Brantley-Finley Cheryl, Lyle Christopher S, Du Lihua, Goodwin Mary E, Hall Toria, Szwedo Dominika, Kaushal G P, Chambers Timothy C
Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
Biochem Pharmacol. 2003 Aug 1;66(3):459-69. doi: 10.1016/s0006-2952(03)00255-7.
Assessment of specific apoptosis and survival pathways implicated in anticancer drug action is important for understanding drug mechanisms and modes of resistance in order to improve the benefits of chemotherapy. In order to better examine the role of mitogen-activated protein kinases, including JNK and ERK, as well as the tumor suppressor p53, in the response of tumor cells to chemotherapy, we compared the effects on these pathways of three structurally and functionally distinct antitumor agents. Drug concentrations equal to 50 times the concentration required to reduce cell proliferation by 50% were used. Vinblastine, doxorubicin, or etoposide (VP-16) induced apoptotic cell death in KB-3 carcinoma cells, with similar kinetic profiles of PARP cleavage, caspase 3 activation, and mitochondrial cytochrome c release. All three drugs strongly activated JNK, but only vinblastine induced c-Jun phosphorylation and AP-1 activation. Inhibition of JNK by SP600125 protected cells from drug-induced cytotoxicity. Vinblastine caused inactivation of ERK whereas ERK was unaffected in cells exposed to doxorubicin or VP-16. Inhibition of ERK signaling by the MEK inhibitor, U0126, potentiated the cytotoxic effects of vinblastine and doxorubicin, but not that of VP-16. Vinblastine induced p53 downregulation, and chemical inhibition of p53 potentiated vinblastine-induced cell death, suggesting a protective effect of p53. In contrast, doxorubicin and VP-16 induced p53, and inhibition of p53 decreased drug-induced cell death, suggesting a pro-apoptotic role for p53. These results highlight the differential roles played by several key signal transduction pathways in the mechanisms of action of key antitumor agents, and suggest ways to specifically potentiate their effects in a context-dependent manner. In addition, the novel finding that JNK activation can occur without c-Jun phosphorylation or AP-1 activation has important implications for our understanding of JNK function.
评估参与抗癌药物作用的特定凋亡和存活途径对于理解药物机制和耐药模式以提高化疗效果至关重要。为了更好地研究丝裂原活化蛋白激酶（包括JNK和ERK）以及肿瘤抑制因子p53在肿瘤细胞对化疗反应中的作用，我们比较了三种结构和功能不同的抗肿瘤药物对这些途径的影响。使用的药物浓度相当于将细胞增殖降低50%所需浓度的50倍。长春碱、阿霉素或依托泊苷（VP - 16）在KB - 3癌细胞中诱导凋亡性细胞死亡，PARP裂解、半胱天冬酶3激活和线粒体细胞色素c释放具有相似的动力学特征。所有三种药物均强烈激活JNK，但只有长春碱诱导c - Jun磷酸化和AP - 1激活。SP600125抑制JNK可保护细胞免受药物诱导的细胞毒性。长春碱导致ERK失活，而在暴露于阿霉素或VP - 16的细胞中ERK未受影响。MEK抑制剂U0126抑制ERK信号传导可增强长春碱和阿霉素的细胞毒性作用，但对VP - 16无效。长春碱诱导p53下调，化学抑制p53可增强长春碱诱导的细胞死亡，提示p53具有保护作用。相反，阿霉素和VP - 16诱导p53，抑制p53可降低药物诱导的细胞死亡，提示p53具有促凋亡作用。这些结果突出了几种关键信号转导途径在关键抗肿瘤药物作用机制中所起的不同作用，并提出了以背景依赖方式特异性增强其作用的方法。此外，JNK激活可在无c - Jun磷酸化或AP - 1激活的情况下发生这一新发现对我们理解JNK功能具有重要意义。
