Radiosensitization of malignant glioma cells through overexpression of dominant-negative epidermal growth factor receptor.
Radiosensitization of malignant glioma cells through overexpression of dominant-negative epidermal growth factor receptor.
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发表时间：
2001-03
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通讯作者：
Guido Lammering;Kristoffer Valerie;Peck-Sun Lin;Ross B. Mikkelsen;J. Contessa;Jeffrey Feden;J. Farnsworth;P. Dent;Rupert Schmidt-Ullrich
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作者：
Guido Lammering;Kristoffer Valerie;Peck-Sun Lin;Ross B. Mikkelsen;J. Contessa;Jeffrey Feden;J. Farnsworth;P. Dent;Rupert Schmidt-Ullrich
表皮生长因子受体（EGFR）在恶性胶质瘤的肿瘤生长控制中起重要作用。我们已经证明，辐射激活EGFR酪氨酸磷酸化（EGFR Tyr-P）和存活的人类癌细胞的增殖，加速细胞再增殖的可能机制，辐射后的主要细胞保护反应。我们现在调查的重要性，辐射诱导的EGFR激活的放射敏感性的人恶性胶质瘤细胞U-87 MG和U-373 MG。通过用含有显性阴性（DN）EGFR-CD 533（Ad-EGFR-CD 533）的腺病毒（Ad）载体以85- 90%的效率转导细胞的遗传方法抑制EGFR的功能。所得细胞被称为U-87-EGFR-CD 533和U-373-EGFR-CD 533。在2戈伊照射后，两种细胞系均表现出EGFR Tyr-P平均3倍的增加。EGFR-CD 533的表达完全抑制了辐射诱导的EGFR活化。在单次辐射暴露后的克隆形成存活测定中，相对于用AdLacZ转导的细胞或未转导的U-87 MG细胞，U-87-EGFR-CD 533细胞存活37%（D37）的辐射剂量低1.4至1.5倍。重复辐射暴露（3 x 2戈伊）放大了该效应，产生1.8-2.0的D37比率。在U-373 MG细胞的克隆形成存活研究中，EGFR-CD 533的放射增敏作用相似。此外，U-87 MG异种移植物的体内研究证实了EGFR-CD 533对肿瘤放射增敏的作用（剂量增强比，1.8）。我们的结论是，通过广告介导的EGFR-CD 533基因转移抑制EGFR功能的结果显着的放射增敏。作为潜在的机制，我们建议中断一个主要的细胞保护反应，涉及EGFR及其下游效应，如丝裂原活化蛋白激酶。该实验首次证明，通过破坏EGFR功能的恶性胶质瘤细胞的放射增敏可以通过基因治疗方法实现。
The epidermal growth factor receptor (EGFR) plays an important role in neoplastic growth control of malignant gliomas. We have demonstrated that radiation activates EGFR Tyr-phosphorylation (EGFR Tyr-P) and the proliferation of surviving human carcinoma cells, a likely mechanism of accelerated cellular repopulation, a major cytoprotective response after radiation. We now investigate the importance of radiation-induced activation of EGFR on the radiosensitivity of the human malignant glioma cells U-87 MG and U-373 MG. The function of EGFR was inhibited through a genetic approach of transducing cells with an Adenovirus (Ad) vector containing dominant-negative (DN) EGFR-CD533 (Ad-EGFR-CD533) at efficiencies of 85-90%. The resulting cells are referred to as U-87-EGFR-CD533 and U-373-EGFR-CD533. After irradiation at 2 Gy, both of the cell lines exhibited a mean 3-fold increase in EGFR Tyr-P. The expression of EGFR-CD533 completely inhibited the radiation-induced activation of EGFR. In clonogenic survival assays after a single radiation exposure, the radiation dose for a survival of 37% (D37) for U-87-EGFR-CD533 cells was 1.4- to 1.5-fold lower, relative to cells transduced with AdLacZ or untransduced U-87 MG cells. This effect was amplified with repeated radiation exposures (3 x 2 Gy) yielding a D37 ratio of 1.8-2.0. In clonogenic survival studies with U-373 MG cells, the radiosensitizing effect of EGFR-CD533 was similar. Furthermore, in vivo studies with U-87 MG xenografts confirmed the effect of EGFR-CD533 on tumor radiosensitization (dose enhancement ratio, 1.8). We conclude that inhibition of EGFR function via Ad-mediated gene transfer of EGFR-CD533 results in significant radiosensitization. As underlying mechanism, we suggest the disruption of a major cytoprotective response involving EGFR and its downstream effectors, such as mitogen-activated protein kinase. The experiments demonstrate for the first time that radiosensitization of malignant glioma cells through disruption of EGFR function may be achieved by genetic therapy approaches.