Department of Urology, Peking University First Hospital, No. 8 Xishiku Street, Beijing 100034, P.R. China.
Department of Urology, The First Affiliated Hospital School of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, Zhejiang Province 310003, P.R. China.
Int J Biol Sci. 2022 Jan 1;18(3):995-1007. doi: 10.7150/ijbs.67329. eCollection 2022.
Exploring the regulatory mechanism of PD-L1 in renal cancer is one of the key strategies to improve the response of renal cancer patients to checkpoint blockade therapy. In this study, the synergistic effect of ascorbic acid (vitamin C) supplementation and the impact of TET2 depletion on anti-PD-L1 therapy were determined in xenograft model experiments. Lymphocyte infiltration and chemokine expression were determined using flow cytometry and qRT-PCR. To determine the downstream targets of TET2, we performed hMeDip-seq and RNA-seq analyses. The molecular mechanism was further confirmed by hMeDip-qPCR, MeDip-qPCR, bisulfite sequencing, Western blotting, qRT-PCR and xenograft model experiments and . The present study demonstrated that ascorbic acid enhanced the efficacy of immunotherapy and that the loss of TET2 function enabled renal cancer cells to evade antitumor immunity. Ascorbic acid treatment significantly increased the intratumoral infiltration of T cells and the expression of cytokines and chemokines, while the loss of TET2 impaired the infiltration of T cells and the expression of cytokines and chemokines. TET2 was recruited to IRF1 by IFN-γ-STAT1 signaling, thereby maintaining IRF1 demethylation and ultimately inducing PD-L1 expression. These results suggest a new strategy of stimulating TET activity to improve immunotherapy for renal cell carcinoma.
探讨 PD-L1 在肾癌中的调控机制是提高肾癌患者对检查点阻断治疗反应的关键策略之一。在这项研究中，通过异种移植模型实验确定了抗 PD-L1 治疗中维生素 C（抗坏血酸）补充的协同作用和 TET2 缺失的影响。使用流式细胞术和 qRT-PCR 测定淋巴细胞浸润和趋化因子表达。为了确定 TET2 的下游靶标，我们进行了 hMeDip-seq 和 RNA-seq 分析。通过 hMeDip-qPCR、MeDip-qPCR、亚硫酸氢盐测序、Western blot、qRT-PCR 和异种移植模型实验进一步证实了分子机制。本研究表明，抗坏血酸增强了免疫疗法的疗效，而 TET2 功能的丧失使肾癌细胞能够逃避抗肿瘤免疫。抗坏血酸处理显著增加了肿瘤内 T 细胞的浸润和细胞因子和趋化因子的表达，而 TET2 的缺失则损害了 T 细胞的浸润和细胞因子和趋化因子的表达。TET2 通过 IFN-γ-STAT1 信号被招募到 IRF1，从而维持 IRF1 的去甲基化，最终诱导 PD-L1 表达。这些结果提示了一种通过刺激 TET 活性来改善肾细胞癌免疫治疗的新策略。
