Neutrophil-derived serine proteinases enhance membrane type-1 matrix metalloproteinase-dependent tumor cell invasion

Background. Matrix metalloproteinase-2 degrades a variety of basement membr ane components and is essential for tumor invasion. We have previously repo rted that membrane type-1 matrix metalloproteinase (MT1-MMP) cooperates wit h neutrophil-derived serine proteinase (NDPs; elastase, cathepsin G, protea se-3) to activate matrix metalloproteinase-2. We therefore hypothesized tha t NDPs enhance tumor-cell invasion. Methods. Clones of human HT1080 fibrosarcoma cells transfected with MT1-MMP sense (HT-SE) or antisense CDNA (HT-AS) were used. These cells express eit her high (HT-SE) or extremely low levels (HT-AS) of MT1-MMP relative to non transfected HT1080 cells (HT-WT). The cells were incubated in the presence or absence of purified NDP: with or without alpha(1)-antitrypsin or the MMP inhibitor batimastat. Cell invasion was measured with the use of Boyden ch ambers with polycarbonate membranes coated with a reconstituted extracellul ar matrix. Results. Under control conditions HT-WT and HT-SE cells were 4-fold more in vasive than HT-AS cells. The addition of NDP increased HT-WT and HT-SE cell invasion 60% to 100% but had no effect on HT-AS cells, alpha(1)-antitrypsi n or batimastat did not decrease the baseline invasiveness of HT-WT and HT- SE cells; however, they abrogated the stimulatory effect of NDP. Conclusions. HT1080 cell invasion depends on MT1-MMP expression. MT1-MMP ov erexpression does not increase invasiveness by itself: NDPs increase invasi on by MT1-MMP expressing cells by activating matrix metalloproteinase-2.