PO.TB01.01 · 肿瘤生物学
内皮细胞重塑在驱动肝细胞癌免疫治疗耐药中的作用
The role of endothelial cell remodeling in driving immunotherapy resistance of hepatocellular carcinoma
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
背景:由于肿瘤微环境(TME)异质性,肝细胞癌(HCC)对免疫检查点阻断(ICB)疗法表现出有限的持久应答。将抗血管内皮生长因子(VEGF)与ICB联合已增强了治疗疗效,但有限的获益提示,理解血管生成之外的内皮细胞(EC)重塑对于增强ICB有效性至关重要。整合分析识别出一个新的转录因子(TF)转录程序,连同溴结构域和末端外结构域(BET)蛋白BRD4表达升高,该程序与ICB耐药HCC中的EC重塑相关。新兴研究表明,该TF的功能通过BRD4被募集至特定增强子区域而依赖于BRD4,用BET抑制剂抑制BRD4可降低其表达。因此,我们旨在阐明指导EC重塑以实现肿瘤免疫抑制的微环境信号及其在促进ICB耐药中的作用。
方法:对来自HCC患者pembrolizumab II期临床试验(NCT03419481)的样本进行单细胞转录组分析。使用通过迭代选择生成的ICB耐药HCC小鼠模型进行验证。BET抑制剂AZD5153以纳米颗粒制剂给药,用于选择性抑制EC中的BRD4和TF表达。采用定量免疫荧光和流式细胞术评估EC和瘤内免疫微环境。
结果:scRNA-seq分析显示,ICB无应答者的肿瘤血管富含紊乱的大血管样内皮细胞(MaVEC),后者可能起源于肝血窦内皮细胞(LEC)。提示在ICB耐药发展过程中存在从LEC到MaVEC的动态转分化过程。值得注意的是,我们识别出一个新的TF作为MaVEC中的顶级调控子,沿LEC至MaVEC轨迹表现出转录因子活性增加,并在MaVEC中与BRD4密切相关。用EC靶向纳米颗粒递送的AZD5153治疗可抑制该TF表达,引起瘤内MaVEC向LEC的显著逆转,并重塑瘤内免疫微环境,导致抗PD-L1疗效增强。
结论:我们的研究揭示了从LEC到MaVEC的动态转分化与HCC中的ICB耐药相关。阻断这一EC转化可使TME从免疫抑制性转变为免疫刺激性,使肿瘤对抗PD-L1治疗重新敏感。该项目可能产生对抗HCC适应性免疫耐药的新策略。
关键词:肝细胞癌,免疫检查点阻断,内皮细胞重塑。
致谢:本工作由优配研究金(14118424)、阿斯利康临床前肿瘤学研究计划及李嘉诚基金会资助。
查看英文原文 English abstract
Background : Hepatocellular carcinoma (HCC) has shown limited durable responses to immune checkpoint blockade (ICB) therapies due to tumor microenvironment (TME)heterogeneity. Combining anti-vascular endothelial growth factor (VEGF) with ICB has enhanced therapeutic efficacy, but the limited benefits suggest that understanding endothelial cell (EC) remodeling beyond angiogenesis is essential for enhancing ICB effectiveness. Integrated analyses identified a novel transcription factor(TF) transcriptional program, coupled with elevated bromodomain and extra terminal domain (BET) protein BRD4 expression, that was associated with EC remodeling in ICB-resistant HCC. Emerging studies have shown that this TF functions depend on BRD4 through its recruitment to a specific enhancer region, and inhibiting BRD4 with BET inhibitors can reduce its expression. Hence, we aim to delineate the microenvironmental cue that direct EC remodeling for tumor immunosuppression and their role in promoting ICB resistance.
Methods: Single-cell transcriptomic profiling was performed on samples from a Phase II clinical trial of pembrolizumab in HCC patients (NCT03419481). An ICB-resistant HCC mouse model generated via iterative selection was utilized for validation. BET inhibitor AZD5153, administered in nanoparticle formulations, was used to suppress BRD4 and TF expression selectively in ECs. Quantitative immunofluorescence and flow cytometry was employed for EC assessment and intratumoral immune microenvironment.
Results: scRNA-seq analysis revealed that tumor vessels in ICB non-responders were enriched with disorganized macrovascular-like endothelial cells (MaVEC), which likely originate from liver sinusoidal endothelial cells (LEC). Suggesting a dynamic trans-differentiation process from LEC to MaVEC during the development of ICB resistance. Notably, we identified a novel TF as the top regulon in MaVEC, exhibiting increased transcription factor activity along the LEC-to-MaVEC trajectory, and closely associated with BRD4 in MaVEC. Treatment with the EC-targeted nanoparticle-delivered AZD5153 can suppress this TF expression, caused remarkable intratumoral MaVEC-to-LEC reversion and reshaped the intratumoral immune microenvironment, leading to an augmented anti-PD-L1 efficacy.
Conclusions : Our study reveals that the dynamic trans-differentiation from LEC to MaVEC is related with ICB resistance in HCC. Blocking this EC transformation shifts the TME from immunosuppressive to stimulatory, re-sensitizing tumors to anti-PD-L1 therapy. This project may yield new strategies to counter adaptive immune resistance in HCC.
Keywords: Hepatocellular carcinoma, Immune-checkpoint blockade, Endothelial cells remodeling.
Acknowledgement: The work is funded by General Research Fund (14118424) & AstraZeneca Pre-clinical Oncology Research Programme & Li Ka Shing Foundation.
利益披露 Disclosure
B. Yin, None.