fosfestrol and diethylstilbestrol-monophosphate

For many years, diethylstilbestrol (DES) and its diphosphate (DESPP; Honvan) have been standard therapies for prostatic carcinoma. The effects of DES, its monophosphate (DESP) and of DESPP on the weights of accessory sex organs of mice and rats, and on the experimental Noble Nb-H and Nb-R prostatic carcinomas of the rat were, therefore, compared. In intact mature mice, all three compounds led to a strong and dose-dependent inhibition of seminal vesicle weights and testosterone levels, whereas only a slight antiandrogenic activity in castrated mice was found. In intact rats, DES, DESP and DESPP strongly inhibited accessory sex organ weights and testosterone levels. In castrated rats, however, no antiandrogenic activity was determinable. The prostate carcinoma-inhibiting effects of DES and DESPP were tested in comparison with castration in the transplantable hormone-sensitive Nb-H and Nb-R prostatic carcinoma in rats. Whereas castration caused only a retardation of tumor growth, DES and DESPP (3 x 0.1 mg/kg and 1.0 mg/kg weekly s.c.) led to an almost complete inhibition, which was significantly (P less than 0.01) better than the effect of castration. As the weights of accessory sex organs were identically reduced by either castration or the estrogens, a direct tumor-inhibiting effect of DES and DESPP in addition to their testosterone-lowering activity is obvious. This was proved in an experiment with castrated rats. The only slightly inhibitory activity of castration was strongly potentiated by concomitant administration of DES. Moreover, histological examinations revealed that Nb-H and Nb-R tumors were much more damaged by treatment with DES or DESPP than after castration. Morphometry of the tumors showed that tumor reduction is associated with a decrease in the ratio of the epithelial to the stromal density, i.e. there was an even more pronounced decrease in epithelial cells than that found by merely measuring tumor area. These studies show that the prostate carcinoma-inhibiting effect of DES and DESPP in the Nb model is superior to the effect of castration and that they act directly on the tumor cells used, even in castrated rats.

Topics: Androgen Antagonists; Animals; Carcinoma; Diethylstilbestrol; Genitalia, Male; Male; Organ Size; Prostatic Neoplasms; Rats; Rats, Inbred Strains; Receptors, Androgen; Tamoxifen

To evaluate a possible direct cytotoxic effect of diethylstilbestrol diphosphate (DESDP) in the treatment of prostate cancer we exposed three prostatic carcinoma cell lines (LNCaP, DU 145, and PC-3), 2 nonprostatic neoplastic cell lines (KB and EJ), and one nontransformed cell line (MRC-5) to diethylstilbestrol (DES), diethylstilbestrol monophosphate, and DESDP at levels occurring in patients' sera during p.o. DES therapy (2 to 5 ng/ml) or DESDP infusions (1 to 20 micrograms/ml), respectively. With 5 ng/ml of DES no effect was seen in LNCaP cells, even after 14 days of exposure. In contrast, drug levels attained during DESDP infusions showed marked, dose-dependent cytotoxicity towards all cell lines under study. Prostatic cells were not exceptionally sensitive. High-dose DES slightly stimulated the synthesis of prostatic acid phosphatase in LNCaP cells. Formation of foci of polygonal cells was induced by 5 micrograms/ml of DES in cultures of MRC-5 fibroblasts. We conclude that, at high doses, DES liberated from DESDP acts upon a regulatory or metabolic mechanism common to many if not all human cells. Preferential sensitivity of prostate cancer cells in vivo may be due to high local phosphatase activity and/or DES accumulation in prostatic tissue.

Topics: Acid Phosphatase; Antineoplastic Agents; Diethylstilbestrol; Humans; Male; Phosphoric Monoester Hydrolases; Prostate; Prostatic Neoplasms; Tumor Cells, Cultured

Diethylstilbestrol (DES), diethylstilbestrol monophosphate (DES-MP) and diethylstilbestrol diphosphate (DES-DP) were tested for their estrogen receptor affinity, estrogenic potency and mammary tumor-inhibiting activity in vitro and in vivo. DES had a much higher receptor binding affinity than its mono- or diphosphate. All three compounds inhibited the growth of the hormone-dependent MCF-7 and hormone-independent MDA-MB 231 breast cancer line only at relatively high concentrations. The estrogenic potency in the immature mouse uterine weight test decreased in the order DES greater than DES-MP much greater than DES-DP. The hormone-dependent MXT mammary tumor of the mouse was inhibited by all three compounds at a dosage of 1.0 mg/kg per week. At a dose of 0.01 mg/kg, DES, DES-MP, and DES-DP stimulated the tumor growth. Thus, for the first time, a biphasic effect on tumor growth was demonstrated in intact mature animals. As the effects of all three compounds were similar in this assay, a cleavage of the phosphate groups is likely. A decrease in estrogenic potency concomitant with a retained antitumor effect of DES-MP and DES-DP compared to DES was not demonstrable in the mature mouse using the MXT assay, only in the uterotrophic test in the immature mouse.

Topics: Animals; Breast Neoplasms; Cell Line; Diethylstilbestrol; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Estradiol; Female; Humans; In Vitro Techniques; Mammary Neoplasms, Experimental; Mice; Mice, Inbred Strains; Neoplasm Transplantation; Receptors, Estradiol; Uterus