CSIG-05. A FIRST COMPREHENSIVE ANALYSIS OF TRANSCRIBED ULTRA CONSERVED REGIONS UNCOVERS IMPORTANT REGULATORY FUNCTIONS OF NOVEL NON-CODING TRANSCRIPTS IN GLIOMAS

Abstract

Abstract Most glioma research has focused on protein-coding genes and much less on non-coding RNAs (ncRNAs). Transcribed Ultra-Conserved Regions (TUCRs) represent a severely understudied class of ncRNAs that are highly conserved across multiple species, including 100% conservation in mouse and rat genomes. These 481 transcripts are highly resistant to variation and are commonly deregulated in cancer, which suggests regulatory and functional importance when considered along with their high degree of conservation. We performed the first-ever analysis of TUCRs in glioblastoma (GBM) and low-grade gliomas (LGG). We first annotated all TUCRs in gliomas and described their genomic locations. We then showed that numerous TUCRs are highly expressed and deregulated in gliomas, and that this deregulation is associated with clinical outcomes. We then used a WGCNA pipeline to predict the functions for all TUCRs in gliomas by compiling gene ontology (GO) terms for coregulated genes. These data were used to identify several TUCRs that are potentially relevant to glioma initiation and progression. Of these, we investigated the most highly upregulated intergenic TUCR, uc.110, in vitro and in vivo in GBM. Knockdown of uc.110 in vitro reduced GBM cell accumulation and invasion and knockdown in vivo inhibited GBM xenograft growth and increased animal survival. We then performed mechanistic analyses of uc.110 and found that it regulates the expression of a Wnt pathway member, membrane frizzled-related protein (MFRP). We discovered that uc.110 sponges the tumor suppressor microRNA miR-544, which targets and inhibits MFRP, thus increasing the bioavailability of MFRP in GBM. This study is the first of its kind in gliomas. It shows important regulatory roles for TUCRs in gliomas and outlines novel methods for studying TUCRs in any disease context.