Identification of HSD17B12 as an enzyme catalyzing drug reduction reactions through investigation of nabumetone metabolism

Abstract

Nabumetone, a nonsteroidal anti-inflammatory prodrug, is converted to a pharmacologically active metabolite, 6-methoxy-2-naphthylacetic acid (6-MNA); however, it is 11-fold more efficiently converted to 4-(6-methoxy-2-naphthyl)butan-2-ol (MNBO) via a reduction reaction in human hepatocytes. The goal of this study was to identify the enzyme(s) responsible for MNBO formation from nabumetone in the human liver. MNBO formation by human liver microsomes (HLM) was 5.7-fold higher than in the liver cytosol. In a panel of 24 individual HLM samples with quantitative proteomics data, the 17β-hydroxysteroid dehydrogenase 12 (HSD17B12) protein level had the high correlation coefficient (r = 0.80, P < 0.001) among 4457 proteins quantified in microsomal fractions during MNBO formation. Recombinant HSD17B12 expressed in HEK293T cells exhibited prominent nabumetone reductase activity, and the contribution of HSD17B12 to the activity in the HLM was calculated as almost 100%. MNBO formation in HepG2 and Huh7 cells was significantly decreased by the knockdown of HSD17B12. We also examined the role of HSD17B12 in drug metabolism and found that recombinant HSD17B12 catalyzed the reduction reactions of pentoxifylline and S-warfarin, suggesting that HSD17B12 prefers compounds containing a methyl ketone group on the alkyl chain. In conclusion, our study demonstrated that HSD17B12 is responsible for the formation of MNBO from nabumetone. Together with the evidence for pentoxifylline and S-warfarin reduction, this is the first study to report that HSD17B12, which is known to metabolize endogenous compounds, such as estrone and 3-ketoacyl-CoA, plays a role as a drug-metabolizing enzyme.

Keywords: Drug metabolism; HSD17B12; Human liver microsomes; Nabumetone.