MicroRNA as Regulators of Cancer Stem Cells and Chemoresistance in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide. The development of resistance to anti-cancer treatment is one of the major challenges in the treatment of CRC, which limits the efficacy of both conventional and targeted therapies in clinical settings. Understanding the mechanisms underpinning resistances is therefore critical in developing novel agents to reverse drug resistance and for more specific targeted treatments. Accumulating studies have reported that microRNAs (miRNAs) are key players in the regulation of cancer cells with intrinsic/acquired drug resistance through varied mechanisms that endow cells with a drug-resistant phenotype. miRNAs have been evolved in the regulation of chemoresistance to various CRC treatments and the stemness of CRC stem cells (CRSCs), sequentially modulating the sensitivity of CRC cells to anti-cancer treatments. Targeting miRNAs may be a novel strategy for eradicating CRSCs, re-sensitizing drug-resistant cells to anti-cancer agents, improving drug efficiency and developing novel biological agents for CRC treatment. This paper highlights the role of miRNAs in the regulation of chemoresistance and CRSCs in CRC, with focus on the mechanisms underlying how miRNAs alter CRSCs fate, and the process of epithelial-to-mesenchymal transition, cell cycle and apoptosis in CRC cells.