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

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.

• Authors: Natarajan Aravindan, Charles R Thomas Jr, Sheeja Aravindan, Aswathi S Mohan, Jamunarani Veeraraghavan, Mohan Natarajan
• Journal: PloS one (PLoS One) Vol. 6 Issue 12 Pg. e29705 ( 2011) ISSN: 1932-6203 [Electronic] United States
• PMID: 22242139 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• 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

Topics

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