Comprehensive Mendelian randomization and colocalization analysis of plasma proteomics to identify new therapeutic targets for bladder cancer

Bladder cancer is characterized by a high recurrence rate and aggressive behavior, with frequent emergence of chemoresistance. Current treatments such as surgery, chemotherapy, and immunotherapy have limited efficacy, underscoring the urgent need for effective early diagnostic biomarkers and novel targeted therapies. Results: In this study, we integrated plasma proteomic data from the UK Biobank Pharma Proteomics Project (UKB-PPP) and the Icelandic deCODE study with genome-wide association study (GWAS) data. We employed two-sample Mendelian randomization (MR), Bayesian colocalization analysis, and SMR/HEIDI tests to systematically identify potential plasma protein targets associated with bladder cancer risk. A total of 199 plasma proteins were found to be significantly associated with bladder cancer risk, among which five proteins (SLURP1, LY6D, WFDC1, NOV, and GSTM3) emerged as core candidate targets. Further validation showed that NOV and GSTM3 demonstrated robust causal associations with bladder cancer across multiple analytical methods, and molecular docking analysis revealed that these two proteins can bind to estrogen/progestin hormone-regulating drugs. Conclusions: Our study identified multiple plasma proteins with causal links to bladder cancer and revealed their potential roles in tumor immune evasion, antioxidant defenses, and tumor metabolism. These findings provide new insights into bladder cancer biology and offer potential targets for precision therapy and drug repositioning.