This study aims to explore the role of IL-22/IL-22R1 in bladder cancer (BC) progression and uncover the underlying mechanisms driving tumor growth and immune evasion.

We evaluated IL22R1 expression and its prognostic significance in The Cancer Genome Atlas (TCGA) BC cohort, followed by validation of IL-22/IL22R1 protein expression and clinical correlations in our cohort using IHC and ELISA. IHC analysis with an Muscle-invasive bladder cancer (MIBC) tissue microarray was conducted to examine the infiltration levels of CD8+ T cells and NK cells in the MIBC microenvironment their relationship with clinical pathological staging.Functional studies were performed using cell viability assays, wound healing, Transwell invasion assays, and subcutaneous xenograft models to assess proliferative, migratory, invasive and tumorigenic capacities. Mechanistically, we employed quantitative proteomics, transcriptome sequencing and STRING network analysis to identify early growth response 1 (EGR1) as a key downstream target, then investigated the IL-22/IL22R1-mediated regulation of EGR1 through Co-IP/MS, RIP and western blotting. Finally, we established co-culture systems of IL-22-stimulated T24 BC cells with PBMCs and analyzed CD8+ T cell effector functions by flow cytometry.

IL22R1 was overexpressed in TCGA BC cohort, positively correlating with more advanced tumor stages and poor prognosis. In our MIBC cohort, IL-22/IL22R1 proteins were upregulated and IL22R1 expression was positively associated with advanced stages. GSEA revealed IL22R1-high BC enriched in proliferation, EMT and antigen presentation pathways. MIBC tissues exhibited reduced CD8+ T, NK cell infiltration, with higher CD8+ T cells associated with lymph node metastasis and NK cells inversely correlated with tumor stages. IL-22 enhanced the proliferation, migration, and invasion of T24 BC cells, proliferation of 5637 BC cells, and xenograft growth, whereas IL22R1 knockdown suppressed these effects. IL-22 downregulated EGR1 and PD-L1 but upregulated Ki-67 in BC xenograft tissues. EGR1 expression was significantly reduced in MIBC tissues and inversely correlated with tumor stages. EGR1 silencing promoted the proliferation, invasion of T24 BC cells, proliferation of 5637 BC cells. Mechanistically, IL22R1 interacts with Y-box binding protein 1 (YBX1) , enhancing its cytoplasmic stability, which then binds EGR1 mRNA to inhibit translation. IL-22-treated T24 cells suppressed CD8+ T cell IFN-γ secretion, restored by IL22R1 knockdown.

High IL22R1 expression in BC is positively associated with poor prognosis. IL-22 promotes the proliferation and invasion of BC cells and increases the tumorigenic ability in vivo. EGR1 expression is reduced in MIBC tissues, with lower levels correlating with advanced stages. IL-22 suppresses EGR1 in BC cells, and EGR1 knockdown enhances the proliferation and invasion of BC cells. IL-22R1 interacts with YBX1 in BC cells, enhancing cytoplasmic stability of YBX1, which binds to EGR1 mRNA to inhibit its translation. IL-22/IL-22R1 signaling in T24 BC cells suppresses IFN-γ secretion by CD8+ T cells.