title: Identification of bioactivating enzymes involved in the hydrolysis of laninamivir octanoate, a long-acting neuraminidase inhibitor, in human pulmonary tissue.
abstract: Laninamivir octanoate (LO) is an octanoyl ester prodrug of the neuraminidase inhibitor laninamivir. After inhaled administration, LO exhibits clinical efficacy for both treatment and prophylaxis of influenza virus infection, resulting from hydrolytic bioactivation into its pharmacologically active metabolite laninamivir in the pulmonary tissue. In this study, we focused on the identification of LO-hydrolyzing enzymes from human pulmonary tissue extract using proteomic correlation profiling-a technology integration of traditional biochemistry and proteomics. In a single elution step by gel-filtration chromatography, LO-hydrolyzing activity was separated into two distinct peaks, designated as peak I and peak II. By mass spectrometry, 1160 and 1003 proteins were identified and quantitated for peak I and peak II, respectively, and enzyme candidates were ranked based on the correlation coefficient between the enzyme activity and the proteomic profiles. Among proteins with a high correlation value, S-formylglutathione hydrolase (esterase D; ESD) and acyl-protein thioesterase 1 (APT1) were selected as the most likely candidates for peak I and peak II, respectively, which was confirmed by LO-hydrolyzing activity of recombinant proteins. In the case of peak II, LO-hydrolyzing activity was completely inhibited by treatment with a specific APT1 inhibitor, palmostatin B. Moreover, immunohistochemical analysis revealed that both enzymes were mainly localized in the pulmonary epithelia, a primary site of influenza virus infection. These findings demonstrate that ESD and APT1 are key enzymes responsible for the bioactivation of LO in human pulmonary tissue.
authors.affiliation: Drug Metabolism & Pharmacokinetics Research Laboratories (K.Ko., D.N., T.I.), and Translational Medicine and Clinical Pharmacology Department (T.M.), Daiichi Sankyo Co., Ltd.; Discovery Science and Technology Department, Daiichi Sankyo RD Novare Co., Ltd. (Y.Og., M.W., Y.Of., K.Ku., A.S.), Tokyo, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Koyama
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ogura
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nakai
authors.forename: Mihoko
authors.initials: M
authors.lastname: Watanabe
authors.forename: Toshiko
authors.initials: T
authors.lastname: Munemasa
authors.forename: Yuka
authors.initials: Y
authors.lastname: Oofune
authors.forename: Kazuishi
authors.initials: K
authors.lastname: Kubota
authors.forename: Akira
authors.initials: A
authors.lastname: Shinagawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Izumi
mesh_terms: D000280:Administration, Inhalation; D000368:Aged; D006146:Guanidines; D006801:Humans; D006868:Hydrolysis / Q000187:drug effects; D008168:Lung / Q000187:drug effects* / Q000201:enzymology*; D008297:Male; D008875:Middle Aged; D009439:Neuraminidase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D011714:Pyrans; D012794:Sialic Acids; D053243:Zanamivir / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D006146:Guanidines; D011714:Pyrans; D012794:Sialic Acids; C546918:laninamivir; D009439:Neuraminidase; D053243:Zanamivir