Structural investigation of B-Raf paradox breaker and inducer inhibitors

J Med Chem. 2015 Feb 26;58(4):1818-31. doi: 10.1021/jm501667n. Epub 2015 Feb 10.

Abstract

The V600E missense mutation in B-Raf kinase leads to an anomalous regulation of the MAPK pathway, uncontrolled cell proliferation, and initiation of tumorigenesis. While the ATP-competitive B-Raf inhibitors block the MAPK pathway in B-Raf mutant cells, they induce conformational changes to wild-type B-Raf kinase domain leading to heterodimerization with C-Raf causing a paradoxical hyperactivation of MAPK pathway. A new class of inhibitors (paradox breakers) has been developed that inhibit B-Raf(V600E) activity without agonistically affecting the MAPK pathway in wild-type B-Raf cells. In this study, we explore the structural, conformational, and cellular effects on the B-Raf kinase domain upon binding of paradox breakers and inducers. Our results indicate that a subtle structural difference between paradox inducers and breakers leads to significant conformational differences when complexed with B-Raf. This study provides a novel insight into the activation of B-Raf by ATP-competitive inhibitors and can aid in the design of more potent and selective inhibitors without agonistic function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cell Survival / drug effects
  • Dose-Response Relationship, Drug
  • Humans
  • Models, Molecular
  • Molecular Structure
  • Protein Kinase Inhibitors / chemical synthesis
  • Protein Kinase Inhibitors / chemistry
  • Protein Kinase Inhibitors / pharmacology*
  • Proto-Oncogene Proteins B-raf / antagonists & inhibitors*
  • Proto-Oncogene Proteins B-raf / genetics
  • Proto-Oncogene Proteins B-raf / metabolism
  • Structure-Activity Relationship

Substances

  • Protein Kinase Inhibitors
  • BRAF protein, human
  • Proto-Oncogene Proteins B-raf