Gambogic acid triggers DNA damage signaling that induces p53/p21Waf1/CIP1 activation through the ATR-Chk1 pathway
Gambogic acid triggers DNA damage signaling that induces p53/p21Waf1/CIP1 activation through the ATR-Chk1 pathway
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DOI：
10.1016/j.canlet.2010.03.016
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发表时间：
2010-10-01
期刊：
影响因子：
9.7
通讯作者：
Guo, Qing-Long
中科院分区：
文献类型：
--
作者：
Rong, Jing-Jing;Hu, Rong;Guo, Qing-Long
藤黄酸（GA）已被广泛研究，在体内和体外显示出有效的抗肿瘤作用。我们已经证实，GA通过下调多种癌细胞系中MDM 2的表达来稳定和激活p53。然而，GA诱导的p53激活可以部分逆转咖啡因，PI 3 k抑制剂。因此，GA是否诱导p53的翻译后修饰和随后的p53激活的问题;如果是这种情况，提出了上游信号通路是负责的。在这里，p53激活和其翻译后修饰之间的关系进行了研究，在人类癌细胞系HepG 2和A549响应GA或阿霉素治疗。GA以浓度或时间依赖性方式诱导p53在位点Ser 15和Ser 20的磷酸化，这是DNA损伤的直接结果，因为检测到γ-HA 2X灶和“彗星”DNA片段。GA通过激活ATM和Rad 3相关通路诱导p53磷酸化，并且GA诱导的Chk 1磷酸化也参与其中。在用GA处理后，AIR活化明显与p53磷酸化以及其靶基因p21（Waf/CIP 1）的活化相关。此外，我们发现当细胞与咖啡因预孵育时，GA诱导的Cdk 1在Thr 161处的去磷酸化被废除，随后是G2/M期阻滞的显著破坏。有趣的是，对咖啡因的敏感性也增强了GA的细胞毒性。综上所述，这些数据表明，在GA处理期间，ATR-Chk 1介导的DNA损伤应答在p53/p21（Waf/CIP 1）激活和下游G2/M停滞中起重要作用。(C)2010爱思唯尔爱尔兰有限公司版权所有。
Gambogic acid (GA) has been wildly studied to show potent anti-tumor effects in vivo and in vitro. We have confirmed that GA stabilized and activated p53 through down-regulating the expression of MDM2 in variety of cancer cell lines. However, GA-induced p53 activation could be partially reversed by caffeine, a PI3k inhibitor. Therefore, questions of whether GA induces post-translational modifications of p53 and subsequent activation of p53; and if that is the case, which upstream signaling pathway(s) is (are) responsible for that are proposed. Here, the relationship between p53 activation and its post-translational modifications was investigated in the human cancer cell lines HepG2 and A549 in response to GA or adriamycin treatment. GA induces p53 phosphorylation at sites Ser15 and Ser20 in a concentration- or time-dependent way, which was a direct result of DNA damage, as gamma-HA2X foci and 'comet' DNA fragments were detected. GA induces p53 phosphorylation through activation of an ATM- and Rad3-related pathway, and GA-induced phosphorylation of Chk1 is also involved. Upon treatment with GA, AIR activation is clearly associated with p53 phosphorylation, as well as activation of its target gene p21(Waf/CIP1). Furthermore, we found the dephosphorylation of Cdk1 at Thr161 induced by GA was abrogated, followed by a remarkable disruption of G2/M arrest when the cells were pre-incubated with caffeine. Interestingly, the sensitivity to caffeine enhanced the cytotoxicity of GA as well. Taken together, these data showed an important role of the DNA damage response mediated by ATR-Chk1 in p53/p21(Waf/CIP1) activation and downstream G2/M arrest during GA treatment. (C) 2010 Elsevier Ireland Ltd. All rights reserved.