Involvement of an aldo-keto reductase (AKR1C3) in redox cycling of 9,10-phenanthrenequinone leading to apoptosis in human endothelial cells.
9,10-Phenanthrenequinone (9,10-PQ), a major quinone found in diesel exhaust particles, is considered to generate reactive oxygen species (ROS) through its redox cycling. Here, we show that 9,10-PQ evokes apoptosis in human aortic endothelial cells (HAECs) and its apoptotic signaling includes ROS generation and caspase activation. The 9,10-PQ-induced cytotoxicity was inhibited by ROS scavengers, indicating that intracellular ROS generation is responsible for the 9,10-PQ-induced apoptosis. Comparison of mRNA expression levels and kinetic constants in the 9,10-PQ reduction among 10 human reductases suggests that aldo-keto reductase 1C3 (AKR1C3) is a 9,10-PQ reductase in HAECs. In in vitro 9,10-PQ reduction by AKR1C3, the reduced product 9,10-dihydroxyphenanthrene and superoxide anions were formed, suggesting the enzymatic two-electron reduction of 9,10-PQ that thereby causes oxidative stress through its redox cycling. In addition, the participation of AKR1C3 in 9,10-PQ-redox cycling was confirmed by the data that AKR1C3 overexpression in endothelial cells augmented the ROS generation and cytotoxicity by 9,10-PQ, and the ROS scavengers inhibited the toxic effects. Pretreatment of the overexpressing cells with AKR1C3 inhibitors, flufenamic acid and indomethacin, suppressed the 9,10-PQ-induced GSH depletion. These results suggest that AKR1C3 is a key enzyme in the initial step of 9,10-PQ-induced cytotoxicity in HAECs.
Laboratory of Biochemistry, Gifu Pharmaceutical University, 5-6-1 Mitahora-Higashi, Gifu, Japan. matsunagat@gifu-pu.ac.jp
Toshiyuki
T
Matsunaga
Marina
M
Arakaki
Tetsuro
T
Kamiya
Satoshi
S
Endo
Ossama
O
El-Kabbani
Akira
A
Hara
D015096:3-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D000074425:Aldo-Keto Reductase Family 1 Member C3; D017209:Apoptosis / Q000187:drug effects*; D001483:Base Sequence; D002478:Cells, Cultured; D017931:DNA Primers; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D006911:Hydroxyprostaglandin Dehydrogenases / Q000378:metabolism*; D010084:Oxidation-Reduction; D010616:Phenanthrenes / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D017382:Reactive Oxygen Species / Q000378:metabolism
D017931:DNA Primers; D010616:Phenanthrenes; D017382:Reactive Oxygen Species; C005399:9,10-phenanthrenequinone; D015096:3-Hydroxysteroid Dehydrogenases; D006911:Hydroxyprostaglandin Dehydrogenases; C487341:AKR1C3 protein, human; D000074425:Aldo-Keto Reductase Family 1 Member C3