Lovastatin overcomes gefitinib resistance through TNF-α signaling in human cholangiocarcinomas with different LKB1 statuses in vitro and in vivo

// Sheng-Huei Yang 1 , Hung-Yun Lin 1, 2 , Vincent H.S. Chang 3 , Chien-Chung Chen 4 , Yun-Ru Liu 5 , Jinghan Wang 6 , Keqiang Zhang 7 , Xiaoqing Jiang 6 , Yun Yen 1 1 PhD Program for Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan 2 Taipei Cancer Center, Taipei Medical University, Taipei, Taiwan 3 Institute of Translational Medicine, Taipei Medical University, Taipei, Taiwan 4 Graduate Institute of Biomedical Materials and Engineering, Taipei Medical University, Taipei, Taiwan 5 Office of Human Research, Taipei Medical University, Taipei, Taiwan 6 The First Department of Biliary Surgery, Eastern Hepatobiliary Surgical Hospital, The Second Military Medical University, Shanghai, China 7 Department of Molecular Pharmacology, City of Hope National Medical Center and Beckman Research Center, Duarte, California, USA Correspondence to: Yun Yen, e-mail: yyen@tmu.edu.tw Keywords: cholangiocarcinomas, combination therapy, lovastatin, gefitinib Received: January 29, 2015      Accepted: June 12, 2015      Published: June 23, 2015 ABSTRACT Gefitinib resistance has been shown to complicate cancer therapy. Lovastatin is a proteasome inhibitor that enhances gefitinib-induced antiproliferation in non-small cell lung cancer. The objective of this study is to investigate the mechanism of lovastatin-induced antiproliferation in gefitinib-resistant human cholangiocarcinoma. Two gefitinib-resistant cholangiocarcinoma cell lines, SSP-25 and HuH-28, were used in this study to determine how to compensate gefitinib resistance. The combined effect of these two drugs was examined using the MTT assay, qPCR, immunoblotting, flow cytometry, and in vivo xenograft. Results indicated that lovastatin enhanced TNF-α-induced cell death in vitro . In addition, the combination of lovastatin with gefitinib enhanced accumulation of TNF-α. Furthermore, the treatment induced a synergistic cytotoxic effect and antiproliferation through apoptosis in SSP-25 cells and cell cycle arrest in HuH-28 cells. Reproductive results were also observed in in vivo xenografts. These observations suggest that the combination of gefitinib and lovastatin might have additive antiproliferative effects against gefitinib-resistant cholangiocarcinoma cells. Based on these observations, we concluded that the combination of gefitinib and lovastatin could be used to overcome gefitinib resistance in cholangiocarcinoma cells.