Fischer Patrick, Schmid Maximilian, Ohradanova-Repic Anna, Schneeweiss Rebecca, Hadatsch Jana, Grünert Odysseus, Benedum Johannes, Röhrer Anna, Staudinger Felix, Schatzlmaier Philipp, Bragato Niccolo, Barna Sandra, Engl Magdalena, Kleinwächter Ava, Georg Dietmar, Widder Joachim, Kerschbaum-Gruber Sylvia, Slade Dea
Department of Radiation Oncology, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria.
Comprehensive Cancer Center, Medical University of Vienna, Spitalgasse 23, 1090, Vienna, Austria.
Cell Death Dis. 2025 Jul 21;16(1):540. doi: 10.1038/s41419-025-07873-w.
Triple negative breast cancer (TNBC) is a heterogeneous and a highly aggressive type of breast cancer. Standard of care for TNBC patients includes surgery, radio-, chemo- and immunotherapy, depending on the stage of the disease. Immunotherapy is ineffective as monotherapy but can be enhanced with taxane chemotherapy or radiotherapy. Radiation can stimulate the immune system by activating the type I interferon (IFN-I) response through cGAS-STING signaling, which recognizes cytosolic double-stranded DNA (dsDNA). Cytosolic dsDNA can be cleared by autophagy, thereby preventing activation of cGAS-STING signaling. Autophagy inhibition was therefore proposed to potentiate the immunostimulatory effects of radiation. Here we show that different molecular features of TNBC cell lines influence the effect of X-ray and carbon ion (C-ion) irradiation and autophagy inhibition on immunogenic signaling. MDA-MB-468, with low basal autophagy and high cytosolic dsDNA, activates the IFN-I response after radiation. In contrast, MDA-MB-231, characterized by high autophagy rates and low cytosolic dsDNA, induces NF-κB signaling and CXCL10 expression upon autophagy inhibition with the VPS34 inhibitor SAR405. Autophagy inhibition in TNBC cells triggers a stronger activation of innate immune cells (monocytes, natural killer cells and dendritic cells) compared to radiation. In BRCA1-mutated MDA-MB-436 cells, C-ion irradiation was more potent compared to X-rays in inducing the NF-κB-driven immunogenic response but failed to activate immune cells. Upregulation of PD-L1 by X-rays, and especially C-ions, may contribute to reduced immune cell activation, underscoring the need for combination strategies with immune checkpoint blockade. Collectively, our study highlights the NF-κB-driven immunostimulatory effects of autophagy inhibition and the importance of understanding the molecular heterogeneity in TNBC with regard to autophagy rates, IFN-I and NF-κB signaling when designing effective treatments that target these pathways.
三阴性乳腺癌（TNBC）是一种异质性且侵袭性很强的乳腺癌类型。TNBC患者的标准治疗方案包括手术、放疗、化疗和免疫治疗，具体取决于疾病的阶段。免疫治疗作为单一疗法无效，但可通过紫杉烷化疗或放疗增强疗效。辐射可通过cGAS-STING信号通路激活I型干扰素（IFN-I）反应来刺激免疫系统，该信号通路可识别胞质双链DNA（dsDNA）。胞质dsDNA可通过自噬清除，从而防止cGAS-STING信号通路的激活。因此，有人提出抑制自噬可增强辐射的免疫刺激作用。在此，我们表明TNBC细胞系的不同分子特征会影响X射线和碳离子（C离子）辐射以及自噬抑制对免疫原性信号的影响。基础自噬水平低且胞质dsDNA含量高的MDA-MB-468细胞在辐射后激活IFN-I反应。相比之下，以自噬率高和胞质dsDNA含量低为特征的MDA-MB-231细胞在用VPS34抑制剂SAR405抑制自噬后会诱导NF-κB信号传导和CXCL10表达。与辐射相比，TNBC细胞中的自噬抑制引发先天免疫细胞（单核细胞、自然杀伤细胞和树突状细胞）更强的激活。在BRCA1突变的MDA-MB-436细胞中，C离子辐射在诱导NF-κB驱动的免疫原性反应方面比X射线更有效，但未能激活免疫细胞。X射线尤其是C离子引起的PD-L1上调可能导致免疫细胞激活减少，这突出了联合免疫检查点阻断策略的必要性。总的来说，我们的研究强调了自噬抑制的NF-κB驱动的免疫刺激作用，以及在设计针对这些途径的有效治疗方法时了解TNBC中自噬率、IFN-I和NF-κB信号传导方面分子异质性的重要性。
