The urokinase‐urokinase receptor system plays a dominant role in the degradation and invasion of extracellular matrix (ECM) by tumor cells. In this system, urokinase bound to its cell receptor converts plasminogen to plasmin, a broad‐spectrum serine protease that participates in the degradation and invasion of connective tissues by tumor cells. In this study, we evaluated whether these activities of plasmin are inhibited by a newly characterized human 32 kDa recombinant serine protease inhibitor called trypsin/tissue factor pathway inhibitor‐2 (rTFPI‐2). We found that rTFPI‐2 dose‐dependently inhibited fluid‐phase plasmin as well as plasmin generated on the ECM and/or the cell surface of HT‐1080 fibrosarcoma cells. The degradation of radiolabeled matrix as well as Matrigel invasion by these tumor cells is also inhibited by rTFPI‐2 in a dose‐dependent fashion. We have reported that rTFPI‐2 is identical to 33 kDa extracellular matrix‐associated serine protease inhibitor (33 kDa MSPI), whereas the 31 and 27 kDa MSPIs are under‐glycosylated forms of the 33 kDa MSPI. We therefore evaluated the ability of MSPIs from the ECM of dermal fibroblasts to inhibit plasmin and found that the plasmin activity was effectively blocked by the MSPIs. We have also evaluated whether the HT‐1080 cells synthesize and secrete the MSPIs and found that the synthesis and secretion of the MSPIs was undetectable in these cells. Collectively, our results suggest that rTFPI‐2/33 kDa MSPI inhibits plasmin on the tumor cell and ECM surfaces as well as the degradation and invasion of matrix by HT‐1080 fibrosarcoma cells. Int. J. Cancer 76:749–756, 1998.© 1998 Wiley‐Liss, Inc.

Botulinum toxin type A may be an effective and safe nonsurgical alternative for the treatment of benign familial pemphigus in intertriginous areas such as the axillae.

Chemical tools for biological investigations of carbohydrate sulfotransferases—a class of enzymes that has been characterized only recently—have been developed by using a small‐molecule library‐screening approach. The inhibitor screen included 139 compounds comprising selected structures from purine libraries as well as commercially available protein‐kinase inhibitors and representatives from other kinase‐inhibitor families. Like kinases, carbohydrate sulfotransferases have attracted significant interest because of their roles in a variety of disease states including chronic inflammation and tumor metastasis.

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The leukocyte adhesion molecule L-selectin mediates lymphocyte homing to secondary lymphoid organs and to certain sites of inflammation. The cognate ligands for L-selectin possess the unusual sulfated tetrasaccharide epitope 6-sulfo sialyl Lewis x (Siaalpha2-->3Galbeta1-->4[Fucalpha1-->3][SO(3)-->6]GlcNAc). Sulfation of GlcNAc within sialyl Lewis x is a crucial modification for L-selectin binding, and thus, the underlying sulfotransferase may be a key modulator of lymphocyte trafficking. Four recently discovered GlcNAc-6-sulfotransferases are the first candidate contributors to the biosynthesis of 6-sulfo sLex in the context of L-selectin ligands. Here we report the in vitro activity of the four GlcNAc-6-sulfotransferases on a panel of synthetic oligosaccharide substrates that comprise structural motifs derived from sialyl Lewis x. Each enzyme preferred a terminal GlcNAc residue, and was impeded by the addition of a beta1,4-linked Gal residue (i.e., terminal LacNAc). Surprisingly, for three of the enzymes, significant activity was observed with sialylated LacNAc, and two of the enzymes were capable of detectable sulfation of GlcNAc in the context of sialyl Lewis x. On the basis of these results, we propose possible pathways for 6-sulfo sialyl Lewis x biosynthesis and suggest that sulfation may be an early committed step.