Most Colorectal Cancer (CRC) patients exhibit limited responsiveness to anti-programmed cell death protein 1 (PD-1) therapy, with the underlying mechanisms remaining elusive. Circular RNAs (circRNAs) play a significant role in tumorigenesis and development, with potential applications in tumor screening and predicting treatment efficacy. However, there are few studies exploring the role of circRNAs in CRC immune evasion. circRNA microarrays were used to identify circPHLPP2. RT-qPCR was used to examine the associations between the expression level of circPHLPP2 and the clinical characteristics of CRC patients. MTS assay, clone formation experiment, subcutaneous tumor implantation and multicolor flow cytometry were used to confirm the biological function of circPHLPP2. RAN-seq, RT-qPCR, and WB experiments were performed to investigate the downstream signaling pathways involved in circPHLPP2. RNA pull-down, RNA immunoprecipitation (RIP) and immunofluorescence staining were performed to identify the proteins associated with circPHLPP2. circPHLPP2 is up-regulated in CRC patients who exhibit resistance to anti-PD-1 based therapy. circPHLPP2 significantly promotes the proliferation and tumor growth of CRC cells. Knockdown of circPhlpp2 enhances the efficacy of anti-PD-1 in vivo. Mechanistically, the specific interaction between circPHLPP2 and ILF3 facilitates the nuclear accumulation of ILF3, which subsequently enhances the transcription of IL36γ. This process reduces NK cell infiltration and impairs NK cells’ granzyme B and IFN-γ production, thereby promoting tumor progression. Overall, our findings reveal a novel mechanism by which circRNA regulates CRC immune evasion. circPHLPP2 may serve as a prognostic biomarker and potential therapeutic target for CRC patients.

中文翻译：

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环状 RNA circPHLPP2 通过结合 ILF3 调节结直肠癌中 IL36γ 转录来促进肿瘤生长和抗 PD-1 耐药


大多数结直肠癌 （CRC） 患者对抗程序性细胞死亡蛋白 1 （PD-1） 疗法的反应有限，潜在机制仍然难以捉摸。环状 RNA （circRNAs） 在肿瘤发生和发展中起着重要作用，在肿瘤筛查和预测治疗效果方面具有潜在应用。然而，很少有研究探讨 circRNAs 在 CRC 免疫逃避中的作用。circRNA 微阵列芯片用于鉴定 circPHLPP2。采用 RT-qPCR 检测 circPHLPP2 表达水平与 CRC 患者临床特征的相关性。采用 MTS 法、克隆形成实验、皮下肿瘤植入和多色流式细胞术确认 circPHLPP2 的生物学功能。进行 RAN-seq 、 RT-qPCR 和 WB 实验，研究参与 circPHLPP2 的下游信号通路。进行 RNA pull-down、RNA 免疫沉淀 （RIP） 和免疫荧光染色以鉴定与 circPHLPP2 相关的蛋白质。circPHLPP2 在对基于抗 PD-1 的治疗表现出耐药性的 CRC 患者中上调。circPHLPP2 显着促进 CRC 细胞的增殖和肿瘤生长。敲低 circPhlpp2 增强了体内抗 PD-1 的疗效。从机制上讲，circPHLPP2 和 ILF3 之间的特异性相互作用促进了 ILF3 的核积累，从而增强了 IL36γ 的转录。这个过程减少了 NK 细胞浸润并损害了 NK 细胞的颗粒酶 B 和 IFN-γ 的产生，从而促进了肿瘤进展。总体而言，我们的研究结果揭示了 circRNA 调节 CRC 免疫逃避的一种新机制。circPHLPP2 可作为 CRC 患者的预后生物标志物和潜在治疗靶点。