Nitric Oxide Synthase (NOS) Expression in Breast Cancer

ABSTRACT

PURPOSE: NO, a diatomic free radical, plays a diverse physiological and pathophysiological roles in the vascular, neuronal and immune systems. It is produced by nitric oxide synthase (NOS) which consists of three different isoforms. In this study we investigated NOS expression in 84 human breast carcinomas and its associations to other clinicopathological factors. METHODS: The immunohistochemical staining for NOS expression in 84 human breast carcinomas were performed and their medical records were reviewed retrospectively. RESULTS: iNOS expression in tumor cells was observed in 48.2% and eNOS expression was detected in 51.9%. iNOS expression in tumor cells has positive correlation with eNOS expression in tumor and is associated with iNOS expression in stroma and endothelial cells. Although iNOS expression in tumor cells has negative correlation with tumor size (P=0.047) and lymph node metastasis (P=0.002), it has no effects on 5 year overall and disease free survivals. iNOS expression in stroma also has negative correlation with tumor size (P=0.016) and nuclear grade (P=0.025). No significant correlation between eNOS expression and clinicopathological factors was observed but eNOS expression in tumor cells contributed to worse 5 year overall survivals (92.1% vs 77.0%) in marginal significance (P=0.053). CONCLUSION: These data suggest that iNOS expression in tumor may have an inhibitory effect in tumor growth and lymph node metastasis. These results may be further investigated.