Abstract 4547: Diazeniumdiolate-based nitric oxide-releasing prodrugs kill lung adenocarcinoma cells in culture and in vivo through alterations in cellular redox balance leading to mitochondrially-mediated apoptosis
Authors: Maciag Anna E. , Chakrapani Harinath , Holland Ryan J. , Morris Nicole L. , Shami Paul J. , Saavedra Joseph E. , Anderson Lucy M. , Keefer Larry K. 
Published: February 2011

Abstract
Lung cancer is the most common and among the most deadly of human malignancies. Early detection is unusual and there are no completely effective therapies in most cases. Diazeniumdiolate-based nitric oxide (NO)-releasing prodrugs are a growing class of promising NO-based therapeutics. Here we show that JS-K (O2-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate) and its homopiperazine analogue are potent tumoristatic agents against non-small cell lung cancer (NSCLC) cells both in vitro and as xenografts in mice. Drug treatment led to 75 - 85% reduction of the growth of H1703 cells in vivo.
The diazeniumdiolate-based NO-releasing compounds displayed a multifaceted mode of action, involving oxidative/nitrosative stress, DNA strand break damage, MnSOD tyrosine nitration and activation of cellular stress signaling. In the NSCLC cells the drugs altered glutathione homeostasis to increase the ratio of oxidized to reduced forms. Altered cellular redox potential associated with Bax dimerization and translocation to mitochondria. Apoptosis was triggered by disruption of the mitochondrial membrane potential leading to membrane permeabilization and cytochrome c release. Apoptosis was induced via a caspase-dependent mechanism and was p53 independent. Activation of effector caspases 3 and 7, cleavage of their nuclear substrate PARP, and morphological changes specific for apoptosis were detected in less than one hour after drug treatment.
The effectiveness of the drugs was significantly correlated with pre-existing high levels of reactive oxygen species (ROS). Many cancer cell types, especially in advanced stage tumors, exhibit increased levels of ROS, and these high-ROS cells are likely to be more vulnerable to damage by further ROS/RNS released from exogenous sources than nonmalignant cells. In the present work, we have identified a subset of 30% of lung adenocarcinoma cell lines that are characterized by high levels of ROS and show that this property of lung cancer cells could be exploited for therapeutic benefits. The levels of endogenous ROS correlated significantly with the drug's toxicity measured as IC50 values. Low levels of peroxide-scavengers peroxiredoxins 1 and 6, and of the DNA repair enzyme OGG1, predispose for the drug's toxicity and could be biomarkers for sensitive tumors. Taken together, the data suggest that diazeniumdiolate-based NO-releasing prodrugs may have application as a personalized therapy for lung cancer, against tumors characterized by high levels of ROS and/or low levels of antioxidant defense/DNA repair mechanisms.
Funded in part under contract HHSN261200800001E
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4547.