Evaluation of Itraconazole as a repurposed small molecule inhibitor of EMT in breast cancer: a molecular docking and dynamics study

CONTEXT: Epithelial-Mesenchymal Transition (EMT) is a critical driver of metastasis and drug resistance in breast cancer. Repurposing FDA-approved drugs offers a rapid strategy to target EMT pathways. This study evaluates Itraconazole, an antifungal agent with reported anti-cancer properties, as a potential multi-target inhibitor of the EMT signaling network. We investigated the binding mechanism and selectivity of Itraconazole against four key EMT regulators: Smoothened (SMO), TGF-βR1, EGFR, and GLI1. Our results identify SMO as the primary target, exhibiting high binding affinity and thermodynamic stability. Conversely, EGFR and GLI1 displayed significant structural instability, indicating a lack of direct inhibition. The study provides atomic-level structural evidence supporting the repurposing of Itraconazole as a selective, combinatorial therapeutic agent to target EMT-driven metastasis. METHODS: Induced Fit Docking (IFD) was performed using the Schrödinger IFD protocol and the Glide XP scoring function within the Schrödinger Maestro suite. The dynamic stability of the protein-ligand complexes was evaluated using 500 ns molecular dynamics (MD) simulations with the Desmond software and the OPLS4 force field. To differentiate false positives and assess pose stability under enhanced sampling, Binding Pose Metadynamics (BPMD) was utilized. Thermodynamic binding free energies were calculated using the Thermal MM/GBSA method. All simulations were analyzed using the Simulation Interaction Diagram and trajectory clustering tools within Schrödinger.