title: Dihydroorotate dehydrogenase is required for N-(4-hydroxyphenyl)retinamide-induced reactive oxygen species production and apoptosis.
abstract: The synthetic retinoid N-(4-hydroxyphenyl)retinamide (4HPR) exhibits anticancer activity in vivo and triggers apoptosis in transformed cells in vitro. Thus, apoptosis induction is acknowledged as a mechanistic underpinning for 4HPR's cancer preventive and therapeutic effects. Apoptosis induction by 4HPR is routinely preceded by and dependent on the production of reactive oxygen species (ROS) in transformed cells. Very little evidence exists, outside the possible involvement of the mitochondrial electron transport chain or the plasma membrane NADPH oxidase complex, that would pinpoint the predominant site of 4HPR-induced ROS production in transformed cells. Here, we investigated the role of dihydroorotate dehydrogenase (DHODH; an enzyme associated with the mitochondrial electron transport chain and required for de novo pyrimidine synthesis) in 4HPR-induced ROS production and attendant apoptosis in transformed skin and prostate epithelial cells. In premalignant prostate epithelial cells and malignant cutaneous keratinocytes the suppression of DHODH activity by the chemical inhibitor teriflunomide or the reduction in DHODH protein expression by RNA interference markedly reduced 4HPR-induced ROS generation and apoptosis. Conversely, colon carcinoma cells that lacked DHODH expression were markedly resistant to the pro-oxidant and cytotoxic effects of 4HPR. Together, these results strongly implicate DHODH in 4HPR-induced ROS production and apoptosis.
authors.affiliation: Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Denver, Aurora, CO 80045, USA. Numsen.Hail@UCDenver.edu
authors.forename: Numsen
authors.initials: N
authors.lastname: Hail
authors.forename: Ping
authors.initials: P
authors.lastname: Chen
authors.forename: Jadwiga J
authors.initials: JJ
authors.lastname: Kepa
authors.forename: Lane R
authors.initials: LR
authors.lastname: Bushman
authors.forename: Colin
authors.initials: C
authors.lastname: Shearn
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D002277:Carcinoma / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D003437:Crotonates / Q000494:pharmacology; D000090722:Dihydroorotate Dehydrogenase; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D017313:Fenretinide / Q000494:pharmacology; D006801:Humans; D006885:Hydroxybutyrates; D008297:Male; D009570:Nitriles; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D012867:Skin / Q000473:pathology; D014052:Toluidines / Q000494:pharmacology
chemical_list: D003437:Crotonates; D000090722:Dihydroorotate Dehydrogenase; D006885:Hydroxybutyrates; D009570:Nitriles; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D014052:Toluidines; D017313:Fenretinide; C527525:teriflunomide; D044925:Oxidoreductases Acting on CH-CH Group Donors
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