title: Emodin induces apoptosis in human promyeloleukemic HL-60 cells accompanied by activation of caspase 3 cascade but independent of reactive oxygen species production.
abstract: Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is an active constituent of Rheum palmatum, and showed inhibitory activity on lipopolysaccharide-induced NO production in our previous study. However, the apoptosis-inducing activity of emodin has remained undefined. Among three structurally related anthraquinones, including emodin, physcion, and chrysophanol, emodin showed the most potent cytotoxic effects on HL-60 cells, accompanied by the dose- and time-dependent appearance of characteristics of apoptosis including an increase in DNA ladder intensity, morphological changes, appearance of apoptotic bodies, and an increase in hypodiploid cells. Emodin at apoptosis-inducing concentrations causes rapid and transient induction of caspase 3/CPP32 activity, but not caspase 1 activity, according to cleavage of caspase 3 substrates poly(ADP-ribose) polymerase and D4-GDI proteins, the appearance of cleaved caspase 3 fragments being detected in emodin- but not physcion- or chrysophanol-treated HL-60 cells. A decrease in the anti-apoptotic protein, Mcl-1, was detected in emodin-treated HL-60 cells, whereas other Bcl-2 family proteins including Bax, Bcl-2, Bcl-XL, and Bad remained unchanged. The caspase 3 inhibitor, Ac-DEVD-CHO, but not the caspase 1 inhibitor, Ac-YVAD-CHO, attenuated emodin-induced DNA ladders, associated with the blockage of PARP and D4-GDI cleavage. Free radical scavenging agents including NAC, catalase, SOD, ALL, DPI, L-NAME and PDTC showed no preventive effect on emodin-induced apoptotic responses, whereas NAC, CAT and PDTC prevented HL-60 cells from ROS (H(2)O(2))-induced apoptosis through inhibition of caspase 3 cascades. Induction of catalase, but not SOD, activity was detected in emodin-treated HL-60 cells by in gel activity assays, and H(2)O(2)-induced intracellular peroxide level was significantly reduced by prior treatment of emodin in HL-60 cells. Our experiments provide evidence that emodin is an effective apoptosis inducer in HL-60 cells through activation of the caspase 3 cascade, but that it is independent of ROS production.
authors.affiliation: Graduate Institute of Pharmacognosy Science, Taipei Medical University, 250 Wu-Hsing Street, Taipei, Taiwan. yc3270@tmu.edu.tw
authors.forename: Yen-Chou
authors.initials: YC
authors.lastname: Chen
authors.forename: Shing-Chuan
authors.initials: SC
authors.lastname: Shen
authors.forename: Woan-Ruoh
authors.initials: WR
authors.lastname: Lee
authors.forename: Foun-Lin
authors.initials: FL
authors.lastname: Hsu
authors.forename: Hui-Yi
authors.initials: HY
authors.lastname: Lin
authors.forename: Ching-Huai
authors.initials: CH
authors.lastname: Ko
authors.forename: Shi-Wen
authors.initials: SW
authors.lastname: Tseng
mesh_terms: D017209:Apoptosis; D020170:Caspase 1 / Q000378:metabolism; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004347:Drug Interactions; D004642:Emodin / Q000494:pharmacology*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000494:pharmacology; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D007951:Leukemia, Myeloid / Q000473:pathology*; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D011506:Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D062949:rho Guanine Nucleotide Dissociation Inhibitor beta; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors
chemical_list: C569658:ARHGDIB protein, human; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D020730:Guanine Nucleotide Dissociation Inhibitors; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; D009842:Oligopeptides; D011506:Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; C099158:acetyl-aspartyl-glutamyl-valyl-aspartal; D062949:rho Guanine Nucleotide Dissociation Inhibitor beta; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D002374:Catalase; D013482:Superoxide Dismutase; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D020170:Caspase 1; D004642:Emodin