Abstract 2374: Identification of altered miRNA-gene interactions in AOM/DSS induced colitis-associated dysplasia

Abstract

Abstract Although significant progress has been made in delineating the pathways that contribute to ulcerative colitis (UC)-associated tumorigenesis, the early molecular alterations that fuel disease progression remain poorly understood. microRNAs (miRs) have emerged as important modulators of inflammatory pathways and their aberrant expression has been associated with initiation and progression of malignancy. The goal of this study is to identify gene-miR interactions that occur early in experimental UC and contribute to the development of colitis-associated dysplasia. The mRNA and miR expression profile of laser microdissected colon specimens (inflamed mucosa vs. dysplasia) from Swiss Webster mice with AOM/DSS-induced colitis was interrogated using the Mouse Gene Expression Microarrays 4x44K v2 (Agilent®) and miRNA Mouse platform (NanoString®). Data were analyzed using R/Bioconductor and nSolverTM (NanoString®). Differentially expressed miRs (n=12, p<0.001) were validated by RT-qPCR (n=9) and used for target prediction (TargetScan v. 7.2). The differential expression of the predicted target genes (mRNA array) vs. miRs was compared and filtered to include only those with contrasting changes in expression (e.g. downregulated miR and upregulated mRNA). The resulting list of 98 genes was subjected to pathway enrichment analysis using EnrichR. Network interactions were calculated using STRING and visualized on Cytoscape v.3.8.0. Gene ontology analyses revealed 23 terms associated with the pathogenesis and progression of UC, including TNFα signaling via NF-kB, G1 to S cell cycle control, Wnt and Hedgehog signaling. Analyses of miR targets revealed that miR-30c, miR-145a and miR-1a controlled the largest number of predicted target genes (35%, 26% and 18%, respectively). These data suggest an important role of these top miRs (putative tumor suppressors) in UC-associated tumorigenesis, based on their downregulation in dysplasias and corresponding upregulation of their oncogenic targets (Sox9, Ccnd2 and Cdk6). Consistent with our findings, Sox9 contributes to carcinogenesis through its effect on stem cells. The Ccnd2/Cdk6 complex is considered a central component of signaling pathways that regulate cell cycle G1/S transition during neoplastic development. Therefore, early interaction of these miRs with their respective target genes may contribute to the transition of inflamed colonic mucosa to dysplasia in mice with experimental colitis. Additional in vitro validation of the predicted interactions remains in progress. (Supported by a generous donation from Aurora and Timothy Hughes). Citation Format: Mariana F. Fragoso, Geysson J. Fernandez, Lisa Vanderveer, Harry S. Cooper, Wen-Chi Chang, Michael Slifker, Karthik Devarajan, Yan Zhou, Eric Ross, Margie L. Clapper. Identification of altered miRNA-gene interactions in AOM/DSS induced colitis-associated dysplasia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2374.