Paclitaxel-induced Apoptsis In Human Osteosarcoma Cell Line And The Apoptotic Effect Of Caspase-6 Gene

Paclitaxel is new broad-spectrum anti-tumor drug, which has a unique mechanism of promoting the stability of microtube and inducing apoptosis. In the present study, the cytotoxic effect of paclitaxel on human osteosarcoma cell line SOSP-9607 was examined by MTT assay, morphological observation, gel electrophoresis of DNA, and cell morphology. The results showed that the cytotoxic effect of paclitaxel on SOSP-9607 cell is achieved by inducing apoptosis. Also, the killing effect of paclitaxel toward SOSP-9607 cell line was conffrmed in vitro. A group of caspase (cycteinyl asparate-specifi protease) was found in mammal. With similar structure, they constitute a proteases family and play a very important role in the process of cell apoptosis. Fourteen members of this family 4 could be classified into two groups: initiators and effectors. Caspases exist in an inactive form in normal cells. When apoptotic signal has been sent in, they will be cleaved and activated. After initiators have been activated, effectors can be activated. Active effectors cleave their substrates after an aspartate residue and induce apoptosis. Caspase-6 is kind of effectors. The relationship between the expression level of caspase and the apoptosis of tumor cell was confirmed by many reports. In this study, we examined the expression of caspase-6 in the osteosarcoma line SOSP-9067 by RT-PCR method. Results showed no expression of caspase-6. We constructed a caspase 6 gene-transfer virus adv5 vectors and transfeced it into the osteosarcoma line SOSP-9607 by way of lipofection. A high expression of caspase 6 was identified by RT-PCR after the transfection. The cell survival rate was assayed by MTT method. The result indicates the caspase 6 may inhibit the growth of the transfected cell. The morphological observation and gel electrophoresis of DNA also confirmed the inhibition effect of caspase 6 was achieved by inducing apoptosis.