title: [Ascorbic acid enhances the apoptosis of U937 cells induced by arsenic trioxide in combination with DMNQ and its mechanism].
abstract: OBJECTIVE
  To investigate whether ascorbic acid could enhance the efficacy of arsenic trioxide (As(2)O(3)) combined with 2, 3-dimethoxy-1, 4-naphthoquinone (DMNQ) in inducing the apoptosis of leukemia cell line U937 and its possible mechanism.
  
  
  METHODS
  Flow cytometry and electron microscopy were applied to detect apoptosis of U937 cells after treatment with various combinations of As(2)O(3), DMNQ and ascorbic acid for 24 hours.
  
  
  RESULTS
  As(2)O(3) and DMNQ induced-apoptosis of U937 cells was enhanced (35.24%-->61.20%) upon cotreatment with ascorbic acid. Catalase could reverse this effect of DMNQ. Ascorbic acid had no effect on DMNQ-induced apoptosis of U937 cells.
  
  
  CONCLUSIONS
  Ascorbic acid enhanced the apoptosis of U937 cells via reactive oxygen species-dependent pathway in the presence of As(2)O(3).
authors.affiliation: Laboratory of Cell Biology, Shanghai Second Medical University, Shanghai 200025, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Gao
authors.forename: Jing
authors.initials: J
authors.lastname: Yi
authors.forename: Guiying
authors.initials: G
authors.lastname: Shi
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Xuegeng
authors.initials: X
authors.lastname: Shi
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Wang
authors.forename: Xueming
authors.initials: X
authors.lastname: Tang
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D004357:Drug Synergism; D005434:Flow Cytometry; D006801:Humans; D009285:Naphthoquinones / Q000494:pharmacology*; D010087:Oxides / Q000494:pharmacology*; D020298:U937 Cells
chemical_list: D001152:Arsenicals; D009285:Naphthoquinones; D010087:Oxides; C063002:2,3-dimethoxy-1,4-naphthoquinone; D001205:Ascorbic Acid; D000077237:Arsenic Trioxide