Tran-Thang C, Vouillamoz D, Kruithof E K, Sordat B
Swiss Institute for Experimental Cancer Research, Epalinges.
J Cell Physiol. 1994 Nov;161(2):285-92. doi: 10.1002/jcp.1041610213.
The plasminogen activation (PA) system of human Co115 colon carcinoma cells was investigated. Analysis at the levels of protein and mRNA of cultured cells and of histozymography of tumor xenografts in nude mice showed that Co115 cells produce only tissue type PA (t-PA) and no urokinase (u-PA). Also, mRNA for the u-PA receptor and for PA inhibitor type 2 (PAI-2), but not for PAI-1, were detected. We developed a quantitative degradation assay using glutaraldehyde-immobilized 125I-laminin to investigate the capacity of Co115 cells to degrade laminin. Laminin degradation by Co115 cells was completely inhibited by 100 micrograms/ml of polyclonal anti-t-PA IgG, by the plasmin inhibitors aprotinin (100 micrograms/ml) or epsilon-aminocaproic acid (EACA; at 0.3 M), but not by antibodies against u-PA or u-PAR nor by nonimmune IgG. Cycloheximide-treated Co115 cells were unable to degrade laminin but increased laminin degradation induced by conditioned medium of Co115 cells or recombinant t-PA. No potentiation was observed when Co115 cells and laminin were kept separated by Transwell inserts. Our results suggest that Co115 human colon carcinoma cells degrade laminin by potentiating t-PA-mediated plasminogen activation at the cell surface which requires close contact between tumor cells and laminin substrate.
对人Co115结肠癌细胞的纤溶酶原激活（PA）系统进行了研究。对培养细胞的蛋白质和mRNA水平以及裸鼠肿瘤异种移植物的组织酶谱分析表明，Co115细胞仅产生组织型PA（t-PA），不产生尿激酶（u-PA）。此外，检测到u-PA受体和2型PA抑制剂（PAI-2）的mRNA，但未检测到PAI-1的mRNA。我们开发了一种使用戊二醛固定的125I-层粘连蛋白的定量降解试验，以研究Co115细胞降解层粘连蛋白的能力。Co115细胞对层粘连蛋白的降解被100微克/毫升的多克隆抗t-PA IgG、纤溶酶抑制剂抑肽酶（100微克/毫升）或ε-氨基己酸（EACA；0.3M）完全抑制，但不被抗u-PA或u-PAR的抗体或非免疫IgG抑制。用环己酰亚胺处理的Co115细胞无法降解层粘连蛋白，但能增加Co115细胞条件培养基或重组t-PA诱导的层粘连蛋白降解。当Co115细胞和层粘连蛋白通过Transwell插入物分开时，未观察到增强作用。我们的结果表明，Co115人结肠癌细胞通过增强细胞表面t-PA介导的纤溶酶原激活来降解层粘连蛋白，这需要肿瘤细胞与层粘连蛋白底物紧密接触。
