Liang Yingying, Mai Lixin, Schneeweiss Jonathan M, Lopez Perez Ramon, Kirschfink Michael, Huber Peter E
Molecular and Radiation Oncology, German Cancer Research Center (DKFZ), 280 INF, 69120 Heidelberg, Germany.
Institute of Immunology, University of Heidelberg, Im Neuenheimer Feld 305, 69120 Heidelberg, Germany.
Cancers (Basel). 2025 Jul 18;17(14):2383. doi: 10.3390/cancers17142383.
: Radiotherapy (RT) is a mainstay of clinical cancer therapy that causes broad immune responses. The complement system is a pivotal effector mechanism in the innate immune response, but the impact of RT is less well understood. This study investigates the interaction between RT and the complement system as a possible approach to improve immune responses in cancer treatment. : Human solid cancer (lung, prostate, liver, breast cancer), lymphoma, and leukemia cells were irradiated using X-rays and treated with polyclonal antibodies or anti-CD20 monoclonal antibodies, respectively. Chromium release assay was applied to measure cell lysis after radiation with or without complement-activating antibody treatment. The expression of membrane-bound complement regulatory proteins (mCRPs; CD46, CD55, CD59), which confer resistance against complement activation, CD20 expression, apoptosis, and radiation-induced DNA double-strand breaks (γH2AX), was measured by flow cytometry. The radiosensitivity of tumor cells was assessed by colony-forming assay. : We demonstrate that RT profoundly impacts complement function by upregulating the expression of membrane-bound complement regulatory proteins (mCRPs) on tumor cells in a dose- and time-dependent manner. Impaired complement-mediated tumor cell lysis could thus potentially contribute to radiotherapeutic resistance. We also observed RT-induced upregulation of CD20 expression on lymphoma and leukemic cells. Notably, complement activation prior to RT proved more effective in inducing RT-dependent early apoptosis compared to post-irradiation treatment. While complement modulation does not significantly alter RT-induced DNA-damage repair mechanisms or intrinsic radiosensitivity in cancer cells, our results suggest that combining RT with complement-based anti-cancer therapy may enhance complement-dependent cytotoxicity (CDC) and apoptosis in tumor cells. : This study sheds light on the complex interplay between RT and the complement system, offering insights into potential novel combinatorial therapeutic strategies and a potential sequential structure for certain tumor types.
放射疗法（RT）是临床癌症治疗的主要手段，可引发广泛的免疫反应。补体系统是先天免疫反应中的关键效应机制，但放射疗法的影响尚不太清楚。本研究调查放射疗法与补体系统之间的相互作用，作为改善癌症治疗中免疫反应的一种可能方法。
使用X射线照射人实体癌（肺癌、前列腺癌、肝癌、乳腺癌）、淋巴瘤和白血病细胞，并分别用多克隆抗体或抗CD20单克隆抗体进行处理。应用铬释放试验来测量在有或没有补体激活抗体处理的情况下辐射后的细胞裂解情况。通过流式细胞术测量赋予抗补体激活抗性的膜结合补体调节蛋白（mCRP；CD46、CD55、CD59）的表达、CD20表达、细胞凋亡和辐射诱导的DNA双链断裂（γH2AX）。通过集落形成试验评估肿瘤细胞的放射敏感性。
我们证明，放射疗法通过以剂量和时间依赖性方式上调肿瘤细胞膜结合补体调节蛋白（mCRP）的表达，对补体功能产生深远影响。补体介导的肿瘤细胞裂解受损因此可能导致放射治疗抗性。我们还观察到放射疗法诱导淋巴瘤和白血病细胞上CD20表达上调。值得注意的是，与照射后治疗相比，放射疗法之前的补体激活在诱导放射疗法依赖性早期细胞凋亡方面被证明更有效。虽然补体调节不会显著改变放射疗法诱导的癌细胞DNA损伤修复机制或内在放射敏感性，但我们的结果表明，将放射疗法与基于补体的抗癌疗法相结合可能会增强肿瘤细胞中补体依赖性细胞毒性（CDC）和细胞凋亡。
本研究揭示了放射疗法与补体系统之间的复杂相互作用，为潜在的新型联合治疗策略以及某些肿瘤类型的潜在序贯结构提供了见解。
