The dual EGFR/HER2 inhibitor lapatinib synergistically enhances the antitumor activity of the histone deacetylase inhibitor panobinostat in colorectal cancer models

Melissa J LaBonte, Peter M Wilson, Will Fazzone, Jared Russell, Stan G Louie, Anthony El-Khoueiry, Heinz-Josef Lenz, Robert D Ladner, Melissa LaBonte Wilson

Research output: Contribution to journalArticlepeer-review

71 Citations (Scopus)

Abstract

As key molecules that drive progression and chemoresistance in gastrointestinal cancers, epidermal growth factor receptor (EGFR) and HER2 have become efficacious drug targets in this setting. Lapatinib is an EGFR/HER2 kinase inhibitor suppressing signaling through the RAS/RAF/MEK (MAP/ERK kinase)/MAPK (mitogen-activated protein kinase) and PI3K (phosphoinositide 3-kinase)/AKT pathways. Histone deacetylase inhibitors (HDACi) are a novel class of agents that induce cell cycle arrest and apoptosis following the acetylation of histone and nonhistone proteins modulating gene expression and disrupting HSP90 function inducing the degradation of EGFR-pathway client proteins. This study sought to evaluate the therapeutic potential of combining lapatinib with the HDACi panobinostat in colorectal cancer (CRC) cell lines with varying EGFR/HER2 expression and KRAS/BRAF/PIK3CA mutations. Lapatinib and panobinostat exerted concentration-dependent antiproliferative effects in vitro (panobinostat range 7.2-30 nmol/L; lapatinib range 7.6-25.8 μmol/L). Combined lapatinib and panobinostat treatment interacted synergistically to inhibit the proliferation and colony formation in all CRC cell lines tested. Combination treatment resulted in rapid induction of apoptosis that coincided with increased DNA double-strand breaks, caspase-8 activation, and PARP cleavage. This was paralleled by decreased signaling through both the PI3K and MAPK pathways and increased downregulation of transcriptional targets including NF-κB1, IRAK1, and CCND1. Panobinostat treatment induced downregulation of EGFR, HER2, and HER3 mRNA and protein through transcriptional and posttranslational mechanisms. In the LoVo KRAS mutant CRC xenograft model, the combination showed greater antitumor activity than either agent alone, with no apparent increase in toxicity. Our results offer preclinical rationale warranting further clinical investigation combining HDACi with EGFR and HER2-targeted therapies for CRC treatment.

Original languageEnglish
Pages (from-to)3635-48
Number of pages14
JournalCancer Research
Volume71
Issue number10
DOIs
Publication statusPublished - 15 May 2011

Bibliographical note

©2011 AACR

Keywords

  • Animals
  • Antineoplastic Agents
  • Apoptosis
  • Cell Line, Tumor
  • Cell Proliferation
  • Colorectal Neoplasms
  • Histone Deacetylase Inhibitors
  • Humans
  • Hydroxamic Acids
  • Indoles
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mutation
  • Neoplasm Transplantation
  • Quinazolines
  • Receptor, Epidermal Growth Factor
  • Receptor, ErbB-2
  • Signal Transduction

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