title: Oxygen-independent degradation of HIF-alpha via bioengineered VHL tumour suppressor complex.
abstract: Tumour hypoxia promotes the accumulation of the otherwise oxygen-labile hypoxia-inducible factor (HIF)-alpha subunit whose expression is associated with cancer progression, poor prognosis and resistance to conventional radiation and chemotherapy. The oxygen-dependent degradation of HIF-alpha is carried out by the von Hippel-Lindau (VHL) protein-containing E3 that directly binds and ubiquitylates HIF-alpha for subsequent proteasomal destruction. Thus, the cellular proteins involved in the VHL-HIF pathway have been recognized as attractive molecular targets for cancer therapy. However, the various compounds designed to inhibit HIF-alpha or HIF-downstream targets, although promising, have shown limited success in the clinic. In the present study, we describe the bioengineering of VHL protein that removes the oxygen constraint in the recognition of HIF-alpha while preserving its E3 enzymatic activity. Using speckle variance-optical coherence tomography (sv-OCT), we demonstrate the dramatic inhibition of angiogenesis and growth regression of human renal cell carcinoma xenografts upon adenovirus-mediated delivery of the bioengineered VHL protein in a dorsal skin-fold window chamber model. These findings introduce the concept and feasibility of 'bio-tailored' enzymes in the treatment of HIF-overexpressing tumours.
authors.affiliation: Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
authors.forename: Roxana I
authors.initials: RI
authors.lastname: Sufan
authors.forename: Eduardo H
authors.initials: EH
authors.lastname: Moriyama
authors.forename: Adrian
authors.initials: A
authors.lastname: Mariampillai
authors.forename: Olga
authors.initials: O
authors.lastname: Roche
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Evans
authors.forename: Nehad M
authors.initials: NM
authors.lastname: Alajez
authors.forename: I Alex
authors.initials: IA
authors.lastname: Vitkin
authors.forename: Victor X D
authors.initials: VX
authors.lastname: Yang
authors.forename: Fei-Fei
authors.initials: FF
authors.lastname: Liu
authors.forename: Brian C
authors.initials: BC
authors.lastname: Wilson
authors.forename: Michael
authors.initials: M
authors.lastname: Ohh
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator / Q000378:metabolism; D057005:Bioengineering; D002292:Carcinoma, Renal Cell / Q000235:genetics / Q000473:pathology / Q000628:therapy; D015687:Cell Hypoxia / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D018014:Gene Transfer Techniques; D049452:Green Fluorescent Proteins / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000737:chemistry / Q000378:metabolism*; D007680:Kidney Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy; D051379:Mice; D009336:Necrosis; D009389:Neovascularization, Pathologic / Q000628:therapy; D010100:Oxygen / Q000494:pharmacology*; D010957:Plasmids / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D020218:Response Elements / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D011993:Recombinant Fusion Proteins; C485184:enhanced green fluorescent protein; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D049452:Green Fluorescent Proteins; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D010100:Oxygen