Synergistic Effects of Taurine and Temozolomide Via Cell Proliferation Inhibition and Apoptotic Induction on U-251 MG Human Glioblastoma Cells

OBJECTIVE: The combination treatment is a way to improve the therapeutic strategy of temozolomide (TMZ) -resistant glioblastoma (GBM). Taurine (TAU) has the potential to inhibit growth in various cancer cells. The aim of this study was to examine the combined effects of TMZ and TAU on cultured human GBM, U-251 MG cells. METHODS: The cells were incubated with TMZ, TAU, and the combination of both in various ratios. MTT assay was performed to measure the cell viability of the treatments and then the synergistic interactions were evaluated by the Chou-Talalay method. The cell cycle and apoptotic properties of the combined treatment on U-251 MG cells were examined by flow cytometry. The Hoechst 33342 stainings were applied to visualize the morphologic change in the apoptotic process. RESULTS: The combined treatment with a dose reduction of each expressed synergistic effect on the decrease of cell viability. The study on the cell cycle resulted in G2/M phase arrest with increasing apoptotic cells in the SubG1 phase. Moreover, the apoptotic effects of the combinations on U-251 MG cells were explained by the increase of apoptotic cells in both early and late stages and illustrated by some characteristics of the apoptotic process including condensed chromatin and fragmented nuclei. CONCLUSION: The study showed that the combination between TMZ and TAU has a potential in anticancer properties against U-251 MG manifested by the induction of G(2)/M arrest and apoptosis. These results suggest that this combination may be useful to enhance the efficacy and reduce some adverse events of GBM treatment in the future.