Epi-reevesioside F inhibits Na+/K+-ATPase, causing cytosolic acidification, Bak activation and apoptosis in glioblastoma.

Abstract

Epi-reevesioside F, a new cardiac glycoside isolated from the root of Reevesia formosana, displayed potent activity against glioblastoma cells. Epi-reevesioside F was more potent than ouabain with IC50 values of 27.3±1.7 vs. 48.7±1.8 nM (P < 0.001) and 45.0±3.4 vs. 81.3±4.3 nM (P < 0.001) in glioblastoma T98 and U87 cells, respectively. However, both Epi-reevesioside F and ouabain were ineffective in A172 cells, a glioblastoma cell line with low Na+/K+-ATPase α3 subunit expression. Epi-reevesioside F induced cell cycle arrest at S and G2 phases and apoptosis. It also induced an increase of intracellular concentration of Na+ but not Ca2+, cleavage and exposure of N-terminus of Bak, loss of mitochondrial membrane potential, inhibition of Akt activity and induction of caspase cascades. Potassium supplements significantly inhibited Epi-reevesioside F-induced effects. Notably, Epi-reevesioside F caused cytosolic acidification that was highly correlated with the anti-proliferative activity. In summary, the data suggest that Epi-reevesioside F inhibits Na+/K+-ATPase, leading to overload of intracellular Na+ and cytosolic acidification, Bak activation and loss of mitochondrial membrane potential. The PI3-kinase/Akt pathway is inhibited and caspase-dependent apoptosis is ultimately triggered in Epi-reevesioside F-treated glioblastoma cells.

• Authors: Jui-Ling Hsu, Fan-Lun Liu, Lih-Ching Hsu, Hsun-Shuo Chang, Wohn-Jenn Leu, Chia-Chun Yu, Wei-Ling Chang, Ih-Sheng Chen, Fan-Lu Kung, Jih-Hwa Guh
• Journal: Oncotarget (Oncotarget) Vol. 6 Issue 27 Pg. 24032-46 (Sep 15 2015) ISSN: 1949-2553 [Electronic] United States
• PMID: 26125228 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antineoplastic Agents
• BAK1 protein, human
• Rhodamines
• Saponins
• bcl-2 Homologous Antagonist-Killer Protein
• reevesioside F
• lissamine rhodamine B
• Ouabain
• Sodium
• Sodium-Potassium-Exchanging ATPase
• Potassium
• Calcium

Topics

• Antineoplastic Agents (chemistry)
• Apoptosis (drug effects)
• Brain Neoplasms (drug therapy, metabolism)
• Calcium (chemistry)
• Cell Line, Tumor
• Cell Proliferation
• Cytosol (metabolism)
• Flow Cytometry
• Glioblastoma (drug therapy, metabolism)
• Humans
• Hydrogen-Ion Concentration
• Inhibitory Concentration 50
• Membrane Potential, Mitochondrial
• Ouabain (chemistry)
• Potassium (chemistry)
• Protein Structure, Tertiary
• Rhodamines (chemistry)
• Saponins (chemistry)
• Sodium (chemistry)
• Sodium-Potassium-Exchanging ATPase (metabolism)
• bcl-2 Homologous Antagonist-Killer Protein (metabolism)