Inhibition of the oncogenic GTPase dynamin-related protein 1 (DRP1) by the FDA-approved drug fosaprepitant: In silico, biophysical, and in vitro characterization of its anti-myeloma activity

Mitochondrial fission plays a crucial role in sustaining cellular homeostasis, and disturbances in this process have been linked to numerous pathological conditions, including cancer. The central regulator of mitochondrial division is the large GTPase dynamin-related protein 1 (DRP1), whose enzymatic activity drives the constriction and separation of mitochondria. Given its pivotal function, DRP1 has gained attention as a potential oncogenic target across several cancer types. However, the availability of small-molecule inhibitors targeting DRP1 remains limited. To discover novel inhibitors, we performed a virtual screening campaign of FDA-approved drugs obtained from the DrugBank database, leading to the identification of three compounds predicted to interact with the GTPase domain of DRP1. Among these, the antiemetic agent fosaprepitant emerged as a promising hit. Computational docking and GTPase activity assays supported its inhibitory potential, which was further confirmed through saturation transfer difference nuclear magnetic resonance (STD-NMR) spectroscopy, demonstrating direct binding between fosaprepitant and DRP1 and elucidating key contact sites. Consistent with inhibition of mitochondrial fission, fosaprepitant treatment in multiple myeloma (MM) cell lines induced mitochondrial hyperfusion, decreased cell viability and colony formation in a DRP1-dependent manner, and disrupted oxidative phosphorylation (OXPHOS), ultimately leading to mitochondrial dysfunction and apoptotic cell death. Overall, this study provides a robust platform for the identification of novel DRP1 inhibitors among FDA-approved compounds, highlighting fosaprepitant as a promising candidate for drug repurposing with anti-cancer potential.