Environmental Dose MEOHP Promotes Bladder Cancer Progress through Hybrid EMT Mechanism: Based on the Adverse Outcome Pathway

Di(2-ethylhexyl) phthalate (DEHP) is one of the major plasticizer pollutants, and numerous studies have reported the harmful effects of DEHP on human health. However, the effects of urinary DEHP metabolites on the progression of bladder cancer remain unclear. Here, we aimed to identify the representative chemical and explore its effect and mechanism on bladder cancer progression with epidemiological and experimental methods based on the adverse outcome pathway (AOP). The quantile-based g -computation (QGC) model showed a positive association between urinary plasticizer metabolites and bladder cancer risks in older men (NHANES 2005–2018), with mono(2-ethyl-5-oxohexyl) phthalate (MEOHP, the secondary-metabolite of DEHP) identified as a main driver factor. We treated human bladder cancer cells with MEOHP at environmentally relevant concentrations (10, 100, and 1000 nM) and found that 100 nM MEOHP exposure activated a hybrid EMT (epithelial–mesenchymal transition) phenotype. Mechanically, we confirmed that the environmental dose of MEOHP increased nuclear transposition of YAP and β-catenin (molecular initiating event, MIE), thereby sustaining the hybrid EMT phenotype of bladder cancer cells through a series of key events. Our study first investigated the effects of plasticizer secondary metabolite on bladder cancer progression, highlighting the potential damage to urinary system health caused by the metabolites of environmental chemicals and providing a new perspective for the toxicity assessment of pollutants in the future.