AKT/TSC2/p70S6K signaling pathway is involved in quinocetone-induced death-promoting autophagy in HepG2 cells.
Quinocetone (QCT, 3-methyl-2-quinoxalin benzenevinylketo-1, 4-dioxide) is widely used as a veterinary drug and animal feed additive in China. Although it promotes growth and improves feed efficiency, QCT's in vitro and in vivo toxicities remain uncertain. This study was conducted to explore the mechanism of QCT-induced autophagy in HepG2 cells. By the results obtained from monodansylcadaverine (MDC) staining, ultrastructural observation by transmission electron microscopy (TEM), as well as Western blotting analysis for LC3, p62, and Beclin-1, it was demonstrated that QCT induced autophagy in HepG2 cells. Furthermore, PI3K/AKT inhibitor significantly enhanced QCT-induced autophagy, while TSC2 knockdown attenuated this process. In addition, inhibition of autophagy by pharmacological approach remarkably increased the viability of QCT-treated cells detected by MTT assay, suggesting that QCT-triggered autophagy may play as a promotion mechanism for cell death. Meanwhile, apoptosis was markedly downregulated after autophagy blockage, and evaluated by flow cytometry and Western blotting analysis for caspase-3 cleavage. Consequently, these results suggested that QCT-induced autophagy was mediated by AKT/TSC2/p70S6K signaling pathway, and inhibition of autophagy promoted QCT-treated cell survival by attenuating apoptosis.
a Department of Pharmacology and Toxicology, College of Veterinary Medicine , China Agricultural University , Beijing , PR China ;
Shen
S
Zhang
b Slaughter Technology Center of Ministry of Agriculture of P.R. China , China Animal Disease Control Center , Beijing , PR China.
Chaoming
C
Zhang
a Department of Pharmacology and Toxicology, College of Veterinary Medicine , China Agricultural University , Beijing , PR China ;
Shusheng
S
Tang
a Department of Pharmacology and Toxicology, College of Veterinary Medicine , China Agricultural University , Beijing , PR China ;
Sijun
S
Deng
a Department of Pharmacology and Toxicology, College of Veterinary Medicine , China Agricultural University , Beijing , PR China ;
Yan
Y
Zhou
a Department of Pharmacology and Toxicology, College of Veterinary Medicine , China Agricultural University , Beijing , PR China ;
Chongshan
C
Dai
a Department of Pharmacology and Toxicology, College of Veterinary Medicine , China Agricultural University , Beijing , PR China ;
Xiayun
X
Yang
a Department of Pharmacology and Toxicology, College of Veterinary Medicine , China Agricultural University , Beijing , PR China ;
Xilong
X
Xiao
D000900:Anti-Bacterial Agents / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D005434:Flow Cytometry; D055785:Gene Knockdown Techniques; D056945:Hep G2 Cells; D022781:Hepatocytes; D006801:Humans; D046529:Microscopy, Electron, Transmission; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D011810:Quinoxalines / Q000633:toxicity*; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism*; D015398:Signal Transduction; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D011810:Quinoxalines; C000624653:TSC2 protein, human; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; C502851:quinocetone; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa
AKT/TSC2/p70S6K; apoptosis; autophagy; quinocetone