Department of Biochemistry, Tokyo Medical University, Tokyo, Japan.
Int J Oncol. 2011 Oct;39(4):981-8. doi: 10.3892/ijo.2011.1072. Epub 2011 Jun 8.
In this study, 2-aminophenoxazine-3-one (Phx-3) exhibited a potent cell growth inhibitory effect with apoptotic features in a dose-dependent manner in various cancer cell lines tested. Comparison of the expression profiles of endoplasmic reticulum (ER) stress-related genes in U266 multiple myeloma cells after treatment with Phx-3 and the ER stress inducers tunicamycin (TNM) and thapsigargin (TPG) indicated that although TNM and TPG potently induced pro-apoptotic transcription factor CHOP (GADD153) within 8 h of treatment, Phx-3 induced almost no CHOP within 48 h of treatment in U266 cells. However, murine embryonic fibroblast (MEF) cells and other cancer cell lines (e.g. A549 lung cancer cells and HL-60 acute leukemia cells) exhibited up-regulation of CHOP after treatment with Phx-3. The potency of CHOP induction in response to Phx-3 appeared to be partially correlated with the cytotoxic sensitivity of Phx-3 among various cell lines tested. MEF cells derived from CHOP knockout mice were more resistant to Phx-3 than wild-type MEF cells. Since Phx-3 has been shown to induce activation of NF-κB, a transcription factor functioning as a repressor of CHOP, we further treated U266 cells with a combination of Phx-3 and NF-κB inhibitors (e.g. BAY11-7082 or parthenolide). This enhanced cytotoxicity along with up-modulation of CHOP in U266 cells. These data suggest that ER stress-mediated CHOP induction by Phx-3 is involved in the cytotoxic effect. Regulation of CHOP expression appears to be a potent therapeutic target for cancer treatment.
在这项研究中，2-氨基苯并恶嗪-3-酮（Phx-3）在各种测试的癌细胞系中表现出剂量依赖性的强效细胞生长抑制作用和凋亡特征。在 Phx-3 处理后的 U266 多发性骨髓瘤细胞中与内质网（ER）应激相关基因的表达谱比较和 ER 应激诱导剂衣霉素（TNM）和 thapsigargin（TPG）表明，虽然 TNM 和 TPG 在治疗后 8 小时内强烈诱导促凋亡转录因子 CHOP（GADD153），但 Phx-3 在 U266 细胞中治疗 48 小时内几乎不诱导 CHOP。然而，鼠胚胎成纤维细胞（MEF）细胞和其他癌细胞系（如 A549 肺癌细胞和 HL-60 急性白血病细胞）在用 Phx-3 处理后显示 CHOP 的上调。对 Phx-3 反应的 CHOP 诱导的效力似乎与在各种测试的细胞系中 Phx-3 的细胞毒性敏感性部分相关。来自 CHOP 敲除小鼠的 MEF 细胞比野生型 MEF 细胞对 Phx-3 更具抗性。由于 Phx-3 已被证明诱导 NF-κB 的激活，NF-κB 是作为 CHOP 抑制剂的转录因子，我们进一步用 Phx-3 和 NF-κB 抑制剂（如 BAY11-7082 或 parthenolide）的组合处理 U266 细胞。这增强了 U266 细胞的细胞毒性以及 CHOP 的上调。这些数据表明 Phx-3 诱导的 ER 应激介导的 CHOP 诱导参与细胞毒性作用。CHOP 表达的调节似乎是癌症治疗的有效治疗靶点。
