implicated in maintenance of glioma stem cell (GSC) properties. Toavoid inclusion of inherent bias ofmiRNA-target prediction algorithms, we have applied biochemical methods to establish direct miRNA-mRNA interaction network relevant and specific to GSCs. We have generated an unbiased global miRNA mediated RNA-RNA interactome by performing RNA-sequencing allRNAspecies (small and largeRNAs) isolated from AGO2-miRISC (microRNA-induced silencing complex) of GSCs and normal human neural stem cells (hNSCs). Additionally, we have also established this interactome after exposure of GSCs and normal hNSCs to hypoxia, a key tumor micro-environmental factor that is known to be pivotal in generating GBM heterogeneity. The rank order list of miRNA-mRNA interaction nodes generated from RNA sequence reads reveals that enrichment of specific RNAs in functional AGO2-miRISC is not a direct function of their relative abundance in cells, thus this biochemically generated interactome is distinct from that generated by bioinformatics tools. We demonstrate that scope and influence of GSC specific miRNA-mRNA network and specific nodes of this interactome varies with hypoxia and tumor region in GBMs.