Digitoxin sensitizes malignant breast cancer cells for radiation in vitro

The malignant breast cancer cell lines T47D and MDA-MB-231 were exami ned for altered radiosensitivity during treatment with the cardiac gl ycosides digoxin and digitoxin. The effects were assessed with a clon ogenic assay and DNA histograms. Digitoxin sensitized both cell lines for radiation when applied at least 3 days before radiation. Digoxin also induced changes in radiosensitivity, but not to the same extent . Digitoxin seems to halt T47D and MDA-MB-231 in the G2M phase of the cell cycle and this may be one explanation for the increased radiose nsitivity.