Sensitization of retinoids and corticoids to epigenetic drugs in MYC-activated lung cancers by antitumor reprogramming

Oncogene. 2017 Mar 2;36(9):1287-1296. doi: 10.1038/onc.2016.296. Epub 2016 Sep 5.

Abstract

Components of the SWI/SNF chromatin remodeling complex, including BRG1 (also SMARCA4), are inactivated in cancer. Among other functions, SWI/SNF orchestrates the response to retinoid acid (RA) and glucocorticoids (GC) involving downregulation of MYC. The epigenetic drugs SAHA and azacytidine, as well as RA and GC, are currently being used to treat some malignancies but their therapeutic potential in lung cancer is not well established. Here we aimed to determine the possible therapeutic effects of azacytidine and SAHA (A/S) alone or in combination with GC plus RA (GC/RA) in lung cancers with either BRG1 inactivation or MYC amplification. In vitro, responses to GC/RA treatment were more effective in MYC-amplified cells. These effects were mediated by BRG1 and involved a reprogramming towards prodifferentiation gene expression signatures and downregulation of MYC. In MYC-amplified cells, administration of GC/RA enhanced the cell growth inhibitory effects of A/S which, in turn, accentuated the prodifferentiation features promoted by GC/RA. Finally, these treatments improved overall survival of mice orthotopically implanted with MYC-amplified, but not BRG1-mutant, cells and reduced tumor cell viability and proliferation. We propose that the combination of epigenetic treatments with retinoids and corticoids of MYC-driven lung tumors constitute a strategy for therapeutic intervention in this otherwise incurable disease.

MeSH terms

  • Animals
  • Antimetabolites, Antineoplastic / pharmacology
  • Antineoplastic Agents / pharmacology
  • Apoptosis / drug effects
  • Azacitidine / pharmacology*
  • Biomarkers, Tumor / genetics
  • Biomarkers, Tumor / metabolism
  • Cell Proliferation / drug effects
  • DNA Helicases / genetics
  • DNA Methylation
  • Drug Resistance, Neoplasm / drug effects*
  • Glucocorticoids / pharmacology*
  • Histone Deacetylase Inhibitors / pharmacology
  • Humans
  • Hydroxamic Acids / pharmacology*
  • Lung Neoplasms / drug therapy*
  • Lung Neoplasms / genetics
  • Lung Neoplasms / pathology
  • Male
  • Mice
  • Mice, Nude
  • Mutation / genetics
  • Nuclear Proteins / genetics
  • Proto-Oncogene Proteins c-myc / genetics
  • Proto-Oncogene Proteins c-myc / metabolism*
  • Transcription Factors / genetics
  • Tretinoin / pharmacology*
  • Tumor Cells, Cultured
  • Vorinostat
  • Xenograft Model Antitumor Assays

Substances

  • Antimetabolites, Antineoplastic
  • Antineoplastic Agents
  • Biomarkers, Tumor
  • Glucocorticoids
  • Histone Deacetylase Inhibitors
  • Hydroxamic Acids
  • MYC protein, human
  • Nuclear Proteins
  • Proto-Oncogene Proteins c-myc
  • Transcription Factors
  • Tretinoin
  • Vorinostat
  • SMARCA4 protein, human
  • DNA Helicases
  • Azacitidine