In silico high-throughput screening system for INMT activators in prostate cancer therapy

Abstract

Prostate cancer (PCa) is one of the leading causes of cancer-related mortality in men, with castration-resistant prostate cancer (CRPC) posing significant therapeutic challenges due to drug resistance mediated by the androgen receptor (AR) signaling pathway. Indolethylamine-N-methyltransferase (INMT), a tumor-suppressive enzyme downregulated in CRPC, regulates pathways associated with apoptosis and proliferation. Leveraging a structure-based drug design strategy, this study aimed to identify novel INMT agonists for CRPC therapy. Virtual screening of the ChemDiv compound library (guided by the INMT crystal structure, PDB ID: 2A14), combined with molecular docking, MM/GBSA binding energy calculations, and molecular dynamics simulations, identified five candidate compounds. Among these, DMPP-4M stably bound to an allosteric site adjacent to the catalytic domain of INMT via hydrogen bonds, π-cation interactions, and hydrophobic forces. In vitro experiments demonstrated that DMPP-4M dose-dependently upregulated INMT expression, inhibited proliferation, and induced apoptosis in CRPC cell models (PC-3, 22RV1). The mechanism involved activation of the pro-apoptotic protein BAX, suppression of the anti-apoptotic protein Bcl-2, and upregulation of cleaved caspase-3 and PARP. Further mechanistic studies revealed that DMPP-4M-mediated INMT activation suppressed the activity of the TGF-β/Smad and Wnt/β-catenin signaling pathways. These findings suggest that DMPP-4M represents a promising INMT-targeted therapeutic agent, offering an AR-independent strategy for CRPC treatment. Subsequent structural optimization and in vivo experimental validation are required to advance its clinical translation potential.