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 mediate by estramustine. Immunohistochemical analysis of tumoru 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 from 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. (orig.)