Inducible nitric oxide synthase expression in benign prostatic hyperplasia, low- and high-grade prostatic intraepithelial neoplasia and prostatic carcinoma.

OBJECTIVE: To elucidate the incidence of inducible nitric oxide synthase (iNOS) expression in benign prostatic hyperplasia (BPH), low- and high-grade prostatic intraepithelial neoplasia (PIN) and prostatic carcinoma lesions, and to explore the role of iNOS in prostate tumorigenesis.
MATERIALS AND METHODS: Immunoreactivity for iNOS was examined in 20 samples each of BPH, high-grade PIN, low-grade PIN and prostatic carcinoma.
RESULTS: Positive iNOS immunostaining was detected in all samples from all patients; iNOS was detected in both basal epithelial cells and secretory cells of the glandular epithelium. High-grade PIN and prostatic carcinoma samples had more intense iNOS immunostaining than low-grade PIN and BPH samples. In all samples, smooth muscle cells showed weak or moderate iNOS immunoreactivity and endothelial cells showed moderate immunostaining.
CONCLUSIONS: Nitric oxide generated by iNOS may be involved in prostate tumorigenesis and further studies with immunohistochemical and molecular biology are needed to determine the exact role of iNOS in the pathogenesis of prostatic carcinoma.