Role for different cell proteinases in cancer invasion and cytolysis.

The crucial role of non-plasminogen dependent serine proteinases is tissue invasive and cytolytic functions of Walker 256 cancer cells has been documented using a rat urinary bladder invasion and a 125I-labelled fibroblast cytolysis assay. The invasive capacity of these cancer cells was abrogated by non toxic concentrations of the serine proteinase inhibitors, diisopropylfluorophosphate and phenylmethylsulfonylfluoride, but not by metallo or cysteine proteinase inhibitors. Although tumour cell collagenase activity and plasminogen activator were demonstrated, these proteolytic enzymes were not essential in these in vitro assays. These results suggest that different categories of proteinases play specific roles in the complicated process of cancer invasion.