Epigenetic dysregulation and biological function of PDX1 in prostate cancer

Aberrant DNA methylation changes lead to abnormal gene expression that contributes to the development and progression of prostate cancer (PCa). Inquiry of genome-wide DNA methylation dataset, we identified the homeodomain pancreatic and duodenal homeobox 1 (PDX1) gene as differentially hypermethylated in PCa compared to normal prostate tissues. Immunohistochemical analysis of matched PCa and normal prostate tissues using tissue microarray showed a significant 2.33-fold (p = 0.0001) higher PDX1 protein expression in the PCa compared to the normal prostate tissues. In PCa cell lines (PC-3 and LNCaP) engineered to stably overexpress or knockdown PDX1, the ectopic PDX1 expression significantly enhanced cell proliferation and migration, whereas PDX1 knockdown suppressed these phenotypic processes. Quantitative RT-PCR and Western blot analysis demonstrated that PDX1 overexpression was associated with increased expression of key metabolic regulators; INSR, IGF1R, CXCR4, CDH2, TWIST1, and SNAI1, whereas there is decreased expression of ESR2, and TNFα. Conversely, PDX1 knockdown led to the opposite effect in expression profiles of these metabolites. Notably, these effects were more pronounced under high-glucose conditions compared to low-glucose environments. Overall, our findings suggest that PDX1 plays a tumor-promoting role in human PCa cells by influencing expression of metabolites in insulin, inflammatory, and epithelial-mesenchymal transition (EMT) signaling pathways. Given its potential role in metabolic regulation, full insights into the function of PDX1 in PCa could contribute to improved treatment and prevention strategies, particularly for men with PCa and comorbidities such as obesity and diabetes.