3'-hydroxy-4'-methoxy-β-methyl-β-nitrostyrene inhibits tumorigenesis in colorectal cancer cells through ROS-mediated DNA damage and mitochondrial dysfunction

// Chun-Hao Tsai 1, 2, * , Amos C. Hung 1, * , Yuan-Yin Chen 1 , Ya-Wen Chiu 1 , Pei-Wen Hsieh 3 , Yi-Chen Lee 1, 4 , Yu-Han Su 1 , Po-Chih Chang 5 , Stephen Chu-Sung Hu 6, 7 , Shyng-Shiou F. Yuan 1, 2, 8 1 Translational Research Center, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan 2 Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan 3 Graduate Institute of Natural Products, School of Traditional Chinese Medicine, and Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan 4 Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan 5 Division of General Surgery, Department of Surgery, E-Da Hospital/I-Shou University, Kaohsiung, Taiwan 6 Department of Dermatology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan 7 Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan 8 Department of Obstetrics and Gynecology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan * These authors have contributed equally to this work Correspondence to: Shyng-Shiou F. Yuan, email: yuanssf@ms33.hinet.net Keywords: β-nitrostyrene, cell cycle, ROS, colorectal cancer, DNA damage Received: August 02, 2016     Accepted: January 03, 2017     Published: February 02, 2017 ABSTRACT The β-nitrostyrene family has been shown to suppress cell proliferation and induce apoptosis in types of various cancers. However, the mechanisms underlying the anticancer effects of β-nitrostyrenes in colorectal cancer remain poorly understood. In this study, we synthesized a β-nitrostyrene derivative, CYT-Rx20 (3’-hydroxy-4’-methoxy-β-methyl-β-nitrostyrene), and investigated its anticancer activities in human colorectal cancer cells both in vitro and in vivo . Our findings showed that treatment with CYT-Rx20 reduced cell viability and induced DNA damage in colorectal cancer cells. In addition, CYT-Rx20 induced cell cycle arrest of colorectal cancer cells at the G2/M phase and upregulated the protein expression of phospho-ERK, cyclin B1, phospho-cdc2 (Tyr15), aurora A, and aurora B, while it downregulated the expression of cdc25A and cdc25C. Furthermore, we found that CYT-Rx20 caused accumulation of intracellular reactive oxygen species (ROS) and reduction of mitochondrial membrane potential. The effects of CYT-Rx20 on cell viability, DNA damage, and mitochondrial membrane potential were reversed by pretreatment with the thiol antioxidant N -acetyl-L-cysteine (NAC), suggesting that ROS-mediated DNA damage and mitochondrial dysregulation play a critical role in these events. Finally, the nude mice xenograft study showed that CYT-Rx20 significantly reduced tumor growth of implanted colorectal cancer cells accompanied by elevated protein expression of aurora A, aurora B, γH2AX, phosphor-ERK, and MDA in the tumor tissues. Taken together, these results suggest that CYT-Rx20 may potentially be developed as a novel β-nitrostyrene-based anticancer agent for colorectal cancer.