title: Arsenic trioxide induces oxidative stress, DNA damage, and mitochondrial pathway of apoptosis in human leukemia (HL-60) cells.
abstract: BACKGROUND
  Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia (AML), which accounts for approximately 10% of all acute myloid leukemia cases. It is a blood cancer that is formed by chromosomal mutation. Each year in the United States, APL affects about 1,500 patients of all age groups and causes approximately 1.2% of cancer deaths. Arsenic trioxide (ATO) has been used successfully for treatment of APL patients, and both induction and consolidated therapy have resulted in complete remission. Recently published studies from our laboratory have demonstrated that ATO pharmacology as an anti-leukemic drug is associated with cytotoxic and genotoxic effects in leukemia cells.
  
  
  METHODS
  In the present study, we further investigated the detailed molecular mechanism of ATO-mediated intrinsic pathway of apoptosis; using HL-60 cells as a test model. Oxidative stress was assessed by spectrophotometric measurements of MDA and GSH levels while genotoxicity was determined by single cell gel electrophoresis (Comet assay). Apoptosis pathway was analyzed by Western blot analysis of Bax, Bcl2 and caspase 3 expression, as well as immunocytochemistry and confocal imaging of Bax and Cyt c translocation and mitochondrial membrane potential depolarization.
  
  
  RESULTS
  ATO significantly (p < 0.05) induces oxidative stress, DNA damage, and caspase 3 activity in HL-60 cells in a dose-dependent manner. It also activated the intrinsic pathway of apoptosis by significantly modulating (p < 0.05) the expression and translocation of apoptotic molecules and decreasing the mitochondrial membrane potential in leukemia cells.
  
  
  CONCLUSIONS
  Taken together, our research demonstrated that ATO induces mitochondrial pathway of apoptosis in HL-60 cells. This apoptotic signaling is modulated via oxidative stress, DNA damage, and change in mitochondrial membrane potential, translocation and upregulation of apoptotic proteins leading programmed cell death.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Kumar
authors.forename: Clement G
authors.initials: CG
authors.lastname: Yedjou
authors.affiliation: Cellomics and Toxicogenomics Research Laboratory, NIH/NIMHD-RCMI Center for Environmental Health, College of Science, Engineering and Technology, Jackson State University, 1400 Lunch Street, Box18750, Jackson, Mississippi MS39217, USA. paul.b.tchounwou@jsums.edu.
authors.forename: Paul B
authors.initials: PB
authors.lastname: Tchounwou
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D004249:DNA Damage; D004354:Drug Screening Assays, Antitumor; D005978:Glutathione / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute; D015227:Lipid Peroxidation; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress; D010087:Oxides / Q000494:pharmacology*; D021381:Protein Transport; D059010:Single-Cell Analysis; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D001152:Arsenicals; C494826:BAX protein, human; D010087:Oxides; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c; C505407:CASP3 protein, human; D053148:Caspase 3; D005978:Glutathione; D000077237:Arsenic Trioxide