title: Mechanistic role of cytochrome P450 (CYP)1B1 in oxygen-mediated toxicity in pulmonary cells: A novel target for prevention of hyperoxic lung injury.
abstract: Supplemental oxygen, which is routinely administered to preterm infants with pulmonary insufficiency, contributes to bronchopulmonary dysplasia (BPD) in these infants. Hyperoxia also contributes to the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) in adults. The mechanisms of oxygen-mediated pulmonary toxicity are not completely understood. Recent studies have suggested an important role for cytochrome P450 (CYP)1A1/1A2 in the protection against hyperoxic lung injury. The role of CYP1B1 in oxygen-mediated pulmonary toxicity has not been studied. In this investigation, we tested the hypothesis that CYP1B1 plays a mechanistic role in oxygen toxicity in pulmonary cells in vitro. In human bronchial epithelial cell line BEAS-2B, hyperoxic treatment for 1-3 days led to decreased cell viability by about 50-80%. Hyperoxic cytotoxicity was accompanied by an increase in levels of reactive oxygen species (ROS) by up to 110%, and an increase of TUNEL-positive cells by up to 4.8-fold. Western blot analysis showed hyperoxia to significantly down-regulate CYP1B1 protein level. Also, there was a decrease of CYP1B1 mRNA by up to 38% and Cyp1b1 promoter activity by up to 65%. On the other hand, CYP1B1 siRNA appeared to rescue the cell viability under hyperoxia stress, and overexpression of CYP1B1 significantly attenuated hyperoxic cytotoxicity after 48 h of incubation. In immortalized lung endothelial cells derived from Cyp1b1-null and wild-type mice, hyperoxia increased caspase 3/7 activities in a time-dependent manner, but endothelial cells lacking the Cyp1b1 gene showed significantly decreased caspase 3/7 activities after 48 and 72 h of incubation, implying that CYP1B1 might promote apoptosis in wild type lung endothelial cells under hyperoxic stress. In conclusion, our results support the hypothesis that CYP1B1 plays a mechanistic role in pulmonary oxygen toxicity, and CYP1B1-mediated apoptosis could be one of the mechanisms of oxygen toxicity. Thus, CYP1B1 could be a novel target for preventative and/or therapeutic interventions against BPD in infants and ALI/ARDS in adults.
authors.affiliation: Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Daniela
authors.initials: D
authors.lastname: Dinu
authors.affiliation: Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Chun
authors.initials: C
authors.lastname: Chu
authors.affiliation: Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Veith
authors.affiliation: Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Krithika
authors.initials: K
authors.lastname: Lingappan
authors.affiliation: Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Xanthi
authors.initials: X
authors.lastname: Couroucli
authors.affiliation: Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: Colin R
authors.initials: CR
authors.lastname: Jefcoate
authors.affiliation: Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: Nader
authors.initials: N
authors.lastname: Sheibani
authors.affiliation: Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA. Electronic address: bmoorthy@bcm.edu.
authors.forename: Bhagavatula
authors.initials: B
authors.lastname: Moorthy
mesh_terms: D055371:Acute Lung Injury / Q000517:prevention & control*; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D065633:Cytochrome P-450 CYP1B1 / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D018496:Hyperoxia / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D008817:Mice, Mutant Strains; D034741:RNA, Small Interfering; D018336:Receptors, Aryl Hydrocarbon / Q000378:metabolism
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D065633:Cytochrome P-450 CYP1B1; D034741:RNA, Small Interfering; D018336:Receptors, Aryl Hydrocarbon; C111235:AHR protein, human; C585496:CYP1B1 protein, human; C585498:Cyp1b1 protein, mouse
keywords: CYP1B1; Cytochrome P450; Endothelial cells; Hyperoxia; Lung