Inserm, U920, Talence, F-33400, France.
BMC Med. 2010 Mar 24;8:19. doi: 10.1186/1741-7015-8-19.
Amifostine (WR-2721, delivered as Ethyol) is a phosphorylated aminothiol compound clinically used in addition to cis-platinum to reduce the toxic side effects of therapeutic treatment on normal cells without reducing their efficacy on tumour cells. Its mechanism of action is attributed to the free radical scavenging properties of its active dephosphorylated metabolite WR-1065. However, amifostine has also been described as a potent hypoxia-mimetic compound and as a strong p53 inducer; both effects are known to potently modulate vascular endothelial growth factor (VEGF-A) expression. The angiogenic properties of this drug have not been clearly defined.
Cancer cell lines and endothelial cells were used in culture and treated with Amifostine in order to study (i) the expression of angiogenesis related genes and proteins and (ii) the effects of the drug on VEGF-A induced in vitro angiogenesis.
We demonstrated that the treatment of several human cancer cell lines with therapeutical doses of WR-1065 led to a strong induction of different VEGF-A mRNA isoforms independently of HIF-1alpha. VEGF-A induction by WR-1065 depends on the activation of the eIF2alpha/ATF4 pathway. This up-regulation of VEGF-A mRNA was accompanied by an increased secretion of VEGF-A proteins fully active in stimulating vascular endothelial cells (EC). Nevertheless, direct treatment of EC with amifostine impaired their ability to respond to exogenous VEGF-A, an effect that correlated to the down-regulation of VEGFR-2 expression, to the reduction in cell surface binding of VEGF-A and to the decreased phosphorylation of the downstream p42/44 kinases.
Taken together, our results indicate that amifostine treatment modulates tumour angiogenesis by two apparently opposite mechanisms - the increased VEGF-A expression by tumour cells and the inhibition of EC capacity to respond to VEGF-A stimulation.
氨磷汀（WR-2721，以依替膦酸二钠的形式提供）是一种磷酸化的氨基硫醇化合物，临床上与顺铂联合使用，以减少治疗对正常细胞的毒副作用，而不降低其对肿瘤细胞的疗效。其作用机制归因于其活性去磷酸化代谢物 WR-1065 的自由基清除特性。然而，氨磷汀也被描述为一种有效的模拟缺氧化合物和一种强 p53 诱导剂；这两种作用都被认为能强烈调节血管内皮生长因子（VEGF-A）的表达。该药物的血管生成特性尚未明确界定。
在培养物中使用癌细胞系和内皮细胞来研究（i）与血管生成相关的基因和蛋白质的表达，以及（ii）该药物对体外诱导的 VEGF-A 血管生成的影响。
我们证明，用治疗剂量的 WR-1065 处理几种人癌细胞系会导致不同的 VEGF-A mRNA 异构体的强烈诱导，而与 HIF-1alpha 无关。WR-1065 诱导的 VEGF-A 依赖于 eIF2alpha/ATF4 通路的激活。这种 VEGF-A mRNA 的上调伴随着 VEGF-A 蛋白的大量分泌，这些蛋白在刺激血管内皮细胞（EC）方面完全有效。然而，直接用氨磷汀处理 EC 会损害它们对外源性 VEGF-A 的反应能力，这种效应与 VEGFR-2 表达的下调、VEGF-A 与细胞表面的结合减少以及下游 p42/44 激酶的磷酸化减少有关。
综上所述，我们的结果表明，氨磷汀治疗通过两种明显相反的机制调节肿瘤血管生成 - 肿瘤细胞增加 VEGF-A 的表达和抑制 EC 对 VEGF-A 刺激的反应能力。
