Elevated expression of estramustine binding protein (EMBP) in prostatic intraepithelial neoplasia (PIN) compared with malignant and benign prostatic epithelia

Lipophilin, a novel heterodimeric protein of human tears

We identified a novel heterodimeric protein, lipophilin AC, in human tears. One of its components, lipophilin A (69 residues; mass, 7575.1; pI, 9.47) was homologous to the C1 and C2 components of prostatein ('estramustine-binding protein'), the major secreted protein of rat prostate. Human lipophilin C (77 residues; mass, 8854.1; pI, 4.94) was homologous to the rat prostatein C3 component and to human mammaglobin, a protein overexpressed in some mammary carcinomas. Tear lipophilins A and C expand the roster of human uteroglobin superfamily members and provide models for exploring these typically steroid-regulated and steroid-binding molecules.

Molecular biology of prostatic intraepithelial neoplasia

High-grade PIN is the most likely precursor of prostatic adenocarcinoma, according to virtually all available evidence to date. The clinical importance of recognizing PIN is based on its strong association with prostatic carcinoma. PIN has a high predictive value as a marker for adenocarcinoma. Its identification in biopsy specimens of the prostate warrants further search for concurrent invasive carcinoma. PIN is associated with progressive abnormalities of phenotype and genotype intermediate between normal prostatic epithelium and cancer, indicating impairment of cell differentiation and regulatory control with advancing stages of prostatic carcinogenesis. There is progressive gain or loss of a wide variety of biomarkers, including morphometric markers, differentiation markers, stromal markers, growth factors and associated receptors, oncogenes, tumor suppressor genes, and chromosomes. Abnormalities in expression of most biomarkers are amplified in the progression from high-grade PIN to localized cancer, metastatic cancer, and hormone-refractory cancer. Oncogenesis of prostatic carcinoma probably occurs through the selection of several genetic changes, each modifying the expression or function of genes controlling cell growth and differentiation. Further studies are needed to evaluate the function and prognostic value of oncogene expression in the normal, preneoplastic, and neoplastic prostate.

Estramustine-binding protein (EMBP) in renal cell carcinoma immunohistochemistry, immunoscintigraphy and in vitro estramustine effects

The present report shows that the human renal cell carcinoma (RCC) cell lines, A498 and CAKI-2, express the estramustine-binding protein (EMBP). The RCC cell lines investigated were highly sensitive for estramustine, with cell arrest in atypical metaphase. In vitro experiments using a fluorimetric cytotoxicity assay (FMCA) showed a pronounced cytotoxic effect mediated by estramustine. Immunohistochemical analysis of tumour specimens from patients with RCC showed positive staining for EMBP in 12/16 cases. Immunoscintigraphy was performed in an experimental system in nude mice, heterotransplanted with the CAKI-2 cell line. A radiolabelled monoclonal anti-EMBP antibody was used. The results show a specific uptake of the antibody in the RCC tumour, expressed as a percentage of the injected dose per gram tissue, which ranged from 4.03 to 6.9. The results obtained form the basis for clinical studies on the feasibility of utilizing estramustine in the management of RCC. Immunoscintigraphy using the monoclonal anti-EMBP antibody is of potential use for in vivo characterization of the malignancy and in the selection patients suitable for treatment with estramustine.

Production of monoclonal antibody against the C1 component of rat estramustine-binding protein: immunohistochemical study of rat prostate

The monoclonal antibody against estramustine-binding protein (EMBP) was produced by immunizing a mouse with EMBP antigen purified from rat ventral prostate. On western blotting analysis this antibody recognized the EMBP C1 component, and in an absorption test it recognized the EMBP antigen. Immunohistochemically, this antibody revealed positive staining for the ventral and dorsolateral prostate. In the epithelium of the ventral prostate, intense immunostaining was observed in the intraluminal secretory product; however, in the epithelium of the dorsolateral prostate, the staining was intense in the cytoplasm of the epithelial cells. These findings suggested differences of EMBP localization in the ventral and the dorsolateral prostate. Since the intensity of immunostaining for EMBP was decreased in the prostate of castrated rats, we considered that this antibody reflected the androgen dependency of EMBP.

Pre-neoplastic lesions of the prostate

Acinar carcinoma of the prostate is the third most frequently registered cancer and its incidence is expected to increase as life expectancy increases. Consequently, there have been attempts to introduce possible screening programmes for early detection of prostatic carcinoma. In this context the histopathologist has a role in that potential pre-neoplastic lesions have to be recognized. Two such pre-neoplastic lesions in the prostate are adenomatous hyperplasia and prostatic intraepithelial neoplasia. In this article the histological features of these lesions, their differential diagnosis and their pre-malignant potential are reviewed.