Effects of Polyamines on TNFalpha- or Tamoxifen-induced Apoptosis in Human Breast Cancer Cells.

PURPOSE To investigate the effects of polyamines on tumor necrosis factor alpha (TNFalpha)-or tamoxifen (TAM)-induced apoptosis in estrogen receptor (ER)-positive MCF- 7 and ER-negative MDA-MB-231 human breast cancer cells. MATERIALS AND METHODS Cell viability was assessed by using MTT assay. Reactive oxygen species (ROS) generation was measured using 2', 7'-dichlorofluorescin diacetste (DCFDA) by fluorescence plate reader. DNA fragmentation was assessed by 1.5% agarose gel electrophoresis. RESULTS TNFalpah and TAM showed significant dose- and time- dependent inhibitory effects on the growth of MCF-7 human cells. However, the growth of MDA-MB-231 cells were not inhibited by TNFalpha or TAM treatment. The generation of ROS was increased in dose-and time-dependent manner by TNFalpha treatment in MCF-7 cells. Polyamines, especially spermine suppressed TNFalpha-induced ROS generation in MCF-7 cells. Antioxidant effects of polyamines were also demonstrated by DNA fragmentation, cell morphology as well as ROS generation assay. Polyamines also blocked TAM-induced cell death in MCF-7 cell. However, MDA-MB-231 cells showed resistance to the cytotoxic effects of TNFalpha or TAM. CONCLUSION These results suggest that polyamines may prevent TNFalpha or TAM-induced apoptosis in MCF-7 human breast cancer cells.