PO.TB10.03 · 肿瘤生物学
NR4A3作为肿瘤相关巨噬细胞中的免疫代谢检查点介导直肠癌的放疗敏感性
NR4A3 functions as an immuno-metabolic checkpoint in tumor-associated macrophages to mediate radiotherapy sensitivity in rectal cancer
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摘要 Abstract
中文摘要
背景：放疗耐药仍是直肠癌治疗中的一大挑战。肿瘤相关巨噬细胞（TAM）是肿瘤免疫微环境的关键组成部分。核受体NR4A3是TAM活化的关键调节因子。本研究旨在探讨巨噬细胞表达的NR4A3在直肠癌放疗敏感性中的作用。
方法：采用转录组RNA测序分析鉴定关键差异基因和通路。应用干扰RNA调节巨噬细胞中NR4A3的表达。通过Western blot、qPCR、ELISA评估信号通路和代谢改变。在巨噬细胞-结直肠癌细胞共培养模型中评估功能效应。
结果：TAM中NR4A3高表达与接受新辅助放疗的直肠癌患者病理反应改善和生存期延长相关。转录组分析显示，放疗后细胞中NR4A3表达和脂质代谢通路发生显著改变。放疗后巨噬细胞中NR4A3表达被诱导，这在体外（THP-1、RAW264.7）、小鼠MC-38异种移植模型和人直肠癌样本中得到一致验证。NR4A3敲低促进M2样极化状态（表现为CD163、IL-10升高）并增强免疫检查点分子（PD-L1、siglec-15）的表达，同时抑制M1标志物（CD86、IL-1beta、TNFalpha）。功能实验显示，NR4A3缺陷的巨噬细胞在共培养系统中丧失了抑瘤能力。另一方面，NR4A3促进巨噬细胞中的胆固醇合成和外流，其中ABCG1被鉴定为关键的下游胆固醇转运体。巨噬细胞来源的胆固醇促进了肿瘤细胞增殖。抑制ABCG1挽救了放疗激活巨噬细胞的抑瘤效应。
结论：NR4A3在TAM中充当放疗诱导的"免疫代谢检查点"，增强M1极化和抗肿瘤免疫，同时驱动ABCG1依赖性胆固醇外流和促肿瘤代谢环境。这些结果阐明了NR4A3在介导放疗对免疫微环境的矛盾效应中的双重作用，并强调了其作为克服直肠癌放疗耐药治疗靶点的潜力。
查看英文原文 English abstract
Background: Radiotherapy resistance remains a major therapeutic challenge in rectal cancer. Tumor-associated macrophages (TAMs) are pivotal components of the tumor immune microenvironment. The nuclear receptor NR4A3 is a key regulator of TAM activation. This study aimed to investigate the role of macrophage-expressing NR4A3 in radiotherapy sensitivity in rectal cancer.
Methods: Transcriptomic RNA sequencing analyses were used to identify key differential genes and pathways. Interfering RNAs were applied to modulate NR4A3 expression in macrophages. Signaling pathways and metabolic alterations were assessed by Western blot, qPCR, ELISA. Functional effects were evaluated in macrophage-colorectal cancer cell co-culture models.
Results: High NR4A3 expression in TAMs correlated with improved pathological response and prolonged survival in rectal cancer patients receiving neoadjuvant radiotherapy. Transcriptomic analysis revealed marked alterations in NR4A3 expression and lipid metabolism pathways in post-radiation cells. NR4A3 expression was induced in macrophages following radiotherapy, which was consistently validated in vitro (THP-1, RAW264.7), in murine MC-38 xenograft models, and human rectal cancer samples. NR4A3 knockdown promoted an M2-like polarization state (evidenced by elevated CD163, IL-10) and enhanced expression of immune checkpoint molecules (PD-L1, siglec-15), while suppressing M1 markers (CD86, IL-1beta, TNFalpha). Functional assays revealed that NR4A3-deficient macrophages lost tumor-suppressive capacity in co-culture systems. On the other hand, NR4A3 promoted cholesterol synthesis and efflux in macrophages, with ABCG1 identified as a critical downstream cholesterol exporter. Macrophage-derived cholesterol contributed to tumor cell proliferation. Inhibiting ABCG1 rescued tumor suppressive effect of radiation-activated macrophages.
Conclusion: NR4A3 acts as a radiation-induced "immuno-metabolic checkpoint" in TAMs, enhancing M1 polarization and antitumor immunity, while concurrently driving ABCG1-dependent cholesterol efflux and a pro-tumor metabolic milieu. These results illuminate the dual role of NR4A3 in mediating the paradoxical effects of radiotherapy on the immune microenvironment and underscore its potential as a therapeutic target for overcoming radiotherapy resistance in rectal cancer.
利益披露 Disclosure
X. Guo, None..
G. Tao, None..
X. Guo, None..
K. Hu, None..
R. Xue, None..
Y. Mo, None..
H. Qiu, None..
Q. Wu, None.