Theranostics 2018; 8(1):109-123. doi:10.7150/thno.20356

Research Paper

PrLZ increases prostate cancer docetaxel resistance by inhibiting LKB1/AMPK-mediated autophagy

Jin Zeng*, Wei Liu*, Yi-Zeng Fan, Da-Lin He, Lei Li

Department of Urology, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China
* These two authors contributed equally to this work.

Abstract

Rationale: Docetaxel-mediated chemotherapy is the first-line standard approach and has been determined to show a survival advantage for metastatic castration-resistant prostate cancer (mCRPC) patients. However, a substantial proportion of patients eventually becomes refractory due to drug resistance. The detailed mechanisms remain unclear. We have previously reported that Prostate Leucine Zipper (PrLZ), a specific oncogene of prostate cancer (PCa), promotes PCa cell growth at the castration-resistant stage, thus suggesting a vital role of PrLZ in the progression of CRPC. In this study, we aimed to investigate the role of PrLZ in docetaxel resistance in PCa, focusing on PrLZ-regulating autophagy pathway.

Methods: Human PCa PC3, LNCaP and C4-2 cell lines were used as the model system in vitro and PCa xenografts and PrLZ-knockout mice were used as the model system in vivo. Docetaxel-induced cell death and apoptosis in PCa were determined by MTT and flow cytometry assay. The role of PrLZ on the regulation of autophagy and liver kinase B1/AMP-activated protein kinase (LKB1/AMPK) signaling pathway was analyzed using immunoblotting, immunoprecipitation, siRNA silencing and plasmid overexpression.

Results: PrLZ increased docetaxel-mediated drug resistance both in vitro and in vivo. Mechanistic dissection revealed that PrLZ interacted with LKB1 and further inhibited the activation of LKB1/AMPK signals, which negatively contributed to the induction of autophagy. Moreover, PrLZ/LKB1-mediated autophagy conferred resistance to docetaxel-induced cell death and apoptosis both in vitro and in vivo.

Conclusion: These findings identify a novel role of PrLZ in autophagy manipulation and provide new insight into docetaxel chemoresistance in PCa, suggesting a new strategy for treating mCRPC by targeting this newly identified signaling pathway.

Keywords: PrLZ, Prostate cancer, Docetaxel, Autophagy, LKB1.

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How to cite this article:
Zeng J, Liu W, Fan YZ, He DL, Li L. PrLZ increases prostate cancer docetaxel resistance by inhibiting LKB1/AMPK-mediated autophagy. Theranostics 2018; 8(1):109-123. doi:10.7150/thno.20356. Available from http://www.thno.org/v08p0109.htm