Expression of inducible nitric oxide synthase in human gastric cancer

INTRODUCTION Inducible nitric oxide synthase (iNOS) is an enzyme that catalyzes the formation of nitric oxide (NO) from L-arginine. iNOS expression and activity results in the production of high levels of NO1]. The generation of physiological levels of NO is important for mucosal function and it also exerts a cytoprotective effect on the gastrointestinal mucosa. However, increased iNOS expression has been observed in patients with chronic inflammatory diseases of the gastrointestinal tract, such as ulcerative colitis2,3], and gastritis4] and it has been speculated that increased NO may induce DNA damage5,6] and angiogenesis7]. Nonetheless, the role of iNOS in human GI neoplasia is largely unkown. Previous studies have demonstrated increased iNOS expression in breast cancer8,9], and increased iNOS activity and protein levels have been demonstrated in colorectal cancer10] and adenocarcinoma of the esophagus11]. However, to date, the role of iNOS in gastric carcinogenesis has not been elucidated.