title: Arsenic trioxide-induced apoptosis in myeloma cells: p53-dependent G1 or G2/M cell cycle arrest, activation of caspase-8 or caspase-9, and synergy with APO2/TRAIL.
abstract: Arsenic trioxide (ATO) has been shown to induce differentiation and apoptosis in acute promyelocytic leukemia (APL) cells concomitant with down-regulation of the PML-RARalpha fusion protein, a product of the t(15:17) translocation characteristic of APL leukemic cells. However, ATO is also a potent inducer of apoptosis in a number of other cancer cells lacking the t(15:17) translocation. The exact mechanism of ATO-induced apoptosis in these cells is not yet clear. We tested the effect of ATO on 7 myeloma cell lines with varying p53 status and report that in cells with mutated p53, ATO induced rapid and extensive (more than 90%) apoptosis in a time- and dose-dependent manner concomitant with arrest of cells in G(2)/M phase of the cell cycle. Myeloma cells with wild-type (wt) p53 were relatively resistant to ATO with maximal apoptosis of about 40% concomitant with partial arrest of cells in G(1) and up-regulation of p21. The use of caspase blocking peptides, fluorescence-tagged caspase-specific substrate peptides, and Western immunoblotting confirmed the involvement of primarily caspase-8 and -3 in ATO-induced apoptosis in myeloma cells with mutated p53 and primarily caspase-9 and -3 in cells expressing wt p53. We also observed up-regulation by ATO of R1 and R2 APO2/TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) receptors. Most important, however, we observed a synergy between ATO and APO2/TRAIL in the induction of apoptosis in the partially resistant myeloma cell lines and in myeloma cells freshly isolated from myeloma patients. Our results justify the use of the combination of these 2 drugs in clinical setting in myeloma patients.
authors.affiliation: University of Texas Health Science Center, San Antonio, TX, USA.
authors.forename: Qun
authors.initials: Q
authors.lastname: Liu
authors.forename: Susan
authors.initials: S
authors.lastname: Hilsenbeck
authors.forename: Yair
authors.initials: Y
authors.lastname: Gazitt
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology*; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004789:Enzyme Activation; D005455:Fluorescent Antibody Technique; D016193:G1 Phase; D016195:G2 Phase; D006131:Growth Inhibitors / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008938:Mitosis; D009101:Multiple Myeloma; D016296:Mutagenesis; D010087:Oxides / Q000494:pharmacology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; D001152:Arsenicals; D015853:Cysteine Proteinase Inhibitors; D006131:Growth Inhibitors; D008562:Membrane Glycoproteins; D010087:Oxides; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D016159:Tumor Suppressor Protein p53; D011065:Poly(ADP-ribose) Polymerases; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D000077237:Arsenic Trioxide