针对 HER3 依赖性核 AKT 的激活可改善非小细胞肺癌的放射治疗。
Targeting HER3-dependent activation of nuclear AKT improves radiotherapy of non-small cell lung cancer.
机构信息
Division of Radiobiology and Molecular Environmental Research, Department of Radation Oncology, University of Tuebingen, Tuebingen, Germany; German Cancer Consortium (DKTK), Partner Site Tuebingen, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Department of Human Oncology, University of Wisconsin, Madison, WI, USA.
出版信息
Radiother Oncol. 2022 Sep;174:92-100. doi: 10.1016/j.radonc.2022.07.008. Epub 2022 Jul 15.
BACKGROUND
AKT1 must be present and activated in the nucleus immediately after irradiation to stimulate AKT1-dependent double-strand breaks (DSB) repair through the fast non-homologous end-joining (NHEJ) repair process. We investigated the subcellular distribution of AKT1 and the role of HER family receptor members on the phosphorylation of nuclear AKT and radiation response.
MATERIALS AND METHODS
Using genetic approaches and pharmacological inhibitors, we investigated the subcellular distribution of AKT1 and the role of HER family receptor members on the activation of nuclear AKT in non-small cell lung cancer (NSCLC) cells in vitro. ɤH2AX foci assay was applied to investigate the role of AKT activating signaling pathway on DSB repair. A mouse tumor xenograft model was used to study the impact of discovered signaling pathway activating nuclear AKT on the radiation response of tumors in vivo.
RESULTS
Our data suggests that neither ionizing radiation (IR) nor stimulation with HER family receptor ligands induced rapid nuclear translocation of endogenous AKT1. GFP-tagged exogenous AKT1 translocated to the nucleus under un-irradiated conditions and IR did not stimulate this translocation. Nuclear translocation of GFP-AKT1 was impaired by the AKT inhibitor MK2206 as shown by its accumulation in the cytoplasmic fraction. IR-induced phosphorylation of nuclear AKT was primarily dependent on HER3 expression and tyrosine kinase activation of epidermal growth factor receptor. In line with the role of AKT1 in DSB repair, the HER3 neutralizing antibody patritumab as well as HER3-siRNA diminished DSB repair in vitro. Combination of patritumab with radiotherapy improved the effect of radiotherapy on tumor growth delay in a xenograft model.
CONCLUSION
IR-induced activation of nuclear AKT occurs inside the nucleus that is mainly dependent on HER3 expression in NSCLC. These findings suggest that targeting HER3 in combination with radiotherapy may provide a logical treatment option for investigation in selected NSCLC patients.
背景
AKT1 必须在照射后立即存在于核内并被激活，以通过快速非同源末端连接（NHEJ）修复过程来刺激 AKT1 依赖性双链断裂（DSB）修复。我们研究了 AKT1 的亚细胞分布以及 HER 家族受体成员在核 AKT 磷酸化和辐射反应中的作用。
材料和方法
我们使用遗传方法和药理学抑制剂，研究了 AKT1 的亚细胞分布以及 HER 家族受体成员在非小细胞肺癌（NSCLC）细胞中激活核 AKT 的作用。应用 γH2AX 焦点测定法研究 AKT 激活信号通路对 DSB 修复的作用。使用小鼠肿瘤异种移植模型研究发现的激活核 AKT 的信号通路对体内肿瘤辐射反应的影响。
结果
我们的数据表明，电离辐射（IR）或 HER 家族受体配体刺激均不会诱导内源性 AKT1 的快速核转位。未照射条件下，GFP 标记的外源性 AKT1 转位到核内，IR 并未刺激这种转位。AKT 抑制剂 MK2206 可使 GFP-AKT1 核转位受损，表现为其在细胞质部分的积累。IR 诱导的核 AKT 磷酸化主要依赖于 HER3 表达和表皮生长因子受体的酪氨酸激酶激活。与 AKT1 在 DSB 修复中的作用一致，HER3 中和抗体 patritumab 以及 HER3-siRNA 在体外均减少 DSB 修复。patritumab 与放疗联合应用可改善异种移植模型中放疗对肿瘤生长延迟的作用。
结论
IR 诱导的核 AKT 激活发生在核内，主要依赖于 NSCLC 中的 HER3 表达。这些发现表明，HER3 靶向联合放疗可能为选定的 NSCLC 患者提供合理的治疗选择。
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