%0 Journal Article %T Sensitivity Evaluation of Two Human Breast Cancer Cell Lines to Tamoxifen through Apoptosis Induction %A Spencer Keene %A Charles Azuelos %A Shyamal K. Majumdar %J Open Journal of Apoptosis %P 70-77 %@ 2168-3840 %D 2014 %I Scientific Research Publishing %R 10.4236/ojapo.2014.34008 %X Tamoxifen citrate (TAM) has been used to treat breast cancer in women for many years. The com-parative effects of TAM in inducing apoptosis were evaluated in estrogen receptor-positive (ER- positive MCF-7) and estrogen receptor-negative (ER-negative MDA-MB-231) human breast cancer cell lines in vitro in order to determine if these two cell lines differ in their sensitivity to TAM. Mi-tochondrial membrane permeability potential disruption was assessed in both cell lines by a lip-ophilic cationic dye (DePsipher assay, Trevigen, Inc.) utilizing fluorescence microscopy. Using this specific fluorochrome, we were able to associate mitochondrial membrane disruption to early, mid-, and late apoptotic cells. TAM induced cell death via apoptosis in both ER-positive and ER- negative cells, however, apoptosis induction was more pronounced in ER-positive MCF-7 compared to ER-negative MDA-MB-231 breast cancer cells. These findings may have some therapeutic use in the treatment of estrogen dependent and estrogen independent breast cancer. %K Tamoxifen %K Apoptosis %K MCF-7 and MDA-MB-231 Human Breast Cancer Cell Lines %K Mitochondrial Membrane Potential Assay %K Estrogen Receptor %U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=50850