二甲双胍通过激活AMPK重新编程CD8+T细胞代谢增强机体抗肿瘤免疫的机制研究

The anti-diabetic agent metformin has attracted attention again for its significant effects on preventing and treating cancer, but the underlying mechanisms remain an enigma. The previously published articles indicated that the activated AMPK can directly reprogramme cellular metabolism, like enhancing glycolysis or (and) fatty acid β-oxidation while simultaneously inhibiting phosphorylation oxidation, thus promoting proliferation, differentiation and maturation of CD8+ T cells under antigenic stimulation. Our laboratory recently found that number and p-AMPK fluorescence level of CD8+ T cells infiltrated in breast cancer tissues from patients with metformin treatment were obviously higher than that from patients without treatment; metformin increased the thymus weight/body weight ratio of mice and enhanced secondary host antitumor immunity only under the condition of a tumor-burdened in mice. On the basis of evidence represented above, we therefore hypothesizes that metformin may transform the metabolic way of CD8+ T cells towards glycolysis or (and) fatty acid β-oxidation by activating AMPK, therefore enhancing T cells-mediated host antitumor immunity. To test the hypothesis, molecular biology techniques and immunological animal models will be utilized. This research will help us to explore the impacts of metformin on metabolism, differentiation and maturation of CD8+ T cells and tumor progression, and provides a theoretical basis for clinical application of metformin as an immune potentiator.

抗糖尿病药物二甲双胍因激活能量感受蛋白AMPK介导防治肿瘤作用而再次备受关注，但其机制尚不明确。既往研究表明活化的AMPK通过重新编程代谢，如增强糖酵解或（和）脂肪酸β-氧化的同时抑制氧化磷酸化，进而促进CD8+T细胞在抗原刺激后的成熟、分化和增殖。课题组前期研究发现：服用二甲双胍患者的乳腺癌组织中CD8+T细胞的浸润数量及p-AMPK水平显著高于未服用组；仅在荷瘤的情况下，二甲双胍才会显著增加小鼠的胸腺/体重比，并增强机体的二次抗肿瘤免疫。基于上述背景及前期结果，我们推测：二甲双胍通过激活AMPK使得 CD8+T细胞的代谢方式向糖酵解或（和）脂肪酸β-氧化转换，进而增强T细胞介导的机体抗肿瘤免疫。为证实假设，我们将利用分子生物学技术及免疫动物模型，探索二甲双胍通过激活AMPK对CD8+T细胞代谢方式、分化、成熟及对肿瘤进展的影响，为二甲双胍作为免疫增强剂应用于肿瘤治疗提供理论依据。

CD8+ T细胞是人体中最为重要的一群淋巴细胞,并在机体抗肿瘤免疫过程中发挥重要作用。研发有效增强机体抗肿瘤免疫功能的治疗方法已经成为肿瘤研究领域的一大热点。 近年来，二甲双胍因防治肿瘤作用而再次备受关注。据报道，二甲双胍所介导的抗肿瘤作用与增强机体抗肿瘤免疫密切相关，但其潜在的调控机制仍不十分清楚。本研究发现：1）乳腺癌标本结果显示服用二甲双胍组的肿瘤内浸润的CD8+ T细胞的数量显著高于未服用组，且高的浸润数量与良好预后显著相关；2）体内结果显示：二甲双胍通过激活AMPK增加乳腺癌组织内CD8+ T细胞的浸润数量，且其通过CD8阳性T细胞介导抗肿瘤作用； 3）二甲双胍通过增强CD8阳性T细胞的脂肪酸代谢及无氧酵解，增加了T效应细胞及T效应记忆细胞的生成，并增强了小鼠的二次抗肿瘤免疫。二甲双胍通过向脂肪酸及糖酵解重编程CD8阳性T细胞代谢，促进效应T细胞及效应记忆T细胞的生成和T细胞在肿瘤组织内的浸润，最终发挥抗肿瘤作用并改善肿瘤相关预后。