CALD1 promotes the expression of PD-L1 in bladder cancer via the JAK/STAT signaling pathway

Background: Bladder cancer (BC) is a common malignant neoplasm with a high rate of recurrence and progression, despite optimal treatment. There is a pressing need to identify new effective biomarkers for the targeted treatment of BC. Methods: The key gene CALD1 was screened via weighed gene co-expression network analysis (WGCNA) from encoding protein genes of BC. Clinical and prognostic significance was explored in The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Cell Counting Kit-8 (CCK-8), flow cytometry, transwell chamber experiment and nude mouse xenograft assay were performed to test cell growth, apoptosis, migration, invasion and tumorigenesis capacities. Immune correlation was analyzed in The Tumor Immune Estimation Resource (TIMER) database. Relevant signaling pathways were explored using gene set enrichment analysis (GSEA). Results: Increased expression of CALD1 was significantly correlated with histological grade, clinical stage, T stage, and lymphatic metastasis. Kaplan-Meier survival curves showed that high CALD1 expression was associated with poor overall survival (OS) and disease-free survival (DFS) in TCGA database, and with poor OS in the four GEO databases. CALD1 promotes growth, migration, invasion, and cell cycle of tumor cell, and inhibits tumor cell apoptosis in vitro and in vivo. CADL1 expression was positively correlated with increased CD274 levels (r=0.357, P=9.71e-14). JAK/STAT signaling pathway was significantly enriched in the high CALD1 expression group. CALD1-mediated PD-L1 overexpression (OE) was via the activation of the JAK/STAT signaling pathway; this effect was blocked by the specific JAK inhibitor Ruxolitinib. Conclusions: CALD1 is a potential molecular marker associated with prognosis. It promotes the malignant progression of BC and upregulates the PD-L1 expression via the JAK/STAT signaling pathway.