miR-1307-3p overexpression inhibits cell proliferation and promotes cell apoptosis by targeting ISM1 in colon cancer

Background: colon adenocarcinoma (COAD) is the most common malignant tumor of gastrointestinal tract. Our study attempts to explore the effect of miR-1307-3p on biological function of COAD cells and its connection with isthmin 1 (ISM1). Methods: The miRNA dataset and clinical information of patients with COAD were downloaded from The Cancer Genome Atlas (TCGA) database. The survival prognosis was analyzed by GGSURV package from R. MicroRNA (miR)-1307-3p was identified by identifying overlapping miRNAs that target ISM1, across two databases (miRDB and Targetscan). Dual luciferase reporter assay was employed to scrutinize the relationship between miR-1307-3p and ISM1. RT-PCR was used to quantify miR-1307-3p and ISM1 expression of colon cancer tissues and cell lines. Western blot was performed to quantify related protein expression. Flow Cytometry, CCK8 and colony formation assays were performed to evaluate the apoptosis, cell cycle, cell viability and proliferation of COAD cells. Results: miR-1307-3p mRNA level decreased in both COAD tissues and cell lines. Overexpression of miR1307-3p suppressed the proliferation, promoted apoptosis and arrested cell cycle at G1 phase, meanwhile, downregulation of ISM1 accelerated the proliferation, inhibited apoptosis and promote cell cycleprogression. The result of dual luciferase reporter assay indicated that miR-1307-3p targeted ISM1 directly and inhibited its expression. The functions of miR-1307-3p regulating cleaved caspase-3, cyclinD1, Ki67 protein levels and activation of Wnt3a/beta-catenin signaling pathway were reversed by ISM1. Conclusions: miR-1307-3p inhibited activation of Wnt3a/beta-catenin signaling through targeting downregulation of ISM1, thereby inhibited proliferation and promote apoptosis of COAD cells.