INHIBITION OF MATRIX METALLOPROTEINASE-9 ACTIVATION BY A SPECIFIC MONOCLONAL-ANTIBODY

Two members of the matrix metalloproteinase (MMP)1 family of enzymes a re expressed at elevated levels in highly aggressive human tumor cells and have been implicated in the catalytic functions of extracellular proteolysis. The zymogen forms of these enzymes are designated proMMP- 2 and proMMP-9, also known as 72kDa and 92kDa type IV collagenases/gel atinases, respectively. The MMP family of enzymes can be activated in vitro by a number of compounds including the organomercurial 4-aminoph enylmercuric acetate (APMA). The natural or in vivo activators of MMP- 2 and MMP-9 are at present unknown. A partially purified preparation o f MMP-9 was used to immunize mice for the isolation of monoclonal anti bodies (mAbs). Three IgG1 mAbs were identified by immunoreactivity wit h purified MMP-9 and are designated 6-6B, 7-11C, and 8-3H. These mAbs react specifically with MMP-9 by ELISA and Western blot. Additionally, these mAbs react with N-glycanase treated 92kDa protein. These mAbs w ere tested for their ability to inhibit enzyme activation in a radio-l abeled gelatin assay. The 6-6B mAb inhibited the activation of MMP-9, but had no effect on MMP-2. These mAbs are highly specific to human MM P-9 and the 6-6B mAb will be extremely useful for examining the autoly tic and catalytic activity of MMP-9 in normal and abnormal biological processes.