Synergistic anticancer effect of cisplatin and Chal-24 combination through IAP and c-FLIPL degradation, Ripoptosome formation and autophagy-mediated apoptosis

// Shaoqing Shi 1, 2 , Qiong Wang 2, 3 , Jennings Xu 2 , Jun-Ho Jang 2, 4 , Mabel T. Padilla 2 , Toru Nyunoya 2, 4 , Chengguo Xing 5 , Lin Zhang 1, 3 , Yong Lin 2 1 Department of Immunology, College of Basic and Forensic Medicine, Sichuan University, Chengdu, China 2 Molecular Biology and Lung Cancer Program, Lovelace Respiratory Research Institute, Albuquerque, NM, USA 3 Laboratory of Molecular and Translational Medicine, West China Second University Hospital, Sichuan University, Chengdu, China 4 Division of Pulmonary and Critical Care Medicine, University of New Mexico and New Mexico VA Health Care System, Albuquerque, NM, USA 5 Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA Correspondence to: Yong Lin, e-mail: ylin@lrri.org Lin Zhang, e-mail: zhanglin@scu.edu.cn Keywords: autophagy, apoptosis, c-IAP, c-FLIP, cisplatin, Chal-24 Received: July 31, 2014 Accepted: November 08, 2014 Published: February 12, 2015 ABSTRACT Drug resistance is a major hurdle in anticancer chemotherapy. Combined therapy using drugs with distinct mechanisms of function may increase anticancer efficacy. We have recently identified the novel chalcone derivative, chalcone-24 (Chal-24), as a potential therapeutic that kills cancer cells through activation of an autophagy-mediated necroptosis pathway. In this report, we investigated if Chal-24 can be combined with the frontline genotoxic anticancer drug, cisplatin for cancer therapy. The combination of Chal-24 and cisplatin synergistically induced apoptotic cytotoxicity in lung cancer cell lines, which was dependent on Chal-24-induced autophagy. While cisplatin slightly potentiated the JNK/Bcl2/Beclin1 pathway for autophagy activation, its combination with Chal-24 strongly triggered proteasomal degradation of the cellular inhibitor of apoptosis proteins (c-IAPs) and formation of the Ripoptosome complex that contains RIP1, FADD and caspase 8. Furthermore, the cisplatin and Chal-24 combination induced dramatic degradation of cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein large (cFLIP L ) which suppresses Ripoptosome-mediated apoptosis activation. These results establish a novel mechanism for potentiation of anticancer activity with the combination of Chal-24 and cisplatin: to enhance apoptosis signaling through Ripoptosome formation and to release the apoptosis brake through c-FLIP L degradation. Altogether, our work suggests that the combination of Chal-24 and cisplatin could be employed to improve chemotherapy efficacy.