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.