Digitoxin and a synthetic monosaccharide analog inhibit cell viability in lung cancer cells.
Mechanisms of digitoxin-inhibited cell growth and induced apoptosis in human non-small cell lung cancer (NCI-H460) cells remain unclear. Understanding how digitoxin or derivate analogs induce their cytotoxic effect below therapeutically relevant concentrations will help in designing and developing novel, safer and more effective anti-cancer drugs. In this study, NCI-H460 cells were treated with digitoxin and a synthetic analog D6-MA to determine their anti-cancer activity. Different concentrations of digitoxin and D6-MA were used and the subsequent changes in cell morphology, viability, cell cycle, and protein expressions were determined. Digitoxin and D6-MA induced dose-dependent apoptotic morphologic changes in NCI-H460 cells via caspase-9 cleavage, with D6-MA possessing 5-fold greater potency than digitoxin. In comparison, non-tumorigenic immortalized bronchial and small airway epithelial cells displayed significantly less apoptotic sensitivity compared to NCI-H460 cells suggesting that both digitoxin and D6-MA were selective for NSCLC. Furthermore, NCI-H460 cells arrested in G(2)/M phase following digitoxin and D6-MA treatment. Post-treatment evaluation of key G2/M checkpoint regulatory proteins identified down-regulation of cyclin B1/cdc2 complex and survivin. Additionally, Chk1/2 and p53 related proteins experienced down-regulation suggesting a p53-independent cell cycle arrest mechanism. In summary, digitoxin and D6-MA exert anti-cancer effects on NCI-H460 cells through apoptosis or cell cycle arrest, with D6-MA showing at least 5-fold greater potency relative to digitoxin.
Department of Basic Pharmaceutical Sciences, West Virginia University, Morgantown, WV 26506, USA.
Hosam A
HA
Elbaz
Todd A
TA
Stueckle
Hua-Yu Leo
HY
Wang
George A
GA
O'Doherty
David T
DT
Lowry
Linda M
LM
Sargent
Liying
L
Wang
Cerasela Zoica
CZ
Dinu
Yon
Y
Rojanasakul
D000970:Antineoplastic Agents / Q000494:pharmacology*; D053453:Caspase 9 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D000071877:Checkpoint Kinase 1; D056744:Cyclin B1 / Q000032:analysis; D045304:Cytochromes c / Q000032:analysis; D004074:Digitoxin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000473:pathology; D011494:Protein Kinases / Q000032:analysis; D012210:Rhamnose / Q000031:analogs & derivatives* / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors
D000970:Antineoplastic Agents; C534699:CCNB1 protein, human; D056744:Cyclin B1; C587796:D6-MA compound; D045304:Cytochromes c; D004074:Digitoxin; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D053453:Caspase 9; D000254:Sodium-Potassium-Exchanging ATPase; D012210:Rhamnose