Nitrodi thermal water downregulates protein S‑nitrosylation in RKO cells

Balneotherapy and spa therapy have been used in the treatment of ailments since time immemorial. Moreover, there is evidence to suggest that the beneficial effects of thermal water continue for months following the completion of treatment. The mechanisms through which thermal water exerts its healing effects remain unknown. Both balneological and hydroponic therapy at 'the oldest spa in the world', namely, the Nitrodi spring on the Island of Ischia (Southern Italy) are effective in a number of diseases and conditions. The aim of the present study was to investigate the molecular basis underlying the therapeutic effects of Nitrodi spring water in low‑grade inflammation and stress‑related conditions. For this purpose, an in vitro model was devised in which RKO colorectal adenocarcinoma cells were treated with phosphate‑buffered saline or phosphate‑buffered saline prepared with Nitrodi water for 4 h daily, 5 days a week for 6 weeks. The RKO cells were then subjected to the following assays: 3‑(4,5‑Dimethylthiazol‑2‑yl)‑2,5‑diphenyl‑2H‑tetrazolium bromide assay, Transwell migration assay, western blot analysis, the fluorimetric detection of protein S‑nitrosothiols and S‑nitrosylation western blot analysis. The results revealed that Nitrodi spring water promoted cell migration and cell viability, and downregulated protein S‑nitrosylation, probably also the nitrosylated active form of the cyclooxygenase (COX)‑2 protein. These results concur with all the previously reported therapeutic properties of Nitrodi spring water, and thus reinforce the concept that this natural resource is an important complementary therapy to traditional medicine.