Tunable-combinatorial mechanisms of acquired resistance limit the efficacy of BRAF/MEK cotargeting but result in melanoma drug addiction

Cancer Cell. 2015 Feb 9;27(2):240-56. doi: 10.1016/j.ccell.2014.11.018. Epub 2015 Jan 15.

Abstract

Combined BRAF- and MEK-targeted therapy improves upon BRAF inhibitor (BRAFi) therapy but is still beset by acquired resistance. We show that melanomas acquire resistance to combined BRAF and MEK inhibition by augmenting or combining mechanisms of single-agent BRAFi resistance. These double-drug resistance-associated genetic configurations significantly altered molecular interactions underlying MAPK pathway reactivation. (V600E)BRAF, expressed at supraphysiological levels because of (V600E)BRAF ultra-amplification, dimerized with and activated CRAF. In addition, MEK mutants enhanced interaction with overexpressed (V600E)BRAF via a regulatory interface at R662 of (V600E)BRAF. Importantly, melanoma cell lines selected for resistance to BRAFi+MEKi, but not those to BRAFi alone, displayed robust drug addiction, providing a potentially exploitable therapeutic opportunity.

Publication types

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

MeSH terms

  • Cell Line, Tumor
  • Drug Resistance, Neoplasm / genetics*
  • Humans
  • MAP Kinase Signaling System / genetics
  • Melanoma / drug therapy*
  • Melanoma / genetics*
  • Melanoma / pathology
  • Molecular Targeted Therapy
  • Mutation
  • Protein Kinase Inhibitors / administration & dosage
  • Proto-Oncogene Proteins B-raf / genetics*

Substances

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

Associated data

  • SRA/SRP049746