Life Beyond Kinases: Structure-Based Discovery of Sorafenib as Nanomolar Antagonist of 5-HT Receptors

Of great interest in recent years has been computationally predicting the novel polypharmacology of drug molecules. Here, we applied an induced-fit protocol to improve the homology models of 5-HT2A receptor, and we assessed the quality of these models in retrospective virtual screening. Subsequently, we computationally screened the FDA approved drug molecules against the best induced-fit 5-HT2A models and chose six top scoring hits for experimental assays. Surprisingly, one well-known kinase inhibitor, sorafenib, has shown unexpected promiscuous 5-HTRs binding affinities, K-i = 1959, 56, and 417 nM against 5-HT2A, 5-HT2B, and 5-HT2C, respectively. Our preliminary SAR exploration supports the predicted binding mode and further suggests sorafenib to be a novel lead compound for 5HTR ligand discovery. Although it has been well-known that sorafenib produces anticancer effects through targeting multiple kinases, carefully designed experimental studies are desirable to fully understand whether its off-target 5-HTR binding activities contribute to its therapeutic efficacy or otherwise undesirable side effects.