Irreversible EGFR inhibitor EKB-569 targets low-LET γ-radiation-triggered rel orchestration and potentiates cell death in squamous cell carcinoma

PLoS One. 2011;6(12):e29705. doi: 10.1371/journal.pone.0029705. Epub 2011 Dec 29.

Abstract

EKB-569 (Pelitinib), an irreversible EGFR tyrosine kinase inhibitor has shown potential therapeutic efficiency in solid tumors. However, cell-killing potential in combination with radiotherapy and its underlying molecular orchestration remain to be explored. The objective of this study was to determine the effect of EKB-569 on ionizing radiation (IR)-associated NFκB-dependent cell death. SCC-4 and SCC-9 cells exposed to IR (2Gy) with and without EKB-569 treatment were analyzed for transactivation of 88 NFκB pathway molecules, NFκB DNA-binding activity, translation of the NFκB downstream mediators, Birc1, 2 and 5, cell viability, metabolic activity and apoptosis. Selective targeting of IR-induced NFκB by EKB-569 and its influence on cell-fate were assessed by overexpressing (p50/p65) and silencing (ΔIκBα) NFκB. QPCR profiling after IR exposure revealed a significant induction of 74 NFκB signal transduction molecules. Of those, 72 were suppressed with EKB-569. EMSA revealed a dose dependent inhibition of NFκB by EKB-569. More importantly, EKB-569 inhibited IR-induced NFκB in a dose-dependent manner, and this inhibition was sustained up to at least 72 h. Immunoblotting revealed a significant suppression of IR-induced Birc1, 2 and 5 by EKB-569. We observed a dose-dependent inhibition of cell viability, metabolic activity and apoptosis with EKB-569. EKB-569 significantly enhanced IR-induced cell death and apoptosis. Blocking NFκB improved IR-induced cell death. Conversely, NFκB overexpression negates EKB-569 -induced cell-killing. Together, these pre-clinical data suggest that EKB-569 is a radiosensitizer of squamous cell carcinoma and may mechanistically involve selective targeting of IR-induced NFκB-dependent survival signaling. Further pre-clinical in-vivo studies are warranted.

Publication types

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

MeSH terms

  • Aminoquinolines / pharmacology*
  • Aniline Compounds / pharmacology*
  • Carcinoma, Squamous Cell / genetics
  • Carcinoma, Squamous Cell / pathology*
  • Cell Death / drug effects
  • Cell Death / radiation effects
  • Cell Line, Tumor
  • DNA, Neoplasm / metabolism
  • ErbB Receptors / antagonists & inhibitors*
  • ErbB Receptors / genetics
  • ErbB Receptors / metabolism
  • Gamma Rays*
  • Gene Expression Regulation, Neoplastic / drug effects
  • Gene Expression Regulation, Neoplastic / radiation effects
  • Humans
  • I-kappa B Kinase / metabolism
  • Linear Energy Transfer*
  • NF-kappa B / metabolism
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / metabolism
  • Protein Kinase Inhibitors / pharmacology*
  • Proto-Oncogene Proteins c-rel / metabolism*
  • Radiation-Sensitizing Agents / pharmacology
  • Signal Transduction / drug effects
  • Signal Transduction / radiation effects
  • Transcription, Genetic / drug effects
  • Transcription, Genetic / radiation effects
  • Up-Regulation / drug effects
  • Up-Regulation / radiation effects

Substances

  • Aminoquinolines
  • Aniline Compounds
  • DNA, Neoplasm
  • NF-kappa B
  • Neoplasm Proteins
  • Protein Kinase Inhibitors
  • Proto-Oncogene Proteins c-rel
  • Radiation-Sensitizing Agents
  • ErbB Receptors
  • I-kappa B Kinase
  • IKBKB protein, human
  • EKB 569