Abstract 3094: Interferon-α induced TLR4 is indispensable for the synergistic induction of Duox2/DuoxA2 by lipopolysacharide (LPS) and IFN-γ in human pancreatic cancer cells

Abstract

Abstract Several bacterial cell wall components, including lipopolysaccharide (LPS), muramyldipeptide (MDP), and flagellin, have been shown to engage their corresponding receptors and mediate NADPH oxidase (NOX)-dependent reactive oxygen species (ROS) generation that may be involved in wound healing, host defense, and the inflammatory response in airway and gastrointestinal epithelial cells. Previously, we reported that two human pancreatic cancer cell lines, BxPC-3 and AsPC-1, respond to the pro-inflammatory cytokine IFN-γ by upregulating the expression of both Dual oxidase 2 and its cognate cofactor DuoxA2 resulting in enhanced ROS production. It has also been reported that human pancreatic cancer cells express TLR4/MyD88, and that signaling downstream of the TLR receptor may be responsible for LPS-induced invasiveness of pancreatic cancer cells. In our studies, we have demonstrated that IFN-γ up-regulates TLR4 and its adaptor protein MyD88 expression in BxPc-3 cells and augments the response of these cells to LPS, resulting in the activation of NFkB signaling, enhancing p65 subunit accumulation in the nucleus. Moreover, we found that p65 binds to the Duox2 promoter, and cooperates with the IFN-γ- induced Stat1 expression to synergistically enhance Duox2/DuoxA2 expression, leading to persistent intra- and extracellular ROS accumulation. TLR4 silencing by RNAi and two independent NF-kB inhibitors (PDTC and BAY11-70829) specifically attenuate LPS- and IFN-γ-mediated Duox2 expression in BxPc-3 cells, underscoring the importance of TLR4 engagement and the activation of NF-kB signaling in regulating Duox2 expression and subsequent ROS generation by LPS and IFN-γ. Our data suggest that sustained extracellular H2O2 accumulation, mediated by LPS- and IFN-γ- induced Duox2/DuoxA2 expression, may contribute to the deleterious effects of cytokine-mediated pancreatic inflammation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3094. doi:1538-7445.AM2012-3094