NF-κB mediates radio-sensitization by the PARP-1 inhibitor, AG-014699

Hunter, J., Willmore, Elaine, Irving, J. A. E, Hostomsky, Z., Veuger, Stephany and Durkacz, Barbara (2012) NF-κB mediates radio-sensitization by the PARP-1 inhibitor, AG-014699. Oncogene, 31 (2). pp. 251-264. ISSN 0950-9232

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Abstract

The stress-inducible transcription factor, nuclear factor (NF)-κB induces genes involved in proliferation and apoptosis. Aberrant NF-κB activity is common in cancer and contributes to therapeutic-resistance. Poly(ADP-ribose) polymerase-1 (PARP-1) is activated during DNA strand break repair and is a known transcriptional co-regulator. Here, we investigated the role of PARP-1 function during NF-κB activation using p65 small interfering RNA (siRNA), PARP siRNA or the potent PARP-1 inhibitor, AG-014699. Survival and apoptosis assays showed that NF-κB p65−/− cells were more sensitive to ionizing radiation (IR) than p65+/+ cells. Co-incubation with p65 siRNA, PARP siRNA or AG-014699 radio-sensitized p65+/+, but not p65−/− cells, demonstrating that PARP-1 mediates its effects on survival via NF-κB. Single-strand break (SSB) repair kinetics, and the effect SSB repair inhibition by AG-014699 were similar in p65+/+ and p65−/− cells. As preventing SSB repair did not radio-sensitize p65−/− cells, we conclude that radio-sensitization by AG-014699 is due to downstream inhibition of NF-κB activation, and independent of SSB repair inhibition. PARP-1 catalytic activity was essential for IR-induced p65 DNA binding and NF-κB-dependent gene transcription, whereas for tumor necrosis factor (TNF)-α-treated cells, PARP-1 protein alone was sufficient. We hypothesize that this stimulus-dependent differential is mediated via stimulation of the poly(ADP-ribose) polymer, which was induced following IR, not TNF-α. Targeting DNA damage-activated NF-κB using AG-014699 may therefore overcome toxicity observed with classical NF-κB inhibitors without compromising other vital inflammatory functions. These data highlight the potential of PARP-1 inhibitors to overcome NF-κB-mediated therapeutic resistance and widens the spectrum of cancers in which these agents may be utilized.

Item Type:	Article
Uncontrolled Keywords:	PARP-1, NF-κB, radio-sensitization, AG-014699, PAR
Subjects:	C700 Molecular Biology, Biophysics and Biochemistry
Department:	Faculties > Health and Life Sciences > Applied Sciences
Depositing User:	Ay Okpokam
Date Deposited:	29 Mar 2017 11:45
Last Modified:	11 Oct 2019 14:17
URI:	http://nrl.northumbria.ac.uk/id/eprint/30274

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