Hypoxia-simulating agents and selective stimulation of arsenic trioxide-induced growth arrest and cell differentiation in acute promyelocytic leukemic cells.
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.
Yan
Hua
H
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.
Peng
Zhen-Gang
ZG
Wu
Ying-Li
YL
Jiang
Yi
Y
Yu
Yun
Y
Huang
Ying
Y
Zhu
Yuan-Shan
YS
Zhao
Qian
Q
Chen
Guo-Qiang
GQ
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
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