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Frequent expression of inducible nitric oxide synthase in esophageal squamous cell carcinomas
H Tanaka1, H Kijima, T Tokunaga
1Department of Surgery, Tokai University School of Medicine, Isehara, Kanagawa 259-1193, Japan.
Abstract:
Nitric oxide (NO) plays important biological roles in cardiovascular, nervous and immune systems, and is synthesized by nitric oxide synthase (NOS). Intracellular NO is known to cause DNA damage as a mutagen. We examined the expression of cytokine-inducible NOS (iNOS) in human esophageal squamous cell carcinomas. Weak iNOS immunoreactivity was seen in the basal and parabasal layers of non-neoplastic esophageal stratified squamous epithelium. iNOS expression was detected in 50 (87.7%) of the 57 esophageal squamous cell carcinomas, regardless of the depth of tumor invasion, histological differentiation and lymph node status. Early-stage cancers, i.e. mucosal squamous cell carcinomas, also showed significant iNOS expression. We speculate that increased iNOS expression is associated with the carcinogenesis of human esophageal cancer.
Insights
Increased expression of inducible nitric oxide synthase (iNOS) is linked to human esophageal squamous cell carcinoma development. This suggests iNOS may play a role in esophageal cancer carcinogenesis.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Nitric oxide (NO) is a signaling molecule with diverse physiological roles.
- Nitric oxide synthase (NOS) synthesizes NO, with intracellular NO implicated in DNA damage.
- Inducible NOS (iNOS) is a key enzyme in NO production.
Purpose of the Study:
- To investigate the expression of iNOS in human esophageal squamous cell carcinomas.
- To determine the correlation between iNOS expression and clinicopathological features of esophageal cancer.
Main Methods:
- Immunohistochemical analysis of iNOS expression in esophageal squamous cell carcinoma tissues.
- Evaluation of iNOS immunoreactivity in relation to tumor invasion, differentiation, and lymph node status.
Main Results:
- Weak iNOS immunoreactivity was observed in normal esophageal epithelium.
- Significant iNOS expression was detected in 87.7% of esophageal squamous cell carcinomas.
- iNOS expression was evident even in early-stage (mucosal) cancers and irrespective of other clinicopathological factors.
Conclusions:
- Increased iNOS expression is a common feature in human esophageal squamous cell carcinomas.
- The study speculates a potential role for elevated iNOS in esophageal cancer carcinogenesis.