Dysfunctional tumor vasculature, hypoxia, and an immunosuppressive microenvironment are significant barriers to effective cancer therapy. Autophagy, which is critical for maintaining cellular homeostasis and apoptosis resistance, is primarily triggered by hypoxia and nutrient deprivation, conditions prevalent in dysfunctional tumor vessels due to poor circulation. However, the role of autophagy in dysfunctional tumor endothelial cells and its impact on treatment and the tumor microenvironment (TME) remain poorly understood. Methods: We used multiplex immunofluorescence and transgene-based imaging to characterize autophagy in endothelial cells from clinical tumor samples, zebrafish xenograft tumors, and murine models. Using a zebrafish xenograft vasculature platform, we analyzed the effects of autophagy inhibitors on the structure and function of the tumor vasculature. In mice, we investigated autophagy inhibition via endothelial-specific autophagy gene knockout (Atg7 iECKO) and the autophagy inhibitor SBI-0206965 and evaluated the synergistic effects of combining SBI-0206965 with low-dose chemotherapy (5-fluorouracil, 5-FU) or PD-1 antibody. Human umbilical vein endothelial cells (HUVECs) were cultured in vitro under hypoxic, glucose-deprived, and serum-free conditions to simulate dysfunctional tumor endothelial cells and to explore the mechanisms by which autophagy inhibition optimizes tumor vasculature. Results: Elevated autophagy was observed in tumor endothelial cells within the dysfunctional vasculature. Autophagy inhibition, through either genetic knockout or pharmacological inhibition, selectively prunes dysfunctional vessels and improves vascular function. It also stimulates the formation of a perivascular immune niche, thereby optimizing the tumor immune microenvironment (TiME). Furthermore, combining the autophagy inhibitor SBI-0206965 with low-dose 5-FU or PD-1 antibody potentiated the anti-tumor effects. Mechanistic studies have indicated that autophagy acts as a protective response to the hypoxic and nutrient-deprived TME, while its inhibition, mediated by p53 activation, promotes tumor endothelial cell apoptosis in dysfunctional tumor vessels, further optimizing the structure and function of the tumor vasculature. Conclusions: Targeting endothelial cell autophagy is a promising strategy for remodeling the dysfunctional tumor vasculature, optimizing the TiME, and boosting the efficacy of chemotherapy and immunotherapy.

中文翻译：

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抑制自噬选择性地修剪功能失调的肿瘤血管并优化肿瘤免疫微环境。


功能失调的肿瘤脉管系统、缺氧和免疫抑制微环境是有效癌症治疗的重大障碍。自噬对于维持细胞稳态和细胞凋亡抵抗至关重要，主要由缺氧和营养剥夺触发，由于血液循环不良，这种情况在功能失调的肿瘤血管中普遍存在。然而，自噬在功能失调的肿瘤内皮细胞中的作用及其对治疗和肿瘤微环境 （TME） 的影响仍然知之甚少。方法： 我们使用多重免疫荧光和基于转基因的成像来表征临床肿瘤样本、斑马鱼异种移植肿瘤和小鼠模型中内皮细胞中的自噬。使用斑马鱼异种移植脉管系统平台，我们分析了自噬抑制剂对肿瘤脉管系统结构和功能的影响。在小鼠中，我们研究了通过内皮特异性自噬基因敲除 （Atg7 iECKO） 和自噬抑制剂 SBI-0206965 的自噬抑制，并评估了 SBI-0206965 与低剂量化疗 （5-氟尿嘧啶，5-FU） 或 PD-1 抗体的协同作用。在缺氧、缺糖和无血清条件下体外培养人脐静脉内皮细胞 （HUVECs），以模拟功能失调的肿瘤内皮细胞并探索自噬抑制优化肿瘤脉管系统的机制。结果： 在功能失调的脉管系统内的肿瘤内皮细胞中观察到自噬升高。自噬抑制，通过基因敲除或药物抑制，选择性地修剪功能失调的血管并改善血管功能。 它还刺激血管周围免疫生态位的形成，从而优化肿瘤免疫微环境 （TiME）。此外，自噬抑制剂 SBI-0206965 与低剂量 5-FU 或 PD-1 抗体联合使用增强了抗肿瘤作用。机制研究表明，自噬对缺氧和营养匮乏的 TME 起保护性反应，而其由 p53 激活介导的抑制作用促进功能失调的肿瘤血管中的肿瘤内皮细胞凋亡，进一步优化肿瘤脉管系统的结构和功能。结论： 靶向内皮细胞自噬是重塑功能失调的肿瘤脉管系统、优化 TiME 以及提高化疗和免疫治疗疗效的一种很有前途的策略。