PI3K pathway regulates ER-dependent transcription in breast cancer through the epigenetic regulator KMT2D

Science. 2017 Mar 24;355(6331):1324-1330. doi: 10.1126/science.aah6893.

Abstract

Activating mutations in PIK3CA, the gene encoding phosphoinositide-(3)-kinase α (PI3Kα), are frequently found in estrogen receptor (ER)-positive breast cancer. PI3Kα inhibitors, now in late-stage clinical development, elicit a robust compensatory increase in ER-dependent transcription that limits therapeutic efficacy. We investigated the chromatin-based mechanisms leading to the activation of ER upon PI3Kα inhibition. We found that PI3Kα inhibition mediates an open chromatin state at the ER target loci in breast cancer models and clinical samples. KMT2D, a histone H3 lysine 4 methyltransferase, is required for FOXA1, PBX1, and ER recruitment and activation. AKT binds and phosphorylates KMT2D, attenuating methyltransferase activity and ER function, whereas PI3Kα inhibition enhances KMT2D activity. These findings uncover a mechanism that controls the activation of ER by the posttranslational modification of epigenetic regulators, providing a rationale for epigenetic therapy in ER-positive breast cancer.

Publication types

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

MeSH terms

  • Animals
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / therapy*
  • Chromatin / metabolism
  • Class I Phosphatidylinositol 3-Kinases / genetics
  • Class I Phosphatidylinositol 3-Kinases / metabolism*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Epigenesis, Genetic*
  • Female
  • HEK293 Cells
  • Hepatocyte Nuclear Factor 3-alpha / genetics
  • Hepatocyte Nuclear Factor 3-alpha / metabolism
  • Humans
  • Lysine / genetics
  • Lysine / metabolism
  • MCF-7 Cells
  • Metabolic Networks and Pathways
  • Methyltransferases / genetics
  • Methyltransferases / metabolism*
  • Mice
  • Mice, Nude
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / metabolism*
  • Pre-B-Cell Leukemia Transcription Factor 1
  • Protein Processing, Post-Translational
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptors, Estrogen / genetics
  • Receptors, Estrogen / metabolism*
  • Transcription, Genetic*

Substances

  • Chromatin
  • DNA-Binding Proteins
  • FOXA1 protein, human
  • Hepatocyte Nuclear Factor 3-alpha
  • KMT2D protein, human
  • Neoplasm Proteins
  • Pre-B-Cell Leukemia Transcription Factor 1
  • Proto-Oncogene Proteins
  • Receptors, Estrogen
  • pbx1 protein, human
  • Methyltransferases
  • Class I Phosphatidylinositol 3-Kinases
  • PIK3CA protein, human
  • AKT1 protein, human
  • Proto-Oncogene Proteins c-akt
  • Lysine