title: Identification of Novel Smoothened Ligands Using Structure-Based Docking.
abstract: The seven transmembrane protein Smoothened is required for Hedgehog signaling during embryonic development and adult tissue homeostasis. Inappropriate activation of the Hedgehog signalling pathway leads to cancers such as basal cell carcinoma and medulloblastoma, and Smoothened inhibitors are now available clinically to treat these diseases. However, resistance to these inhibitors rapidly develops thereby limiting their efficacy. The determination of Smoothened crystal structures enables structure-based discovery of new ligands with new chemotypes that will be critical to combat resistance. In this study, we docked 3.2 million available, lead-like molecules against Smoothened, looking for those with high physical complementarity to its structure; this represents the first such campaign against the class Frizzled G-protein coupled receptor family. Twenty-one high-ranking compounds were selected for experimental testing, and four, representing three different chemotypes, were identified to antagonize Smoothened with IC50 values better than 50 μM. A screen for analogs revealed another six molecules, with IC50 values in the low micromolar range. Importantly, one of the most active of the new antagonists continued to be efficacious at the D473H mutant of Smoothened, which confers clinical resistance to the antagonist vismodegib in cancer treatment.
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Celine
authors.initials: C
authors.lastname: Lacroix
authors.affiliation: Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America.|Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat Aviv, Israel.
authors.forename: Inbar
authors.initials: I
authors.lastname: Fish
authors.affiliation: Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America.
authors.forename: Hayarpi
authors.initials: H
authors.lastname: Torosyan
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Pranavan
authors.initials: P
authors.lastname: Parathaman
authors.affiliation: Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America.
authors.forename: John J
authors.initials: JJ
authors.lastname: Irwin
authors.affiliation: Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America.
authors.forename: Brian K
authors.initials: BK
authors.lastname: Shoichet
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.|Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Stephane
authors.identifier: http://orcid.org/0000-0001-7241-9044
authors.initials: S
authors.lastname: Angers
mesh_terms: D019943:Amino Acid Substitution; D000813:Anilides / Q000737:chemistry*; D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D062105:Molecular Docking Simulation; D020125:Mutation, Missense; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics; D011725:Pyridines / Q000737:chemistry*; D000072086:Smoothened Receptor / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics
chemical_list: D000813:Anilides; D000970:Antineoplastic Agents; C538724:HhAntag691; D009363:Neoplasm Proteins; D011725:Pyridines; C491023:SMO protein, human; C491022:Smo protein, mouse; D000072086:Smoothened Receptor