Abstract 1673: Alternative NF-κB signaling promotes inflammatory cell recruitment and lung tumor formation

Abstract

Abstract Nuclear factor-κB (NF-κB) is a transcription factor that can be activated through either the classical or alternative signaling pathways. In lung tumors, high levels of classical and alternative pathway components have been observed. While many studies have demonstrated that classical NF-κB signaling is a central pathway regulating inflammation and tumorigenesis, the role of alternative NF-κB signaling remains undefined. We hypothesize that alternative NF-κB signaling in the lung epithelium plays a key role in inflammation and lung tumor formation through paracrine signaling to the inflammatory microenvironment. To investigate alternative NF-κB signaling in the lung epithelium, we generated a transgenic mouse model with doxycycline (dox)-inducible expression of the alternative pathway component p52 in airway epithelial cells (designated ALTA for alternative pathway trans-activated). When placed on dox, nuclear p52 is increased in the lungs of ALTA mice with no effect on activation of other NF-κB components. Surprisingly, alternative pathway activation alone did not cause a significant increase in inflammatory cell recruitment. However, in conjunction with the inflammatory stimulus lipopolysaccharide (LPS), alternative pathway activation caused increased mortality, which was associated with a significant increase in inflammation and increased lung permeability. To determine the effect of alternative pathway activation on lung tumor formation, mice were injected with the lung carcinogen urethane. Six weeks after urethane administration, ALTA mice demonstrated an increased number of bronchoalveolar lavage neutrophils, and by 6 months post-urethane, ALTA mice had an increased number of tumors, increased tumor size, and more advanced lesions. Together, these data suggest that alternative NF-κB signaling plays an important role in stimulus-induced inflammatory cell recruitment and that alternative pathway activation can promote lung tumor formation and progression. By defining the role of alternative NF-κB signaling in tumor formation, we hope to gain insight into the role of inflammation in lung carcinogenesis and to identify novel pathways and signaling targets that could potentially serve as therapeutic targets. Citation Format: Jamie Alicyn Ausborn, Dong-Sheng Cheng, Vasiliy Polosukhin, Wei Han, Fiona Yull, Timothy Blackwell. Alternative NF-κB signaling promotes inflammatory cell recruitment and lung tumor formation. [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 1673. doi:10.1158/1538-7445.AM2014-1673