5-Lipoxygenase-mediated endogenous DNA damage.
Lipoxygenases (LOs) convert polyunsaturated fatty acids into lipid hydroperoxides. Homolytic decomposition of lipid hydroperoxides gives rise to endogenous genotoxins such as 4-oxo-2(E)-nonenal, which cause the formation of mutagenic DNA adducts. Chiral lipidomics analysis was employed to show that a 5-LO-derived lipid hydroperoxide was responsible for endogenous DNA-adduct formation. The study employed human lymphoblastoid CESS cells, which expressed both 5-LO and the required 5-LO-activating protein (FLAP). The major lipid peroxidation product was 5(S)-hydroperoxy-6,8,11,14-(E,Z,Z,Z)-eicosatetraenoic acid, which was analyzed as its reduction product, 5(S)-hydroxy-6,8,11,14-(E,Z,Z,Z)-eicosatetraenoic acid (5(S)-HETE)). Concentrations of 5(S)-HETE increased from 0.07 +/- 0.01 to 45.50 +/- 4.05 pmol/10(7) cells upon stimulation of the CESS cells with calcium ionophore A23187. There was a concomitant increase in the 4-oxo-2(E)-nonenal-derived DNA-adduct, heptanone-etheno-2'-deoxyguanosine (HepsilondGuo) from 2.41 +/- 0.35 to 6.31 +/- 0.73 adducts/10(7) normal bases. Biosynthesis of prostaglandins, 11(R)-hydroxy-5,8,12,14-(Z,Z,E,Z)-eicosatetraenoic acid, and 15(R,S)-hydroxy-5,8,11,13-(Z,Z,Z,E)-eicosatetraenoic acid revealed that there was cyclooxygenase (COX) activity in the CESS cells. Western blot analysis revealed that COX-1 was expressed by the cells, but there was no COX-2 or 15-LO-1. FLAP inhibitor reduced HepsilondGuo-adducts and 5(S)-HETE to basal levels. In contrast, aspirin, which had no effect on 5(S)-HETE, blocked the formation of prostaglandins, 15-HETE, and 11-HETE but did not inhibit HepsilondGuo-adduct formation. These data showed that 5-LO was the enzyme responsible for the generation of the HepsilondGuo DNA-adduct in CESS cells.
Jian
Wenying
W
From the Centers for Cancer Pharmacology and Excellence in Environmental Toxicology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160.
Lee
Seon Hwa
SH
From the Centers for Cancer Pharmacology and Excellence in Environmental Toxicology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160.
Williams
Michelle V
MV
From the Centers for Cancer Pharmacology and Excellence in Environmental Toxicology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160.
Blair
Ian A
IA
From the Centers for Cancer Pharmacology and Excellence in Environmental Toxicology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160.
D058927:5-Lipoxygenase-Activating Proteins; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D001241:Aspirin / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D002460:Cell Line; D051545:Cyclooxygenase 1 / Q000378:metabolism; D018736:DNA Adducts / Q000096:biosynthesis; D004249:DNA Damage / Q000502:physiology*; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000096:biosynthesis; D007476:Ionophores / Q000494:pharmacology; D007975:Leukotriene B4 / Q000096:biosynthesis; D015227:Lipid Peroxidation; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D008954:Models, Biological; D011453:Prostaglandins / Q000096:biosynthesis
D058927:5-Lipoxygenase-Activating Proteins; C548592:ALOX5AP protein, human; D002352:Carrier Proteins; D018736:DNA Adducts; D006893:Hydroxyeicosatetraenoic Acids; D007476:Ionophores; D008565:Membrane Proteins; D011453:Prostaglandins; D007975:Leukotriene B4; D000001:Calcimycin; C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; D001094:Arachidonate 5-Lipoxygenase; D051545:Cyclooxygenase 1; C496511:PTGS1 protein, human; D001241:Aspirin