The molecular mechanisms of
jaw cyst expansion probably involve interactions of
matrix metalloproteinases (
MMPs) and the tissue inhibitors of
MMPs (TIMPs). In this study, molecular species of
gelatinases present in neutral
salt extracts of
cyst walls and cyst fluids were characterized by functional activity measurements (type I
gelatin and
alpha-casein zymography) and immunologically (Western-blotting). The effects of various
protein thiol-group or
cysteine-switch reactants involved in the activation of
collagenases were studied on
cyst gelatinases and a
gelatinases purified from human gingival fibroblasts (72 kD
MMP-2), gingival keratinocytes (92 kD
MMP-9) and polymorphonuclear neutrophilic leukocytes (92 kD
MMP-9). Western-blotting revealed the presence of both 92 kD (MMP-9) and 72 kD (MMP-2)
gelatinases in
cyst wall extracts and cyst fluids. Western-blot studies further suggested that
jaw cyst gelatinases were only in part complexed with and thus inhibited by
TIMP-1 or
TIMP-2, suggesting that both MMP-9 and MMP-2 may participate in
cyst expansion. MMP-2 was also partially fragmented to a 68 kD form and additional lower molecular weight
proteinases (< 60 kD) were detected by
alpha-casein zymography and by Western-blotting, suggesting proteolytic fragmentation. MMP-9 was at least partially activated by all
protein-
thiol group reactants and rather resistant to oxidative inhibition by
hypochlorite (NaOCl); in contrast, MMP-2 was activated by APMA but not at all by
gold thioglucose (GTG) and was clearly inactivated by
hypochlorite (NaOCl).(ABSTRACT TRUNCATED AT 250 WORDS)