A miRNA-200c/cathepsin L feedback loop determines paclitaxel resistance in human lung cancer A549 cells in vitro through regulating epithelial–mesenchymal transition

Authors: Yi-fan ZHAO1, Mei-ling HAN1,2, Ya-jie XIONG1, Long WANG1, Yao FEI1, Xiao SHEN1, Ying ZHU1, Zhong-qin LIANG1
1 Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
2 Department of Pharmacy, Wuxi Children’s Hospital, Wuxi 214013, China
Corresponding to: Zhong-qin LIANG:,
DOI: 10.1038/aps.2017.164
Received: 3 July 2017
Accepted: 18 September 2017
Advance online: 7 December 2017


Cathepsin L (CTSL), a cysteine protease, is closely related to tumor occurrence, development, and metastasis, and possibly regulates cancer cell resistance to chemotherapy. miRNAs, especially the miR-200 family, have been implicated in drug-resistant tumors. In this study we explored the relationship of CTSL, miRNA-200c and drug resistance, and the potential regulatory mechanisms in human lung cancer A549 cells and A549/TAX cells in vitro. A549/TAX cells were paclitaxel-resistant A549 cells overexpressing CTSL and characterized by epithelial-mesenchymal transition (EMT). We showed that miRNA-200c and CTSL were reciprocally linked in a feedback loop in these cancer cells. Overexpression of miRNA-200c in A549/TAX cells decreased the expression of CTSL, and enhanced their sensitivity to paclitaxel and suppressed EMT, whereas knockdown of miRNA-200c in A549 cells significantly increased the expression of CTSL, and decreased their sensitivity to paclitaxel and induced EMT. Overexpression of CTSL in A549 cells significantly decreased the expression of miRNA-200c, and reduced their sensitivity to paclitaxel and induced EMT, but these effects were reversed by miRNA-200c, whereas knockdown of CTSL in A549/TAX cells attenuated paclitaxel resistance and remarkably inhibited EMT, but the inhibition of miRNA-200c could reverse these effects. Therefore, miRNA-200c may be involved in regulating paclitaxel resistance through CTSL-mediated EMT in A549 cells, and CTSL and miRNA-200c are reciprocally linked in a feedback loop.
Keywords: human lung cancer; paclitaxel resistance; CTSL; miRNA-200c; EMT; feedback loop