PARTIAL CHARACTERIZATION OF NOVEL SERINE PROTEINASE-INHIBITORS FROM HUMAN UMBILICAL VEIN ENDOTHELIAL-CELLS

Serine proteinase inhibitors play major roles in physiological and pat hophysiological processes such as angiogenesis, intravascular fibrinol ysis, wound healing, and tumor invasion, and metastasis. Here, we repo rt that human umbilical vein endothelial cells (HUVEC) synthesize thre e inhibitors (33,000, 31,000, and 27,000 Ha) which inhibit degradation of gelatin or casein by trypsin, elastase, plasmin, and alpha-chymotr ypsin, The 33- and 31-kDa inhibitors were constitutively found in the cell lysate and extracellular matrix, but not in the conditioned mediu m of HUVEC, Following treatment with phorbol 12-myristate-13-acetate ( PMA), all the three inhibitors were expressed in the CM and increased activity was found in cell lysates and extracellular matrix, The inhib itors were not detected in PMA-treated cells in the presence of cycloh eximide or actinomycin D, The inhibitors specifically bound to trypsin and were recovered from trypsin affinity column as smaller-sized inhi bitors without loss of antitrypsin activity, Polyclonal antibodies to inter-alpha-trypsin inhibitor did not cross-react with the 33-, 31-, a nd 27-kDa inhibitors, These results suggest that HUVEC synthesize and secrete novel 33-, 31-, and 27-kDa serine proteinase inhibitors. (C) 1 995 Academic Press, Inc.