Cinobufagin inhibits tumor growth by inducing intrinsic apoptosis through AKT signaling pathway in human nonsmall cell lung cancer cells

Abstract

// Guangxin Zhang 1 , Chao Wang 2, 3 , Mei Sun 4 , Jindong Li 1 , Bin Wang 1 , Chengyan Jin 1 , Peiyan Hua 1 , Ge Song 1 , Yifan Zhang 1 , Lisa L.H. Nguyen 2 , Ranji Cui 5 , Runhua Liu 2 , Lizhong Wang 2 , Xingyi Zhang 1 1 Department of Thoracic Surgery, Second Hospital of Jilin University, Changchun, P.R. China 2 Department of Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA 3 Department of Integrative Endemic Area, Tongji Hospital of Huazhong University of Science and Technology, Wuhan, P.R. China 4 Department of Pathology, Second Hospital of Jilin University, Changchun, P.R. China 5 Jilin Provincial Key Laboratory on Molecular and Chemical Genetic, Second Hospital of Jilin University, Changchun, P.R. China Correspondence to: Xingyi Zhang, email: xingyizhang@live.com Lizhong Wang, email: lwang12@uab.edu Keywords: cinobufagin, non-small cell lung cancer, apoptosis, reactive oxygen species, mitochondrial transmembrane potential Received: December 07, 2015      Accepted: February 18, 2016      Published: March 3, 2016 ABSTRACT The cinobufagin (CB) has a broad spectrum of cytotoxicity to inhibit cell proliferation of various human cancer cell lines, but the molecular mechanisms still remain elusive. Here we observed that CB inhibited the cell proliferation and tumor growth, but induced cell cycle arrest and apoptosis in a dose-dependent manner in non-small cell lung cancer (NSCLC) cells. Treatment with CB significantly increased the reactive oxygen species but decreased the mitochondrial membrane potential in NSCLC cells. These effects were markedly blocked when the cells were pretreated with N-acetylcysteine, a specific reactive oxygen species inhibitor. Furthermore, treatment with CB induced the expression of BAX but reduced that of BCL-2, BCL-XL and MCL-1, leading to an activation of caspase-3, chromatin condensation and DNA degradation in order to induce programmed cell death in NSCLC cells. In addition, treatment with CB reduced the expressions of p-AKT T308 and p-AKT S473 and inhibited the AKT/mTOR signaling pathway in NSCLC cells in a time-dependent manner. Our results suggest that CB inhibits tumor growth by inducing intrinsic apoptosis through the AKT signaling pathway in NSCLC cells.