Phenytoin and cyclosporin A suppress the expression of MMP-1, TIMP-1, and cathepsin L, but not cathepsin B in cultured gingival fibroblasts.
BACKGROUND
Fibroblasts are known not only to synthesize and secrete extracellular matrix proteins, but also to degrade them for connective tissue remodeling. Drug-induced gingival overgrowth is characterized by a massive accumulation of extracellular matrix components in gingival connective tissues. Although some previous reports suggested that causative drugs stimulated the fibroblast proliferation, the results are not conclusive yet. In this study, we hypothesized that drug-induced gingival overgrowth could be a consequence of impaired ability of matrix degradation rather than an enhanced proliferation of gingival fibroblasts induced by these drugs.


METHODS
Normal human gingival fibroblasts were cultured with or without either 20 microg/ml of phenytoin or 200 ng/ml of cyclosporin A. Total RNA and cellular proteins were collected every day for RT-PCR analyses and for measuring lysosomal enzyme activity. In addition, an immunohistochemical study was performed to detect lysosomal enzymes in cells from enlarged gingiva of the patients with phenytoin-induced gingival overgrowth.


RESULTS
RT-PCR analyses revealed that these drugs suppressed the expression of MMP-1, TIMP-1, and cathepsin L, but not that of cathepsin B in a time-dependent manner. Then, we measured the activity of lysosomal enzymes and cathepsin B and L. The results indicated that although cathepsin B activity was not observed to be impaired, regardless of the drugs used in these cells, both total and active forms of combined activity of cathepsins B and L were suppressed in a time-dependent manner.


CONCLUSIONS
The results indicate that, besides suggested effects of these drugs on gingival fibroblasts and/or on accumulated cells in the gingival tissues, extracellular matrix-degrading ability, particularly that by cathepsin L, is also suppressed by cyclosporin A and phenytoin in gingival fibroblasts, and that lysosomal enzyme plays an important role in the pathogenesis of drug-induced gingival hyperplasia.
Yamada
H
H
Department of Periodontology and Endodontology, Okayama University Dental School, Japan.
Nishimura
F
F
Naruishi
K
K
Chou
H H
HH
Takashiba
S
S
Albright
G M
GM
Nares
S
S
Iacopino
A M
AM
Murayama
Y
Y
D000927:Anticonvulsants / Q000494:pharmacology*; D002401:Cathepsin B / Q000187:drug effects*; D056668:Cathepsin L; D002403:Cathepsins / Q000037:antagonists & inhibitors*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology*; D003546:Cysteine Endopeptidases; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D010450:Endopeptidases; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004792:Enzyme Precursors / Q000037:antagonists & inhibitors; D005109:Extracellular Matrix / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005881:Gingiva / Q000166:cytology / Q000187:drug effects*; D005885:Gingival Hyperplasia / Q000139:chemically induced / Q000201:enzymology / Q000473:pathology; D006801:Humans; D008247:Lysosomes / Q000187:drug effects / Q000201:enzymology; D061965:Matrix Metalloproteinase Inhibitors; D010672:Phenytoin / Q000494:pharmacology*; D013997:Time Factors; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000037:antagonists & inhibitors*
D000927:Anticonvulsants; D015853:Cysteine Proteinase Inhibitors; D004791:Enzyme Inhibitors; D004792:Enzyme Precursors; D061965:Matrix Metalloproteinase Inhibitors; D019715:Tissue Inhibitor of Metalloproteinase-1; D010672:Phenytoin; D016572:Cyclosporine; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; C534281:CTSL protein, human; D056668:Cathepsin L