The effect of 2-methoxyoestrone-3-O-sulphamate on the growth of breast cancer cells and induced mammary tumours.

2-Methoxyoestrogens are emerging as a new class of drug that can inhibit tumour growth and angiogenesis. As sulphamoylation of oestrogens enhances their potency and bioavailability we have synthesized 2-methoxyoestrone-3-O-sulphamate (2-MeOEMATE) and compared its ability to inhibit the proliferation of breast cancer cells with that of 2-methoxyoestrone (2-MeOE1). 2-MeOEMATE (1 microM) inhibited the growth of oestrogen receptor positive MCF-7 breast cancer cells by 52% whereas 2-MeOE1 had little effect at this concentration. 2-MeOEMATE also inhibited the growth of oestrogen receptor negative MDA-MB-231 breast cancer cells. Exposure of cells to 2-MeOEMATE caused them to round up and become detached suggesting that this compound may induce cells to undergo apoptosis. Cell cycle analysis revealed that 2-MeOEMATE caused cells to arrest in the G(2)/M phase with the increase in G(2)/M arrested cells being detectable by 12 hr. Exposure of MCF-7 cells to 2 L-MeOEMATE for 24 hr followed by culture in drug-free medium for 24 hr did not reverse the arrest of cells in the G(2)/M phase. TUNEL analysis confirmed that 2-MeOEMATE induced apoptosis in a significant proportion of treated MCF-7 cells. In an in vivo study, employing nitrosomethylurea-induced mammary tumours in intact rats, 2-MeOE1 (20mg/kg/d, p.o. for 11 days) had little effect on tumour growth. In contrast, the same dose of 2-MeOEMATE resulted in the almost complete regression of 2/3 tumours over an 11-day period. We conclude that 2-MeOEMATE should have considerable therapeutic potential for the treatment of breast tumours.

Lack of suppression of increased circulating prolactin by 2-hydroxyestrone.

To study the effect of 2-hydroxyestrone (2-OHE1) on circulating prolactin (PRL) in a hyperprolactinaemic state, seven anovulatory women with hyperprolactinaemia were given a 2-OHE1 infusion at a rate of 80 microgram/h for 3 h following a control infusion. Plasma samples for PRL determination were obtained at 30-minute intervals for 6h. No changes in PRL levels were observed during the 2-OHE1 infusion as compared with the control period. It was concluded under conditions of the present experiment that 2-OHE1 does not suppress circulating PRL in hyperprolactinaemic anovulatory women.

Failure of 2-hydroxyoestrone to lower prolactin concentrations in hyperprolactinaemic women.

The catechol oestrogen 2-hydroxyoestrone has been reported to lower serum prolactin concentrations acutely in normal women and it has been proposed that it may be effective in suppressing prolactin secretion in hyperprolactinaemic patients. Five women with hyperprolactinaemia and anovulation were studied. Following a control infusion, 2-hydroxyoestrone was given at a rate of 80 micrograms/h for 4 h. In no patient was there a fall in prolactin levels and no changes were observed in gonadotrophin concentrations. We conclude that a short-term infusion of 2-hydroxyoestrone, at a dose which will produce high blood levels of the steroid, does not affect prolactin or gonadotrophin secretion in hyperprolactinaemic states.

Effect of catechol estrogens on rat mammary tumors.

The effect of 1,3,5(10)-estratriene-3, 16 alpha, 17 beta-triol (estriol), 1, 3, 5(10)-estratriene-2,3-diol-17-one (2-hydroxyestrone), and 1,3,5(10)-estratriene-2,3,17 beta-triol (2-hydroxyestradiol) on the growth of dimethylbenz(a)anthracene-induced mammary tumor and of R3230AC-transplantable mammary tumor was compared with that produced by estradiol benzoate treatment. Estriol showed minimal inhibition of tumor growth in dimethylbenz(a)anthracene-induced tumor and no effect on R3230AC tumor while 2-hydroxyestrone showed no effect of tumor inhibition. On the other hand, 2-hydroxyestradiol showed appreciable inhibition of tumor growth in both tumors studied. That 2-hydroxyestradiol has been found to bind to estrogen receptors in mammary tumors and is uterotropic suggests that the inhibition of tumor growth by 2-hydroxyestradiol may be similar to the mechanism of inhibition of mammary tumors by high concentrations of estradiol.