In vitro studies of paclitaxel mediated apoptosis in osteosarcoma cell line

Objective To study the growth inhibitory and apoptosis inducting effect of paclitaxel on human osteoblastic cell line U-2 OS. Methods U-2 OS cells were treated with various concentrations of paclitaxel. Proliferation was determined by cell count in a Neubauer cytometer chamber. Viability was assessed by trypanblau dye exclusion. Paclitaxel induced morphologic alterations were visualized, using light and transmission electron microscopy. The extent of paclitaxel induced apoptosis was determined by flow cytometry and immunohistochemical detection (TdT mediated dUTP nick end labeling technique, TUNEL). Results Paclitaxel had a growth inhibitory and apoptosis inducting effect on U-2 OS cell. The cell treated with paclitaxel initially show G2/M arrest; follow by apoptosis. A characteristic apoptosis change including nuclear disintegration and chromatin agglomerate were displayed. Lots of multinucleate cells appeared, which was not seen on the cell treated with other chemotherapeutic agents such as cisplatin and adriamycin. Also, extensive DNA cleavage was detected by immunohistochemical technique. Conclusion Paclitaxel has an obvious growth inhibitory and apoptosis inducting effect on osteosarcoma cell line by induce a G2/M arrest and inhibit the mitosis. The effect of paclitaxel displays a time dependent and dose dependent manner.