RESUMO
Anticancer therapy based on recombinant arginine-degrading enzymes has been proposed for the treatment of several types of malignant cells deficient in arginine biosynthesis. One of the predicted side effects of such therapy is restricted bioavailability of nitric oxide as arginine catabolic product. Prolonged NO limitation may lead to unwanted disturbances in NO-dependent vasodilation, cardiovascular and immune systems. This problem can be overcome by co-supplementation with exogenous NO donor. However, NO may potentially counteract anticancer effects of therapy based on arginine deprivation. In this study, we evaluate for the first time the effects of an exogenous NO donor, sodium nitroprusside, on viability and metastatic properties of two human melanoma cell lines SK-MEL-28 and WM793 under arginine-deprived conditions. It was revealed that NO did not rescue melanoma cells from specific effects evoked by arginine deprivation, namely decreased viability and induction of apoptosis, dramatically reduced motility, invasiveness and clonogenic potential. Moreover, sodium nitroprusside co-treatment augmented several of these antineoplastic effects. We report that a combination of NO-donor and arginine deprivation strongly and specifically impaired metastatic behavior of melanoma cells. Thus, sodium nitroprusside can be considered as an adjuvant for the more efficient treatment of malignant melanoma and possibly other tumors with arginine-degrading enzymes.