A novel mechanism of action of chemically modified tetracyclines: inhibition of COX-2-mediated prostaglandin E2 production.
Tetracyclines (doxycycline and minocycline) inhibit inducible NO synthase expression and augment cyclooxygenase (COX)-2 expression and PGE2 production. In contrast, chemically modified tetracyclines (CMTs), such as CMT-3 and -8 (but not CMT-1, -2, and -5), that lack antimicrobial activity, inhibit both NO and PGE2 production in LPS-stimulated murine macrophages, bovine chondrocytes, and human osteoarthritis-affected cartilage, which spontaneously produces NO and PGE2 in ex vivo conditions. Furthermore, CMT-3 augments COX-2 protein expression but inhibits net PGE2 accumulation. This coincides with the ability of CMT-3 and -8 to inhibit COX-2 enzyme activity in vitro. The action of CMTs is distinct from that observed with tetracyclines because 1) CMT-3-mediated inhibition of PGE2 production coincides with modification of COX-2 protein, which is distinct from the nonglycosylated COX-2 protein generated in the presence of tunicamycin, as observed by Western blot analysis and 2) CMT-3 and -8 have no significant effect on COX-2 mRNA accumulation. In contrast, CMT-3 and -8 do not inhibit COX-1 expression in A549 human epithelial cells at the level of protein and mRNA accumulation or modification of COX-1 protein. CMT-3 and -8 inhibit the sp. act. of COX-2 (but not COX-1) in cell-free extracts. These results demonstrate differential action of CMT-3 (Metastat) on COX-1 and -2 expression, which is distinct from other tetracyclines.
Patel
R N
RN
Department of Rheumatology, Hospital for Joint Diseases, New York 10003, USA.
Attur
M G
MG
Dave
M N
MN
Patel
I V
IV
Stuchin
S A
SA
Abramson
S B
SB
Amin
A R
AR
D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D002460:Cell Line; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D015232:Dinoprostone / Q000037:antagonists & inhibitors* / Q000096:biosynthesis* / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D006031:Glycosylation / Q000187:drug effects; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D008565:Membrane Proteins; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism / Q000502:physiology; D009924:Organ Culture Techniques; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000187:drug effects; D013754:Tetracyclines / Q000737:chemistry / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014415:Tunicamycin / Q000494:pharmacology
D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D013754:Tetracyclines; C117155:tetracycline CMT-3; C117153:tetracycline CMT-8; D014415:Tunicamycin; D009569:Nitric Oxide; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone