Effects Of Tubeimoside-1 On The Apoptosis Of Human Glioma U251 Cell Line And Its Underling Mechanism

Objective: Tubeimoside-1(TBMS I) is a natural compound isolated from tubeimoside, which has been widely used as a traditional Chinese herbal medicine. The purpose of the present study is to investigate the anti-tumor effect and the underling mechanism of TBMS1 on glioma U251 cell line in vitro.Methods: The MTT assay was performed to evaluate the effect of TBMS I on glioma cell proliferation. The fluorescent microscopy was used to observe the changes in nuclei morphology of U251 cells after TBMS I treatment. Flow cytometry analysis was performed to evaluate the effect of TBMS I on glioma cell apoptosis and measure the concentration of intracellular reactive oxygen species(ROS). The level of mi R-21 and PDCD4 m RNA was detected by real-time fluorescent quantitative PCR. The western blot analysis was used to evaluate the protein change.Results: TBMS I inhibited glioma cancer cell proliferation in a dose- and time-dependent manner. After treatment with TBMS I for 24 h, chromatin condensation, nuclear fragmentation and apoptotic bodies were clearly observed in U251 cells via fluorescent microscopy using Hoechst 33258 staining, which indicated apoptosis. In addition, flow cytometry analysis demonstrated that TBMS I induced glioma cell apoptosis in a concentration-dependent manner. Western blotting showed that TBMS1 induced apoptosis by increasing the expression of FADD,caspase-8,caspase-3, Bax and down regulating the level of Bcl-2. Furthermore, we found that TBMS1 induced apoptosis by increasing the concentration of ROS through the release of Cytochrome C and activation of Caspase-3.Moreover, PCR analysis showed that after tubeimoside-1 treatment, the expression of mi R-21 tended to decrease gradually, downregulation of mi R-21 in U251 cell line resulted in increased expression of PDCD4. The expression of PDCD4 has also been enhanced by tubeimoside-1 using Western blot analysis.Conclusion: Tubeimoside-1 significantly suppressed proliferation and induced apoptosis of U251 cells.These findings indicate that TBMS1 may be developed as a possible therapeutic agent for the management of glioma.