title: Geldanamycin induces degradation of hypoxia-inducible factor 1alpha protein via the proteosome pathway in prostate cancer cells.
abstract: Hypoxia-inducible factor 1 (HIF-1) is a heterodimeric transcription factor composed of alpha and beta subunits. HIF-1 is critically involved in cellular responses to hypoxia, glycolysis, and angiogenesis. Here, we show that treatment of prostate cancer PC-3 and LNCaP cells with the benzoquinone ansamycin geldanamycin, an Hsp90-specific inhibitor, induced degradation of HIF-1alpha protein in a dose- and time-dependent manner under both normoxia and hypoxia. This inhibition was also shown in other common cancer types tested. Rapid degradation of nuclear HIF-1alpha protein levels was accompanied by respective inhibition in HIF-1alpha functional transcription activity of VEGF. No difference between HIF-1alpha mRNA levels before or after geldanamycin treatment was found. Moreover, [35S]methionine pulse-chase analysis revealed that HIF-1alpha protein half-life was markedly decreased in the presence of geldanamycin compared with that in control. The geldanamycin-induced degradation of HIF-1alpha was reversed by proteosome inhibitors lactacystin and MG-132. We conclude that geldanamycin induces reduction of HIF-1alpha levels and its downstream transcriptional activity by accelerating protein degradation independent of O2 tension. Thus, benzoquinone ansamycin drugs and their derivatives, such as 17-allyl-aminogeldanamycin, are excellent candidates as small molecule drug inhibitors of HIF-1 overexpression in cancer cells.
authors: Winship Cancer Institute, Department of Hematology and Oncology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors: Nicola J
authors: NJ
authors: Mabjeesh
authors: Dawn E
authors: DE
authors: Post
authors: Margaret T
authors: MT
authors: Willard
authors: Balveen
authors: B
authors: Kaur
authors: Erwin G
authors: EG
authors: Van Meir
authors: Jonathan W
authors: JW
authors: Simons
authors: Hua
authors: H
authors: Zhong
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000493:pharmacokinetics / Q000494:pharmacology*; D016227:Benzoquinones; D004305:Dose-Response Relationship, Drug; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D047029:Lactams, Macrocyclic; D008297:Male; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D011809:Quinones / Q000493:pharmacokinetics / Q000494:pharmacology*; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
chemical_list: D000903:Antibiotics, Antineoplastic; D016227:Benzoquinones; C497442:HIF1A protein, human; D018841:HSP90 Heat-Shock Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D047029:Lactams, Macrocyclic; D011809:Quinones; D014157:Transcription Factors; C001277:geldanamycin