INTRODUCTION: Nitric oxide is an important bioactive and signaling molecule that mediates a diverse array of actions such as vasodilatation, neurotransmission, and iron metabolism. Also, it can act as a carcinogen. Recent studies have examined the expression and activity of the NOS isoforms in several human cancers. OBJECTIVES: To investigate the expression of nitric oxide synthases in gastric carcinomas and correlate the results. MATERIAL AND METHODS: The immunohistochemistry expression of constitutive and inducible nitric oxide synthases (NOS-1, NOS-2 e NOS-3) were evaluated in 128 cases of gastric cancer classified according to Lauren system. RESULTS: The rate of expression of NOS-1 was 92 (70%) of the 12 cases, NOS-2 was 36 (30%) and NOS-3 was 54 (42%) of the cases. The expression of NOS-3 was associated with the intestinal type of carcinoma and deeply invasive tumors showed high rate of expression of NOS-2. CONCLUSION: There is high expression of all the isoforms of nitric oxide synthases in gastric cancer; the constitutive isoforms show higher expression than the inducible forms. The high expression of the inducible form in deeply invasive tumors is related with tumoral progression and dissemination in the gastric mucosa.
Gastric cancer; Nitric oxide; Nitric oxide synthases
