Abstract 4912: Hyperthermia induced NO repressed NFκB regulates IR-induced EMT, CSC self-renewal and pluripotency

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Abstract Based on clinical evidence, hyperthermia treatment (HT) in combination with radiation (IR) achieves superior local control for recurrent chest wall breast cancer (BCa). The effect of HT combined with IR is due partly to its independent cytotoxic effects, and partly to its radiosensitizing effect. Recently, we have shown that apoptosis upon hyperthermia of BCa cells is regulated by NO-mediated suppression of NFκB. Also, we have demonstrated that tumor cells that survive a course of IR are instrumental in tumor relapse and progression. Accordingly, we investigated whether HT exerts NO-NFκB axis dependent regulation of IR-induced alterations in factors that drive the EMT, CSCs self-renewal capacity and pluripotency maintenance in surviving BCa Cells. Human breast adenocarcinoma (MCF-7) cells either mock-irradiated or exposed IR (2Gy) with or without HT (43°C for 1h) were analyzed for transcriptional regulation of 93 stem cell related molecules using QPCR profiling. NFκB (p50/p65) overexpression, muting by ΔIκBα (with IR) and NO induction by SNP (with HT) approach were used to delineate the role of HT-induced NO and the selective targeting of IR-induced NFκB. Nanog, Sox-2, ABCG-2, N-Cadherin and Myc expressions were examined with immunoblotting. IR profoundly increased the transactivation of 80 stem-cell related molecules. Interestingly, HT reverted the activation of 79 IR-induced genes. Attenuation of all 80 IR-induced genes observed after blocking NFκB with ΔIκBα and by increasing intracellular NO with SNP demonstrated the significant role of NO dependent NFκB suppression in HT-induced inhibition of IR modulated stem-cell related transcriptome. Expression levels of Nanog, Sox-2, ABCG-2, N-Cadherin and Myc validates the potential of HT in mitigating IR-induced stemness. Together this data demonstrates that HT attenuates IR-induced stemness in BCa cells and further imply that HT induced increase in NO may alleviate stemness by selectively targeting IR-induced NFκB. Citation Format: Corinne Dinges, Mohan Natarajan, Sheeja Aravindan, Terence S. Herman, Natarajan Aravindan. Hyperthermia induced NO repressed NFκB regulates IR-induced EMT, CSC self-renewal and pluripotency. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4912. doi:10.1158/1538-7445.AM2014-4912