Abstract 1875: A novel series of metabolic activators of PKM2 alter oncogene-meditated changes in tumor cell metabolism.

Rather than relying on oxidative phosphorylation for the generation of ATP, human tumor cells primarily utilize aerobic glycolysis to metabolize glucose (the Warburg effect). Pyruvate kinase is a metabolic enzyme that converts phosphoenolpyruvate (PEP) to pyruvate, catalyzing the rate-limiting step of glycolysis. The M1 isoform of pyruvate kinase (PKM1) that is the principal isoform in most adult differentiated tissues, while the PKM2 splice variant is the main isoform in embryonic tissues and in all cancer cells. Unlike the M1 splice form (PKM1), which is found in its tetrameric active form in cells, PKM2 is found in cells as an inactive dimer under normal physiological conditions. Tetramerization of PKM2 requires binding of the allosteric activator fructose-1,6-bisphosphate (FBP), an upstream glycolytic intermediate, resulting in a fully active enzyme. Regulation of PKM2 activity in cancer cells may allow glycolytic intermediates to be diverted into other biosynthetic pathways necessary for biomass production. PKM2 expression enhances tumorigenicity of cells while PKM1 expression represses it. This suggests that activators of PKM2 may have anti-tumor properties by forcing PKM2 to act more like PKM1. We have a series of small molecule PKM2 activators that exhibit low nM activation activity in biochemical and cell-based assays. These compounds increase pyruvate kinase activity in cancer cells and lead to an increase in pyruvate and ATP production. Our studies show that PKM2 activators inhibit the growth of lung cancer cell lines in vitro and in vivo and can reverse the metabolic changes induced by oncogenes such as k-Ras and c-Myc in lung cancer cells. The current lead compound was tested in established subcutaneously implanted A549 lung adenocarcinoma xenografts, where we observed a statistically significant 54% decrease in tumor growth, with no observable toxicity. These data suggest that this class of PKM2 activators is effective as tumor cell metabolic regulators with anti-tumor activity for lung cancer and potentially other malignancies. Citation Format: Brigham L. Bahr, Jenny Stevens, Spencer Squire, Christopher Moreno, Lee T. Call, Bret J. Stephens, Alexis Mollard, Steven L. Warner, David J. Bearss. A novel series of metabolic activators of PKM2 alter oncogene-meditated changes in tumor cell metabolism. [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 1875. doi:10.1158/1538-7445.AM2013-1875