Abstract 1406: Design and synthesis of novel cardiac glycosides by targeting the DNA damage response for cancer therapy

Abstract Cardiac Glycosides (CGs) are used to treat congestive heart disease. Their application has since been extended to cancer treatment. While the mechanism of action is still unknown, it was previously believed that Na+/K+ ATPase might play a crucial role in cancer mitigation. However, we recently reported that cardiac glycosides could specifically enhance the anti-cancer effect of chemotherapy in KRAS mutant lung cancer by inhibiting the DNA Damage Response (DDR), and these effects were independent of the Na+/K+ ATPase. Mechanistically, we showed that cardiac glycosides induced the degradation of UHRF1, an important player in promoting DNA double strand break (DSB) repair through homologous recombination. These results suggest the promise of derivatizing cardiac glycosides into potential chemo sensitizing agents. Yet, one of the major challenges with these compounds is their cardiotoxicity. This has created a need for developing a strategy to generate less cardiotoxic drugs that are effective in inhibiting the DNA damage response to safe and effective anticancer activity. Herein we report a multi-step synthetic route utilizing k-strophanthidin as the initial building block. A systematic structural design was applied that included modification of the sugar moiety, glycoside linker, stereochemistry, and lactone ring to create a library of O-glycosides and MeON-neoglycosides. These molecules were screened for anti-cancer properties by exploring their influence on the signaling/expression of various downstream kinases in the DDR pathway. We discovered the inhibitory activity of O-glycosides to be more potent than the MeON-neoglycosides or benzylidene-lactone modified compounds. These results demonstrate the ability to chemically synthesize CG derivatives to optimize for anticancer activity with the goal of identifying less cardiotoxic CGs. Citation Format: Diana Ainembabazi, Xinran Geng, Navnath Gavande, YouWei Zhang, John Turchi. Design and synthesis of novel cardiac glycosides by targeting the DNA damage response for cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1406.