Structural basis for Smoothened receptor modulation and chemoresistance to anticancer drugs

Nat Commun. 2014 Jul 10;5:4355. doi: 10.1038/ncomms5355.

Abstract

The Smoothened receptor (SMO) mediates signal transduction in the hedgehog pathway, which is implicated in normal development and carcinogenesis. SMO antagonists can suppress the growth of some tumours; however, mutations at SMO have been found to abolish their antitumour effects, a phenomenon known as chemoresistance. Here we report three crystal structures of human SMO bound to the antagonists SANT1 and Anta XV, and the agonist, SAG1.5, at 2.6-2.8 Å resolution. The long and narrow cavity in the transmembrane domain of SMO harbours multiple ligand binding sites, where SANT1 binds at a deeper site as compared with other ligands. Distinct interactions at D473(6.54f) elucidated the structural basis for the differential effects of chemoresistance mutations on SMO antagonists. The agonist SAG1.5 induces a conformational rearrangement of the binding pocket residues, which could contribute to SMO activation. Collectively, these studies reveal the structural basis for the modulation of SMO by small molecules.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Crystallography
  • Cyclohexylamines / pharmacology
  • Drug Resistance, Neoplasm / physiology*
  • Hedgehog Proteins / physiology
  • Humans
  • Lysine / analogs & derivatives
  • Lysine / pharmacology
  • Models, Molecular*
  • Phthalazines / pharmacology
  • Piperazines / pharmacology
  • Pyrazoles / pharmacology
  • Receptors, G-Protein-Coupled / chemistry*
  • Receptors, G-Protein-Coupled / drug effects*
  • Receptors, G-Protein-Coupled / physiology
  • Signal Transduction / physiology
  • Smoothened Receptor
  • Thiophenes / pharmacology

Substances

  • 2-N,N-bis(carboxymethyl)lysine
  • Anta XV
  • Antineoplastic Agents
  • Cyclohexylamines
  • Hedgehog Proteins
  • Phthalazines
  • Piperazines
  • Pyrazoles
  • Receptors, G-Protein-Coupled
  • SAG compound
  • SANT-1 compound
  • SMO protein, human
  • Smoothened Receptor
  • Thiophenes
  • Lysine