MicroRNAs have been implicated in drug resistance of osteosarcoma (OS). MicroRNA-301a (miR-301a) is up-regulated and functions as an oncogene in various cancers. However, little is known about the role of miR-301a in drug resistance of OS cells. In this study, we found that doxorubicin induced time-dependent expression of miR-301a in OS cells. Meantime, doxorubicin promoted HMGCR expression and inhibited AMPK alpha 1 expression, which was further facilitated by miR-301a overexpression. Luciferase reporter assay identified AMPK alpha 1 as direct target gene of miR-301a. Notably, miR-301a reduced doxorubicin-induced cell apoptosis whereas anti-miR-301a enhanced apoptosis in OS cells, suggesting that up-regulation of miR-301a contributed to chemoresistance of OS cells. Consistently, our data showed that miR-301a and HMGCR were up-regulated in chemotherapy-resistant OS compared to those in control OS. Our findings suggested that miR-301a might be a potential biomarker for chemotherapy-resistant OS and a promising therapeutic target for overcoming drug resistance of OS. (C) 2015 Elsevier Inc. All rights reserved.