Tamoxifen Sensitizes Gallbladder Cancer to Cisplatin Resistance by Impaired Glucose Metabolism via Activation of AMPK Signaling
36 Pages Posted: 18 Dec 2018More...
Purpose: Gallbladder cancer (GBC) is the leading malignancy of biliary system showing refractory chemoresistance to current first-line drugs. Growing epidemiological evidences have established that the incidence of GBC exhibits significant gender predominance with females 2-3 fold higher than males, suggesting estrogen/estrogen receptors (ERs) signaling might be a critical driver of tumorigenesis in gallbladder. This study aims to evaluate the antitumor activity of tamoxifen (TAM), a major agent of hormonal therapy for breast cancer, in preclinical GBC model. Experimental
Design: The antitumor activity of TAM alone or with cisplatin was examined using cell viability, apoptosis and in vivo models.
Results: Increased ERɑ expression was found in GBC tissues and predicted poor clinical outcomes. TAM was showed effective against a variety of GBC cell lines. Mechanical investigations revealed that TAM enabled potent reactive oxygen species (ROS) production by reduced nuclear factor (erythroid-derived 2)-like 2(Nrf2) expression and its target genes, leading to the activation of Adenosine Monophosphate Activated Protein Kinase (AMPK), which subsequently induced impaired glycolysis and survival advantages. Moreover, the inhibitory effect of TAM for GBC cells was remarkably attenuated by N-acetyl-L-cysteine (NAC) and AMPK inhibitor, suggesting ROS/AMPK axis was required for TAM tumor-suppressive function. Notably, TAM was demonstrated to sensitize GBC cells to cisplatin (CDDP) both in vitro and in vivo. In agreement with these findings, elimination of estrogens by ovariectomy in nude mice prevented CDDP resistance.
Conclusions: These results provide basis for TAM-mediated chemosensitivity for GBC and shed novel light on the potential application of endocrine therapy for patients with GBC.
Funding Statement: This work was supported by National Science Foundation of China (81472240，81272748 and 81072011)，Science and Technology Commission of Shanghai Municipality (16411952700, 10411955400, and 09411960800), Program for Outstanding Academic Leader of Shanghai (2016, JW)
Declaration of Interests: The authors declare no conflict of interest.
Ethics Approval Statement: The collection and analysis of patient samples were approved by the Ethical Committee of Renji Hospital, Shanghai Jiao Tong University School of Medicine, and written informed consent was obtained from all patients. All methods and experiments were carried out in accordance with the approved guidelines and regulations.
Animal maintenance and experimental procedures were strictly performed following the guidelines of the Animal Care and Use Committee of Shanghai Jiao Tong University and approved by IACUC committee of Shanghai Jiao Tong University
Keywords: chemoresistance; gallbladder cancer; tamoxifen; AMPK; Metabolism
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