Modulation of cytotoxic effect of anticancer drugs by dipyridamole in HeLa cells in vitro.

Exponentially growing HeLa cells were treated with various antitumor drugs and dipyridamole (DP), and the cell growth inhibition ratio was determined. Enhanced growth inhibition was found in combined treatment with DP and 5-fluorouracil, 1-hexylcarbamoyl-5-fluorouracil, methotrexate, adriamycin, daunomycin, 4'-0-tetrahydropyranyl-adriamycin, actinomycin D and vincristine. In contrast, reduction of the cytotoxic effect of cytosine arabinoside and enocitabine was found when these were combined with DP.