| 摘要: | 鼻咽癌是一種源自鼻咽上皮的惡性腫瘤，由於其解剖位置深入難以接近，致使手術切除相當困難。而鼻咽癌對放射治療通常較為敏感，因此多數患者會接受放療並合併化療。放療會在正常細胞與腫瘤細胞中誘導多種損傷相關分子模式（DAMPs），進而活化細胞內 DNA 感測路徑與 DNA 損傷反應（DDR）通路，這些訊號傳導能有效強化免疫反應。然而，放射治療也可能誘發免疫抑制相關反應，例如調節型 T 細胞（Treg）的增加與上調 T 細胞中免疫檢查點分子的表現，進而削弱放療的效果。
在本篇研究中，我們旨在探討放射治療如何調控鼻咽癌患者的免疫反應。我們先前以單細胞 RNA 定序分析第 I 期鼻咽癌患者接受放射治療前後成對的周邊血單核細胞（PBMCs）樣本，結果顯示儘管放療活化了細胞質 DNA 感測與 DDR 相關通路，cGAS–STING 路徑卻被顯著抑制，同時伴隨多種免疫抑制相關分子的上調。由於 cGAS–STING 訊號在啟動免疫反應中扮演著關鍵角色，我們進一步評估 STING 活化劑（如 diABZI）對多種免疫細胞株（如Jurkat、THP1、THP1-derived macrophage）與鼻咽癌細胞株的影響。
我們的結果顯示，diABZI 刺激可於癌細胞與免疫細胞中誘導 ATM、γH2AX 與 NBS1 等 DNA 損傷反應分子之活化，並進一步活化先天免疫反應（如 IRF3、STING、NF-κB）並提升巨噬細胞的殺傷能力。而在鼻咽癌細胞中，diABZI 刺激可抑制細胞生長、上調 CYLD 表現、抑制 IκB 活化，進而促使癌細胞的分化與凋亡。
在後續小鼠實驗中，將diABZI 與放療結合使用可進一步活化 STING 並促進免疫細胞增殖，導致脾臟腫大且與腫瘤體積縮小呈顯著相關。此外，diABZI 亦降低了免疫抑制分子如 TGFβ1 與 FOXP3 的表現，且這些分子的表現與 ATM 的活化呈明顯負相關。
總結而言，我們的成果證實，活化 STING 與 ATM 通路能有效增強抗腫瘤免疫反應，減低放射治療所引發的免疫抑制，進而提升整體腫瘤控制效果。
;Nasopharyngeal carcinoma (NPC) is a malignant tumor originating from nasopharyngeal epithelium. Due to the anatomically inaccessible location, it is challenging to treat by surgically removal. NPC is generally sensitive to radiotherapy (RT), most patients receive RT and concurrent chemotherapy. RT induces various types of damage associated molecular patterns (DAMPs) in both normal and cancer cells, triggering the activation of intracellular DNA sensing pathways and DNA damage response (DDR) pathway. Activation of these signaling enhances immune responses. However, RT also induces suppressive immune responses, such as Treg expansion and upregulation of immune checkpoints in T cells, which compromise the therapeutic effects of radiotherapy. In this study, we aimed to understand how RT regulates immune responses in NPC patients. Our previous single-cell RNA sequencing data analyzed on paired peripheral blood mononuclear cells (PBMCs) samples collected before and after RT from stage I NPC patients revealed that RT suppressed the cGAS-STING pathway, although it activated cytosolic DNA sensing signaling and DNA damage response. Moreover, RT enhanced expression of immunosuppressive molecules. Since the cGAS-STING signaling plays a crucial role in activating immune response, we evaluated the STING agonist (e.g., diABZI)-mediated effects on multiple immune cell lines (e.g., Jurkat, THP1, THP1-derived macrophage) and NPC cells. Results showed that treating diABZI triggered activation of DNA damage response, including ATM, γH2AX, and NBS1 in both cancer and immune cells. Further, diABZI treatment resulted in activation of innate immune response (e.g., IRF3, STING, NF-kB) and enhanced macrophage killing ability. In NPC cells, diABZI treatment inhibited cell growth and upregulated CYLD level and suppressed activation of IκB, resulting in cancer cell differentiation and apoptosis. In mouse animal experiments, combination treatment of diABZI and RT resulted in STING activation and an increased immune cell proliferation, leading to splenomegaly, while significantly correlated with a reduced tumor volume. Moreover, diABZI decreased the expression of immunosuppressive markers such as TGFβ1 and FOXP3, which were negatively correlated with ATM activation. In conclusion, our results demonstrate that activation of the STING and ATM pathways effectively enhances anti-tumor immune response and reduces radiotherapy-induced immunosuppression, ultimately leading to improved tumor control. |
