Novel Synthetic Monoketone Transmute Radiation-Triggered NFκB-Dependent TNFα Cross-Signaling Feedback Maintained NFκB and Favors Neuroblastoma Regression

Sheeja Aravindan,Natarajan Aravindan,Vibhudutta Awasthi,Terence S Herman,Mohan Natarajan,Zhaozhong Han

doi:10.1371/journal.pone.0072464

Abstract

Recently, we demonstrated that radiation (IR) instigates the occurrence of a NFκB-TNFα feedback cycle which sustains persistent NFκB activation in neuroblastoma (NB) cells and favors survival advantage and clonal expansion. Further, we reported that curcumin targets IR-induced survival signaling and NFκB dependent hTERT mediated clonal expansion in human NB cells. Herein, we investigated the efficacy of a novel synthetic monoketone, EF24, a curcumin analog in inhibiting persistent NFκB activation by disrupting the IR-induced NFκB-TNFα-NFκB feedback signaling in NB and subsequent mitigation of survival advantage and clonal expansion. EF24 profoundly suppressed the IR-induced NFκB-DNA binding activity/promoter activation and, maintained the NFκB repression by deterring NFκB-dependent TNFα transactivation/intercellular secretion in genetically varied human NB (SH-SY5Y, IMR-32, SK–PN–DW, MC-IXC and SK–N-MC) cell types. Further, EF24 completely suppressed IR-induced NFκB-TNFα cross-signaling dependent transactivation/translation of pro-survival IAP1, IAP2 and Survivin and subsequent cell survival. In corroboration, EF24 treatment maximally blocked IR-induced NFκB dependent hTERT transactivation/promoter activation, telomerase activation and consequent clonal expansion. EF24 displayed significant regulation of IR-induced feedback dependent NFκB and NFκB mediated survival signaling and complete regression of NB xenograft. Together, the results demonstrate for the first time that, novel synthetic monoketone EF24 potentiates radiotherapy and mitigates NB progression by selectively targeting IR-triggered NFκB-dependent TNFα-NFκB cross-signaling maintained NFκB mediated survival advantage and clonal expansion.

Highlights

In United States, each year 650 children are diagnosed with neuroblastoma (NB) [1], an embryonal malignancy of sympathetic nervous system that is remarkable for its clinical heterogeneity [2]
We have shown that IR-induced PFC-dependent NFκBmediates survival advantage after RT [13] and, we investigated the potential of EF24 in the regulation of IR-induced NFκB-mediated IAP1, IAP2, Survivin and subsequent survival advantage
As RT is widely used in the treatment of NB in combination with chemotherapy, surgery, immunotherapy and/or stem cell therapy, any means of potentiating IR-induced cell killing and mitigating radioresistance in surviving tumor cells would highly benefit these children

Summary

Introduction

In United States, each year 650 children are diagnosed with neuroblastoma (NB) [1], an embryonal malignancy of sympathetic nervous system that is remarkable for its clinical heterogeneity [2]. High recurrence rate (20.2%) entailing substantial fractions of both local (17%-74% of patients) [4,5,6,7,8] and distant metastasis (46.8%) present considerable challenges for the clinical management of NB. Clinical and laboratory evidence suggests that several human cancers contain populations of rapidly proliferating clonogens that can have substantial impact on local control following chemoradiotherapy [9]. We demonstrated the radiation triggered NFκB initiates TNFα cross signaling dependent maintenance of NFκB that in turn promotes survival advantage in both in vitro and in vivo NB models [13]. To that end, identifying ‘drug-deliverables’ that selectively disrupt IRinduced NFκB-TNFα feedback signaling and impedes NFκB maintenance could deter NFκB-dependent survival advantage and potentiate RT in NB cure

Methods

Results

Conclusion