Abstract
Endothelial calcium-dependent nitric oxide (NO) synthase has been shown to be expressed in human malignant breast tumours, and its presence correlates with tumour grade. Moreover, NO, being synthesised in breast tumour cells, may increase tumour blood flow and promote angiogenesis. In view of these aspects, we have assessed the distribution of NO synthase within a series of benign breast tumours using a monoclonal antibody against human endothelial calcium-dependent NO synthase. Activity was predominantly localised in apocrine metaplastic cells of fibrocystic disease, as well as in endothelia throughout all tissue sections. Consistent with previous reports, no endothelial calcium-dependent NO synthase immunoreactivity was observed in poorly differentiated infiltrating duct carcinoma cells. In conclusion, expression of endothelial calcium-dependent NO synthase in human breast apocrine metaplasia may be of significance in view of the NO's vascular effects in benign breast disease.
Highlights
Apocrine metaplasia or pink cell change of the breast, associated with cystic breast epithelium is characterised by high cylindrical cells with granular eosinophilic cytoplasm and luminal cytoplasmic projections (Bonser et al, 196L)
Vascular endothelial cells in the samples were used as the positive control; a non-immune serum was used for the negative control
Immunolabelling of vascular endothelial cells was widespread throughout all tissue sections (Figure 2)
Summary
The staining reactions were performed on frozen sections of 30 samples of breast tissue. A monoclonal anti-eNOS antibody was used at a concentration of 2.5 pg ml- 1 (Transduction Laboratories, Lexington, KY, USA). Specificity of the staining for eNOS was evident from its elimination by preabsorption with the eNOS peptide and the absence of staining with preimmune serum as was recently described (Dinerman et al, 1994). A high-performance biotinstreptavidin detection system was used (Bio Genex, San Ramon, CA, USA). Vascular endothelial cells in the samples were used as the positive control; a non-immune serum was used for the negative control. The sections were counterstained with Mayer's haematoxylin and mounted with an aqueous medium
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