Study On The Apoptosis Of PC-3 Cells Induced By Nano-paclitaxel

In an attempt to improve water solubility,increase bioavailability and reduce toxicity of paclitaxel,nano-paclitaxel was prepared of SAS method and preliminary anti-tumor activity was evaluated.Compared with paclitaxel,nano-paclitaxel still exhibited good anti-tumor activity. In this study,anti-tumor activity and the mechanism of action of nano-paclitaxel were researched. The results were as follows:1.Growth inhibition was analyzed by MTT assay of several tumor cell lines including human lymphoid cancer cells(CEM),human breast cancer cells(MCF-7),human lung adenocarcinoma cells(A549),human prostate cancer cells(PC-3).The results showed that the IC50 values of the four cell lines treated with nano-paclitaxel for 48h were 2.06±1.46μM,5.89±1.07μM,10.56±5.07μM and 0.62±0.17μM respectively. However, the IC50 values of the four cell lines treated with paclitaxel for 48h were 1.73±0.13μM, 3.82±1.25μM,15.71±3.21μM and 1.60±1.25μM. It was suggesting that PC-3 cell line was the most sensitive.2.The mice bearing tumor of S180 was selected to evaluate the anti-tumor activity in vivo of nano-paclitaxel. Inhibition rate of nano-paclitaxel and paclitaxel were 58.66% and 61.16% at a dose of 10mg/kg,respectively. The result showed that nano-paclitaxel exhibited good anti-tumor activity in vivo towards transplanted sarcoma S180 in mice,and the effect was almost similar to that of paclitaxel.3.The apoptotic cells morphological changes were observed using transmission electron microscopy and laser scanning confocal microscope. It was showed that there were significant morphological changes in the apoptosis of PC-3 cells afer treated with 0.5μM nano-paclitaxel for 48h.4.The cell cycle distribution was analyzed by flow cytometry to investigate the effects of nano-paclitaxel on the cell cycle. The result showed that PC-3 cells were treated with different concentrations of nano-paclitaxel for 48h,the change of the cell cycle was observed.There was an accumulation of PC-3 cell in the G2/M phase. It was showed that nano-paclitaxel could induce apoptosis in PC-3 cells,which is related to the accumulation of the G2/M phase cells.5.Alterations of mitochondrial membrane potential of PC-3 cells induced by nano-paclitaxel were investigated by the Rh123 staning and flow cytometry. The result showed that the percentage of cells treated with nano-paclitaxel in low fluorescence produced a time-dependent increase,indicating that nano-paclitaxel induced apoptosis of PC-3 cells by alterating the mitochondrial membrane potential.6.The changes of Ca2+ concentrations in PC-3 cells induced by nano-paclitaxel were investigated by flow cytometry and Fluo-3 AM fluorescent probe.The data showed that after PC-3 cells were treated with different concentrations of nano-paclitaxel for 24h,the levels of intracellar Ca2+ were elevated. The results support a role of mitochondria pathway in apoptosis induced by nano-paclitaxel.7.We investigated nano-paclitaxel induce intracellar ATP level changes of PC-3 cells. It was found that nano-paclitaxel cound reduce the intracellar of ATP level,which is the further evidence of the apoptosis induced by nano-paclitaxel caused by mitochondrial pathway.8.The changes of hydrogen peroxide levels in PC-3 cells induced by nano-paclitaxel were investigated. The results showed that after PC-3 cells were induced by nano-paclitaxel for 1h, the concentrations of hydrogen peroxide in PC-3 cells showed a dose-dependent increasing. In addition,the concentration of hydrogen peroxide in PC-3 cells may be reduced in present of CsA. These results indicated that nano-paclitaxel induced apoptosis involving mitochondrial PTP pathway. Moreover, oxidative damage,although present,is not involved in the apoptotic process.In summary,nano-paclitaxel exhibited good anti-tumor activity in vivo and in vitro, which may be involved in apoptosis induction. The mechanism of apoptosis induced by nano-paclitaxel may be related to the activation of mitochondrial apoptotic pathway. The study offered a significant future work to improve water solubility and increase bioavailability. In addition,it also provides a development of new products for future study and clinical application.