Human CYP2S1 metabolizes cyclooxygenase- and lipoxygenase-derived eicosanoids.
CYP2S1 is a recently described dioxin-inducible cytochrome P450. We previously demonstrated that human CYP2S1 oxidizes a number of carcinogens but only via the peroxide shunt. In this article, we investigated whether human CYP2S1 can metabolize cyclooxygenase- and lipoxygenase-derived lipid peroxides in a NADPH-independent fashion. Human CYP2S1 metabolizes prostaglandin G(2) (PGG(2)) (K(m) = 0.267 ± 0.072 μM) into several products including 12S-hydroxy-5Z,8E,10E-heptadecatrienoic acid (12-HHT). It also metabolizes prostaglandin H(2) (PGH(2)) (K(m) = 11.7 ± 2.8 μM) into malondialdehyde, 12-HHT, and thromboxane A(2) (TXA(2)). The turnover to 12-HHT by human CYP2S1 (1.59 ± 0.04 min(-1)) is 40-fold higher than that of TXA(2) (0.04 min(-1)). In addition to PGG(2) and PGH(2) metabolism, human CYP2S1 efficiently metabolizes the hydroperoxyeicosatetraenoic acids (5S-, 12S-, and 15S-) and 13S-hydroperoxyoctadecadienoic acid into 5-oxo-eicosatetraenoic acid (turnover = 16.7 ± 0.3 min(-1)), 12-oxo-eicosatetraenoic acid 1 (11.5 ± 0.9 min(-1)), 15-oxo-eicosatetraenoic acid (16.9 ± 0.8 min(-1)), and 13-octadecadienoic acid (20.2 ± 0.9 min(-1)), respectively. Other cytochromes P450 such as CYP1A1, 1A2, 1B1, and 3A4 underwent similar conversions but at slower rates. The fatty acid hydroperoxides were also converted by human CYP2S1 to several epoxyalcohols. Our data indicate that fatty acid endoperoxides and hydroperoxides represent endogenous substrates of CYP2S1 and suggest that the enzyme CYP2S1 may play an important role in the inflammatory process because some of the products that CYP2S1 produces play important roles in inflammation.
Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California at Los Angeles, 650 Charles E. Young Dr., Los Angeles, CA 90095, USA.
Peter
P
Bui
Satoshi
S
Imaizumi
Sudheer Reddy
SR
Beedanagari
Srinivasa T
ST
Reddy
Oliver
O
Hankinson
D001711:Biotransformation; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015777:Eicosanoids / Q000378:metabolism*; D006801:Humans; D008084:Lipoxygenase / Q000378:metabolism*; D008861:Microsomes / Q000201:enzymology; D015394:Molecular Structure; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D053719:Tandem Mass Spectrometry; D014162:Transfection
D015777:Eicosanoids; D011994:Recombinant Proteins; D003577:Cytochrome P-450 Enzyme System; D008084:Lipoxygenase; C422564:CYP2S1 protein, human; D011451:Prostaglandin-Endoperoxide Synthases