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

Haoyuan Zheng, Cao S, Zhuoling Kong, Peng Xin, Jianbin Bi, Jianfeng Wang

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.