Hypoxia-inducible factor-1alpha-induced differentiation of myeloid leukemic cells is its transcriptional activity independent.
Hypoxia or hypoxia mimetic has been shown to induce differentiation together with the accumulation of hypoxia-inducible factor-1alpha (HIF-1alpha) protein of myeloid leukemic cells and normal hematopoietic progenitors. To provide direct evidence for the role of HIF-1alpha in acute myeloid leukemia (AML) cell differentiation and its mechanisms, we generated myeloid leukemic U937T transformants, in which HIF-1alpha was tightly induced by tetracycline withdrawal. The results showed that the conditional HIF-1alpha induction triggered granulocytic differentiation of these transformants, while the suppression of HIF-1alpha expression by specific short hairpin RNAs (shRNAs) effectively inhibited hypoxia-induced differentiation of U937 cells, as evidenced by morphology, maturation-related antigens as well as expressions of myeloid differentiation signatures and hematopoietic cells-specific cytokine receptors. The specific shRNAs-inhibited expression of HIF-1beta, an essential partner for transcription activity of HIF-1, failed, while the inhibition of hematopoietic differentiation-critical CCAAT/enhancer-binding protein-alpha (C/EBPalpha) significantly eliminated HIF-1alpha-mediated myeloid leukemic cell differentiation. Collectively, this work provided several lines of direct evidence for the role of HIF-1alpha protein through its nontranscriptional activity in myeloid cell differentiation, in which C/EBPalpha elicits a role as an effector downstream to HIF-1alpha. These discoveries would shed new insights for understanding mechanisms underlying leukemogenesis and designing the new therapeutic strategy for differentiation induction of AML.
Song
L-P
LP
Institute of Health Science, Shanghai Institutes for Biological Sciences and Graduate School of Chinese Academy of Sciences-Shanghai Jiao-Tong University School of Medicine, Shanghai, China.
Zhang
J
J
Wu
S-F
SF
Huang
Y
Y
Zhao
Q
Q
Cao
J-P
JP
Wu
Y-L
YL
Wang
L-S
LS
Chen
G-Q
GQ
D022762:CCAAT-Enhancer-Binding Proteins / Q000502:physiology; D002454:Cell Differentiation / Q000235:genetics*; D015687:Cell Hypoxia / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D003115:Colony-Stimulating Factors / Q000378:metabolism; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors / Q000502:physiology*; D007951:Leukemia, Myeloid / Q000235:genetics / Q000473:pathology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D015533:Transcriptional Activation / Q000502:physiology*; D014162:Transfection; D020298:U937 Cells
D022762:CCAAT-Enhancer-Binding Proteins; C515848:CEBPA protein, human; D003115:Colony-Stimulating Factors; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D034741:RNA, Small Interfering