Abstract

Abstract NAD(P)H: quinone oxidoreductase (NQO1) is a cytosolic redox-regulating enzyme modulated by Nrf2-mediated stress signaling pathways, with an established role in regulation of stress-related transcription factors. In these studies we investigate the role of NQO1 in regulation of mitogen-activated protein kinase (MAPK) signaling pathways. Quantitative PCR and western blot studies showed that constitutive levels of several MAPK members are upregulated in NQO1-null mouse skin as well as in skin-derived keratinocytes, relative to WT. However, though total protein levels are increased, inducibility of these kinases by known MAPK inducers such as EGF and benzo[a]pyrene (BP) is significantly decreased in NQO1-null cells. NQO1 regulation of MAPK signaling was confirmed by studies showing that NQO1 knockdown by siRNA led to decreased MAPK activation, and overexpression of NQO1 protein led to increased MAPK activation by EGF. Similarly, downregulation of activity via dicoumarol caused loss of ERK phosphorylation, while NQO1 activation via t-BHQ caused increased ERK phosphorylation, which was blocked by MAPK pathway-specific inhibitors. To investigate the functional role of MAPK deactivation in skin-derived keratinocytes, studies with BP and menadione showed that lack of NQO1 expression led to increased susceptibility to ROS generation, and that this ROS generation causes increased toxicity. Taken together, these results show a significant role for NQO1 in regulation of MAPK signaling pathways, which ultimately lead to protection against ROS-mediated apoptosis. Citation Format: Brad A. Patrick, Anil K. Jaiswal. NAD(P)H:quinone oxidoreductase 1 (NQO1) regulates MAPK activation and cellular protection against chemical stress. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4306. doi:10.1158/1538-7445.AM2013-4306

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