Laboratory of Functional Genomics, SAIC-Frederick Inc., NCI-Frederick, 1050 Boyles Street, Frederick, MD 21702, USA.
J Exp Clin Cancer Res. 2010 Jul 9;29(1):91. doi: 10.1186/1756-9966-29-91.
Preclinical toxicity of adaphostin has been related to oxidative stress. This study investigated the regulatory mechanism underlying adaphostin induction of heme oxygenase 1 (HMOX1) which plays a significant role in modulation of drug-induced toxicity in the non-small cell lung cancer cell line model, NCI-H522.
The transcriptional response of NCI-H522 to adaphostin prominently involved oxidative stress genes, particularly HMOX1. Reactive oxygen species (ROS) involvement was additionally established by generation of ROS prior to modulation of adaphostin-toxicity with antioxidants. To identify up-stream regulatory elements of HMOX1, immunofluorescence was used to evaluate nuclear translocation of the transcription factor, NF-E2-related factor 2 (Nrf2), in the presence of adaphostin. The PI3-kinase inhibitor, wortmannin, was employed as a pharmacological inhibitor of this process.
Generation of ROS provided a substantial foundation for the sensitivity of NCI-H522 to adaphostin. However, in contrast to leukemia cell lines, transcriptional response to oxidative stress was associated with induction of HMOX1, which was dependent on nuclear translocation of the transcription factor, Nrf2. Pretreatment of cells with wortmannin inhibited translocation of Nrf2 and induction of HMOX1. Wortmannin pretreatment was also able to diminish adaphostin induction of HMOX1, and as a consequence, enhance the toxicity of adaphostin to NCI-H522.
Adaphostin-induced oxidative stress in NCI-H522 was mediated through nuclear translocation of Nrf2 leading to upregulation of HMOX1. Inhibition of Nrf2 translocation by wortmannin inhibited this cytoprotective response, and enhanced the toxicity of adaphostin, suggesting that inhibitors of the PI3K pathway, such as wortmannin, might augment the antiproliferative effects of adaphostin in solid tumors that depend on the Nrf2/ARE pathway for protection against oxidative stress.
阿帕司他的临床前毒性与氧化应激有关。本研究探讨了阿帕司他诱导血红素加氧酶 1（HMOX1）的调节机制，血红素加氧酶 1 在非小细胞肺癌细胞系模型 NCI-H522 中对药物诱导的毒性有重要的调节作用。
NCI-H522 对阿帕司他的转录反应主要涉及氧化应激基因，特别是 HMOX1。通过在抗氧化剂调节阿帕司他毒性之前产生活性氧（ROS），进一步确立 ROS 的参与。为了鉴定 HMOX1 的上游调节元件，在存在阿帕司他的情况下，使用免疫荧光评估转录因子 NF-E2 相关因子 2（Nrf2）的核转位。使用 PI3-激酶抑制剂wortmannin 作为该过程的药理学抑制剂。
ROS 的产生为 NCI-H522 对阿帕司他的敏感性提供了重要基础。然而，与白血病细胞系不同，对氧化应激的转录反应与 HMOX1 的诱导有关，这依赖于转录因子 Nrf2 的核转位。细胞用 wortmannin 预处理可抑制 Nrf2 的转位和 HMOX1 的诱导。wortmannin 预处理还能够减弱阿帕司他诱导的 HMOX1，从而增强阿帕司他对 NCI-H522 的毒性。
阿帕司他在 NCI-H522 中诱导的氧化应激是通过 Nrf2 的核转位介导的，导致 HMOX1 的上调。wortmannin 抑制 Nrf2 转位抑制了这种细胞保护反应，并增强了阿帕司他的毒性，这表明 PI3K 通路的抑制剂，如 wortmannin，可能增强阿帕司他在依赖 Nrf2/ARE 通路来抵抗氧化应激的实体肿瘤中的抗增殖作用。
