MicroRNA-24 regulates the growth and chemosensitivity of the human colorectal cancer cells by targeting RNA-binding protein DND1.

PURPOSE:This study was designed to investigate the role and therapeutic potential of miR-24 in colorectal cancer (CRC). METHODS:The CRC cell lines HCT116, RKO, SW480, SW48, and the non-cancer cell line CCD-18Co were used in the present study. The miR-24 expression was determined by qRT-PCR analysis. Cell viability was determined by MTT assay. Apoptosis was examined by acridine orange (AO)/ethidium bromide (EB) and annexin V/propidium iodide (PI) staining. Transfection was performed by Lipofectamine 2000. Protein levels were examined by western blot analysis. RESULTS:miR-24 was significantly downregulated in CRC cell lines. Ectopic expression of miR-24 caused significant decrease in the cell viability by initiating apoptotic cell death of colorectal SW48 cancer cells, indicative of its tumor suppressive role. Moreover, miR-24 overexpression also enhanced the chemosensitivity of SW48 cells to 5-fluorouracil (5-FU). In silico analysis together with dual luciferase reporter assay indicated the RNA binding protein DND1 was the potential target of miR-24 in SW48 cells. Investigation of DND1 expression in CRC cell lines showed up to 5.3-fold upregulation of DND1. Nonetheless, ectopic expression of miR-24 in SW48 cells resulted in the downregulation of DND1 expression. Additionally, silencing of DND1 in the SW48 cells also caused inhibition of SW48 cell proliferation. Moreover, overexpression of DND1 could rescue the tumor suppressive effects of miR-24, indicating direct involvement of DND1 in the miR-24 mediated inhibitory effects on SW48 cell proliferation. CONCLUSION:The miR-24 acts as a tumor suppressor and may prove essential in the treatment of CRC.

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