The expression of estramustine-binding protein in the human prostatic cancer cell line DU 145 is not androgen...

Estramustine-binding protein (EMBP) constitutes one of the major proteins in the prostatic gland, it binds estramustine and estromustine, the active metabolites of estramustine phosphate (Estracyt). Previous studies in rats have indicated that the expression of EMBP is androgen dependent, with diminishing quantities following castration and estrogen treatment as well as restored pre-castration production upon administration of androgens. In this study, we have used the human prostatic cancer cell line DU 145 transplanted in female and male nude mice. This cell line, which is sex hormone independent, gave rise to subcutaneous tumors in the rats with no difference in growth characteristics between the males and females. The expression of EMBP was analysed by radioimmunoassay, immunohistochemical and Western blot techniques. No difference was seen between the two sexes with respect to EMBP content, demonstrating that the expression of EMBP, in contrast to that reported for the normal prostate, is neither androgen- nor estrogen-dependent in tumor tissues.