Expression of pancreatic secretory trypsin inhibitor: After surgical stress and its' significance.

胰腺分泌性胰酶抑制因子(PSTI)是由Kazal等人首先分离得到的。1948年。从那时起，PSTI一直被认为只存在于胰腺中，是一种特殊的胰酶抑制物，可以阻止胰腺和胰液中胰蛋白酶原的自我激活。在本项目中，我们证明了血清中的PSTI是一种急性时相反应物，并且随着手术应激或侵袭的反应而显著增加。上升的幅度远远大于以前已知的急性期反应物的上升幅度。各种恶性肿瘤患者的血清PSTI也升高。晚期或转移性恶性肿瘤患者血清PSTI升高的发生率和幅度要大得多。通过免疫过氧化物酶染色，我们发现超过三分之一的各种肿瘤组织中含有PSTI免疫反应细胞，人PSTI mRNA与小鼠表皮生长因子(EGF)mRNA的核苷酸序列高度同源。人PSTI刺激人成纤维细胞DNA合成。此外，我们还揭示了PSTI与各种培养细胞的特异性结合，并且PSTI的结合位置与EGF的受体不同。这些结果表明，血清中PSTI升高的生理作用与促进生长以防御组织破坏有关。

Pancreatic secretory trypsin inhibitor (PSTI) was first isolated by Kazal et al. in 1948. Since then PSTI has been thought to exist only in the pancreas and to be a specific trypsin inhibitor that prevents autoactivation of trypsinogen in the pancreas and pancreatic juice. In the present project, we demonstrated that PSTI in serum is an acute phase reactant and that it increases remarkably in response to surgical stress or invasion. The magnitude of the elevation is far greater than those of acute phase reactants previously known. Serum PSTI was also elevated in patients with various malignancies. The incidence and the magnitude of the elevation of serum PSTI were far greater in patients with advanced or metastasized malignancies. By immunoperoxidase staining, we found that more than one-third of various cancer tissues contained PSTI-immunoreactive cells.The nucleotide sequences of human PSTI mRNA and mouse epidermal growth factor (EGF) mRNA were highly homologous. Human PSTI stimulated DNA synthesis in human fibroblasts. Moreover, we revealed that PSTI bound specifically to various cultured cells, and that the binding site for PSTI was distinct from the receptor for EGF. these results suggested that the physiological role of increased PSTI in serum is related to growth stimulation for host defence against tissue destruction.