Hypoxia-Induced Changes in L-Cysteine Metabolism and Antioxidative Processes in Melanoma Cells

This study was performed on human primary (WM115) and metastatic (WM266-4) melanoma cell lines developed from the same individual. The expression of proteins involved in L-cysteine metabolism (sulfurtransferases, and cystathionine β-synthase) and antioxidative processes (thioredoxin, thioredoxin reductase-1, glutathione peroxidase, superoxide dismutase 1) as well as the level of sufane sulfur, and cell proliferation under hypoxic conditions were investigated. Hypoxia in WM115 and WM266-4 cells was confirmed by induced expression of carbonic anhydrase IX and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 4 by the RT-PCR and Western blot methods. It was shown that, under hypoxic conditions the inhibition of WM115 and WM266-4 melanoma cell proliferation was associated with decreased expression of thioredoxin reductase-1 and cystathionine β-synthase. These two enzymes may be important therapeutic targets in the treatment of melanoma. Interestingly, it was also found that in normoxia the expression and activity of 3-mercaptopyruvate sulfurtransferase in metastatic WM266-4 melanoma cells was significantly higher than in primary melanoma WM115 cells.