Abstract 4555: Design and discovery of novel small molecule redox modulators as therapies for pancreatic cancer.

Abstract

Abstract Pancreatic cancer is a complex disease. Late stage detection, poor prognosis, and resistance to available chemotherapeutics highlight the need to discover new and potent anticancer agents for its effective treatment. Altered cellular bioenergetics and oxidative stress are emerging hallmarks of most forms of cancer including pancreatic cancer. Cancer cells are more prone to reactive oxygen species (ROS)-mediated cell death due to their inherent elevated basal oxidative stress as compared to normal cells. Increased basal ROS levels could represent the Achilles’ heel of cancer cells. Even though cancer cells have adapted to survive in an oxidative stress environment, exogenous oxidative insults can overwhelm the adaptive antioxidant capacity of cancer cells and trigger ROS-mediated cell death We have identified a novel class of compounds that act as redox modulators and specifically induce cell death in cancer cells. Compound 3a was identified through a medium throughput screen of ∼1000 highly diverse in-house compounds and chemotherapeutic agents for their ability to alter cellular bioenergetics using XF 24 extracellular flux analyzer (Seahorse Bioscience, Billerica, MA). Further structural optimizations led to the discovery of a more potent analog, 3b that displayed anti-proliferative activities at low micromolar levels in both drug-sensitive and drug-resistant cancer cell lines. Treatment with compound 3b causes Akt activation resulting in increased cellular oxygen consumption, oxidative stress and depletion of cellular antioxidant pool in pancreatic cancer cells. Akt is a pro-survival kinase that is upregulated in several forms of human cancers. Hyperactive Akt inhibits apoptosis induced by numerous stimuli. However, Akt is unable to inhibit ROS-mediated cell death, and in fact, Akt aids in ROS-directed cell death by inducing cellular oxygen consumption, promoting ROS generation, and impairing ROS degeneration. Moreover, oxidative stress induced by 3b promoted activation of stress kinases (p38/JNK) and resulted in cancer cell apoptosis. Treatment with antioxidants was able to reduce cell death confirming ROS-mediated cytotoxicity. In conclusion, our novel class of compounds are promising leads that by exacerbating oxygen consumption, ROS production, and reducing the antioxidant capacity of cancer cells tip the balance towards activation of stress kinases that ultimately leads to cell death. Citation Format: Divya Pathania, Mario Sechi, Michele Palomba, Vanna Sanna, Francesco Berrettini, Angela Sias, Laleh Taheri, Nouri Neamati. Design and discovery of novel small molecule redox modulators as therapies for pancreatic cancer. [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 4555. doi:10.1158/1538-7445.AM2013-4555