Wang Y, Dang J, Liang X, Doe W F
Division of Clinical Sciences, John Curtin School of Medical Research, Australian National University, Canberra.
Clin Exp Metastasis. 1995 May;13(3):196-202. doi: 10.1007/BF00132208.
Activity of receptor-bound urokinase plasminogen activator (uPA) on the surface of colon cancer cells appears to be a function of the number of uPA receptors. The regulation of uPA therefore may determine the invasive phenotype. The effects of amiloride on the modulation of uPA mRNA and protein induced by phorbol ester (PMA) and cycloheximide (CHX) were studied in four colon cancer cell lines, HCT116, KM12SM, LIM1215 and LS123. Northern blot analyses showed that PMA induced uPA mRNA that peaked at 2-48 h in HCT116 cells. In all colon cancer cell lines tested, the expression of uPA mRNA by PMA was super-induced after the addition of the protein synthesis inhibitor CHX, suggesting that stimulation of uPA gene expression does not require de novo protein synthesis. uPA mRNA was also induced by CHX alone, indicating that there may be a labile protein which inhibits uPA mRNA processing. Amiloride profoundly inhibited uPA mRNA production at concentrations between 0.1-1 mM in the presence or absence of PMA or CHX. uPA protein levels on the colon cancer cell surface reflected PMA induction and amiloride inhibition of uPA mRNA levels. Transcriptional elongation experiments using isolated nuclei indicated that while the induction effects of PMA or CHX on uPA gene expression were mediated at the post-transcriptional level, amiloride acted at both transcription and post-transcription levels. The inhibitory effects of amiloride on uPA gene expression reported in this paper may offer the prospect of developing new therapeutic approaches to the prevention of invasion and metastasis by adenocarcinomas.
结肠癌细胞表面受体结合型尿激酶型纤溶酶原激活剂（uPA）的活性似乎是uPA受体数量的函数。因此，uPA的调节可能决定侵袭表型。在四种结肠癌细胞系HCT116、KM12SM、LIM1215和LS123中研究了氨氯地平对佛波酯（PMA）和环己酰亚胺（CHX）诱导的uPA mRNA和蛋白调节的影响。Northern印迹分析表明，PMA诱导HCT116细胞中的uPA mRNA在2 - 48小时达到峰值。在所有测试的结肠癌细胞系中，添加蛋白质合成抑制剂CHX后，PMA对uPA mRNA的表达产生超诱导作用，这表明uPA基因表达的刺激不需要从头合成蛋白质。单独使用CHX也可诱导uPA mRNA，这表明可能存在一种不稳定的蛋白质抑制uPA mRNA的加工。在存在或不存在PMA或CHX的情况下，氨氯地平在0.1 - 1 mM的浓度下可显著抑制uPA mRNA的产生。结肠癌细胞表面的uPA蛋白水平反映了PMA对uPA mRNA水平的诱导和氨氯地平的抑制作用。使用分离细胞核的转录延伸实验表明，虽然PMA或CHX对uPA基因表达的诱导作用在转录后水平介导，但氨氯地平在转录和转录后水平均起作用。本文报道的氨氯地平对uPA基因表达的抑制作用可能为开发预防腺癌侵袭和转移的新治疗方法提供前景。
