Critical period of induction by tamoxifen of genital organ abnormalities in female mice.

Genital organs of C57BL/Tw female mice given 5 daily injections of 100 micrograms tamoxifen (Tx) from the day of birth (day 0) were examined at 5, 10, 15, 20, 30 and 60 days of age. The incidence of polyovular follicles (PF) in Tx mice was higher, but the development of uterine glands and tunica muscularis uteri in Tx mice was lower than in the age-matched controls. Uteri of 15-day-old Tx mice underwent a weight increase resulting from edematous change in the stromal tissue lacking type I collagen and fibronectin. Adenosis-like lesions were found in the vaginae of 5- to 30-day-old Tx mice. Mice given neonatal injections of 100 micrograms clomiphene (Clm) and nafoxidine (Naf) were also examined at 60 days. Tx caused much greater damage to the ovary and uterus than did Clm and Naf. In order to examine the critical period of induction by Tx of female genital organ abnormalities, mice were given 5 daily injections of Tx starting at different early postnatal ages. Tx injections starting within 5 days caused a high incidence of PF in the ovary and aplasia of tunica muscularis in the uterus. The Tx treatment also induced atrophy of the uterine luminal epithelium when started within 7 days. The present study suggests, therefore, that the postnatal limit of the critical period for the female genital organs lies within 7 days after birth.

Abnormal development of the os penis in male mice treated neonatally with tamoxifen.

The os penis of male C57BL/Tw mice given 5 daily injections of 100 micrograms tamoxifen (Tx) starting on the day of birth (day 0) was examined at ages of 5-60 days; the bones of males given Tx injections for 5 days starting at 0-10 days and of those given neonatal injections of 100 micrograms clomiphene or nafoxidine were examined at 60 days. In the control males given the vehicle alone, the proximal segment of the os penis, composed of a compact cell mass found at day 0, developed at 5 days into the membrane bone with bone marrow and hyaline cartilage; the distal segment, composed of mesenchymatous cells until 10 days, developed at 30 days into fibrocartilage characterized by a distribution of type I collagen. By contrast, in Tx mice, fibrocartilage in the distal segment, and hyaline cartilage characterized by a distribution of type II collagen, and bone marrow in the proximal segment disappeared by 30 days. The maximum area of the proximal and distal segments gradually increased with age in control mice, whereas the proximal segment area remained unchanged in Tx mice. In clomiphene and nafoxidine mice at 60 days, the proximal segment was composed of hyaline cartilage; however, the distal segment lacked fibrocartilage. Hyaline cartilage in the proximal segment and fibrocartilage in the distal segment disappeared in all 60-day-old mice given Tx starting within 5 days. Neonatal castration did not suppress the formation of bone marrow and fibrocartilage in the os penis, though the bone size was smaller than in the intact controls. Formation of spines on the glans penis skin was suppressed by Tx given within 5 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of renal carcinoma: a phase III randomized trial of oral medroxyprogesterone (Provera), hydroxyurea, and nafoxidine.

Seventy patients with metastatic renal carcinoma were randomized to receive hydroxyurea, nafoxidine, or medroxyprogesterone (Provera) orally. Sixty patients were considered evaluable, with a response rate of 5% for medroxyprogesterone (one complete remission) and hydroxyurea (one partial remission) and a response rate of 16% for nafoxidine (two complete remissions and one partial remission). Differences in response rates and duration of survival were not statistically significant. The major toxicity observed with hydroxyurea was hematologic, and the major toxic effect of nafoxidine was an ichthyosis-like skin rash. Toxicity for medroxyprogesterone was minimal.

Studies on mechanisms of estrogen and antiestrogen action in human breast cancer.

PIP: Studies have shown that patients whose tumors are ER (estrogen receptor) positive have at least tenfold chance of responding successfully to endocrine therapy. However, not all ER-containing tumors necessarily respond, and ERs are thus considered necessary but not sufficient markers of hormone dependence. It has been proposed that progesterone receptors (PgR) found in human breast tumors may serve as a marker of estrogen action in breast cancer, since PgR synthesis is known to be controlled by estrogens in the uterus. The authors have recently worked on a modal system which shows that PgR are under estrogen control and that PgR synthesis involves the ER. Their study concerning the effects of antiestrogens show that tamoxifen (TAM) is a potent inducer of PgR on the cells and that TAM's estrogenic property is masked at very high doses (1 mcg/M) which also inhibit cell growth. Nafoxidine (NAF), another antiestrogen, had little effect on PgR when tested over a wide dose range. It has been reported that growth-inhibitory effects of both antiestrogens can be reversed by estradiol; this indicates that the effects of these compounds are mediated through the ER system. A complex system in cells in which ER binding and translocation and turnover of nuclear receptors or their processing mediate the induction of PgR by estradiol is described.^ieng

Selective blockade of estrogen-induced uterine responses by the antiestrogen nafoxidine.

The response of the immature rat uterus to the antiestrogen, nafoxidine (Upjohn U-11, 100A), is maximum at a dose of 5 micrograms. This dose of nafoxidine sustains the uterine response for at least 72 h. After treatment with 5 micrograms nafoxidine for 24 h, uterine cytosol contains approximately one half the total number of estrogen receptors originally present in uteri of untreated animals, and uterine nuclei also contain approximately one half the receptors originally present in unstimulated tissue. The total amount of uterine estrogen receptor, however, is not altered 24 h after treatment with nafoxidine relative to saline-treated controls, while estradiol treatment doubles the total amount of receptor relative to controls. Pretreatment with 5 micrograms nafoxidine for 24 h does not block the uterine response occurring 4 h after the subsequent administration of estradiol, but does block the uterine response occurring 24 h after the subsequent administration of estradiol. These results suggest that uterine nuclei contain different acceptor sites for regulating short term and long term uterine responses to estrogen.

Fundamental differences in the action of estrogens and antiestrogens on the uterus: comparison between compounds with similar duration of action.

In order to understand differences in the mechanism of action of estrogens and antiestrogens, it is essential to make comparisons between compounds with similar duration of action. Hence, in these studies, we compare the action of a long-acting estrogen (17alpha-ethinyl estriol-3-cyclopentyl ether, EE3CPE) and a long-acting antiestrogen (U-11,100AUA) on the immature rat uterus and analyze different dosage regimens (single and multiple injections) in studying the effects of these compounds on the uterine estrogen receptor and on uterine growth and sensitivity to estradiol. During the first 24 h, UA (50 microng) and EE3CPE (5 microng) evoke remarkably similar receptor distribution patterns and uterine wet weight increase; however, pronounced differences are seen with long-term, multiple injection regimens (every 12 or 24 h for 72 h). Such treatment with UA results in maintenance of high nuclear receptor levels and very low cytoplasmic receptor levels (ca. 10% of total), but no further increase in uterine weight, DNA or protein content, or total receptor content beyond 24-48 h. In contrast, multiple injections of EE3CPE produce not only a prolonged nuclear retention of receptor, but a progressive increase in total receptor content in the tissue and 35-50% of total receptor is cytoplasmic; uterine weight and DNA and protein content also continue to increase markedly above the 24 h level, and responsiveness to estradiol is maintained. However, regardless of whether the uterus continues to grow (as the EE3CPE) or stops growing after 24-48 h (as with UA), the receptor content on a cell basis is similar. Hence, uterine responsiveness to estradiol and continued uterine growth appear not to be related to the total content of receptor per cell, but rather are correlated with the cytoplasmic receptor level within the cell. As there is a continuous translocation of cytoplasmic receptor to the necleus in the growing uterus, the antagonistic action of antiestrogens appears to derive from their ability to effect a marked perturbation in the subcellular distribution of receptor, whereby very little of receptor (ca. 10%) is cytoplasmic, and further estrogen receptor accumulation (most likely synthesis) is blocked.

Comparative trial of nafoxidine and ethinyloestradiol in advanced breast cancer: an E.O.R.T.C. study.

A randomized clinical trial of nafoxidine, a non-steroidal oestrogen antagonist, and ethinyloestradiol in postmenopausal patients with advanced breast cancer produced objective remissions in 31% of 49 women receiving nafoxidine and in 14% of 49 receiving ethinyloestradiol. The differences in remission rates was almost significant (0.05 less than P less than 0.10). Life-threatening complications were more frequent with ethinyloestradiol than with nafoxidine but the latter produced specific toxic reactions on skin and hair that may limit its practical usefulness. Synthetic oestrogen antagonists may occupy a privileged place in the treatment of breast cancer, and other representatives of this new class of compounds should be accurately assessed in randomized clinical trials.

Controlled clinical trial of L-dopa and nafoxidine in advanced breast cancer: an E.O.R.T.C. study.

L-Dopa lowers plasma prolactin levels, and there have been reports that patients with advanced breast cancer have been successfully treated with L-dopa. To test the potential value of L-dopa in this disease a randomized clinical trial of L-dopa and nafoxidine (as the reference compound) was conducted in postmenopausal women with advanced breast cancer. Objective remissions were obtained in sever out of 36 patients (19%) treated with nafoxidine but in none out of 40 patients treated with L-dopa. L-Dopa in the dose schedule used seems to be ineffective in advanced breast cancer.