Tumor cell proteinase visualization and quantification using a fluorescent transition-state analog probe.

The fluorescent proteinase transition-state analog inhibitor, dansyl-L-argininal (DnsArgH), may be a selective probe of cysteine and serine-type proteinases in a fibrosarcoma tumor cell line (HSDM1C1). DnsArgH binds with high affinity to proteinases because of its transition-state analog properties, and on association it gives a dramatically increased fluorescent yield. The DnsArgH binding is inhibited by the serine proteinase inhibitor diisopropyl fluorophosphate and by the cysteine proteinase inhibitor p-chloromercuribenzoate. The fluorescence emission appears at its maximum steady-state yield immediately on addition of DnsArgH to the HSDM1C1 fibrosarcoma cells. The immediacy of the DnsArgH reaction supports the contention that DnsArgH binding may be to cell surface-associated proteinases. Quantification of the cell proteinase concentration, by comparison of the fluorescence yield obtained from DnsArgH interactions with bovine trypsin and papain, indicates 10(-15) to 10(-16) mol of proteinase per HSDM1C1 cell. In fluorescence microscopy, DnsArgH fluorescence appears distributed throughout the fibrosarcoma cell without association to organelles. DnsArgH fluorescence from normal fibroblast controls (IMR-90) was found to be substantially lower than in the transformed fibrosarcoma cells, supporting a hypothesis that proteinases have a role in malignancy.