title: Inhibition of L-leucine methyl ester mediated killing of THP-1, a human monocytic cell line, by a new anti-inflammatory drug, T614.
abstract: T614 (3-formylamino-7-methylsulfonylamino-6-phenoxy-4H-1-benzopyran-4-o ne) is a member of the family of methanesulfonanilide non-steroidal anti-inflammatory drugs (mNSAIDs), most of which act as cyclooxygenase (COX)-2 inhibitors. L-leucine methyl ester (Leu-OME) is a reagent which has been shown to kill phagocytes following interaction with intracellular proteases. There are two pathways whereby Leu-OME becomes cytotoxic to phagocytes. Within lysosomes, Leu-OME is converted into free Leu, which causes disruption of the lysosomes and subsequent cell necrosis. The other is the conversion of Leu-OME into (Leu-Leu)(n)-OME, which is associated with the induction of apoptosis. In the present study, we examined the action of T614 on Leu-OME mediated killing of THP-1, a human monocytic cell line. We revealed that T614 and phenylmethyl sulfonyl fluoride (PMSF), a serine protease inhibitor, inhibited Leu-OME mediated killing of THP-1 cells. All the other mNSAIDs, including nimesulide (NIM-03), fluosulide (CGP28238), FK3311 and NS398, also rescued THP-1 from Leu-OME mediated killing, although to a lesser degree. Of the classical NSAIDs tested, a protective effect was observed with diclofenac at high concentration, but not with naproxen or indomethacin. Unlike conventional lysosomal inhibitors, such as chloroquine and ammonium chloride (NH(4)Cl), T614 and PMSF did not raise lysosomal pH, as measured by flow cytometry using fluorescein isothiocyanate dextran (FITC-dextran). Therefore, the mechanism whereby T614 and PMSF inhibit Leu-OME killing is distinct from that of chloroquine or NH(4)Cl. Based on the similarity of T614 and PMSF, we suggest that, besides their roles as COX-2 inhibitors, T614 and other mNSAIDs may act as lysosomal protease inhibitors.
authors.affiliation: Department of Allergy and Rheumatology, University of Tokyo School of Medicine, 7-3-1 Hongo, Bunkyo, 113, Tokyo, Japan. tetsuji-tky@umin.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Sawada
authors.forename: S
authors.initials: S
authors.lastname: Hashimoto
authors.forename: S
authors.initials: S
authors.lastname: Tohma
authors.forename: Y
authors.initials: Y
authors.lastname: Nishioka
authors.forename: T
authors.initials: T
authors.lastname: Nagai
authors.forename: T
authors.initials: T
authors.lastname: Sato
authors.forename: K
authors.initials: K
authors.lastname: Ito
authors.forename: T
authors.initials: T
authors.lastname: Inoue
authors.forename: M
authors.initials: M
authors.lastname: Iwata
authors.forename: K
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism / Q000633:toxicity*; D001578:Benzopyrans / Q000378:metabolism / Q000633:toxicity*; D016923:Cell Death / Q000187:drug effects / Q000276:immunology; D004151:Dipeptides / Q000633:toxicity; D006131:Growth Inhibitors / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007930:Leucine / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D010664:Phenylmethylsulfonyl Fluoride / Q000633:toxicity; D013449:Sulfonamides / Q000378:metabolism / Q000633:toxicity*; D014407:Tumor Cells, Cultured; D020298:U937 Cells
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D001578:Benzopyrans; D004151:Dipeptides; D006131:Growth Inhibitors; D013449:Sulfonamides; C077313:T 614; C045139:leucyl-leucine-methyl ester; C030365:leucine methyl ester; D010664:Phenylmethylsulfonyl Fluoride; D007930:Leucine