Real-time imaging of apoptosis induction of human breast cancer cells by the traditional Chinese medicinal herb tubeimu.

Traditional Chinese Medicine (TCM) has been used for thousands of years, including treatment for cancer. Use of modern technology and the scientific method to evaluate the efficacy of TCM for cancer should enable its more widespread use. In the present study, the efficacy of the TCM tubeimu, extracted from the tuber of the plant Bolbostemma paniculatum, on the MDA-MB-231 human breast cancer cell line was evaluated. The MDA-MB-231 cell line was engineered to express red fluorescent protein (RFP) in the cytoplasm and green fluorescent protein (GFP) linked to histone H2B in the nucleus, which allows real-time imaging of nuclear-cytoplasmic dynamics. Apoptosis was readily visualized in these cells by nuclear shape changes and fragmentation. The MDA-MB-231 RFP-GFP cells were cultured either in two-dimensions on plastic or in three-dimensions on Gelfoam®. Cells were treated with a dichloromethane extract of fresh tubeimu. Apoptosis was further monitored by DNA fragmentation determined by gel electrophoresis. Tubeimu induced apoptosis of MDA-MB-231 cells, as observed by fluorescence microscopy, as early as 24 hours of treatment in vitro in two-dimensional culture. By 48 hours' treatment, DNA fragmentation could be observed. The frequency of apoptosis increased through at least 72 hours' treatment, with most of the cells being killed. Tubeimu also induced apoptosis of MDA-MB-231 cells in three-dimensional culture on Gelfoam®, but to a lesser extent than in 2D culture. The results of the present study indicate the potential of tubeimu in breast cancer therapy.