Hypoxia Causes Downregulation of Dicer in Hepatocellular Carcinoma, Which Is Required for Upregulation of Hypoxia-Inducible Factor 1α and Epithelial-Mesenchymal Transition.
Purpose:A role of Dicer, which converts precursor miRNAs to mature miRNAs, in the tumor-promoting effect of hypoxia is currently emerging in some tumor entities. Its role in hepatocellular carcinoma (HCC) is unknown.Experimental Design:HepG2 and Huh-7 cells were stably transfected with an inducible Dicer expression vector and were exposed to hypoxia/normoxia. HepG2-Dicer xenografts were established in nude mice; hypoxic areas and Dicer were detected in HCC xenografts and HCCs from mice with endogenous hepatocarcinogenesis; and epithelial-mesenchymal transition (EMT) markers were analyzed by immunohistochemistry or by immunoblotting. The correlation between Dicer and carbonic anhydrase 9 (CA9), a marker of hypoxia, was investigated in resected human HCCs.Results:Hypoxia increased EMT markersin vitroandin vivoand led to a downregulation of Dicer in HCC cells. The levels of Dicer were downregulated in hypoxic tumor regions in mice with endogenous hepatocarcinogenesis and in HepG2 xenografts. In human HCCs, the levels of Dicer correlated inversely with those of CA9, indicating that the negative regulation of Dicer by hypoxia also applies to HCC patients. Forced expression of Dicer prevented the hypoxia-induced increase in hypoxia-inducible factor 1α (HIF1α), HIF2α, hypoxia-inducible genes (CA9, glucose transporter 1), EMT markers, and cell migration.Conclusions:We here identify downmodulation of Dicer as novel essential process in hypoxia-induced EMT in HCC and demonstrate that induced expression of Dicer counteracted hypoxia-induced EMT. Thus, targeting hypoxia-induced downmodulation of Dicer is a promising novel strategy to reduce HCC progression.Clin Cancer Res; 23(14); 3896-905. ©2017 AACR.
Department of Medicine 1, University Hospital Frankfurt, Frankfurt, Germany.|The Immunology and Infectious Diseases Laboratory, Therapeutic Chemistry Department, The National Research Center, Dokki, Cairo, Egypt.
Ahmed Atef
AA
Ibrahim
Department of Medicine 1, University Hospital Frankfurt, Frankfurt, Germany.
Christian
C
Schmithals
Institute of Pharmaceutical Biology, Goethe-University of Frankfurt Biocenter, Frankfurt/Main, Germany.
Erik
E
Kowarz
Department of Medicine 1, University Hospital Frankfurt, Frankfurt, Germany.
Verena
V
Köberle
Department of Medicine 1, University Hospital Frankfurt, Frankfurt, Germany.
Bianca
B
Kakoschky
Department of Medicine 1, University Hospital Frankfurt, Frankfurt, Germany.
Thomas
T
Pleli
Department of General and Visceral Surgery, HELIOS Dr. Horst Schmidt-Kliniken, Wiesbaden, Germany.
Otto
O
Kollmar
Department of Medicine 1, University Hospital Frankfurt, Frankfurt, Germany.|Department of Biology, Technical University of Darmstadt, Darmstadt, Germany.
Scarlett
S
Nitsch
Department of Medicine 1, University Hospital Frankfurt, Frankfurt, Germany.
Oliver
O
Waidmann
Department of Medicine 1, University Hospital Frankfurt, Frankfurt, Germany.
Fabian
F
Finkelmeier
Department of Medicine 1, University Hospital Frankfurt, Frankfurt, Germany.
Stefan
S
Zeuzem
Institute of Anatomy 2, University Hospital Frankfurt, Frankfurt, Germany.
Horst-Werner
HW
Korf
Institute of Biochemistry I, Goethe-University Frankfurt, Frankfurt am Main, Germany.
Tobias
T
Schmid
Institute of Biochemistry I, Goethe-University Frankfurt, Frankfurt am Main, Germany.
Andreas
A
Weigert
Department of Medicine 1, University Hospital Frankfurt, Frankfurt, Germany.
Bernd
B
Kronenberger
Institute of Pharmaceutical Biology, Goethe-University of Frankfurt Biocenter, Frankfurt/Main, Germany.
Rolf
R
Marschalek
Department of Medicine 1, University Hospital Frankfurt, Frankfurt, Germany. piiper@med.uni-frankfurt.de.
Albrecht
A
Piiper
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics*; D063646:Carcinogenesis / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000473:pathology; D049109:Cell Proliferation / Q000235:genetics; D053487:DEAD-box RNA Helicases / Q000235:genetics*; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D056945:Hep G2 Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics*; D008113:Liver Neoplasms / Q000235:genetics* / Q000473:pathology; D051379:Mice; D043244:Ribonuclease III / Q000235:genetics*; D000072258:Tumor Hypoxia / Q000235:genetics; D023041:Xenograft Model Antitumor Assays; D000099162:Endothelial PAS Domain-Containing Protein 1
D051792:Basic Helix-Loop-Helix Proteins; D053487:DEAD-box RNA Helicases; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D043244:Ribonuclease III; D000099162:Endothelial PAS Domain-Containing Protein 1; C497442:HIF1A protein, human; C408087:DICER1 protein, human