Crystal structures of prostaglandin D(2) 11-ketoreductase (AKR1C3) in complex with the nonsteroidal anti-inflammatory drugs flufenamic acid and indomethacin.
It is becoming increasingly well established that nonsteroidal anti-inflammatory drugs (NSAID) protect against tumors of the gastrointestinal tract and that they may also protect against a variety of other tumors. These activities have been widely attributed to the inhibition of cylooxygenases (COX) and, in particular, COX-2. However, several observations have indicated that other targets may be involved. Besides targeting COX, certain NSAID also inhibit enzymes belonging to the aldo-keto reductase (AKR) family, including AKR1C3. We have demonstrated previously that overexpression of AKR1C3 acts to suppress cell differentiation and promote proliferation in myeloid cells. However, this enzyme has a broad tissue distribution and therefore represents a novel candidate for the target of the COX-independent antineoplastic actions of NSAID. Here we report on the X-ray crystal structures of AKR1C3 complexed with the NSAID indomethacin (1.8 A resolution) or flufenamic acid (1.7 A resolution). One molecule of indomethacin is bound in the active site, whereas flufenamic acid binds to both the active site and the beta-hairpin loop, at the opposite end of the central beta-barrel. Two other crystal structures (1.20 and 2.1 A resolution) show acetate bound in the active site occupying the proposed oxyanion hole. The data underline AKR1C3 as a COX-independent target for NSAID and will provide a structural basis for the future development of new cancer therapies with reduced COX-dependent side effects.
The School of Biosciences, The University of Birmingham, Birmingham, United Kingdom.
Andrew L
AL
Lovering
Jon P
JP
Ride
Christopher M
CM
Bunce
Julian C
JC
Desmond
Stephen M
SM
Cummings
Scott A
SA
White
D000595:Amino Acid Sequence; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism* / Q000494:pharmacology; D001665:Binding Sites; D003460:Crystallization; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D005439:Flufenamic Acid / Q000378:metabolism*; D006911:Hydroxyprostaglandin Dehydrogenases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D007213:Indomethacin / Q000378:metabolism*; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry
D000894:Anti-Inflammatory Agents, Non-Steroidal; D016861:Cyclooxygenase Inhibitors; D011994:Recombinant Proteins; D005439:Flufenamic Acid; D006911:Hydroxyprostaglandin Dehydrogenases; C031051:prostaglandin-F synthase; D007213:Indomethacin