Additive growth-inhibitory effects of DL-alpha-difluoromethylornithine and antiestrogens on MCF-7 breast cancer cell line.
We studied the growth inhibitory effects of DL-alpha-difluoromethylornithine, and antiestrogens (tamoxifen, 4-hydroxytamoxifen, trioxifene, keoxifene, and LY117018) as single agents and in combinations on the proliferation of a breast cancer cell line, MCF-7. At 0.1 mM difluoromethylornithine, the proliferation of MCF-7 cells was inhibited to 75 +/- 6% of the controls. Treatment of the cells with 0.1 microM 4-hydroxytamoxifen reduced cell growth to 72 +/- 4%. Combination of 0.1 mM difluoromethylornithine and 0.1 microM 4-hydroxytamoxifen reduced cell growth to 38 +/- 5%, indicating additive growth inhibitory effects. Similar additive effects were observed with all 5 antiestrogens in combination with difluoromethylornithine.
D001943:Breast Neoplasms / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D000518:Eflornithine / Q000008:administration & dosage*; D004965:Estrogen Antagonists / Q000008:administration & dosage*; D006131:Growth Inhibitors; D006801:Humans; D011700:Putrescine / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000166:cytology* / Q000187:drug effects
D004965:Estrogen Antagonists; D006131:Growth Inhibitors; D011700:Putrescine; D000518:Eflornithine