Inverse PPARβ/δ agonists suppress oncogenic signaling to the ANGPTL4 gene and inhibit cancer cell invasion

Oncogene. 2013 Oct 31;32(44):5241-52. doi: 10.1038/onc.2012.549. Epub 2012 Dec 3.

Abstract

Besides its established functions in intermediary metabolism and developmental processes, the nuclear receptor peroxisome proliferator-activated receptor β/δ (PPARβ/δ) has a less defined role in tumorigenesis. In the present study, we have identified a function for PPARβ/δ in cancer cell invasion. We show that two structurally divergent inhibitory ligands for PPARβ/δ, the inverse agonists ST247 and DG172, strongly inhibit the serum- and transforming growth factor β (TGFβ)-induced invasion of MDA-MB-231 human breast cancer cells into a three-dimensional matrigel matrix. To elucidate the molecular basis of this finding, we performed chromatin immunoprecipitation sequencing (ChIP-Seq) and microarray analyses, which identified the gene encoding angiopoietin-like 4 (ANGPTL4) as the major transcriptional PPARβ/δ target in MDA-MB-231 cells, previously implicated in TGFβ-mediated tumor progression and metastatic dissemination. We show that the induction of ANGPTL4 by TGFβ and other oncogenic signals is strongly repressed by ST247 and DG172 in a PPARβ/δ-dependent fashion, resulting in the inhibition of ANGPTL4 secretion. This effect is attributable to these ligands' ability to induce a dominant transcriptional repressor complex at the site of transcription initiation that blocks preinitiation complex formation through an histone deacetylase-independent, non-canonical mechanism. Repression of ANGPTL4 transcription by inverse PPARβ/δ agonists is functionally linked to the inhibition of cancer cell invasion into a three-dimensional matrix, as (i) invasion of MDA-MB-231 cells is critically dependent on ANGPTL4 expression, (ii) recombinant ANGPTL4 stimulates invasion, and (iii) reverses the inhibitory effect of ST247 and DG172. These findings indicate that a PPARβ/δ-ANGPTL4 pathway is involved in the regulation of tumor cell invasion and that its pharmacological manipulation by inverse PPARβ/δ agonists is feasible.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acrylonitrile / analogs & derivatives*
  • Acrylonitrile / pharmacology
  • Angiopoietin-like 4 Protein
  • Angiopoietins / genetics*
  • Angiopoietins / metabolism
  • Binding Sites
  • Cell Line, Tumor
  • Cell Movement
  • Gene Expression Regulation, Neoplastic
  • Histone Deacetylases / metabolism
  • Humans
  • Neoplasm Invasiveness
  • PPAR delta / agonists
  • PPAR delta / physiology*
  • Piperazines / pharmacology*
  • Retinoid X Receptors / metabolism
  • Signal Transduction*
  • Sulfonamides / pharmacology*
  • Thiophenes / pharmacology*
  • Transcription Initiation, Genetic / drug effects
  • Transforming Growth Factor beta / physiology

Substances

  • 2-(2-bromophenyl)-3-((4-(1-methylpiperazine)amino)phenyl)acrylonitrile
  • ANGPTL4 protein, human
  • Angiopoietin-like 4 Protein
  • Angiopoietins
  • PPAR delta
  • Piperazines
  • Retinoid X Receptors
  • Sulfonamides
  • Thiophenes
  • Transforming Growth Factor beta
  • methyl 3-(N-(4-(hexylamino)-2-methoxyphenyl)sulfamoyl)thiophene-2-carboxylate
  • Histone Deacetylases
  • Acrylonitrile