Identification and mechanism of action of the acylguanidine MRT-83, a novel potent Smoothened antagonist.

Abstract

There is a clear need to develop novel pharmacological tools to improve our understanding of Smoothened (Smo) function in normal and pathological states. Here, we report the discovery, the mechanism of action, and the in vivo activity of N-(2-methyl-5-(3-(3,4,5-trimethoxybenzoyl)guanidino)phenyl)biphenyl-4-carboxamide (MRT-83), a novel potent antagonist of Smo that belongs to the acylguanidine family of molecules. MRT-83 fits to a proposed pharmacophoric model for Smo antagonists with three hydrogen bond acceptor groups and three hydrophobic regions. MRT-83 blocks Hedgehog (Hh) signaling in various assays with an IC50 in the nanomolar range, showing greater potency than the reference Smo antagonist cyclopamine. MRT-83 inhibits Bodipy-cyclopamine binding to human and mouse Smo but does not modify Wnt signaling in human embryonic kidney 293 transiently transfected with a Tcf/Lef-dependent Firefly luciferase reporter together with a Renilla reniformis luciferase control reporter. MRT-83 abrogates the agonist-induced trafficking of endogenous mouse or human Smo to the primary cilium of C3H10T1/2 or NT2 cells that derive from a pluripotent testicular carcinoma. Stereotaxic injection into the lateral ventricle of adult mice of MRT-83 but not of a structurally related compound inactive at Smo abolished up-regulation of Patched transcription induced by Sonic Hedgehog in the neighboring subventricular zone. These data demonstrate that MRT-83 efficiently antagonizes Hh signaling in vivo. All together, these molecular, functional and biochemical studies provide evidence that MRT-83 interacts with Smo. Thus, this novel Smo antagonist will be useful for manipulating Hh signaling and may help develop new therapies against Hh-pathway related diseases.

• Authors: Hermine Roudaut, Elisabeth Traiffort, Tatiana Gorojankina, Ludwig Vincent, Helene Faure, Angele Schoenfelder, Andre Mann, Fabrizio Manetti, Antonio Solinas, Maurizio Taddei, Martial Ruat
• Journal: Molecular pharmacology (Mol Pharmacol) Vol. 79 Issue 3 Pg. 453-60 (Mar 2011) ISSN: 1521-0111 [Electronic] United States
• PMID: 21177415 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Benzamides
• Guanidines
• Hedgehog Proteins
• N-(2-methyl-5-(3-(3,4,5-trimethoxybenzoyl)guanidino)phenyl)biphenyl-4-carboxamide
• Patched Receptors
• Receptors, Cell Surface
• Receptors, G-Protein-Coupled
• SMO protein, human
• Smo protein, mouse
• Smoothened Receptor
• Veratrum Alkaloids
• Wnt Proteins
• cyclopamine

Topics

• Animals
• Benzamides (pharmacology)
• Cell Line
• Cerebellum (cytology, drug effects, metabolism)
• Dose-Response Relationship, Drug
• Gene Expression (drug effects)
• Guanidines (pharmacology)
• HEK293 Cells
• Hedgehog Proteins (metabolism)
• Humans
• Mice
• Patched Receptors
• Protein Binding
• Receptors, Cell Surface (antagonists & inhibitors, biosynthesis)
• Receptors, G-Protein-Coupled (antagonists & inhibitors, biosynthesis)
• Signal Transduction (drug effects)
• Smoothened Receptor
• Veratrum Alkaloids (pharmacology)
• Wnt Proteins (drug effects, physiology)