Shintani S, Zhang T, Aslam A, Sebastian K, Yoshimura T, Hamakawa H
Department of Oral and Maxillofacial Surgery, Showa University school of Dentistry, Tokyo 145-8515, Japan.
Int J Oncol. 2006 Nov;29(5):1111-7. doi: 10.3892/ijo.29.5.1111.
Development of new molecular target therapeutic agents is expected to improve clinical outcome, ideally with efficacy in both single and combined treatment modalities. Because of the potential for affecting multiple signaling pathways, inhibition of the molecular chaperone heat shock protein 90 (Hsp90) may provide a strategy for enhancing tumor cell radiation sensitivity. Therefore, we have investigated the effects of Hsp90 inhibitor 17-Allylamino-17-demethoxygeldanamycin (17-AAG) on radiation sensitivity of human tumor cells in vitro. We evaluated the effects of 17-AAG using oral squamous cell carcinoma (OSCC) cell lines (HSC2, HSC3 and HSC4), including two types of SAS cells with a wild-type (SAS/neo), or a mutated p53 status (SAS/Trp248). Apoptosis and clonogenic survival were examined after exposure of the cells to radiation. For mechanistic insight, we analyzed cell cycle, several signaling factors and molecular markers including Akt, Raf-1, p38 MAPK, Cdc25B, Cdc25C, Cdk2 and p21. Treatment of OSCC cell lines with 17-AAG resulted in cytotoxicity and, when combined with radiation, enhanced the radiation response. However, the responses depended on p53 status. 17-AAG enhanced the radiation sensitivity significantly and induced apoptosis in the SAS/neo cell which has a wild-type p53. But the radiation sensitizing effect of 17-AAG was limited in the SAS/Trp248 cell which has a mutated p53. We also measured the total levels of several prosurvival and cell cycle signaling proteins. Akt, Raf-1 and Cdc25C expression were down-regulated in 17-AAG-treated cells. These data indicate that 17-AAG inhibits the proliferation and enhances the radiation sensitivity of human OSCC cells in various levels. However, enhancement of radiation sensitivity by the Hsp90 inhibitor depended on p53 status. Therefore, Hsp90 therapy combined with radiation might synergize with conventional therapies in patients with wild-type p53.
开发新的分子靶向治疗药物有望改善临床疗效，理想情况下在单一和联合治疗模式中均有效。由于分子伴侣热休克蛋白90（Hsp90）有可能影响多个信号通路，抑制Hsp90可能为增强肿瘤细胞辐射敏感性提供一种策略。因此，我们研究了Hsp90抑制剂17-烯丙胺基-17-去甲氧基格尔德霉素（17-AAG）对人肿瘤细胞体外辐射敏感性的影响。我们使用口腔鳞状细胞癌（OSCC）细胞系（HSC2、HSC3和HSC4）评估了17-AAG的作用，其中包括两种具有野生型（SAS/neo）或突变型p53状态（SAS/Trp248）的SAS细胞。在细胞接受辐射后检测细胞凋亡和克隆形成存活率。为了深入了解作用机制，我们分析了细胞周期、包括Akt、Raf-1、p38 MAPK、Cdc25B、Cdc25C、Cdk2和p21在内的几种信号因子和分子标志物。用17-AAG处理OSCC细胞系会导致细胞毒性，并且与辐射联合使用时会增强辐射反应。然而，反应取决于p53状态。17-AAG显著增强了具有野生型p53的SAS/neo细胞的辐射敏感性并诱导其凋亡。但17-AAG在具有突变型p53的SAS/Trp248细胞中的辐射增敏作用有限。我们还测量了几种促存活和细胞周期信号蛋白的总水平。在17-AAG处理的细胞中，Akt、Raf-1和Cdc25C的表达下调。这些数据表明17-AAG在不同水平上抑制人OSCC细胞的增殖并增强其辐射敏感性。然而，Hsp90抑制剂对辐射敏感性的增强取决于p53状态。因此，Hsp90疗法与辐射联合使用可能会在野生型p53患者中与传统疗法产生协同作用。
