title: Cytotoxicity of digitoxin and related cardiac glycosides in human tumor cells.
abstract: The saponin digitonin, the aglycone digitoxigenin and five cardiac glycosides were evaluated for cytotoxicity using primary cultures of tumor cells from patients and a human cell line panel (representing different cytotoxic drug-resistance patterns). Of these seven compounds, proscillaridin A was the most potent (IC(50): 6.4--76 nM), followed by digitoxin, and then ouabain, digoxin, lanatoside C, digitoxigenin and digitonin. Correlation analysis of the log IC(50) values for the cell lines in the panel showed that compound cytotoxicity was only slightly influenced by resistance mechanisms that involved P-glycoprotein, topoisomerase II, multidrug resistance-associated protein and glutathione-mediated drug resistance. Digitoxin and digoxin expressed selective toxicity against solid tumor cells from patients, while proscillaridin A expressed no selective toxicity against either solid or hematological tumor cells. The results revealed marked differences in cytotoxicity between the cardiac glycosides, both in potency and selectivity, and modes of action for cytotoxicity that differ from that of commonly used anticancer drugs.
authors.affiliation: Division of Pharmacognosy, Department of Medicinal Chemistry, Biomedical Centre, Uppsala University, PO Box 574, 751 23 Uppsala, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Johansson
authors.forename: P
authors.initials: P
authors.lastname: Lindholm
authors.forename: J
authors.initials: J
authors.lastname: Gullbo
authors.forename: R
authors.initials: R
authors.lastname: Larsson
authors.forename: L
authors.initials: L
authors.lastname: Bohlin
authors.forename: P
authors.initials: P
authors.lastname: Claeson
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002316:Cardiotonic Agents / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival; D004074:Digitoxin / Q000494:pharmacology*; D006801:Humans; D015394:Molecular Structure; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured / Q000187:drug effects* / Q000473:pathology
chemical_list: D000970:Antineoplastic Agents; D002316:Cardiotonic Agents; D004074:Digitoxin