title: Hypoxia-simulating agents and selective stimulation of arsenic trioxide-induced growth arrest and cell differentiation in acute promyelocytic leukemic cells.
abstract: OBJECTIVE
  We recently reported that hypoxia-mimetic agents cobalt chloride (CoCl2 CoCl2 ) and desferrioxamine (DFO) could induce differentiation of acute myeloid leukemic (AML) cells. Here, we investigate whether these two agents influence the in vitro differentiation-inducing effect of arsenic trioxide (As2O3) on AML cells, an effective drug for the treatment of acute promyelocytic leukemia (APL) that is a unique subtype of AML with a specific fusion protein, PML-RARalpha.
  
  
  METHODS
  The APL cell line NB4 and non-APL promonocytic leukemic cell line U937 were treated with As2O3 (0.5 microM) combined with CoCl2 (50 microM) or DFO (10 microM). The U937/PR9 subclone, whose expression of PML-RARalpha protein can be induced by Zn2+, was also investigated. Cellular differentiation was evaluated by morphological criteria and myeloid differentiation-related antigens and marker gene expression. The hypoxia-inducible factor-1alpha (HIF-1alpha) mRNA and protein were detected, respectively, by semi-quantitative/real-time quantitative reverse transcription polymerase chain reaction and immunoblots. PML-RARalpha protein was also analyzed.
  
  
  RESULTS
  CoCl2 and DFO potentiated the growth-inhibiting and differentiation-inducing effects of low-dose As2O3, the latter enhancing CoCl2 and DFO-induced accumulation of HIF-1alpha protein in NB4 cells but not in U937 cells. These two hypoxia-mimetic agents also accelerated As2O3-induced modulation and degradation of PML-RARalpha protein in NB4 cells. Furthermore, inducible expression of the fusion gene restored the co-operative effects of As2O3 and CoCl2/DFO on U937/PR9 cells in terms of growth arrest, differentiation induction and HIF-1alpha protein accumulation.
  
  
  CONCLUSIONS
  Mimicked hypoxia enhanced As2O3-induced differentiation, in which HIF-1alpha and PML/RARalpha proteins played an important role. These data provide new insights into the understanding of the mechanisms of the action of As2O3 in the treatment of patients with APL.
authors.affiliation: Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Rui-Jin Hospital, Shanghai Jiao-Tong University (SJU-SM, formerly named Shanghai Second Medical University), Shanghai 200025, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Yan
authors.forename: Zhen-Gang
authors.initials: ZG
authors.lastname: Peng
authors.forename: Ying-Li
authors.initials: YL
authors.lastname: Wu
authors.forename: Yi
authors.initials: Y
authors.lastname: Jiang
authors.forename: Yun
authors.initials: Y
authors.lastname: Yu
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.forename: Yuan-Shan
authors.initials: YS
authors.lastname: Zhu
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhao
authors.forename: Guo-Qiang
authors.initials: GQ
authors.lastname: Chen
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology*; D001853:Bone Marrow / Q000378:metabolism / Q000473:pathology; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D015687:Cell Hypoxia / Q000187:drug effects*; D045744:Cell Line, Tumor / Q000166:cytology / Q000187:drug effects; D003035:Cobalt / Q000494:pharmacology*; D003676:Deferoxamine / Q000494:pharmacology*; D004357:Drug Synergism; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000096:biosynthesis / Q000235:genetics; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics; D015514:Oncogene Proteins, Fusion / Q000096:biosynthesis / Q000235:genetics; D010087:Oxides / Q000494:pharmacology*; D010100:Oxygen / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014212:Tretinoin / Q000494:pharmacology; D020298:U937 Cells / Q000166:cytology / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D001152:Arsenicals; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009363:Neoplasm Proteins; D015514:Oncogene Proteins, Fusion; D010087:Oxides; C093476:promyelocytic leukemia-retinoic acid receptor alpha fusion oncoprotein; D003035:Cobalt; D014212:Tretinoin; C018021:cobaltous chloride; D003676:Deferoxamine; D000077237:Arsenic Trioxide; D010100:Oxygen