Exploring ZPLD1 as a Prognostic Indicator and Therapeutic Target in Bladder Cancer

Bladder cancer (BLCA) remains a leading urological malignancy with rising incidence and a dismal prognosis; therefore, reliable prognostic markers and actionable therapeutic targets are urgently needed. The extracellular-matrix-related gene Zona-Pellucida-like Domain-containing Protein 1 (ZPLD1) has not been investigated in BLCA. We therefore aimed to delineate the expression landscape, prognostic value, immune contexture, and druggability of ZPLD1 in BLCA.

A multi-level integrative design was employed. RNA-seq (TPM) and clinical data were retrieved from TCGA-BLCA (n = 412 tumors, 19 normals) and GSE121711 (n = 8 tumors, 10 normals). We performed differential expression, ROC analysis, and logistic regression in R. Kaplan-Meier and multivariate Cox regression (with VIF control) defined survival associations; a nomogram was built. Gene set enrichment analysis (GSEA) explored pathways; ssGSEA and ESTIMATE characterized immune infiltration and checkpoint gene expression. The mRNA expression-based stemness index (mRNAsi) and drug sensitivity (RNAactDrug, CCLE/GDSC) were correlated. We inspected Genomic alterations via cBioPortal. Quantitative real-time PCR (qRT-PCR) validated ZPLD1 in 5637 and HT-1376 cell lines versus SV-HUC-1 normal urothelial cells.

ZPLD1 was markedly up-regulated in BLCA compared with normal tissues (mean 0.200 ± 0.019 vs 0.033 ± 0.010; p = 0.003) with an AUC of 0.704 for discriminating tumor from normal. High ZPLD1 independently predicted poorer overall survival (HR 2.004; 95% CI 1.037-3.874; p = 0.039) and disease-specific survival (HR 1.64; p = 0.007). GSEA revealed enrichment of focal adhesion, chemokine signaling, and PPAR pathways. ZPLD1 positively correlated with Th1 cells, macrophages, neutrophils, NK CD56dim cells, PD-L1, CTLA-4, LAG-3 and PD-1 (all p < 0.001) but negatively with SIGLEC15. Higher ZPLD1 was associated with lower cancer stemness (r = -0.23; p < 0.001) and altered sensitivity to TKI258, Topotecan, Paclitaxel, 5-FU, and Vorinostat. ZPLD1 was altered in 2% of TCGA-BLCA cases, mostly as missense mutations and amplifications. qRT-PCR confirmed elevated ZPLD1 in BLCA cell lines (p < 0.001).

ZPLD1 emerges as a novel, independent poor-prognosis biomarker that orchestrates an inflamed but checkpoint-restricted microenvironment and modulates drug response in BLCA. These findings position ZPLD1 as a candidate for risk stratification and combination immunotherapy, although prospective multi-center validation and mechanistic studies are required.

This study establishes ZPLD1 as a prognostic indicator and potential therapeutic target in BLCA, paving the way for precision oncology strategies integrating ZPLD1-guided patient selection and immune-drug combinations.