Nitrotyrosine in esophageal squamous cell carcinoma and relevance to p53 expression

We have examined the expression of nitrotyrosine, a marker of peroxynitrite formation, in 55 esophageal cancers by immunohistochemistry. Nitrotyrosine was detected in 21 of 55 (38.2%) esophageal cancers. Comparison of nitrotyrosine expression and the pathological findings showed that there was a significant association between the expression of nitrotyrosine and each of the depth of tumor invasion (P<0.01), occurrence of metastasis (P<0.05), pathological stage (P<0.01), smoking status (P<0.05) and alcohol intake (P<0.05). The survival rate of patients with nitrotyrosine-negative cancer was significantly higher than that of patients with nitrotyrosine-positive cancer (log-rank test, P<0.01). p53 was detected in 29 of 55 (52.7%) esophageal cancers, however, p53 expression did not correlate with nitrotyrosine expression. In conclusion, nitrotyrosine, a product of nitrogen species, is expressed in esophageal squamous cell carcinoma, which suggests that exogenous risk factors, such as tobacco and alcohol, through NO, are associated with carcinogenesis and progression of esophageal squamous cell carcinoma.