[Lipid peroxidation and activity of antioxidative enzymes in patients with multiple myeloma]

Reactive oxygen species and other free radicals are known to be the mediators of phenotypic and genotypic changes that lead from mutation to neoplasia. The imbalance in tumor cell antioxidant defense mechanism can influence also the sensitivity to cytoreductive therapy. In erythrocytes it can results to hemolysis which is one of pathogenetic mechanisms of anemia in cancer patients.

We investigated the parameters of lipid peroxidation (malondialdehyde-MDA) and antioxidant enzymes here represented by superoxide dismutase (SOD) and glutathione peroxidase (GPx) in multiple myeloma. Nine patients of various clinical stage and activity of disease were studied. A significant higher concentration of total MDA in plasma (1.20 +/- 0.24 mumol/l v.s. 0.64 +/- 0.22 mumol/l, p < 0.0001) as well as in erythrocytes (2.72 +/- 0.81 mumol/l v.s. 1.03 +/- 0.44 mumol/l, p < 0.0001) was found comparing to the control group. The levels of free MDA in plasma (0.31 +/- 0.09 mumol/l v.s. 0.49 +/- 0.17 mumol/l, p < 0.05) and in erythrocytes (0.29 +/- 0.20 mumol/l v.s. 0.59 +/- 0.22 mumol/l, p < 0.001) were decreased in myeloma patients. A significantly lower activity of GPx (19.17 +/- 4.07 U/g v.s. 23.26 +/- 3.61 U/g Hb, p < 0.05) and SOD (1882.46 +/- 181.73 U/g v.s. 2347.13 +/- 502.51 U/g Hb, p < 0.05) in erythrocytes were found.

We didn't observe evident relationship between the concentration of MDA or activities of SOD and GPx and either the stage of disease or level and type of paraprotein. We can conclude, that higher concentration of total MDA as a parameter of lipid peroxidation, is significantly increased in patients with multiple myeloma. It could be consequence of impaired antioxidant defence. These results propose possible role of free radicals with reduced antioxidant activity of SOD and GPx in multiple myeloma. As we can consider the role of free radicals in pathogenesis of malignant proliferation, prognostic value and the change during the course of therapy should by studied.