Digitoxin, in non toxic concentrations, induces apoptotic cell death in Jurkat T cells in vitro

Reports concerning the anti-cancer effects of digitalis interested us in performing an in vitro study of digitoxin and digoxin on 5 differ ent malig cell lines. Two breast cancer cell lines, MDA-MB-231 (recep tor negative), T47D (receptor positive) and three malignant hematolog ical cell lines, Jurkat, Daudi and K562, were tested for sensitivity for digitoxin and digoxin. Peripheral blood mononuclear cells (PBMC) and natural killer cells (NK), both non stimulated and interleukin 2 (IL-2) stimulated, were used as control cells. Digitoxin has growth i nhibitory effects on both breast cancer cell lines and inhibited prol iferation and decreased viability of two of the three malingnant hema tological cell lines tested. Digitoxin exerted these effects in thera peutic concentrations for treating cardiac congestion. In the hematol ogical cell lines Jurkat and Daudi digitoxin induced apoptotic cell d eath. PBMC and NK cells, both non-stimulated and IL-2 stimulated, wer e not affected by the same concentrations of digitoxin. Digitoxin als o ahowed inhibiting properties on the malignant cell lines, but the e ffects were less pronounced and not dose dependent. Digitoxin may be a prototype anti-cancer drug exerting its effect throuth a mechanism other than cytotoxicity.