Catherine Malet

Progesterone effect on cell growth, ultrastructural aspect and estradiol receptors of normal human breast epithelial (HBE) cells in culture.

The stimulating effect of estradiol (E2) on breast cell growth is well documented. However, the actions of progesterone (P) and its derivatives remain controversial. Additional information is therefore necessary. On a culture system of normal human breast epithelial (HBE) cells, we observed an inhibitory effect on cell growth of a long-term P treatment (7 days) in the presence or absence of E2, using two methods: a daily cell count providing a histometric growth index, and [3H]-thymidine incorporation during the exponential phase of cell growth. A scanning electron microscopy study confirmed these results. Cells exhibited a proliferative appearance after E2 treatment, and returned to a quiescent appearance when P was added to E2. In both studies, P proved to be as efficient as the synthetic progestin R5020. Moreover, the immunocytochemical study of E2 receptors indicated that E2 increases its own receptor level whereas P and R5020 have the opposite effect, thus limiting the stimulatory effect of E2 on cell growth. In the HBE cell culture system and in long-term treatment, P and R5020 appear predominantly to inhibit cell growth, both in the presence and absence of E2.

17β-estradiol dehydrogenase (E2DH) activity in T47D cells

Abstract Activity of NAD-dependent 17β-hydroxysteroid dehydrogenase (E2DH), the enzyme which converts estradiol (E2) into its less active metabolite estrone (E1), has been previously characterized in normal human breast cells in culture and in benign and malignant breast tumors. E2DH activity is far greater in epithelial cells than in fibroblasts. Moreover, it is progesterone dependent in epithelial cells. It was therefore interesting to explore E2DH in the progesterone receptor (PR)-rich T47D cell line as a possible marker of hormone dependence in breast cancer cells. In T47D cells, transformation of [ 3 H]E2 to E1 is limited. The metabolism seems to be preferentially oriented in the way E1 → E2 in these cells. However, in the presence of the cofactor NAD the conversion of E2 into E1 increases. Moreover, treatment of T47D cells in culture by the progestin R5020 stimulates E2 to E1 conversion 2- to 3-fold. Stimulation of E2DH (E2 → E1) activity reflects both the presence and the operability of PR. This observation underlines the possible interest of E2DH assay in parallel to estradiol receptor and PR to evaluate hormone-dependence of breast cancer.

Effect of 4-hydroxytamoxifen isomers on growth and ultrastructural aspects of normal human breast epithelial (HBE) cells in culture

In the search for a breast cancer prevention strategy which would avoid undesirable effects of orally administered tamoxifen, the percutaneous administration of the highly active metabolite 4OHTamoxifen (4OHTam) has been proposed. Percutaneous 4OHTam penetrates the skin to reach breast tissues. It, thus, avoids the hepatic first pass effect, and offers an optimal local/systemic effect. However, trans-4OHTamoxifen can spontaneously isomerize into the cis-isomer, which may have estrogen agonist action. The aim of this study was to examine the effect of cis-4OHTam on normal human breast epithelial (HBE) cells in culture. Spontaneous isomerization of trans- into cis-4OHTam occurred within 24-48h, but stabilized rapidly at a trans/cis ratio of 70/30, whether in stock solution, culture medium or cultured cells. The cis-4OHTam did not stimulate HBE cell growth according to histometric cell counts and scanning electron microscopy analysis, but inhibited E(2)-induced cell growth, albeit two to three times less than trans-4OHTam. In conclusion, spontaneous isomerization of trans- to cis-4-OHTam is limited and 4OHTam retains a marked antiestrogenic effect. It may prove to be a useful alternative to tamoxifen in breast cancer prevention, especially if administered percutaneously.

Estrogen and antiestrogen actions on transforming growth factorβ (Tgfβ) in normal human breast epithelial (HBE) cells

We have previously shown that estradiol (E2) increases the growth of normal human breast epithelial (HBE) cells and the antiestrogen 4-hydroxytamoxifen (4-OHT) inhibits estrogen-induced proliferation. These effects of estrogens and antiestrogens on proliferation have also been well documented in breast cancer cells. One mechanism for the antiproliferative effects of antiestrogens is the stimulation of TGFbeta in hormone-dependent MCF-7 and T47D cells. The role of this inhibitory growth factor in normal human breast cells has not been well studied. Accordingly, we measured the amounts of total and active TGFbeta1 and TGFbeta2 by specific E(max) immunoassay (EIA) in culture medium from normal breast cells (epithelial and fibroblasts) and from various ER- and ER+ breast cancer cell lines. We established that HBE cells are sensitive to the antiproliferative effect of TGFbetas, and studied the effect of E2 and 4-OHT, alone or in combination, on the secretion and activation of TGFbetas by HBE cells. HBE cells secrete TGFbeta1 and even more TGFbeta2, and are sensitive to these factors. However, in contrast to MCF-7 cells, TGFbeta secretion in normal breast cells is not regulated by E2 and 4-OHT.

The Influence of Steroid Hormones and Antihormones on the Growth and Differentiation of Normal Human Breast Cells in Culture

Breast cancer still remains the most frequent cancer in women, occurring in 1 out of 9 women, whereas advances in therapeutics have not led to a decrease in mortality. Only a policy of early screening in high-risk populations and of prevention based on a clear pathophysiological understanding could lead to a decrease in the mortality due to this cancer.

Hormone dependence of breast tissue estradiol and progesterone interaction.

Abstract In 1987, the most frequent cancer in women is breast cancer, which occurs in 1 out of 11 women. Hormonal factors, especially estrogens, seem to be involved at least as cancer promoters based on epidemiologic studies (1–4) and experimental data in animals (5–9), whereas progesterone could be protective. Apart from the puberal period during which breast growth depends essentially on estradiol (E 2 ) secreted alone, breast tissue as endometrium is subjected to alternate secretions of E 2 and P as soon as ovulatory cycles occur. It is essential to define the estrogen-progestogen balance in order to be able to maintain or to re-establish it (9,10). • in spontaneous menstrual cycles, which may be dysovulatory • in hormonal treatments, either contraception or replacement therapy for menopause • as well as in benign breast diseases, which are known to occur preferentially in a hormonal environment of unopposed estrogen effect (11,12) and which-under certains conditions-may predispose to breast cancer (13). However, it will take many years for epidemiologists to collect data and verify this hypothesis and its implementations in the prevention of breast cancer. It seems therefore essential to gather as much information as possible on breast hormone dependence, in particular the respective roles of E 2 and P - or progestins - on cell multiplication and differentiation, and their mechanisms of action.