Shao Chenyi, Zhang Yingyi, Li Hang, Chen Jiajia, Huang Ting, Li Jiaze, Wen Simeng, Wang Sen, Fan Saijun, Zhao Yu
Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, P. R. China.
School of Disaster and Emergency Medicine, Tianjin University, Tianjin, P. R. China.
Cancer Commun (Lond). 2025 Mar;45(3):218-244. doi: 10.1002/cac2.12636. Epub 2024 Dec 19.
The majority of patients with prostate cancer (PCa) exhibit intrinsic resistance to immune checkpoint blockade (ICB) following radiotherapy (RT). This resistance is generally attributed to the limited antigen presentation of heterogeneous cells within tumors. Here, we aimed to isolate and characterize these diverse subgroups of tumor post-RT to understand the molecular mechanisms of their resistance to ICB.
Single-cell RNA-sequencing (scRNA-seq) was used to profile senescent cancer cell clusters induced by RT in LNCaP cells. The expression and phosphorylation levels of ataxia telangiectasia and Rad3-related protein (ATR) were assessed by immunohistochemistry in clinical samples from patients with or without RT. Co-immunoprecipitation, mutagenesis, and Western blotting were used to measure the interactions between proteins. Xenograft experiments were performed to assess the tumor immune response in the mice.
We identified a subset of PCa cells that exhibited resistance to RT, characterized by a reduced antigen presentation capability, which enhanced their ability to evade immune detection and resist cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) blockade. scRNA-seq revealed that the senescent state was a transient phase of PCa cells post-RT, particularly in CTLA-4 blockade treatment-resistant cells. This state was marked by increased cytosolic ATR level. Cytosolic ATR phosphorylated CD86 in its cytosolic domain and enhanced the interaction between CD86 and its E3 ligase MARCH1 through electrostatic attraction. Depletion or inhibition of Atr increased the sensitivity to immune attack and improved responses to anti-Ctla-4 antibody treatment in a mouse model.
Our findings indicate that the activation of cytosolic ATR, which is associated with cellular senescence, impedes the effectiveness of combined RT and ICB treatments. This discovery may provide valuable insights for improving the efficacy of combined RT and ICB therapies in PCa.
大多数前列腺癌（PCa）患者在放疗（RT）后对免疫检查点阻断（ICB）表现出内在抗性。这种抗性通常归因于肿瘤内异质性细胞的抗原呈递有限。在此，我们旨在分离并表征放疗后肿瘤的这些不同亚群，以了解其对ICB抗性的分子机制。
使用单细胞RNA测序（scRNA-seq）对LNCaP细胞中放疗诱导的衰老癌细胞簇进行分析。通过免疫组织化学评估有或无放疗的患者临床样本中共济失调毛细血管扩张症和Rad3相关蛋白（ATR）的表达和磷酸化水平。使用免疫共沉淀、诱变和蛋白质印迹法来检测蛋白质之间的相互作用。进行异种移植实验以评估小鼠中的肿瘤免疫反应。
我们鉴定出一组对放疗具有抗性的PCa细胞，其特征在于抗原呈递能力降低，这增强了它们逃避免疫检测和抵抗细胞毒性T淋巴细胞相关蛋白4（CTLA-4）阻断的能力。scRNA-seq显示衰老状态是PCa细胞放疗后的一个短暂阶段，特别是在对CTLA-4阻断治疗耐药的细胞中。这种状态的特征是胞质ATR水平升高。胞质ATR在其胞质结构域中磷酸化CD86，并通过静电吸引增强CD86与其E3连接酶MARCH1之间的相互作用。在小鼠模型中，Atr的缺失或抑制增加了对免疫攻击的敏感性并改善了对抗Ctla-4抗体治疗的反应。
我们的研究结果表明，与细胞衰老相关的胞质ATR的激活阻碍了放疗和ICB联合治疗的有效性。这一发现可能为提高PCa中放疗和ICB联合疗法的疗效提供有价值的见解。
