Melanomas suppress lipid peroxidation in host mice

Tumor growth can often induce signs of oxidative stress in host organism. To assess the situation as for melanoma, the oxidative stress markers (specific malondialdehyde-thiobarbituric acid complexes: MDA-TBA; and less specific thiobarbituric acid reactive substances: TBARS) were measured in sera, liver and tumors of B16- and Cloudman S91- bearing mice and compared to those of control animals. The MDA-TBA levels (unlike TBARS) in the sera and liver of melanoma-bearing mice were significantly lower compared to controls. In addition, a significantly higher concentration of vitamin E was found in the blood and liver of both melanoma models compared to controls. Contrary to expectation, it appears that melanoma-bearing mice are able to suppress the level of lipid peroxidation. The free radical balance in melanoma-bearing hosts is unique and differs from other tumor types. This should be taken into consideration when designing a human melanoma therapy.