Anti-tumor effect of miR-1291 in colorectal cancer

Background: MiR-1291 has an anti-tumor effect in carcinoma of kidney, esophagus, pancreas, and prostate. However, it’s role in colorectal cancer (CRC) has not been elucidated.Methods: In this study, we explored the effect of miR-1291 in CRC cells (HCT116, DLD-1, and HT29) in vitro, and performed a tumor growth inhibitory assay in a mouse therapeutic model using DLD-1 cells. Flow cytometric analysis and Western blotting were performed to examine a role of miR-1291 in cell cycle regulation. We performed luciferase reporter assay to verify the interaction between DCLK1 and miR-1291 in HCT116 cells. Cancer stemness was evaluated by identifying the expression of BMI1 and CD133, as well as performing sphere formation assay. Results: We found that miR-1291 significantly suppressed the proliferation, invasion, cell mobility, and colony formation capability of CRC cell lines. MiR-1291 caused altered expression of the cell cycle-regulatory proteins, representatively CDK inhibitors p21WAF1/CIP1 and p27KIP1 or CDK4. Moreover, intravenous administration of miR-1291 loaded on the super carbonate apatite delivery system significantly inhibited a tumor growth in the DLD-1 xenograft mouse model. A luciferase reporter assay showed that miR-1291 directly bound the 3’ UTR sequence of DCLK1 and suppressed its expression at both the mRNA and protein levels in HCT116 expressing the DCLK1 protein. In addition, miR-1291 suppressed cancer stem cell (CSC) markers BMI1 and CD133 as well as sphere formation ability in HCT116 cells. Conclusions: Taken together, these findings indicate that miR-1291 has an anti-tumor effect by modulating multiple functions, including cell cycle, invasiveness, and cancer stemness. Our data suggest that miR-1291 could be a promising nucleic acid medicine against CRC.