Biology, Cell

Breast cancer is the most common malignant cancer and leading cause of death in women between the ages of 40 and 55. Among dietary phytochemicals with demonstrated anti-tumor activities are genistein (4', 5', 7-trihydroxyisoflavone) and pomegranate (punica granatum). The present study was to demonstrate the potential anticancer activities of genistein and pomegranate and the mechanism of action in human breast cancer cells. Study design. MCF-7 cells were grown in RPMI medium and then seeded in 48-well MTP, and cultured at 37C, 5% CO2 for 36hr to achieve 80-90% confluence. The cells were then exposed to varying concentrations of genistein and pomegranate for 24 and 48hr. The treated cells were tested for (i) post-treatment sensitivity using MTT and Trypan Blue exclusion assay, and (ii) treatment-induced apoptosis using Rh123, Acridine Orange-Ethidium Bromide nuclear stains and Caspase binding assay. Results. Data indicated that both compounds effectively killed cancer cells mostly via apoptosis induction.

The survival of rat retinal ganglion cells (RGCs) after axotomy has been shown to be enhanced by Brain Derived Neurotrophic Factor (BDNF). It was, therefore, of interest to determine whether previously observed changes in the differential regulation of fast axonally transported proteins (FTPs) occur in rat RGCs during the early response to axotomy or whether such changes are obviated by the action of BDNF at the cell body level. It was of further interest to determine whether these regeneration-associated changes are sustained during the period of BDNF-enhanced cell survival. It was found that, within 2 days of injury and BDNF injection, rat RGCs initiate a growth-like cellular response that includes the differential synthesis and transport of the same profile of FTPs found to be induced in axotomized animals following injection of a saline control solution. Thus, supplementation of rat RGCs with BDNF does not obviate the changes required to reinstate active cellular regrowth. It is, therefore, unlikely that the loss of a trophic factor, such as BDNF, is the signal for axotomy-induced changes. Although a single injection of BDNF at the time of injury prolongs cell survival to at least 5 days, it is not sufficient to sustain the elevation in FTPs. This result indicates that the regulatory mechanisms that promote cell growth are distinct and separate from those that promote cell survival. This study extended beyond the above findings to affirm that apoptosis of axotomized rat RGCs is mediated by the activation of the cysteine protease, caspase-3. Such activation was demonstrated within 12 hours of axotomy and appeared to become increasingly prevalent in a central to peripheral gradient, as might be anticipated by the loss of glial derived neurotrophic support. Such activation was completely prevented by intraocular injection of BDNF, indicating that BDNF acts upstream of caspase-3 to prevent the proteolytic cascade that leads to apoptosis.