Adriamycin action on human breast cancer cells: Enhancement by medroxyprogesterone acetate

Abstract

Abstract Exposure of cultured human breast cancer cells (MCF‐7) to medroxyprogesterone acetate (MPA) prior to treatment with adriamycin (ADR) enhanced the effect of the cytotoxic drug on cell yield after further growth of viable cells. Pre‐treatment with oestradiol (E 2 ) produced similar synergism, but no such effect was observed using dexamethasone. Exposure to ADR before MPA led to an additive effect, but not to synergism. When cells resistant to the growth‐inhibitory action of MPA were examined, progestogen/drug synergism could still be demonstrated. We conclude that the effects of ADR, like those of methotrexate and vincristine, can be enhanced by pre‐treatment with MPA and that further clinical trials of such a regimen are needed.