Expression of inducible nitric oxide synthase in cutaneous adnexal tumours of the head and neck

Significance of inducible nitric oxide synthase expression in benign and malignant breast epithelium: an immunohistochemical study of 151 cases

The role of calcium independent inducible nitric oxide synthase (iNOS) in breast carcinoma is controversial, and the implications of iNOS expression on prognosis are not known. In this study, we aimed to investigate the significance of immunohistochemical iNOS expression in 100 invasive ductal carcinomas. In addition, 11 normal breast tissues, 20 cases of usual ductal hyperplasias (UDHs) and 20 fibroadenomas were included. We found that 78% of malignant and 75% of benign cases showed iNOS immunoreactivity. However, the intensity and the quantity of iNOS expression were significantly higher in the cancer group when compared with benign breasts (P<0.001), suggesting a role of iNOS in breast carcinogenesis. We were unable to show a correlation between iNOS expression and tumor grade, axillary lymph node status, and estrogen receptor expression. In 50 axilla negative cases having 5--12 years follow-up, disease free survival (DFS) rate was significantly lower in cases showing strong iNOS expression (P=0.05). As strong iNOS expression was correlated with short DFS, we concluded that further studies would be necessary to elucidate if iNOS expression might be a useful prognostic marker in breast carcinoma, especially in the axilla negative group.

The role of nitric oxide synthases and nitrotyrosine in retinoblastoma

BACKGROUND

To investigate the potential involvement of the nitric oxide (NO) pathway in retinoblastoma, the authors correlated immunoreactivity for endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and nitrotyrosine (NT) with the degree of tumor invasiveness in retinoblastoma.

METHODS

eNOS, iNOS, and NT reactivity was evaluated by immunohistochemistry in 34 archival retinoblastoma specimens and in a human Y79 retinoblastoma cell line. The tumors were divided into 2 groups: Group A tumors (n = 17 tumors) with no invasion and Group B tumors (n = 17 tumors) with invasion of the choroid, optic nerve, and/or orbit. The expression levels of eNOS, iNOS, and NT were correlated with invasiveness of the tumors.

RESULTS

In Group A tumors (n = 17 tumors) without invasion, eNOS was positive in 17 of 17 tumors (100%), iNOS was positive in 14 of 17 tumors (82%), and NT was positive in 17 of 17 tumors (100%). In Group B tumors (n = 17 tumors) with invasion, eNOS was positive in 17 of 17 tumors (100%), iNOS was positive in 16 of 17 tumors (94%), and NT was positive in 17 of 17 tumors (100%). The invasive cohort showed significantly higher expression of iNOS (P < 0.0001) and NT (P < 0.020) compared with the noninvasive cohort. Y79 cells also expressed eNOS, iNOS, and NT; and nonneoplastic retina was positive for eNOS, iNOS, and NT.

CONCLUSIONS

Taken together, the results suggested that retinoblastomas can produce NO. The roles of NO in the biology of retinoblastoma and in the prognosis for patients with retinoblastoma remain to be established.