Cytotoxic and cytostatic effects of digitoxigenin monodigitoxoside (DGX) in human lung cancer cells and its link to Na,K-ATPase

• Published in: Biomedicine & pharmacotherapy 2018-01, Vol.97, p.684-696
• Main Authors: Schneider, Naira Fernanda Zanchett, Persich, Lara, Rocha, Sayonarah C., Ramos, Ana Carolina Pacheco, Cortes, Vanessa Faria, Silva, Izabella Thaís, Munkert, Jennifer, Pádua, Rodrigo M., Kreis, Wolfgang, Taranto, Alex G., Barbosa, Leandro A., Braga, Fernão C., Simões, Cláudia M.O.
• Format: Article
• Language: English
• Subjects: Cardenolides; Cell death; Digitoxigenin monodigitoxoside; Na,K-ATPase; Non-small cell lung cancer; Short and long-term analyses
• ISSN: 0753-3322; 1950-6007
• DOI: 10.1016/j.biopha.2017.10.128

[Display omitted] •DGX potently inhibits the growth of NSCLC cells.•DGX strongly induced cytotoxic effects on H460 cells.•DGX induced cytostatic effects on A549 cells.•DGX reduced cell survival in long-term analysis in both NSCLC.•DGX inhibited Na,K-ATPase activity on A549 cells, pig kidney and in human red blood cells. Cardiac glycosides (CGs) are natural compounds widely used to treat several cardiac conditions and more recently have been recognized as potential antitumor agents. They are known as Na,K-ATPases ligands, which is a promising drug target in cancer. In this study, the short and long-lasting cytotoxic effects of the natural cardenolide digitoxigenin monodigitoxoside (DGX) were evaluated against two non-small cell lung cancer lines (A549 and H460 cells). It was found that DGX induced cytotoxic effects in both cells and the apoptotic effects were more pronounced on H460 cells. In long-term analysis, using the clonogenic and the cumulative population doubling (CPD) assays, DGX showed a reduction of cell survival, after 15days without re-treatment. To better understand DGX effects in A549 cells, several assays were conducted. In cell cycle analysis, DGX caused an arrest in S and G2/M phases. This compound also increased the number of cells in subG1 phase in a concentration- and time-dependent manner. The presence of β-galactosidase positive cells, large nucleus and flattened cells indicated senescence. Additionally, DGX inhibited Na,K-ATPase activity in A549 cells, as well as in purified pig kidney and in human red blood cell membrane preparations, at nanomolar range. Moreover, results of molecular docking showed that DGX binds with high efficiency (−11.4Kcal/mol) to the Na,K-ATPase (PDB:4HYT). Taken together, our results highlight the potent effects of DGX both in A549 and H460 cells, and disclose its link with Na,K-ATPase inhibition.