TIAM1 signaling drives prostatic budding and branching phenotypes and is a potential therapeutic target for BPH

Benign prostatic hyperplasia (BPH) is the most prevalent urologic disease in men aged over 50 years. However, the molecular mechanisms that drive BPH pathophysiology remain elusive. In this study, we integrated bioinformatic and experimental analyses of human BPH to identify TIAM1-RAC1 signaling pathway as a promising candidate for a molecular-based approach for BPH therapy. First, elevated TIAM1 expression in a BPH transcriptomic signature that was generated from the analysis of RNA-seq data from three independent BPH patient cohorts was validated at the protein level in a fourth patient cohort. Additional bioinformatic analyses of the BPH transcriptomic signature pointed to TIAM1-RAC1 pathway as the potential lead therapeutic pathway; and NSC23766 - a small molecule inhibitor of TIAM1 signaling - as a developmental lead compound for BPH therapy. Next, a proof-of-concept pharmacological approach of TIAM1-RAC1 inhibition in human prostatic cells using NSC23766 resulted in attenuated organoid budding and branching - a developmental program associated with prostatic nodule formation and BPH pathogenesis. Finally, shRNA-based genetic knock-down of TIAM1 in human prostatic cells led to a reduction in budding and branching phenotypes thereby phenocopying the effects of NSC23766. Together, our observations implicate elevated TIAM1 as a driver of budding and branching in BPH, and our studies pave the way for TIAM1-RAC1 based targeted approach for the treatment of the disease.