癌症是威胁人类健康和寿命的主要挑战之一。据世界卫生组织统计，2021 年全 球十大疾病相关死亡中，癌症位居第二。目前，癌症治疗手段主要包括手术切除、 放疗、化疗、靶向治疗及免疫治疗等。CD8+ T 细胞作为抗肿瘤免疫的主要效应细胞 之一，也是肿瘤免疫疗法发挥作用的核心细胞。因此，恢复 CD8+ T 细胞功能是增 强机体抗肿瘤免疫的重点。CD8+ T 细胞在活化过程中，由于其快速增殖和分化的需 要，CD8+ T 细胞代谢发生重编程，供能方式从氧化磷酸化转化为有氧糖酵解，葡萄 糖需求量显著增强。然而，由于肿瘤微环境乏氧、低糖、低 pH 的特点，CD8+ T 细 胞糖代谢能力受到抑制。因此，探究 T 细胞活化及抗肿瘤过程中的糖代谢改变及相 应机制，开发相应治疗策略可提高肿瘤免疫治疗响应率，使更多患者受益于免疫疗 法，这对于肿瘤的治疗，延长肿瘤患者生存周期都具有十分重要的意义。

本研究首先通过定量 PCR 筛选 CD8+ T 细胞活化及抗肿瘤过程中表达改变的葡 萄糖转运体，鉴定到 GLUT10 的表达在 CD8+ T 细胞活化及抗肿瘤过程中显著上调。 此外，相比于幼稚 CD8+ T 细胞(Naïve CD8+ T cell)，效应 CD8+ T 细胞表面 GLUT10 表达水平更高。通过构建 T 细胞上特异性敲除 GLUT10 的转基因小鼠(Cd4creGlut10fl/fl)，我们发现，GLUT10 敲除抑制 CD8+ T 细胞体外活化以及活化过 程中增殖及效应因子的分泌。此外，相比于野生型小鼠，Cd4creGlut10fl/fl 小鼠皮下肿 瘤生长加快。OT-I CD8+ T 细胞过继小鼠模型也表明，GLUT10 敲除导致 CD8+ T 细 胞体内特异性肿瘤杀伤能力下降。CD8+ T 细胞上 GLUT10 敲除降低 T 细胞葡萄糖 摄取和糖酵解能力。以上结果表明，在 CD8+ T 细胞活化及抗肿瘤过程中，GLUT10 是 CD8+ T 细胞葡萄糖摄取所依赖的主要转运体。进一步的探究中，我们发现单纯 恢复肿瘤微环境中的葡萄糖并不能恢复 CD8+ T 细胞肿瘤杀伤能力，即葡萄糖匮乏 并不是导致 CD8+ T 细胞糖代谢异常的唯一因素。通过代谢组学筛选，我们鉴定到 肿瘤微环境中高浓度的乳酸抑制 CD8+ T 细胞葡萄糖摄取能力，同时抑制肿瘤细胞 葡萄糖摄取和乳酸分泌可增强 CD8+ T 细胞抗肿瘤免疫功能。

机制上，我们发现，当胞外乳酸浓度升高，大量乳酸将被 CD8+ T 细胞摄取并 堆积于细胞内。这些乳酸通过与 GLUT10 蛋白第六段胞内区结合(Intracelluar Region
6, IR6)，进而抑制 GLUT10 葡萄糖转运的功能，最终影响 CD8+ T 细胞的葡萄糖摄 取。此外，尽管胞外酸化不影响 GLUT10 与葡萄糖结合，但 pH 值降低可促进乳酸 和 GLUT10 结合，从而加剧乳酸对 CD8+ T 细胞糖摄取抑制。通过针对乳酸与 GLUT10 结合的 IR6 结构域设计模拟肽，我们得到了可穿透细胞膜的 PG10.1、PG10.2、PG10.3 三条模拟肽，其中 PG10.3 可明显打断乳酸与 GLUT10 结合。功能学上，模 拟肽 PG10.3 可恢复由乳酸抑制的 CD8+ T 细胞的葡萄糖摄取以及特异性肿瘤杀伤能 力。此外，模拟肽 PG10.3 通过靶向 GLUT10 抑制小鼠皮下肿瘤生长，增强肿瘤浸 润 CD8+ T 细胞活化、增殖和效应功能。治疗学上，模拟肽 PG10.3 与 GLUT1 抑制 剂 WZB117 或 PD-1 抗体联用可达到更好的协同抑制肿瘤的效果。

综上，本研究发现GLUT10是CD8+ T细胞活化和抗肿瘤过程中所依赖的主要 葡萄糖转运体。肿瘤微环境中高浓度的乳酸通过与 GLUT10 的 IR6 结构域结合的方 式抑制 GLUT10 葡萄糖转运能力，进而导致 CD8+ T 细胞增殖能力和效应功能下降。 通过筛选 IR6 结构域模拟肽 PG10.3 打断乳酸与 GLUT10 结合可恢复 CD8+ T 细胞 抗肿瘤功能。模拟肽 PG10.3 与 PD-1 抗体联用进一步抑制小鼠皮下肿瘤生长。该研 究为肿瘤免疫治疗提供潜在的治疗靶点和药物。

Cancer remains one of the most formidable challenges to human health and longevity. According to World Health Organization statistics, cancer ranked as the second leading cause of disease-related deaths globally in 2021. Current cancer treatment modalities primarily include surgical resection, radiotherapy, chemotherapy, targeted therapy, and immunotherapy. Among immune cells, CD8+ T cells serve as the principal effector cells mediating anti-tumor immunity and represent the cornerstone of tumor immunotherapy efficacy. Consequently, restoring CD8+ T cell functionality has become a critical focus for enhancing anti-tumor immune responses.

During activation, CD8+ T cells undergo metabolic reprogramming to meet the heightened bioenergetic demands of rapid proliferation and differentiation, shifting their primary energy production from oxidative phosphorylation to aerobic glycolysis with substantially increased glucose requirements. However, the hypoxic, glucose-deprived, and acidic characteristics of the tumor microenvironment (TME) significantly suppress CD8+ T cell glycolytic capacity. Therefore, investigating metabolic alterations in T cell activation and anti-tumor processes, elucidating underlying mechanisms, and developing corresponding therapeutic strategies could improve response rates to tumor immunotherapy, benefiting more patients and holding profound significance for cancer treatment and survival extension.

This study initially employed quantitate PCR screening to identify differentially expressed transporters during CD8+ T cell activation and anti-tumor responses, revealing marked upregulation of GLUT10 expression. Compared to naïve CD8+ T cells, effector CD8+ T cells exhibited substantially higher GLUT10 surface expression. Through generating T cell-specific GLUT10 knockout transgenic mice (Cd4creGlut10fl/fl), we demonstrated that GLUT10 deletion impaired CD8+ T cell activation, proliferation, and effector cytokine secretion in vitro. Furthermore, Cd4creGlut10fl/fl mice exhibited accelerated subcutaneous tumor growth compared to wild-type controls. The OT-I CD8+ T cell adoptive transfer model confirmed that GLUT10 knockout compromised CD8+ T cell- mediated specific tumor cytotoxicity in vivo. Mechanistically, GLUT10 deficiency primarily disrupted CD8+ T cell glucose uptake and glycolytic capacity, establishing GLUT10 as the dominant glucose transporter supporting CD8+ T cell effector functions during activation and anti-tumor responses.

Notably, simply restoring glucose availability in the TME failed to rescue CD8+ T cell tumor-killing capacity, indicating that glucose deprivation alone cannot account for CD8+ T cell metabolic dysfunction. Metabolomics identified high lactate concentrations in the TME as a critical inhibitor of CD8+ T cell glucose uptake, while simultaneously 

suppressing tumor cell lactate secretion and glucose uptake enhanced CD8+ T cell anti- tumor immunity.

Mechanistically, the study found that when the extracellular lactate concentration increases, large amounts of lactate are taken up by CD8+ T cells and accumulate intracellularly. Lactate was found to bind the sixth intracellular region (IR6) of GLUT10, thereby inhibiting its glucose transport function and ultimately impairing CD8+ T cell glucose uptake. Additionally, although extracellular acidification does not affect the binding of GLUT10 to glucose, a lower pH promotes the binding of lactate to GLUT10, exacerbating the inhibition of lactate on glucose uptake in CD8+ T cells. Through rational design of IR6-targeting mimetic peptides, we developed three candidates (PG10.1, PG10.2, PG10.3), with PG10.3 demonstrating potent disruption of lactate-GLUT10 binding. Functionally, PG10.3 restored lactate-impaired CD8+ T cell glucose uptake and tumor- killing capacity. Therapeutically, PG10.3 administration significantly suppressed subcutaneous tumor growth in mice while enhancing tumor-infiltrating CD8+ T cell activation, proliferation and effector functions. Combination therapy with the GLUT1 inhibitor WZB117 or PD-1 antibodies yielded superior synergistic anti-tumor effects.

In summary, this study identifies GLUT10 as the principal glucose transporter supporting CD8+ T cell activation and anti-tumor responses. The high lactate concentration in TME suppresses CD8+ T cell glucose uptake through IR6 domain binding, leading to impaired proliferation and effector functions. The IR6-targeting mimic peptide PG10.3 effectively restores anti-tumor immunity by blocking lactate-GLUT10 interaction and demonstrates combinatorial efficacy with PD-1 blockade. These findings provide both a promising therapeutic target and a novel drug candidate for cancer immunotherapy.