δ-Tocopherol Enhances Docetaxel-Induced Growth Inhibition and Apoptosis in Ovarian Cancer SKOV3 Cells

Docetaxel is the first-line chemotherapeutic drug for ovarian cancer. However, its clinical use is limited owing to its serious side effects. Therefore, it is of great clinical significance to enhance the efficacy of docetaxel at lower doses in a less-toxic manner. In this study, we investigated whether delta-tocopherol could enhance the anti-tumor effects of docetaxel on ovarian cancer SKOV3 cells in vitro. For docetaxel and delta-tocopherol, IC50 values of 1.89 nM and 11.41 mu M, respectively, were obtained, in SKOV3 cells. The combination of delta-tocopherol and docetaxel had a synergistic cell growth inhibition effect, with lower cell viability and more cell arrest at the S phase compared to either delta-tocopherol or docetaxel alone. In addition, the combination of delta-tocopherol and docetaxel had a synergistic cell apoptosis induction effect, with more apoptotic cells and reduced anti-apoptotic protein expression compared to either delta-tocopherol or docetaxel alone. Furthermore, we identified 3 hoursub genes (CAT, EP300, CREBBP), which predicted the prognosis of ovarian cancer, which correlated with delta-tocopherol and docetaxel. In conclusion, the combination of delta-tocopherol and docetaxel presented synergistic cell growth inhibition and cell apoptosis induction effects in SKOV3 cells at a low dose, which suggesting that delta-tocopherol could improve the serious side effects of docetaxel.