title: Reactive oxygen species activate and tetracyclines inhibit rat osteoblast collagenase.
abstract: Recent studies have demonstrated that tetracyclines (TCs) scavenge reactive oxygen species (ROS). Hypochlorous acid (HOCl), an ROS produced by neutrophils, has been shown to activate neutrophil procollagenase. The objective of the present study was to determine whether (1) HOCl also activated osteoblast procollagenase and (2) TCs inhibited this enzyme in the presence of HOCl. HOCl (5 microM) activated the proenzyme approximately sixfold (P < 0.01) from the medium of PTH-treated UMR-106-01 osteoblastic osteosarcoma cells as determined by functional collagenase assay (3H-methyl-labeled collagen substrate). Doxycycline (50-400 microM) and chemically modified tetracycline, CMT-1 (100-400 microM), significantly inhibited collagenase activity 50-90% and 40-80%, respectively, in the presence of 5 microM HOCl. Concentrations of 6-25 microM doxycycline and 10-50 microM CMT-1 had no significant effect. Furthermore, an excess concentration of cation (50 mM CaCl2 or 50 microM ZnCl2) added to the incubation mixtures containing either doxycycline or CMT-1 did not restore collagenase activity, as demonstrated by SDS-PAGE-fluorography. These data suggested that TCs reduced available HOCl and thus prevented the hypochlorous acid conversion of the osteoblast proenzyme to active collagenase. TCs may have therapeutic potential in the treatment of periodontitis and other diseases by several mechanisms that inhibit pathologic collagen breakdown.
authors.affiliation: School of Dental Medicine, Department of Oral Biology and Pathology, State University of New York at Stony Brook.
authors.forename: N S
authors.initials: NS
authors.lastname: Ramamurthy
authors.forename: A T
authors.initials: AT
authors.lastname: Vernillo
authors.forename: R A
authors.initials: RA
authors.lastname: Greenwald
authors.forename: H M
authors.initials: HM
authors.lastname: Lee
authors.forename: T
authors.initials: T
authors.lastname: Sorsa
authors.forename: L M
authors.initials: LM
authors.lastname: Golub
authors.forename: B R
authors.initials: BR
authors.lastname: Rifkin
mesh_terms: D000818:Animals; D017364:Collagenases / Q000378:metabolism*; D004318:Doxycycline / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D004792:Enzyme Precursors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006997:Hypochlorous Acid / Q000494:pharmacology*; D061965:Matrix Metalloproteinase Inhibitors; D010006:Osteoblasts / Q000187:drug effects / Q000201:enzymology*; D012516:Osteosarcoma / Q000473:pathology; D051381:Rats; D017382:Reactive Oxygen Species / Q000494:pharmacology*; D013754:Tetracyclines / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D004792:Enzyme Precursors; D061965:Matrix Metalloproteinase Inhibitors; D017382:Reactive Oxygen Species; D013754:Tetracyclines; D006997:Hypochlorous Acid; D017364:Collagenases; C022440:procollagenase; D004318:Doxycycline