Optogenetically controlled RAF to characterize BRAF and CRAF protein kinase inhibitors

Sci Rep. 2016 Mar 30:6:23713. doi: 10.1038/srep23713.

Abstract

Here, we applied optoRAF, an optogenetic tool for light-controlled clustering and activation of RAF proteins that mimics the natural occurring RAS-mediated dimerization. This versatile tool allows studying the effect on BRAF and CRAF homodimer- as well as heterodimer-induced RAF signaling. Vemurafenib and dabrafenib are two clinically approved inhibitors for BRAF that efficiently suppress the kinase activity of oncogenic BRAF (V600E). However in wild-type BRAF expressing cells, BRAF inhibitors can exert paradoxical activation of wild-type CRAF. Using optoRAF, vemurafenib was identified as paradoxical activator of BRAF and CRAF homo- and heterodimers. Dabrafenib enhanced activity of light-stimulated CRAF at low dose and inhibited CRAF signaling at high dose. Moreover, dabrafenib increased the protein level of CRAF proteins but not of BRAF proteins. Increased CRAF levels correlate with elevated RAF signaling in a dabrafenib-dependent manner, independent of light activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Drug Screening Assays, Antitumor
  • Enzyme Induction / radiation effects
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Imidazoles / pharmacology
  • Indoles / pharmacology
  • Optogenetics
  • Oximes / pharmacology
  • Phosphorylation
  • Protein Kinase Inhibitors / pharmacology*
  • Protein Processing, Post-Translational
  • Proto-Oncogene Proteins B-raf / antagonists & inhibitors*
  • Proto-Oncogene Proteins B-raf / genetics
  • Proto-Oncogene Proteins B-raf / metabolism
  • Proto-Oncogene Proteins c-raf / antagonists & inhibitors*
  • Proto-Oncogene Proteins c-raf / genetics
  • Proto-Oncogene Proteins c-raf / metabolism
  • Signal Transduction
  • Sulfonamides / pharmacology
  • Vemurafenib

Substances

  • Antineoplastic Agents
  • Imidazoles
  • Indoles
  • Oximes
  • Protein Kinase Inhibitors
  • Sulfonamides
  • Vemurafenib
  • BRAF protein, human
  • Proto-Oncogene Proteins B-raf
  • Proto-Oncogene Proteins c-raf
  • dabrafenib