Participation of cathepsin B in emodin-induced apoptosis in HK-2 Cells.
Emodin (1,3,8-trihydroxy-6-methyl-anthraquinone) and rhein (4,5-dihydroxyanthraquinone-2-carboxyl acid) are two main active compounds in total rhubarb anthraquinones (TRAs), which showed nephrotoxicity in Sprague Dawley (S.D.) rats in our previous study. However, it is unknown yet whether emodin and rhein have cytotoxic effects on kidney. To address this issue, HK-2 cells, a human proximal tubular epithelial cell line, were treated with different concentrations of emodin or rhein, and cell viability and morphological changes were investigated. The ratio of hypodiploid cells and the activity of caspase 3 protease were also detected. Results showed that addition of emodin but not rhein at concentrations above 40microM for 24h reduced cell viability and induced apoptosis in HK-2 cells. Additionally, emodin at apoptosis-inducing concentrations caused expression of cathepsin B (CB) protein and activation of CB protease. Addition of CB inhibitor, CA-074, significantly attenuated the ratio of hypodiploid and apoptotic cells, partially blocked caspase 3 activation and inhibited reduction of cell viability induced by emodin. These data indicate that emodin possesses cytotoxic effects on HK-2 cells partially through induction of CB protein and activation of CB protease.
Wang
Cuifen
C
Jiangsu Center for Drug Screening, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, China; Department of Pharmacology, Southeast University, Nanjing 210009, China.
Jiang
Zhenzhou
Z
Yao
Jincheng
J
Wu
Xudong
X
Sun
Li
L
Liu
Chunhui
C
Duan
Weigang
W
Yan
Ming
M
Sun
Lixin
L
Liu
Jun
J
Zhang
Luyong
L
D000880:Anthraquinones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D002401:Cathepsin B / Q000037:antagonists & inhibitors / Q000502:physiology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004642:Emodin / Q000633:toxicity*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000880:Anthraquinones; D004791:Enzyme Inhibitors; D053148:Caspase 3; D002401:Cathepsin B; D004642:Emodin; C020491:rhein