Design and discovery of novel quinazolinedione-based redox modulators as therapies for pancreatic cancer

Background: Altered cellular bioenergetics and oxidative stress are emerging hallmarks ofmost cancers including
pancreatic cancer. Elevated levels of intrinsic reactive oxygen species (ROS) in tumors make them more susceptible
to exogenously induced oxidative stress. Excessive oxidative insults overwhelm their adaptive antioxidant
capacity and trigger ROS-mediated cell death. Recently, we have discovered a novel class of quinazolinediones
that exert their cytotoxic effects by modulating ROS-mediated signaling.
Methods: Cytotoxic potentialwas determined by colorimetric and colony formation assays. An XF24 Extracellular
Flux Analyzer, and colorimetric and fluorescent techniques were used to assess the bioenergetics and oxidative
stress effects, respectively. Mechanism was determined by Western blots.
Results: Compound 3a (6-[(2-acetylphenyl)amino]quinazoline-5,8-dione) was identified through a medium
throughput screen of ~1000 highly diverse in-house compounds and chemotherapeutic agents for their ability
to alter cellular bioenergetics. Further structural optimizations led to the discovery of a more potent analog, 3b
(6-[(3-acetylphenyl)amino]quinazoline-5,8-dione) that displayed anti-proliferative activities in lowmicromolar
range in both drug-sensitive and drug-resistant cancer cells. Treatmentwith 3b causes Akt activation resulting in
increased cellular oxygen consumption and oxidative stress in pancreatic cancer cells. Moreover, oxidative stress
induced by 3b promoted activation of stress kinases (p38/JNK) resulting in cancer cell death. Treatmentwith antioxidants
was able to reduce cell death confirming ROS-mediated cytotoxicity.
Conclusion: In conclusion, our novel quinazolinediones are promising lead compounds that selectively induce
ROS-mediated cell death in cancer cells and warrant further preclinical studies.
General significance: Since 3b (6-[(3-acetylphenyl)amino]quinazoline-5,8-dione) exerts Akt-dependent ROSmediated
cell death, itmight provide potential therapeutic options for chemoresistant and Akt-overexpressing cancers.