α-tocopherol protects against cisplatin-induced toxicity without interfering with antitumor efficacy

Our aim was 2-fold: to investigate the role of α-tocopherol supplementation on the antitumor activity of DDP and to evaluate the effect of α-tocopherol on the survival and neurotoxicity of DDP-treated mice. Experiments performed on the M 14 human melanoma line demonstrated that α-tocopherol supplementation did not influence the efficacy of DDP; the inhibition of cell survival and of the in vivo tumor growth after treatment with α-tocopherol and DDP combination was similar to that observed after DDP alone. Conversely, α-tocopherol was also able to increase survival of mice treated with a high dose of DDP. While DDP alone produced death in about 70% of mice, the combination reduced deaths to about 30%. Analysis of oxidative stress markers and peroxidative damage in organs indicated that the protective effect of α-tocopherol was mainly related to its antioxidant activity. A significant increase in the concentration of TBARS and decreased PUFAs and catalase activity were observed after DDP treatment, while with α-tocopherol the levels of these markers were comparable to those observed in untreated mice. Histologic analysis performed on peripheral nerve revealed that α-tocopherol also protected mice from severe neurologic damage induced by DDP treatment. In conclusion, our results demonstrate that α-tocopherol protects against the systemic toxicity and neurotoxicity induced by DDP without interfering with its antitumor activity and suggest that this combination is a promising strategy to improve the therapeutic index of DDP-based chemotherapy.