Role of cytochrome P4502E1 activation in proximal tubular cell injury induced by hydrogen peroxide.
BACKGROUND
There is now good evidence to suggest that cytochrome P450 (CYP450) may act as an iron-donating catalyst for the production of hydroxyl ion (OH*), which contributes to proximal tubular cell injury. However, it remains unclear which isoform of CYP450 is involved in this process. Cytochrome P4502E1 (CYP2E1) is a highly labile isoform which is not only involved in free radical generation, but has also been shown to be a source of iron in cisplatin-induced renal injury. This study investigates the role of CYP2E1 in the proximal tubular cell injury induced by hydrogen peroxide (H2O2).


METHODS
Porcine proximal tubular cells (LLC-PK1) were incubated with H2O2 (1 mM) for 4 h in the presence or absence of 0.1 mM of two CYP2E1 inhibitors; diallyl sulfide (DAS), or disulfiram (DSF), desferrioxamine (DFO) (0.1-0.4 mM), or catalase (CT) (78, 150, 300 U/mL). Cell death was determined by measuring LDH release. CYP2E1 activity was determined by p-nitrophenol hydroxylation after 2 h incubation with H2O2.


RESULTS
Exposure of LLC-PKI to H2O2 significantly increased cell death. CT, DFO, DAS and DSF significantly reduced H2O2-mediated cell death. Incubation with H2O2 increased CYP2EI activation in time- and dose-dependent manner, which was significantly reduced by CT, DFO, DAS and DSF.


CONCLUSIONS
We propose that CYP2E1 activation occurs possibly due to OH* and contributes to H2O2-mediated LLC-PK1 cell necrosis by acting as a source of iron and perpetuating the generation of OH* via the Fenton reaction. Inhibition of CYP2E1 may be a novel approach for the prevention of tubular injury caused by oxidative stress.
Department of Experimental Medicine and Nephrology, St Bartholomew's and the Royal London School of Medicine and Dentistry, Queen Mary-University of London, London, UK. s_alghamdi@go.com
Saeed S
SS
Al-Ghamdi
Prabal K
PK
Chatterjee
Martin J
MJ
Raftery
Christoph
C
Thiemermann
Muhammad M
MM
Yaqoob
D000498:Allyl Compounds / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured; D019392:Cytochrome P-450 CYP2E1 / Q000494:pharmacology*; D065691:Cytochrome P-450 CYP2E1 Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis / Q000378:metabolism*; D003676:Deferoxamine / Q000494:pharmacology; D004221:Disulfiram / Q000494:pharmacology; D004347:Drug Interactions; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism*; D018374:LLC-PK1 Cells / Q000187:drug effects / Q000502:physiology*; D018384:Oxidative Stress; D011336:Probability; D012680:Sensitivity and Specificity; D013440:Sulfides / Q000494:pharmacology; D013552:Swine
D000498:Allyl Compounds; D065691:Cytochrome P-450 CYP2E1 Inhibitors; D013440:Sulfides; C038491:allyl sulfide; D003577:Cytochrome P-450 Enzyme System; D006861:Hydrogen Peroxide; D019392:Cytochrome P-450 CYP2E1; D003676:Deferoxamine; D004221:Disulfiram