Matrix metalloproteinase inhibition suppresses MMP-2 activity and activation of PANC-1 cells in vitro.

We have shown previously that the metalloproteinase inhibitor, BB-94, prolongs survival and attenuates MMP-2 activity in a murine model of pancreatic cancer. The purpose of this study was to determine the effect of BB-94 on the activity and activation of MMP-2 by PANC-1 cells in vitro. The poorly differentiated pancreatic cancer cell line PANC-1 was stimulated in vitro with the phorbol ester PMA (20 nM) and grown in the presence of increasing doses of BB-94 (0, 40, 200, and 400 ng/ml) for 24 h. Activation of MMP-2 was determined by gel zymography. In a separate experiment detailing the effects of BB-94 on MMP-2 activity, PANC cells were stimulated for 24 h with PMA and run out on four separate zymograms, each incubated in the previously noted concentrations of BB-94. Using densitometry, band intensity on all gels was determined and compared for each concentration of BB-94. The Matrigel assay was used to determine BB-94's effect on the invasive potential of PANC cells at the previously studied concentrations. The presence of MT-MMP (a putative component of MMP-2 activation) was confirmed using Western blot in each group. BB-94 inhibited the conversion of latent to active MMP-2 in a dose-dependent fashion. BB-94 also inhibited the activity of MMP-2 when run out on gel zymograms incubated with increasing concentrations of BB-94. Decreased activity and activation of MMP-2 by BB-94 were manifested by a significant reduction in the invasive potential of PANC as determined by the Matrigel assay. MT-MMP was universally present in each study group. The previously described salutary effects of MMP blockade in mice implanted with pancreatic cancer can be explained in vitro by a dose-dependent diminution of MMP-2 activity and activation in PANC cells exposed to BB-94.