Background: The Transmembrane Protease Serine 2/ERG (TMPRSS2/ERG) gene fusion results in the overexpression of ERG and dysregulation of pathways critical for prostate cancer (PC) tumor progression, invasion, and metastasis. This study aims to target the TMPRSS2/ERG fusion in the Scavenger Receptor Cysteine-Rich (SRCR) domain presents a promising and novel therapeutic strategy to control the aggression of PC malignancy. The study aims to identify targeted novel small molecules against the TMPRSS2 protein for lead identification and validation.

Methods: High-throughput virtual screening (HTVS) against the ChemBridge library was followed by protein-ligand interaction profilers, GROMACS, and GMX_Molecular Mechanics Poisson-Boltzmann Surface Area (MMPBSA) techniques were used for the lead identification. VCaP, LNCaP, human umbilical vein endothelial cells (HUVEC), and RWPE-1 cells were involved in the in vitro validations.

Results: HTVS identified TES7832 with favorable binding affinities of –8.0 kcal/mol to the SRCR domain of TMPRSS2. Molecular dynamic simulations demonstrated stable binding interactions with Root Mean Square Deviation values around 0.15 nm. The ΔG binding calculation was –36.76 kcal/mol (mean ± 5.63 standard deviation). Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) supported favorable small-molecule characteristics. TES7832 inhibited TMPRSS2 activity dose-dependently with a half-maximal inhibitory concentration (IC₅₀ value) of 484.1 ± 21.88 nM. The compound was selective to control the proliferation of VCaP cells expressing the TMPRSS2/ERG gene fusion with a 50% growth inhibition concentration (GI₅₀) value of 392 ± 39.15 nM. TES7832 reduced ERG and androgen receptor (AR) positive populations of VCaP cells while sparing the LNCaP or HUVEC cells that do not possess TMPRSS2/ERG fusion. The compound favored apoptosis and G₂/M cell cycle arrest in VCaP cells and inhibited hepatocyte growth factor (HGF)-induced transmigration of these cells.

Conclusion: TES7832 targeted the SRCR domain of the TMPRSS2/ERG fusion to downregulate ERG and AR activity in PC cells to control proliferation and induce apoptosis. This selectivity of TES7832 warrants further preclinical developments of the molecule against the TMPRSS2/ERG fusion-driven PC malignancy.