PO.CL08.01 · 临床研究
MCT4驱动的乳酸穿梭在受照射肿瘤微环境中上调中性粒细胞PD-L1表达从而促进肺癌免疫抑制
MCT4-driven lactate shuttle in the irradiated tumor microenvironment upregulates neutrophils PD-L1 expression for immunosuppression in lung cancer
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摘要 Abstract
中文摘要
目的：尽管已知肿瘤代谢异质性可塑造肿瘤微环境（TME），但放疗的代谢后果仍未明确界定。因此，本研究旨在阐明放射诱导的TME代谢改变，界定其在放射抵抗中的功能作用，并识别可靶向的代谢脆弱性。
方法：通过对放疗后5天肺癌患者血清及照射后48小时收集的肿瘤间质液进行代谢组学分析，研究代谢扰动。采用基于13C6-葡萄糖的代谢流分析评估糖酵解通量。通过胞外酸化率（ECAR）测量评估乳酸动态。对Lewis模型来源的肿瘤进行空间scRNA测序。使用所有可获得的组蛋白修饰抗体来鉴定中性粒细胞的乳酸化位点。采用Cut&Tag实验阐明下游基因。
结果：患者血清与受照射肿瘤的代谢组学分析显示乳酸显著升高。随后的功能分析表明，放射诱导NSCLC细胞发生代谢重编程，其特征为糖酵解通量增强、ECAR升高及乳酸分泌增加。蛋白质组学筛选鉴定出MCT4为照射后上调最显著的糖酵解调节因子。阻断MCT4可减弱放射诱导的糖酵解增强并抑制乳酸外排。对调控机制的进一步研究揭示，放射触发RAB3B表达，其与HSC70竞争结合MCT4，从而抑制HSC70介导的MCT4自噬。在体内，Mct4基因缺失逆转了放射诱导的富含乳酸的TME。空间scRNA测序进一步揭示，照射诱导了免疫抑制性中性粒细胞表型，而该表型可被MCT4抑制有效逆转。机制上，肿瘤来源的乳酸经MCT1被中性粒细胞内化，驱动组蛋白H4赖氨酸5乳酸化，进而促进PD-L1转录并损害CD8+ T细胞功能。阻断肿瘤乳酸外排可逆转中性粒细胞的组蛋白乳酸化及PD-L1表达，从而增强放疗疗效。
结论：本研究证明放射通过增强糖酵解能力及乳酸外排重编程肿瘤代谢。这一乳酸激增驱动中性粒细胞PD-L1表达并抑制CD8+ T细胞活性。我们的发现提出，靶向MCT4发挥双重治疗效应：逆转放射诱导的代谢适应，并破坏免疫抑制性中性粒细胞重塑，从而为增强放疗疗效提供策略。
查看英文原文 English abstract
Purposes: Although tumor metabolic heterogeneity is known to shape tumor microenvironments (TME), the metabolic consequences of radiotherapy remain poorly defined. Thus, this study aims to elucidate the radiation-induced metabolic alterations in the TME, delineate their functional roles in radioresistance, and identify targetable metabolic vulnerabilities.
Methods: Metabolic perturbations were investigated through metabolomic profiling of lung cancer patients serum 5 days after radiotherapy and tumor interstitial fluid collected at 48h post-irradiation. Glycolytic flux was assessed via 13 C 6 -glucose-based metabolic flux analysis. Lactate dynamics were assessed through extracellular acidocation rate (ECAR) measurements. Spatial scRNA sequencing was conducted on tumors from Lewis models. All the histone modification antibodies available were used to identify the lactylation site of neutrophils. Cut&Tag assay was performed to elucidate the downstream genes.
Results: Metabolomic profiling of patients serums and irradiated tumors revealed a significantly elevation of lactate. Subsequent functional analyses demonstrated that radiation induces metabolic reprogramming in NSCLC cells, characterized by amplified glycolytic flux, elevated ECAR, and enhanced lactate secretion. Proteomic screening identified MCT4 as the most prominently upregulated glycolytic regulators post-irradiation. MCT4 blockade attenuated radiation-induced glycolytic potentiation and suppressed lactate efflux. Further investigation into the regulatory mechanism revealed that radiation triggers RAB3B expression, which competes with HSC70 for binding to MCT4, inhibiting the HSC70-mediated autophagy of MCT4. In vivo, Gene depletion of Mct4 reversed radiation-induced lactate-enriched TME. Spatial scRNA sequencing further revealed that irradiation induced an immunosuppressive neutrophil phenotype, which was effectively reversed by MCT4 inhibition. Mechanistically, tumor-derived lactate was internalized by neutrophils via MCT1, driving histone H4 lysine 5 lactylation, which subsequently promoted PD-L1 transcription and impaired CD8 + T cells functions. Blocking lactate efflux from tumor reversed histone lactylation and PD-L1 expression in neutrophils, thereby potentiating radiotherapy efficacy.
Conclusion: Our study demonstrates that radiation reprograms tumor metabolism by enhancing glycolytic capacity and lactate efflux. This lactate surge drives PD-L1 expression of neutrophils and suppress the activity of CD8 + T cells. Our findings propose that targeting MCT4 exerts dual therapeutic effects: reversing radiation-induced metabolic adaptation and disrupting immunosuppressive neutrophil remodeling, thereby providing a strategy to amplify radiotherapy efficacy.
利益披露 Disclosure
W. Yuan, None..
Y. Wang, None..
L. Kong, None..
M. Zhou, None..
Y. Sun, None..
K. Yang, None.