Lipid A radiosensitizes hypoxic EMT-6 tumor cells:: Role of the NF-κB signaling pathway
Lipid A radiosensitizes hypoxic EMT-6 tumor cells:: Role of the NF-κB signaling pathway
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DOI：
10.1016/s0360-3016(03)00662-x
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发表时间：
2003-11-01
影响因子：
7
通讯作者：
Storme, GA
中科院分区：
文献类型：
--
作者：
De Ridder, M;Verovski, VN;Storme, GA
目的：脂质 A 在实验肿瘤模型和晚期癌症患者中都显示出有希望的免疫刺激作用。本研究探讨脂质 A 是否可以通过核因子 kappaB (NF-kappaB) 信号激活诱导型一氧化氮合酶 (iNOS) 或环氧合酶 2 (COX-2) 来直接调节肿瘤细胞的放射反应。方法和材料：将缺氧的 EMT-6 肿瘤细胞暴露于脂质 A，并通过蛋白质印迹和酶法分析 COX-2 和 iNOS 的水平。 EMT-6 细胞的缺氧放射反应通过克隆形成存活率来评估。通过 p65 亚基的免疫染色和荧光素酶报告基因测定来检查 NF-kappaB 的激活。结果：Lipid A 剂量依赖性地增加 iNOS 的表达和活性，在血浆可达到浓度 3-30 mug/mL 时效果最大。 COX-2 介导的前列腺素 E2 的产生持续较高，并被脂质 A 进一步上调。缺氧 EMT-6 细胞的放射敏感性增加至 2.5 倍，并被 iNOS 抑制剂氨基胍抵消，但不能被 COX-2 抑制剂 NS-398 抵消。放射增敏机制与 NF-kappaB 信号传导有关，因为苯胂氧化物的抑制会损害 iNOS 激活和放射反应。结论：脂质 A 在血浆相关浓度下是一种有效的缺氧细胞放射增敏剂，这为进一步研究中将脂质 A 与放射治疗相结合提供了理论依据。 (C) 2003 爱思唯尔公司。
Purpose: Lipid A has shown promising immunostimulatory effects in both experimental tumor models and advanced stage cancer patients. This study examines whether lipid A may directly modulate the radioresponse of tumor cells by activating inducible nitric oxide synthase (iNOS) or cyclooxygenase-2 (COX-2) through nuclear factor-kappaB (NF-kappaB) signaling.Methods and Materials: Hypoxic EMT-6 tumor cells were exposed to lipid A and analyzed for the level of COX-2 and iNOS by-Western blotting and enzymatic assays. The hypoxic radioresponse of EMT-6 cells was estimated by clonogenic survival. The activation of NF-kappaB was examined by immunostaining of its p65 subunit and by luciferase reporter gene assay.Results: Lipid A dose-dependently increased the expression and activity of iNOS with a maximal effect at plasma achievable concentrations of 3-30 mug/mL. The COX-2 mediated production of prostaglandin E2 was constitutively high and further upregulated by lipid A. The radiosensitivity of hypoxic EMT-6 cells was increased up to 2.5 times and counteracted by the iNOS inhibitor aminoguanidine but not by the COX-2 inhibitor NS-398. The mechanism of radiosensitization was linked to NF-kappaB signaling, because its inhibition by phenylarsine oxide impaired both iNOS activation and radioresponse.Conclusions: Lipid A is an efficient hypoxic cell radiosensitizer at plasma relevant concentrations, which provides a rationale to combine lipid A with radiotherapy in further studies. (C) 2003 Elsevier Inc.