MicroRNA-21: a therapeutic target for reversing drug resistance in cancer

Introduction: Drug resistance is a major clinical obstacle to the successful treatment of human cancer. The microRNAs-21 (miR-21), an oncomiR, may play an important role in the progress of drug resistance. Areas covered: This review covers all related literature on miR-21 in drug resistance of human cancers and analyzes the expression, biological functions and targets of it. This study also envisages future developments toward its clinical and therapeutic applications in cancer treatment. Expert opinion: The miR-21 may promote the drug resistance of various cancers. Inhibitors of miR-21 may function as effective approaches for reversing drug resistance in cancer cells. There is a tough way from discovering the function of miR-21 to clinical use. Further understanding of miR-21-mediated signaling pathways will help to promote the therapeutic-clinical use of miR-21 in cancer.