Keppler D, Waridel P, Abrahamson M, Bachmann D, Berdoz J, Sordat B
Experimental Pathology Unit, Swiss Institute for Experimental Cancer Research, Lausanne.
Biochim Biophys Acta. 1994 May 25;1226(2):117-25. doi: 10.1016/0925-4439(94)90018-3.
The lysosomal cysteine proteinase cathepsin B is shown to be secreted by ten human colon carcinoma cell lines and to accumulate in culture media as a latent enzyme. The cell lines also secrete a physiological inhibitor of cathepsin B, cystatin C. A significant correlation was found between secretion of the latent enzyme and the inhibitor (r = 0.755, P < 0.01). The aim of the present study was to modulate the respective secretion of the two antagonists to test whether or not latency of cathepsin B was due to the concomitant secretion of the inhibitor. SW480 colon carcinoma cells were treated with the acidotropic agent ammonium chloride, phorbol 12-myristate 13-acetate, and the inflammatory cytokines TGF-beta, TNF-alpha, and IL-1 beta. Ammonium chloride significantly increased latent cathepsin B levels without affecting the constitutive secretion of cystatin C. Phorbol 12-myristate 13-acetate induced a 4- to 5-fold increase in secreted latent cathepsin B, but did not alter significantly the accumulation of cystatin C in media. The cytokines, TGF-beta, TNF-alpha, and IL-1 beta, had no major effect on the expression of these two antagonists. Latent cathepsin B released from human carcinoma cells could be efficiently activated by neutrophil elastase at neutral pH. It is concluded that latent cathepsin B is a true proenzyme rather than an enzyme-inhibitor complex. In addition, our data from neutrophil elastase activation experiments indicate that a proteolytic system for activation of the tumor cell-secreted latent enzyme may exist in vivo.
溶酶体半胱氨酸蛋白酶组织蛋白酶B被证明可由十种人类结肠癌细胞系分泌，并以潜伏酶的形式在培养基中积累。这些细胞系还分泌组织蛋白酶B的一种生理性抑制剂——胱抑素C。在潜伏酶和抑制剂的分泌之间发现了显著相关性（r = 0.755，P < 0.01）。本研究的目的是调节这两种拮抗剂各自的分泌，以测试组织蛋白酶B的潜伏性是否归因于抑制剂的伴随分泌。用亲酸剂氯化铵、佛波酯12 - 肉豆蔻酸酯13 - 乙酸酯以及炎性细胞因子转化生长因子 - β、肿瘤坏死因子 - α和白细胞介素 - 1β处理SW480结肠癌细胞。氯化铵显著提高了潜伏组织蛋白酶B的水平，而不影响胱抑素C的组成性分泌。佛波酯12 - 肉豆蔻酸酯13 - 乙酸酯使分泌的潜伏组织蛋白酶B增加了4至5倍，但未显著改变培养基中胱抑素C的积累。细胞因子转化生长因子 - β、肿瘤坏死因子 - α和白细胞介素 - 1β对这两种拮抗剂的表达没有主要影响。从中性pH下嗜中性粒细胞弹性蛋白酶可有效激活从人类癌细胞释放的潜伏组织蛋白酶B这一现象得出结论，潜伏组织蛋白酶B是一种真正的酶原而非酶 - 抑制剂复合物。此外，我们从嗜中性粒细胞弹性蛋白酶激活实验获得的数据表明，体内可能存在一个激活肿瘤细胞分泌的潜伏酶的蛋白水解系统。
