Kalopanaxsaponin A induces apoptosis in human leukemia U937 cells through extracellular Ca2+ influx and caspase-8 dependent pathways.
In the present study, we investigated the effect of KPS-A on the apoptotic activity and the molecular mechanism of the action in human leukemia. Treatment with KPS-A significantly increased apoptotic DNA fragmentation in human histiocytic lymphoma U937 cells as shown by DAPI staining, flow cytometry, and agarose gel electrophoresis. In addition, stimulation of U937 cell with KPS-A induced a series of intracellular events: (1) the activations of caspase-8, caspase-9, and caspase-3; (2) the translocations of Bid and Bax proteins to mitochondria; (3) the loss of mitochondrial membrane potential; and (4) the increased release of cytochrome c to the cytosol. Pretreatment with a specific caspases-8, -9 or -3 inhibitor, neutralized the pro-apoptotic activity of KPS-A in U937 cells. We further demonstrated that KPS-A markedly induced an increase in intracellular Ca2+ level, which was reversed by EGTA, a general calcium chelator, but not by TMB-8 and dantrolene, intracellular Ca2+ release blockers. Moreover, KPS-A-induced DNA fragmentation and caspase activation were substantially reduced in the presence of EGTA. Taken together, these results suggest that KPS-A may play therapeutic role for leukemia via the potent apoptotic activity through Ca2+/caspases-8/MPT/caspases-9/caspases-3 signaling pathway.
Choi
Jung-Hye
JH
Department of Biochemistry, College of Pharmacy, Kyung-Hee University, 1 Hoegi-Dong, Seoul 130-701, South Korea.
Lee
Heon-Woo
HW
Park
Hee-Juhn
HJ
Kim
Sung-Hoon
SH
Lee
Kyung-Tae
KT
D017209:Apoptosis / Q000187:drug effects*; D051023:BH3 Interacting Domain Death Agonist Protein / Q000493:pharmacokinetics; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism*; D053453:Caspase 9 / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D053938:DNA Fragmentation / Q000187:drug effects; D004587:Electrophoresis, Agar Gel; D005434:Flow Cytometry; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D012503:Saponins / Q000494:pharmacology*; D020298:U937 Cells; D051028:bcl-2-Associated X Protein / Q000493:pharmacokinetics
D051023:BH3 Interacting Domain Death Agonist Protein; D002121:Calcium Channel Blockers; D002614:Chelating Agents; D012503:Saponins; D051028:bcl-2-Associated X Protein; C460644:kalopanax saponin A; D009828:Oleanolic Acid; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D002118:Calcium