Human miRNome Profiling in Colon Adenoma-carcinoma Sequence Reveal Early Deregulation of miR-1246, Which Exhibits Oncogenic Properties in Vitro by Targeting AXIN2 and CFTR

Abstract Background: Regulatory changes occurring early in colorectal cancer development remain poorly investigated. Since the majority of cases develop from polyps in the adenoma-carcinoma pathway, a search of early molecular features, such as aberrations in miRNA expression occurring prior to cancer development, would enable identification of potentially causal, rather than consequential, candidates in the progression of polyp to cancer. This study aim was to discover early miRNA expression changes in adenoma-carcinoma sequence and to investigate the role of deregulated miRNAs in CRC development.Methods: Small RNA-seq data analysis was performed to identify deregulated miRNAs and their isoforms among HC, AP and CRC tissue samples. Deregulated miRNAs were validated using RT-qPCR in the independent patient group. MTT, colony formation and wound healing assays were performed in order to evaluate hsa-miR-1246 function in CRC cells. Luciferase and Western blot assays were used to test hsa-miR-1246 gene targets.Results: In the current study by employing small RNA-seq profiling of colon biopsy samples, we describe differentially expressed miRNAs and their isoforms in the adenoma-carcinoma pathway. Analysis of healthy-adenoma-carcinoma sequence in an independent validation group enabled to identify early deregulated miRNAs including hsa-miR-1246 and hsa-miR-215-5p and up-regulation of hsa-miR-1246 in plasma samples of patients with CRC. Loss-of-function experiments revealed that inhibition of hsa-miR-1246 leads to reduced cell viability, colony formation and migration rate, thereby indicating an oncogenic effect of this miRNA in vitro. Subsequent western blot and luciferase reporter assay provided evidence of hsa-miR-1246 being involved in the regulation of target AXIN2 and CFTR genes’ expression. Conclusions: The present study revealed possible involvement of hsa-miR-1246 in early colorectal cancer development and regulation of tumor suppressors AXIN2 and CFTR.