title: Cyclin-dependent kinase 5 stabilizes hypoxia-inducible factor-1α: a novel approach for inhibiting angiogenesis in hepatocellular carcinoma.
abstract: We recently introduced CDK5 as target in HCC, regulating DNA damage response. Based on this and on our previous knowledge about vascular effects of CDK5, we investigated the role of CDK5 in angiogenesis in HCC, one of the most vascularized tumors. We put a special focus on the transcription factor HIF-1α, a master regulator of tumor angiogenesis.The interaction of CDK5 with HIF-1α was tested by Western blot, PCR, reporter gene assay, immunohistochemistry, kinase assay, co-immunoprecipitation, mass spectrometry, and mutation studies. In vivo, different murine HCC models, were either induced by diethylnitrosamine or subcutaneous injection of HUH7 or HepG2 cells. The correlation of vascular density and CDK5 was assessed by immunostaining of a microarray of liver tissues from HCC patients.Inhibition of CDK5 in endothelial or HCC cells reduced HIF-1α levels in vitro and in vivo, and transcription of HIF-1α target genes (VEGFA, VEGFR1, EphrinA1). Mass spectrometry and site directed mutagenesis revealed a stabilizing phosphorylation of HIF-1α at Ser687 by CDK5. Vascular density was decreased in murine HCC models by CDK5 inhibition.In conclusion, inhibiting CDK5 is a multi-modal systemic approach to treat HCC, hitting angiogenesis, as well as the tumor cells themselves.
authors.affiliation: Department of Pharmacy, Pharmaceutical Biology, University of Munich, Munich, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Herzog
authors.affiliation: Department of Pharmacy, Pharmaceutical Biology, University of Munich, Munich, Germany.
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Ehrlich
authors.affiliation: Department of Pharmacy, Pharmaceutical Biology, University of Munich, Munich, Germany.
authors.forename: Lisa
authors.initials: L
authors.lastname: Pfitzer
authors.affiliation: Department of Pharmacy, Pharmaceutical Biology, University of Munich, Munich, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Liebl
authors.affiliation: Laboratory for Functional Genome Analysis (LAFUGA), Gene Center Munich, University of Munich, Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Fröhlich
authors.affiliation: Laboratory for Functional Genome Analysis (LAFUGA), Gene Center Munich, University of Munich, Munich, Germany.
authors.forename: Georg J
authors.initials: GJ
authors.lastname: Arnold
authors.affiliation: Department of Medicine I, Institute of Cancer Research, Comprehensive Cancer Center Vienna, Medical University of Vienna, Vienna, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Mikulits
authors.affiliation: Department of Medicine I, Institute of Cancer Research, Comprehensive Cancer Center Vienna, Medical University of Vienna, Vienna, Austria.
authors.forename: Christine
authors.initials: C
authors.lastname: Haider
authors.affiliation: Department of Pharmacy, Pharmaceutical Biology, University of Munich, Munich, Germany.
authors.forename: Angelika M
authors.initials: AM
authors.lastname: Vollmar
authors.affiliation: Department of Pharmacy, Pharmaceutical Biology, University of Munich, Munich, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Zahler
mesh_terms: D000818:Animals; D001483:Base Sequence; D006528:Carcinoma, Hepatocellular / Q000098:blood supply / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D051360:Cyclin-Dependent Kinase 5 / Q000235:genetics* / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D056945:Hep G2 Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D008113:Liver Neoplasms / Q000098:blood supply / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008810:Mice, Inbred C57BL; D016513:Mice, SCID; D009389:Neovascularization, Pathologic / Q000235:genetics* / Q000378:metabolism; D055550:Protein Stability; D034622:RNA Interference; D012689:Sequence Homology, Nucleic Acid; D014183:Transplantation, Heterologous
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051360:Cyclin-Dependent Kinase 5; C495905:CDK5 protein, human
keywords: CDK5; HCC; HIF-1α; angiogenesis