Enhancer-targeted genome editing selectively blocks innate resistance to oncokinase inhibition

Genome Res. 2014 May;24(5):751-60. doi: 10.1101/gr.166231.113. Epub 2014 Jan 17.

Abstract

Thousands of putative enhancers are characterized in the human genome, yet few have been shown to have a functional role in cancer progression. Inhibiting oncokinases, such as EGFR, ALK, ERBB2, and BRAF, is a mainstay of current cancer therapy but is hindered by innate drug resistance mediated by up-regulation of the HGF receptor, MET. The mechanisms mediating such genomic responses to targeted therapy are unknown. Here, we identify lineage-specific enhancers at the MET locus for multiple common tumor types, including a melanoma lineage-specific enhancer 63 kb downstream from the MET TSS. This enhancer displays inducible chromatin looping with the MET promoter to up-regulate MET expression upon BRAF inhibition. Epigenomic analysis demonstrated that the melanocyte-specific transcription factor, MITF, mediates this enhancer function. Targeted genomic deletion (<7 bp) of the MITF motif within the MET enhancer suppressed inducible chromatin looping and innate drug resistance, while maintaining MITF-dependent, inhibitor-induced melanoma cell differentiation. Epigenomic analysis can thus guide functional disruption of regulatory DNA to decouple pro- and anti-oncogenic functions of a dominant transcription factor and block innate resistance to oncokinase therapy.

Publication types

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

MeSH terms

  • Cell Line, Tumor
  • Chromatin / genetics
  • Chromatin / metabolism
  • Drug Resistance, Neoplasm / genetics*
  • Enhancer Elements, Genetic*
  • Gene Expression Regulation, Neoplastic*
  • Genome, Human*
  • Humans
  • Indoles / pharmacology
  • Melanoma / genetics
  • Microphthalmia-Associated Transcription Factor / genetics
  • Microphthalmia-Associated Transcription Factor / metabolism
  • Promoter Regions, Genetic
  • Protein Kinase Inhibitors / pharmacology
  • Proto-Oncogene Proteins B-raf / antagonists & inhibitors*
  • Proto-Oncogene Proteins B-raf / genetics
  • Proto-Oncogene Proteins B-raf / metabolism
  • Proto-Oncogene Proteins c-met / genetics
  • Proto-Oncogene Proteins c-met / metabolism
  • Sulfonamides / pharmacology
  • Transcriptome
  • Vemurafenib

Substances

  • Chromatin
  • Indoles
  • MITF protein, human
  • Microphthalmia-Associated Transcription Factor
  • Protein Kinase Inhibitors
  • Sulfonamides
  • Vemurafenib
  • MET protein, human
  • Proto-Oncogene Proteins c-met
  • BRAF protein, human
  • Proto-Oncogene Proteins B-raf

Associated data

  • GEO/GSE50686