Harnessing BET Inhibitor Sensitivity Reveals AMIGO2 as a Melanoma Survival Gene

Mol Cell. 2017 Nov 16;68(4):731-744.e9. doi: 10.1016/j.molcel.2017.11.004.

Abstract

Bromodomain and extraterminal domain inhibitors (BETi) represent promising therapeutic agents for metastatic melanoma, yet their mechanism of action remains unclear. Here we interrogated the transcriptional effects of BETi and identified AMIGO2, a transmembrane molecule, as a BET target gene essential for melanoma cell survival. AMIGO2 is upregulated in melanoma cells and tissues compared to human melanocytes and nevi, and AMIGO2 silencing in melanoma cells induces G1/S arrest followed by apoptosis. We identified the pseudokinase PTK7 as an AMIGO2 interactor whose function is regulated by AMIGO2. Epigenomic profiling and genome editing revealed that AMIGO2 is regulated by a melanoma-specific BRD2/4-bound promoter and super-enhancer configuration. Upon BETi treatment, BETs are evicted from these regulatory elements, resulting in AMIGO2 silencing and changes in PTK7 proteolytic processing. Collectively, this study uncovers mechanisms underlying the therapeutic effects of BETi in melanoma and reveals the AMIGO2-PTK7 axis as a targetable pathway for metastatic melanoma.

Keywords: AMIGO2; BET; BET inhibition; BRD2; BRD4; PTK7; enhancers; melanoma.

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Cell Adhesion Molecules / metabolism
  • Cell Cycle Proteins
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Enhancer Elements, Genetic*
  • Female
  • Humans
  • Male
  • Melanoma / drug therapy
  • Melanoma / genetics
  • Melanoma / metabolism*
  • Melanoma / pathology
  • Neoplasm Metastasis
  • Neoplasm Proteins / metabolism*
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism
  • Receptor Protein-Tyrosine Kinases / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism

Substances

  • AMIGO2 protein, human
  • Antineoplastic Agents
  • BRD2 protein, human
  • BRD4 protein, human
  • Cell Adhesion Molecules
  • Cell Cycle Proteins
  • Neoplasm Proteins
  • Nerve Tissue Proteins
  • Nuclear Proteins
  • Transcription Factors
  • PTK7 protein, human
  • Receptor Protein-Tyrosine Kinases
  • Protein-Serine-Threonine Kinases