Lopez-Lopez R, Langeveld C H, Pizao P E, van Rijswijk R E, Wagstaff J, Pinedo H M, Peters G J
Department of Medical Oncology, Free University Hospital, Amsterdam, The Netherlands.
Anticancer Drug Des. 1994 Aug;9(4):279-90.
The trypanocidal drug, suramin, has been shown to possess antitumour activity, both in vitro and in vivo. Its mechanism of action, however, remains unclear although an effect on signal transduction has been proposed. We therefore studied the in vitro effect of suramin on protein kinase C (PKC), on adenylate cyclase and on the intracellular calcium concentrations [Ca2+]i in human cancer cell lines. Ca(2+)- and phospholipid-dependent PKC was isolated from a normal rat spleen, and compared with that of the human cancer cell lines MCF-7 (breast cancer) and PC3 (prostate cancer). PKC was inhibited by 50% at 55, 40 and 27 microM suramin in the three PKC sources, respectively, while 300 microM of suramin gave 97, 95 and 99% inhibition. With 50 nM staurosporine, a known PKC inhibitor, we observed 80, 99 and 96% inhibition in these three different sources of PKC. Six day exposure of these cell lines to suramin, causing 50% growth inhibition, decreased the Ca(2+)- and phospholipid-dependent PKC activity in MCF-7 cells to 52% of the control and in PC3 cells to 48% at equitoxic concentrations (45 and 150 microM suramin, respectively). These concentrations of suramin slightly increased (approximately 2-fold) the adenylate cyclase activity in MCF-7 cells, but not in PC3 cells. In MCF-7 and PC3 cells, we measured the [Ca2+]i using Fura-2 fluorescence and observed a decrease in MCF-7 cells from 126 to 99 nM when the cells were exposed for 6 days to 45 microM suramin. In PC3 cells, [C2+]i decreased from 131 to 117 nM after exposure to 150 microM suramin. In conclusion, suramin inhibited the Ca(2+)- and phospholipid-dependent PKC activity in both cell lines in a dose-dependent manner. Only in the more sensitive MCF-7 cell line was a significant effect of suramin on intracellular Ca2+ and adenylate cyclase observed, indicating that one of the mechanisms of action of suramin could be mediated by perturbations of intracellular signalling pathways.
杀锥虫药苏拉明已被证明在体外和体内均具有抗肿瘤活性。然而，尽管有人提出它对信号转导有影响，但其作用机制仍不清楚。因此，我们研究了苏拉明在体外对人癌细胞系中蛋白激酶C（PKC）、腺苷酸环化酶和细胞内钙浓度[Ca2+]i的影响。从正常大鼠脾脏中分离出钙和磷脂依赖性PKC，并与人类癌细胞系MCF-7（乳腺癌）和PC3（前列腺癌）的PKC进行比较。在三种PKC来源中，苏拉明浓度分别为55、40和27微摩尔时，PKC活性分别被抑制50%，而300微摩尔的苏拉明则产生97%、95%和99%的抑制作用。使用已知的PKC抑制剂50纳摩尔的星形孢菌素，我们在这三种不同来源的PKC中观察到80%、99%和96%的抑制作用。将这些细胞系暴露于苏拉明6天，导致50%的生长抑制，在等效毒性浓度（分别为苏拉明45和150微摩尔）下，MCF-7细胞中钙和磷脂依赖性PKC活性降至对照的52%，PC3细胞中降至48%。这些浓度的苏拉明使MCF-7细胞中的腺苷酸环化酶活性略有增加（约2倍），但对PC3细胞没有影响。在MCF-7和PC3细胞中，我们使用Fura-2荧光测量[Ca2+]i，当细胞暴露于45微摩尔苏拉明6天时，观察到MCF-7细胞中的[Ca2+]i从126纳摩尔降至99纳摩尔。在PC3细胞中，暴露于150微摩尔苏拉明后，[Ca2+]i从131纳摩尔降至117纳摩尔。总之，苏拉明以剂量依赖性方式抑制了两种细胞系中钙和磷脂依赖性PKC活性。仅在更敏感的MCF-7细胞系中观察到苏拉明对细胞内Ca2+和腺苷酸环化酶有显著影响，这表明苏拉明的作用机制之一可能是通过干扰细胞内信号通路介导的。
