miR-24 induces human T cell exhaustion though mitochondria energy metabolic reprograming via suppressing MYC and FGF11

Exhausted T cells (TExh) is a barrier for cancer immunotherapy, evidences demonstrate that transcriptional regulation is essential for TEX induction; however the factors that manipulate exhausted phenotype are largely unexplored. Here we showed that the microRNA (miR)-24, previously established to be enriched in eoxosmes from nasopharyngeal carcinoma (NPC) cells and promote T cell dysfunction, induced T cells to express high level of TIM-3, PD-1 and CD39 but to display low IFNg and GrB secretion and diminished proliferation ability ( a TExh phenotype) through inhibiting energy metabolism in vitro. Forced miR-24 expression inhibited ATP production through mitochondrial oxidative phosphorylation, while blockade of endogenous miR-24 the mitochondrial formation became massive and tubular and the levels of mitochondrial constituent proteins including Mfn1, Mfn2, P-Drp1 and TOMM20 was increased in OKT-3 stimulated T cells. MiR-24-mediated TEX and mitochondria metabolism reprogramming were regulated by suppressing MYC and FGF11 expression. Moreover, MYC enhanced the FGF11 transcription to promote mitochondria ATP production. Importantly, clinical data showed an increased TEX phenotype in circuiting and tumor-infiltrating T cells from NPC patients. Thus, our findings support that inhibition of miR-24-mediated mitochondria metabolism reprogramming can be titrated to break TExh immune barrier in NPC immunotherapy. Examination of 2 different treatments in human T cells.

耗竭性T细胞（Exhausted T cells, TExh）是癌症免疫治疗的关键障碍。已有研究证实，转录调控对于T细胞耗竭（TEX）的诱导不可或缺，但调控T细胞耗竭表型的核心因子仍未被广泛揭示。本研究发现，此前被证实富集于鼻咽癌细胞外泌体、且可促进T细胞功能异常的微小RNA（microRNA, miR）-24，可通过在体外抑制能量代谢，诱导T细胞高表达TIM-3、PD-1与CD39，同时降低干扰素γ（IFN-γ, IFNg）与颗粒酶B（GrB）的分泌水平，并削弱增殖能力，最终形成TExh表型。过表达miR-24可通过抑制线粒体氧化磷酸化减少ATP生成；而阻断内源性miR-24后，经OKT-3单抗刺激的T细胞内线粒体形态会变得粗大且呈管状，同时Mfn1、Mfn2、P-Drp1及TOMM20等线粒体组成蛋白的表达水平均显著升高。miR-24介导的TEX发生与线粒体代谢重编程，可通过抑制MYC与FGF11的表达实现调控；此外，MYC可增强FGF11的转录，进而促进线粒体ATP生成。值得注意的是，临床数据显示，鼻咽癌（nasopharyngeal carcinoma, NPC）患者外周血及肿瘤浸润T细胞中的TExh表型比例均有所升高。综上，本研究结果表明，靶向抑制miR-24介导的线粒体代谢重编程，可通过精准调控以破解TExh介导的免疫屏障，为鼻咽癌免疫治疗提供潜在干预策略。本研究还在人T细胞中开展了两种不同处理方案的相关实验。