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.

EGFR Inhibitors as Therapeutic Agents in Head and Neck Cancer

“…In the EGFR-dependent activation of NF-κB, phosphorylated EGFR activates PI3K, ERK1/2, and STAT3, all of which are associated with increased NF-κB activity (Fig. 4.3) [116]. RNAi knockdown of components of the NF-κB pathway and pharmacologic inhibition of NF-κB enhanced cell death induced by erlotinib in EGFR-mutant lung cancer cells [119] support relevance of this signaling axis.…”

“…NF-κB induction of matrix metalloproteinase-1, -2, -9, and -14 fibronectin and ß1 integrin, and vascular endothelial growth factor C, is strongly associated with tumor progression and metastasis [115]. In SCCHN, NF-κB activation has been described as both independent of and dependent on EGFR signaling [116]- [118]. In the EGFR-dependent activation of NF-κB, phosphorylated EGFR activates PI3K, ERK1/2, and STAT3, all of which are associated with increased NF-κB activity (Fig.…”

High Energy Particle Radiation-associated Oncogenic Transformation in Normal Mice: Insight into the Connection between Activation of Oncotargets and Oncogene Addiction

“…Total RNA extraction and real-time QPCR profiling were performed at 30 days post-exposure as described earlier2021. We used custom-made transcriptome profilers (www.Realtimeprimers.com) pertaining to interacting functional networks of oncogene addiction.…”

Anti-Pancreatic Cancer Deliverables from Sea: First-Hand Evidence on the Efficacy, Molecular Targets and Mode of Action for Multifarious Polyphenols from Five Different Brown-Algae

“…Panc-1, Panc-3.27, BxPC-3 and Mia-PaCa-2 cells (5×10 5 cells) grown in 4-well plate (Nunc) treated with 100 µg/ml of dichloromethane (DD-DCM, SA-DCM, SM-DCM, PT-DCM, HT-DCM) or ethyl acetate (DD-EA, SA-EA, SM-EA, PT-EA, HT-EA) fractions were analyzed after 24 h for nuclear morphology as described earlier [21].…”