Abstract 3425: MiR-215-5p is a tumor suppressor in colorectal cancer targeting EGFR ligand epiregulin and its transcriptional inducer HOXB9

Abstract

Abstract Growing evidence suggests that microRNAs (miRNAs) are involved in the development and progression of colorectal cancer (CRC). In the present study, deregulation and functioning of tumor suppressive miR-215-5p was evaluated in CRC. In total, 448 tumor tissues and 325 paired adjacent healthy tissues have been used for miRNA expression analyses. We proved that miR-215-5p is significantly down-regulated in tumor tissues compared to non-tumor adjacent tissues and its decreased levels correlate with the presence of lymph node metastases, tumor stage, and shorter overall survival in CRC patients. To identify specific cellular processes affected by ectopic expression of miR-215-5p, a series of in vitro experiments have been performed using transient transfection of miR-215-5p mimics into four CRC cell lines. Increased levels of miR-215-5p significantly reduced proliferation, clonogenicity, and migration of CRC cells, lead to cell cycle arrest in G2/M phase and p53-dependent induction of apoptosis. The ability of miR-215-5p to inhibit tumor growth was confirmed in vivo by use of NSG mice model and stable cell line over-expressing miR-215-5p. Finally, we proved epiregulin and HOXB9 to be the direct targets of miR-215-5p by luciferase assay and western blot analyses. Since epiregulin is EGFR ligand and HOXB9, is its transcriptional inducer, we suggest, that the main molecular link between miR-215-5p and CRC cells phenotypes presents the EGFR signaling pathway, which is one of the canonical pathogenic pathways in CRC. This work was supported by Ministry of Health of the Czech Republic, grant nr. 15-33158A, 15-34553A, 15-31627A, 15-34678A, 16-31314A, 16-31765A and by grant of Czech Grant Agency nr. 16-18257S. Citation Format: Petra Faltejskova-Vychytilova, Jana Merhautova, Pablo Conesa-Zamora, Katerina Slaba, Tana Machackova, Marek Svoboda, Marek Vecera, Jitka Mlcochova, Jaroslav Juracek, Jiri Sana, Parwez Ahmad, Natalia Gablo, Ondrej Slaby. MiR-215-5p is a tumor suppressor in colorectal cancer targeting EGFR ligand epiregulin and its transcriptional inducer HOXB9 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3425. doi:10.1158/1538-7445.AM2017-3425