Anti-tumor effect of miR-1291 in colon cancer cells

Background: Cancer stem cells (CSCs) are drug-tolerant and cause distant metastasis and recurrence in various cancers, including colorectal cancer (CRC). Thus, CSC-targeted therapy may be an effective curative approach in CRC. MiR-1291 has an anti-tumor effect in carcinoma of kidney, esophagus, pancreas, and prostate. However, there is no report about the effect of miR-1291 on CRC.Methods: In this study, we took CSC marker DCLK-1 as a target gene, and screened promising miRNAs that may suppress DCLK-1 by using TargetScan Human. We performed luciferase reporter assay, quantitative real-time PCR analysis, and Western blot analysis to verify the interaction between DCLK-1 and miR-1291 in CRC cells. We also confirmed the function of miR-1291 on cancer stemness by identifying the expression of Bmi1 and CD133 in CRC cells by quantitative real-time PCR analysis, Western blot analysis, and flow cytometric analysis, as well as performing sphere formation assay. We also explored the effect of miR-1291 on cell proliferation, invasion, and wound-healing, colony formation, and cell cycle regulation. Results: We found a 7-base seed sequence of miR-1291 that matches the 3’ UTR sequence of DCLK-1 using TargetScan Human. A luciferase reporter assay showed that miR-1291 directly bound the 3’ UTR sequence of DCLK-1 and suppressed its expression at both the mRNA and protein levels. In addition, miR-1291 suppressed CSC markers Bmi1 and CD133 as well as sphere formation ability in CRC cells. Moreover, miR-1291 significantly suppressed the proliferation, invasion, wound-healing, and colony formation capability of colon cancer cell lines. MiR-1291 caused altered expression of the cell cycle-regulatory proteins representatively, CDK inhibitors p21WAF1/CIP1 and p27KIP1. Conclusions: Taken together, these findings indicate that miR-1291 has an anti-tumor effect by modulating multiple functions, including, cancer stemness, cell cycle, and invasiveness. Our data suggest that miR-1291 could be a promising nucleic acid medicine against CRC.