title: Heme Oxygenase-1 and breast cancer resistance protein protect against heme-induced toxicity.
abstract: Heme is the functional group of diverse hemoproteins and crucial for many cellular processes. However, heme is increasingly recognized as a culprit for a wide variety of pathologies, including sepsis, malaria, and kidney failure. Excess of free heme can be detrimental to tissues by mediating oxidative and inflammatory injury. Protective mechanisms against free heme are therefore pivotal for cellular survival. We postulated that overexpression of Heme Oxygenase-1 (HO-1) and Breast Cancer Resistance Protein (BCRP) would protect against heme-induced cytotoxicity. HO-1 is a heme-degrading enzyme generating carbon monoxide, iron, and biliverdin/bilirubin, while BCRP is a heme efflux transporter. Human embryonic kidney cells were transduced using a baculovirus system as a novel strategy to efficiently overexpress HO-1 and BCRP. Exposing cells to heme resulted in a dose-dependent increase in reactive oxygen species formation, DNA damage and cell death. Heme-induced cell death was significantly attenuated when cells overexpressed HO-1, BCRP, or both. The protective effects of HO-1 overexpression were most pronounced, while co-treatment with the HO-activity inhibitor tin mesoporphyrin reversed these protective effects. Also cells treated with the anti-oxidants N-acetylcysteine or HO-effector molecule bilirubin showed protection against heme insults, which may explain the increased protection by HO-1 compared to BCRP. In conclusion, both HO-1 and BCRP protect against heme-induced toxicity and may thus form novel therapeutic targets for heme-mediated pathologies.
authors.affiliation: Department of Orthodontics and Craniofacial Biology, Radboud University Nijmegen Medical Centre, Nijmegen Centre for Molecular Life Sciences, PO Box 9101, 6500 HB Nijmegen, The Netherlands. f.wagener@dent.umcn.nl
authors.forename: Frank A D T G
authors.initials: FA
authors.lastname: Wagener
authors.forename: Anita C A
authors.initials: AC
authors.lastname: Dankers
authors.forename: Frank
authors.initials: F
authors.lastname: van Summeren
authors.forename: Alwin
authors.initials: A
authors.lastname: Scharstuhl
authors.forename: Jeroen J M W
authors.initials: JJ
authors.lastname: van den Heuvel
authors.forename: Jan B
authors.initials: JB
authors.lastname: Koenderink
authors.forename: Sebastiaan W C
authors.initials: SW
authors.lastname: Pennings
authors.forename: Frans G M
authors.initials: FG
authors.lastname: Russel
authors.forename: Rosalinde
authors.initials: R
authors.lastname: Masereeuw
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000502:physiology*; D001562:Benzimidazoles / Q000378:metabolism; D015153:Blotting, Western; D004249:DNA Damage; D057809:HEK293 Cells; D006418:Heme / Q000633:toxicity*; D051547:Heme Oxygenase-1 / Q000378:metabolism*; D006801:Humans; D009363:Neoplasm Proteins / Q000502:physiology*; D016877:Oxidants / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D001562:Benzimidazoles; D009363:Neoplasm Proteins; D016877:Oxidants; D017382:Reactive Oxygen Species; D006418:Heme; D051547:Heme Oxygenase-1; C017807:bisbenzimide ethoxide trihydrochloride