肿瘤相关成纤维细胞衍生的趋化因子 12 通过抑制 P62 介导的 PD-L1 自噬降解增强膀胱癌的免疫逃逸。

BACKGROUND: Cancer-associated fibroblasts (CAFs), the predominant stromal cell of tumor microenvironment (TME), play an important role in tumor progression and immunoregulation by remodeling extracellular matrix (ECM) and secreting cytokines. However, little is known about the details of the underlying mechanism in bladder cancer. METHODS: Bioinformatics analysis was performed to analyze the prognostic value of CAFs and CXCL12 using GEO, TCGA and SRA databases. The effects of CXCL12 on bladder cancer progression were investigated through in vitro and in vivo assays. The biological mechanism of the effect of CXCL12 on PDL1 were investigated using western blotting, immunoprecipitation, RT-PCR, immunofluorescence, mass spectrometry, protein stability, and flow cytometry. RESULTS: The results demonstrated that CAFs-derived CXCL12 promoted cancer cell migration and invasion and upregulated PDL1. Mechanistically, upon binding to its specific receptor, CXCL12 activated the downstream JAK2/STAT3 pathway and rapidly up-regulated the expression of deubiquitinase CYLD. CYLD deubiquitinated P62 causing P62 accumulation, which in turn inhibited the autophagic degradation of PDL1. In vivo experiments demonstrated that blocking CXCL12 inhibited tumor growth, reduced tumor PDL1 expression and increased immune cell infiltration. CONCLUSIONS: This study revealed a novel mechanism for the role of CXCL12 in P62-mediated PDL1 autophagic regulation. Combined application of CXCL12 receptor blocker and PD1/PDL1 blocker can more effectively inhibit PDL1 expression and enhance antitumor immune response. Targeting CAFs-derived CXCL12 may provide an effective strategy for immunotherapy in bladder cancer.

背景：癌症相关成纤维细胞（CAFs）是肿瘤微环境（TME）中的主要基质细胞，通过重塑细胞外基质（ECM）和分泌细胞因子，在肿瘤进展和免疫调节中发挥重要作用。然而，关于膀胱癌中潜在机制的细节知之甚少。

方法：使用 GEO、TCGA 和 SRA 数据库进行生物信息学分析，分析 CAFs 和 CXCL12 的预后价值。通过体外和体内实验研究 CXCL12 对膀胱癌进展的影响。使用 Western blot、免疫沉淀、RT-PCR、免疫荧光、质谱、蛋白质稳定性和流式细胞术研究 CXCL12 对 PDL1 影响的生物学机制。

结果：结果表明，CAFs 衍生的 CXCL12 促进了癌细胞的迁移和侵袭，并上调了 PDL1。在机制上，CXCL12 与其特异性受体结合后，激活下游 JAK2/STAT3 通路，迅速上调去泛素化酶 CYLD 的表达。CYLD 去泛素化 P62 导致 P62 积累，从而抑制 PDL1 的自噬降解。体内实验表明，阻断 CXCL12 抑制肿瘤生长，降低肿瘤 PDL1 表达并增加免疫细胞浸润。

结论：本研究揭示了 CXCL12 在 P62 介导的 PDL1 自噬调节中的作用的新机制。联合应用 CXCL12 受体阻滞剂和 PD1/PDL1 阻滞剂可以更有效地抑制 PDL1 表达并增强抗肿瘤免疫反应。靶向 CAFs 衍生的 CXCL12 可能为膀胱癌的免疫治疗提供一种有效策略。