Data-mining-based biomarker evaluation and experimental validation of SHTN1 for bladder cancer

Gene therapy in bladder cancer (BLCA) remains an area ripe for exploration. Recent studies have highlighted the crucial role of SHTN1 in the initiation and progression of various cancers and SHTN1 may have interacted with the FGFR gene. However, its specific function in BLCA remains unclear.

We investigated the association between SHTN1 expression and prognosis, immune infiltration, and the tumor microenvironment (TME) across multiple malignancies using 433 BLCA samples from The Cancer Genome Atlas (TCGA). Differential gene expression analysis, functional annotation via Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) were performed for SHTN1-related genes by using R packages. Immune response and TME scores, along with drug sensitivity profiles of SHTN1, were analyzed using R packages. Immunohistochemistry (IHC) and western blotting were conducted to assess SHTN1 expression in surgical specimens from BLCA patients.CCK8 assay and cells wound healing assay were performed.The bioinformatics was analyzed by R software. Significant differences were evaluated using unpaired t test.

SHTN1 expression levels were significantly elevated in BLCA associated with poor prognosis (p < 0.01). Receiver operating characteristic (ROC) curves and nomograms demonstrated the diagnostic and prognostic efficacy of SHTN1 in BLCA. Notably, SHTN1 expression was higher in high-grade BLCA compared to lower-grade (p = 5.6e-10), a finding corroborated by IHC and western blotting. Pathway enrichment analysis revealed significant involvement of the Neuroactive ligand-receptor interaction and Chemical carcinogenesis - DNA adducts signaling pathways among SHTN1 differentially expressed genes. In terms of immune infiltration, T cells CD8, T cells follicular helper, and dendritic cells were predominant in the SHTN1 low-expression group, whereas macrophages M0 and M2, and mast cells were predominant in the high-expression group. Multivariate Cox regression analysis identified SHTN1 as an independent prognostic factor for overall survival (HR = 2.93; 95 % CI = 1.40-6.13; p = 0.004).CCK8 and wound healing experiments showed that SHTN1 knockdown reduced the cell proliferation and migration. Western blot showed that the EMT pathway was clearly associated with SHTN1.

Our findings suggest that SHTN1 holds promise as a prognostic and diagnostic biomarker for BLCA. Moreover, it is closely associated with elevated immune infiltration and distinct characteristics of the tumor microenvironment in BLCA.