title: Thapsigargin induces apoptosis when autophagy is inhibited in HepG2 cells and both processes are regulated by ROS-dependent pathway.
abstract: Thapsigargin (TG), is widely used to induce endoplasmic reticular stress. Treated with TG for a long time, cells suffer the unfolded protein response (UPR) to elude apoptosis, but may activate autophagy. However, the switch between autophagy and apoptosis is unclear. To clarify the key signal for selection of these two protective responses, we studied the correlation of autophagy and apoptosis in HepG2 cells exposed to TG with time. TG induced apoptosis in HepG2 cells was evidenced by typical cell morphological changes and the activation of caspase-12, caspase-9 and caspase-3. Meanwhile, cytochrome c was released following with the dissipation of mitochondrial membrane potential (MMP), and the ratio of Bax/Bcl-2 was increased. TG-induced autophagy was confirmed by the accumulation of MDC, GFP-LC3 staining autophagic vacuoles, and the improved expression of LC3 II and Beclin-1. Additionally, inhibited autophagy via chloroquine (CQ) markedly enhanced the apoptosis induced by TG, which was linked to the Bcl-2 family. Furthermore, TG induced the generation of reactive oxygen species (ROS), and the ROS scavenger effectively suppressed TG-induced apoptosis and autophagy. All these results proved that restraint of autophagy may enhance TG-induced apoptosis through increasing the Bax/Bcl-2 ratio and both processes were regulated by ROS.
authors.affiliation: Department of Pharmacology and Toxicology, College of Veterinary Medicine, China Agricultural University, Beijing 100094, People's Republic of China; Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, People's Republic of China.
authors.forename: Congcong
authors.initials: C
authors.lastname: Wang
authors.affiliation: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, People's Republic of China.
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.affiliation: Department of Pharmacology and Toxicology, College of Veterinary Medicine, China Agricultural University, Beijing 100094, People's Republic of China.
authors.forename: Shusheng
authors.initials: S
authors.lastname: Tang
authors.affiliation: Department of Pharmacology and Toxicology, College of Veterinary Medicine, China Agricultural University, Beijing 100094, People's Republic of China.
authors.forename: Dongxu
authors.initials: D
authors.lastname: Zhao
authors.affiliation: Department of Pharmacology and Toxicology, College of Veterinary Medicine, China Agricultural University, Beijing 100094, People's Republic of China.
authors.forename: Chaoming
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Pharmacology and Toxicology, College of Veterinary Medicine, China Agricultural University, Beijing 100094, People's Republic of China.
authors.forename: Shen
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Pharmacology and Toxicology, College of Veterinary Medicine, China Agricultural University, Beijing 100094, People's Republic of China.
authors.forename: Sijun
authors.initials: S
authors.lastname: Deng
authors.affiliation: Department of Pharmacology and Toxicology, College of Veterinary Medicine, China Agricultural University, Beijing 100094, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Pharmacology and Toxicology, College of Veterinary Medicine, China Agricultural University, Beijing 100094, People's Republic of China. Electronic address: xiaoxl@cau.edu.cn.
authors.forename: Xilong
authors.initials: X
authors.lastname: Xiao
mesh_terms: D017209:Apoptosis; D001343:Autophagy / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002738:Chloroquine / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D056945:Hep G2 Cells; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D019284:Thapsigargin / Q000494:pharmacology*
chemical_list: D017382:Reactive Oxygen Species; D019284:Thapsigargin; D002738:Chloroquine
keywords: Apoptosis; Autophagy; HepG2 cells; ROS; Thapsigargin