The WHO claims estrogens are 'carcinogenic': is this true?

Estrogens are in the list of carcinogenic chemicals from the World Health Organization (WHO). However, estrogens require additional factors such as stromal factors or progestogens to increase the ratio of proliferation/apoptosis for initiation of replication errors and consequent mutations to occur. These mutations require at least 5-10 years to develop into clinically detectable cancer, whereby this review is focused on breast cancer. The US National Cancer Institute highlighted a second mechanism of carcinogenicity: certain estrogen metabolites are capable of inducing DNA damage, even in low concentration. They can be assessed in the tissue and circulation. However, those deleterious reactions require excessive unrestricted oxidative cell stress, for example in industrial areas with heavy pollution. We have shown that this can be avoided using transdermal instead of oral estradiol treatment, especially important in smokers. The spectrum of metabolites is also influenced by other exogenous factors such as nutrition, physical activity and certain diseases. Reduction of breast cancer risk as demonstrated in the Women's Health Initiative (WHI) was explained by pro-apoptotic estrogen effects working after a certain 'time gap'. In addition, certain estrogen metabolites are carcinoprotective, if no genetic polymorphisms would impair their beneficial activities. Thus, since additional factors are required for both main pathways of carcinogenicity and because estrogens can even have carcinoprotective effects, we cannot agree with the statement from the WHO.

PGRMC1 promotes triple-negative breast cancer cell growth via suppressing ferroptosis

OBJECTIVE

Triple-negative breast cancer (TNBC) is the most malignant form of breast cancer with increasing incidence and mortality worldwide. The progesterone receptor membrane component-1 (PGRMC1) is a well-identified hormone receptor with unknown functions in TNBC. The current study aims to explore the involvement of PGRMC1 in regulation of glutathione metabolism and ferroptosis during development of TNBC, providing new therapy options for TNBC patients.

METHODS

Bioinformatic analysis, cell proliferation assay, western blot assay and other biochemistry methods were performed in TNBC cells.

RESULTS

Our results revealed that the expression of PGRMC1 is higher in TNBC than the other subtypes of breast cancer. Interestingly, as an iron binding protein, increased PGRMC1 expression in TNBC cells leads to resistance to ferroptosis inducer. On the contrary, silenced PGRMC1 expression enhanced sensitivity of MDA-MB231 cells to Erastin. Mechanistically, overexpression of PGRMC1 decreased the intracellular free iron concentration, which was reduced by AG205 treatment.

CONCLUSIONS

PGRMC1 increases the possibility of TNBC development through binding to intracellular iron and suppressing ferroptosis, providing the molecular basis of combined treatment for TNBC.

Primary choice of estrogen and progestogen as components for HRT: a clinical pharmacological view

Prescribing hormone replacement therapy (HRT) requires consideration of the selection of its two components, the estrogen and the progestogen. In terms of the estrogen, the decision is mainly whether to use estradiol (E2) or conjugated equine estrogens (CEE). These are the components needed to efficiently treat climacteric symptoms or/and prevent osteoporosis, currently the only labeled indications. There is still controversy regarding the adequate dosages comparing E2 and CEE; however, the consensus is that the differences in the efficacy of E2 and CEE are not a real issue. Therefore, other criteria have to be used. The first reason to add the progestogen is to avoid the development of endometrial cancer (i.e. to achieve 'endometrial safety'). Any available 'fixed-combined' HRT preparation has to be tested for sufficient endometrial efficacy, because the first question the health authorities ask before product registration relates to endometrial safety. We can generally rely on the endometrial safety of these fixed-combined products. However, it could be that we want to use 'free' combinations, which are necessary if we use transdermal E2 (patches, gel, spray), but also to individualize schedules, for example when treating bleeding problems. The question here is how to attain knowledge about the endometrial efficacy of the different progestogens and how to monitor therapy. We will try to answer these two questions from a 'clinical pharmacology' point of view, as a discipline which preferably considers pharmacological properties, but also relating to clinical practice, to achieve individualized therapy with optimal efficacy, best tolerability and minimal risks.

First live birth in China after cryopreserved ovarian tissue transplantation to prevent premature ovarian insufficiency

OBJECTIVE

This article reports the first live birth after cryopreserved ovarian tissue transplantation to prevent premature ovarian insufficiency in China.

METHODS

A patient with myelodysplastic syndrome received ovarian tissue cryopreservation before hematopoietic stem cell transplantation, and six ovarian cortex strips were thawed and transplanted into her peritoneal pocket 2 years later.

RESULTS

Pregnancy occurred spontaneously 27 months after grafting, and a healthy girl was born at 38 weeks gestation. Until now, the child has developed normally without any major diseases.

CONCLUSIONS

We report the first live birth resulting from ovarian tissue cryopreservation and transplantation in China.

E2 + norethisterone promotes the PI3K-AKT pathway via PGRMC1 to induce breast cancer cell proliferation

OBJECTIVE

This study aimed to find evidence that progesterone receptor membrane component 1 (PGRMC1) promotes estradiol (E2) + norethisterone (NET)-induced breast cancer proliferation through activation of the phosphatidylinositol-3-kinase (PI3K)-AKT pathway.

METHODS

PGRMC1-mediated breast cancer cellular proliferation and phosphorylation of PGRMC1 were studied using wild-type (hemagglutinin [HA]-tagged) MCF-7 cells, which were stably transfected with expression vector containing HA (MCF-7-HA cells), PGRMC1 (MCF-7-PGRMC1 cells) and Ser181 point mutated PGRMC1 (MCF-7-PGRMC1-S181A cells). Bioinformatics, cell proliferation, western blot, isobaric tags for relative and absolute quantitation (iTRAQ)-based RNA sequencing, real-time quantitative polymerase chain reaction (RT-qPCR) and cell cycle in vitro assays were performed to indicate the function of PGRMC1 and its possible mechanisms in breast cancer.

RESULTS

NET + E2 elicited a significant proliferation in MCF-7-Vec at 10^-6 M and 10^-10 M, respectively. MCF-7-PGRMC1 did increase the phosphorylation of AKT or ERK, which can be blocked by treatment with casein kinase 2 (CK2) inhibitor quinalizarin or in MCF-7-PGRMC1-S181A cells. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the PI3K-AKT pathway is upregulated in MCF-7-PGRMC1 cells. Importantly, upregulation of the PI3K-AKT pathway mainly through promotion of cell cycle regulation strongly promoted cell proliferation in MCF-7-PGRMC1 cells.

CONCLUSIONS

CK2 is involved in phosphorylation of PGRMC1 at S181. The mechanism for the action of PGRMC1 for mediating proliferative progestogen effects obviously starts with promotion cell cycle regulation, and then activation of the PI3K-AKT pathway.

First pregnancy in China after ovarian tissue transplantation to prevent premature ovarian insufficiency

OBJECTIVE

This article reports the first case of pregnancy after frozen-thawed ovarian tissue transplantation to prevent iatrogenic premature ovarian insufficiency in China.

METHODS

Ovarian tissue cryopreservation was performed in a patient with myelodysplastic syndrome (MDS) before multi-agent chemotherapy and hematopoietic stem cell transplantation. Two years later, she showed complete remission from MDS, and six frozen-thawed ovarian tissue strips were transplanted into the peritoneal pocket.

RESULTS

The patient's ovarian activity was restored 3 months after transplantation, and pregnancy occurred spontaneously 27 months after grafting. Until now, the pregnancy has progressed for 30 weeks, and the repeated ultrasound showed normal fetal development.

CONCLUSION

This is the first pregnancy resulting from ovarian tissue cryopreservation and transplantation in China.

Genitourinary syndrome of menopause in Chinese perimenopausal and postmenopausal women

OBJECTIVE

The aim of this study was to investigate genitourinary syndrome of menopause (GSM) in a large cohort, analyzing the dependency on age and menopausal status and possible differences between non-hysterectomized and hysterectomized women.

METHODS

Data were assessed by validated questionnaires, collected over 2 years for all eligible women attending our 'Menopause Clinic' from 31 Chinese provinces. Simple and unconditional logistic regression analysis was used with adjustments by all analyzed factors.

RESULTS

A total of 4063 women (mean age 50.53 ± 6.57 years), 2107 perimenopausal and 1956 postmenopausal, were included. Almost all GSM symptoms were more frequent and severe in postmenopausal women. GSM was more frequent in hysterectomized women compared to non-hysterectomized women. Independent of menopausal status, low sexual interest (92.78%), urinary incontinence (91.65%) and vaginal dryness (91.60%) were the top three GSM symptoms. Most severe were low sexual interest (21.01%), vaginal pain (20.10%) and decreased sexual pleasure (17.13%). Prevalence and severity of GSM were not related to age, but were related to menopausal status and increased with time since menopause.

CONCLUSIONS

Within 2 years, more than 4000 women with GSM traveled from all over China to our specialized clinic, indicating the great importance of GSM. Hysterectomy can increase the risk of GSM, and GSM symptoms increase from perimenopause to postmenopause and with an increase of time since menopause, pointing to the dependency on the loss of ovarian function.

PGRMC1 can trigger estrogen-dependent proliferation of breast cancer cells: estradiol vs. equilin vs. ethinylestradiol

Objective: Previous studies have shown that progesterone receptor membrane component 1 (PGRMC1) expressed in breast cancer tissue can predict a worse prognosis for breast cancer patients. Moreover, we demonstrated that PGRMC1 can increase the proliferation of progestogens. However, the role of PGRMC1 in terms of estrogen-induced proliferation and comparing different estrogens is still unclear. Methods: Non-transfected and PGRMC1-transfected T-47D cells were stimulated with estradiol (E2), with equilin (EQ), or with ethinylestradiol (EE) at 1, 10, and 100 nmol/l. Increase of proliferation was compared with a control (without estrogens) and with the estrogen-induced stimulation in empty vector cells vs. PGRMC1-transfected cells. Results: The empty vector cells showed significant proliferation (12-15%) with all three estrogens only at the highest concentration, with no relevant differences between the estrogens. PGRMC1-transfected cells showed about three-fold higher proliferation (29-66%), whereby E2 elicited the strongest and EE the lowest proliferating effects, significantly lower compared to E2 and also compared to EQ. No significant differences were seen between E2 and EQ. Conclusions: PGRMC1 increases strongly the estrogen-dependent breast cell proliferation. The proliferating effects of EE may be lower compared to E2 and EQ. This could have importance in comparing hormone therapy and contraception. Thus, PGRMC1 not only could predict the risk using progestogens but also of different estrogens.

Treatment of vaginal atrophy with estriol and lactobacilli combination: a clinical review

In recent years, a vast quantity of clinical data has been accumulated on the pathophysiology of symptomatic vulvovaginal atrophy (VVA)/genitourinary syndrome of menopause (GSM) in peri- and postmenopausal women and on the treatment options for these conditions. Guidelines from several societies have recently been updated in favor of VVA/GSM vaginal therapy with the lowest possible doses of estrogens. The combination of a vaginal ultra-low dose of 0.03 mg of estriol (E3) and lyophilized, viable Lactobacillus acidophilus KS400 (0.03 mg-E3/L) is a unique product with a dual mechanism of action supporting not only the proliferation and maturation of the vaginal epithelium, but also restoration of the lactobacillary microflora. It has been demonstrated efficiently to establish and maintain a healthy vaginal ecosystem. Use of this combination considerably improves the clinical signs and symptoms as well as the quality of life of menopausal women suffering from vaginal atrophy. This combination therapy is well tolerated with a low overall incidence of side-effects and negligible estriol absorption. Based on recent scientific evidence and current treatment guidelines, the 0.03 mg-E3/L combination could be considered one of the options for the treatment of symptomatic vaginal atrophy in aging menopausal women.

Dependency of cardiovascular risk on reproductive stages and on age among middle-aged Chinese women

OBJECTIVE

To assess the 10-year cardiovascular risk in middle-aged Chinese women living in the same community and the impact of reproductive aging and age.

METHODS

This was a cross-sectional study in the Yuetan Community of Beijing. Data on lifestyle habits, prevalence and treatment of chronic diseases with significance for cardiovascular disease (CVD) development were collected by interview. CVD risk factors were assessed by physical examination and laboratory tests. The 10-year cardiovascular risk was calculated using the Framingham 10-year risk score. STRAW +10 criteria were used for the stages of reproductive aging.

RESULTS

A total of 536 women, aged 40-60 years, were enrolled. The incidences of hypertension, dyslipidemia, abdominal obesity, glucose intolerance and diabetes were 32.6%, 45.7%, 65.5%, 37.9% and 10.1%, respectively. After adjustment, the incidence of hypertension and diabetes increased with age and with reproductive aging. Dyslipidemia and glucose intolerance were only associated with age. Abdominal obesity was related neither to age nor to reproductive aging. The 10-year cardiovascular risk ranged from 1% to 24.8%; 11.6% of women had a moderate or high Framingham 10-year risk score.

CONCLUSIONS

CVD risk factors were frequent and more than 10% of the women were at moderate or high risk of developing cardiovascular disease within the next 10 years. To our knowledge, this was demonstrated for the first time in middle-aged Chinese women. Thus, women should maintain a healthy lifestyle and physicians should monitor them to prevent CVD.

Impact of smoking on estrogenic efficacy

Depending on the type, duration and intensity of cigarette smoking, the efficacy of endogenous and exogenous estrogen can be reduced or completely cancelled. Not only does smoking diminish the beneficial effects of estrogen on hot flushes and urogenital symptoms and its positive effects on lipid metabolism, but smoking also can reduce estrogen's ability to prevent osteoporosis and perhaps also cardiovascular diseases. This is mainly caused by dose-dependent elevated hepatic clearance, partially in conjunction with lower estrogen levels, and has been demonstrated so far only with oral estrogen applications. Compensation for the failure of therapeutic action should not be made by increasing the dose in smokers since this might result in the production of potentially mutagenic estrogen metabolites associated with a higher risk of breast cancer. Since the favorable effects of estrogens seem to be not lost in smokers when estrogens are applied transdermally, this route should be preferred in smokers. The most important conclusion from the data presented is that the effects of smoking are very complex and dependent on a multiplicity of factors, so that different types of clinically relevant negative effects must be expected. Women who continue to smoke despite all warnings should be informed that smoking, in addition to all its other negative effects, can also jeopardize the success of hormone replacement therapy.

Genomic and non-genomic actions of progestogens in the breast

Evidence is growing that progestogens may enhance breast cancer risk under hormone therapy in the postmenopause or hormonal contraception. However, differences may exist within the progestogen class and certain progestogens may have a higher potency in terms of breast cancer risk. The mechanism(s) by which these progestogens might influence breast cancer risk appear to be mediated via genomic and/or non-genomic effects triggered by activated progestogen receptors. In general, regulation of gene expression by progestogen receptors seems to be a multifactorial process involving both actions which often converge. In the present review, we describe the known genomic and non-genomic effects in the breast, especially focusing on the progestins. This article is part of a Special Issue entitled 'Menopause'.

Risks and benefits of hormone therapy: has medical dogma now been overturned?

BACKGROUND

In an integrated overview of the benefits and risks of menopausal hormone therapy (HT), the Women's Health Initiative (WHI) investigators have claimed that their 'findings … do not support use of this therapy for chronic disease prevention'. In an accompanying editorial, it was claimed that 'the WHI overturned medical dogma regarding menopausal [HT]'.

OBJECTIVES

To evaluate those claims.

METHODS

Epidemiological criteria of causation were applied to the evidence.

RESULTS

A 'global index' purporting to summarize the overall benefit versus the risk of HT was not valid, and it was biased. For coronary heart disease, an increased risk in users of estrogen plus progestogen (E + P), previously reported by the WHI, was not confirmed. The WHI study did not establish that E+ P increases the risk of breast cancer; the findings suggest that unopposed estrogen therapy (ET) does not increase the risk, and may even reduce it. The findings for stroke and pulmonary embolism were compatible with an increased risk, and among E+ P users there were credible reductions in the risk of colorectal and endometrial cancer. For E+ P and ET users, there were credible reductions in the risk of hip fracture. Under 'worst case' and 'best case' assumptions, the changes in the incidence of the outcomes attributable to HT were minor.

CONCLUSIONS

Over-interpretation and misrepresentation of the WHI findings have damaged the health and well-being of menopausal women by convincing them and their health professionals that the risks of HT outweigh the benefits.

Ospemifene, a non-oestrogen selective oestrogen receptor modulator for the treatment of vaginal dryness associated with postmenopausal vulvar and vaginal atrophy: a randomised, placebo-controlled, phase III trial

OBJECTIVE

To evaluate the efficacy and safety of ospemifene, a novel selective oestrogen receptor modulator, in the treatment of vaginal dryness in postmenopausal women with vulvovaginal atrophy (VVA).

STUDY DESIGN

A 12 week, multicentre, randomised, double-blind, parallel-group phase III study of women (40-80 years) with VVA and self-reported vaginal dryness as their most bothersome symptom.

MAIN OUTCOME MEASURES

The co-primary efficacy endpoints were the change from baseline to Week 12 in (1) percentage of parabasal cells in the maturation index (MI), (2) percentage of superficial cells in the MI, (3) vaginal pH, and (4) severity of vaginal dryness. Safety assessments included physical examination, cervical Papanicolaou test and clinical laboratory analyses. Endometrial thickness and histology was also assessed.

RESULTS

A total of 314 women were randomised to once-daily ospemifene 60 mg/day (n=160) or placebo (n=154). Significant improvements in the percentages of parabasal and superficial cells in the MI and vaginal pH were observed with ospemifene compared with placebo (p<0.001 for all parameters). The mean change from baseline in severity score of vaginal dryness reported by women receiving ospemifene compared with those receiving placebo approached statistical significance (p=0.080). Improvements in each of the four co-primary endpoints with ospemifene were statistically significant compared to placebo in the per protocol population. The majority of treatment-emergent adverse events were considered mild to moderate in severity.

CONCLUSIONS

Once-daily oral ospemifene 60 mg was effective for the treatment of VVA in postmenopausal women with vaginal dryness.

Possible role of PGRMC1 in breast cancer development

Hormone therapy may increase the risk of breast cancer. Thus, especially the addition of synthetic progestins may play a decisive role according to the results of clinical studies. Overexpression of a special receptor, i.e. the progesterone receptor membrane component-1 (PGRMC1), may offer a potential new pathway to explain the observed increase in breast cancer risk in the combined arm of the Women's Health Initiative. PGRMC1 is expressed in breast cancer tissue and may be important in tumorigenesis. The expression of PGRMC1 in breast cancer tissue is significantly different from that in normal mammary glands. Certain synthetic progestins can increase the proliferation of PGRMC1-overexpressing breast cancer cells and may thus be involved in tumorigenesis, while progesterone and certain synthetic progestins such as nomegestrol or chlormadinone acetate react neutrally. Our investigations point towards an important role of estrogen receptor-α in the signaling cascade, resulting in the proliferative effect induced by progestins. Thus, activation of PGRMC1 may explain the increased breast cancer risk observed during treatment with certain progestins. Very recently, PGRMC1 was investigated in serum samples of lung cancer patients and matched healthy patients; significantly higher concentrations were shown in the cancer patients. Therefore, PGRMC1 might be a predictor for other cancers as well but, according to clinical trials, its importance for a possible screening tool, particularly for breast cancer risk during hormone therapy, seems of interest.

Attitude of German women towards hormone therapy: results of a lay survey

OBJECTIVE

Hormone therapy (HT) use has experienced a substantial change since publication of Women's Health Initiative (WHI) controlled trial. We aimed to investigate the attitude towards HT in German women aged 45-60 years.

STUDY DESIGN

A questionnaire was sent to 9785 randomly selected women in Germany aged between 45 and 60 years.

RESULTS

Response rate was 19.3% (n = 1,893). Of those, 81% experienced climacteric symptoms. Vasomotor symptoms were most frequently reported (71.2%; n = 1332). Of the respondents, 19.7% (n = 369) used HT. The most frequently mentioned benefits of HT were the improvement of climacteric complaints (71.2%; n = 1346), followed by the relief of osteoporosis (37.2%; n = 697) and the "anti-aging" effect (16.3%; n = 305). Breast cancer was stated as the main risk (64.9%; n = 1215), closely followed by weight gain (53.4%; n = 1000) and thromboembolism (48%; n = 898). About 44% of the women who has been advised by gynaecologists choose a HT, whereas this rate dropped down to 14.3% and 11.3% for women who have been advised by friends or media.

CONCLUSION

German women were generally aware of the main risks and benefits of HT. "More informed" women appear to be more likely to use HT compared to "less informed" women. The media produces negative impression of HT.

Proliferative effects of estradiol- or ethinylestradiol-progestogen combinations on human breast cancer cells in an intermitted and a long-term regimen

Currently the use of natural estradiol as estrogenic component in oral contraceptives is more and more extended. It is unknown whether the application of this estrogen is associated with a different breast cancer risk as compared to the common use of the synthetic ethinylestradiol. In addition with the intention to reduce menstruation associated symptoms and bleeding periods an extended-cycle regimen is currently considered. In the present in vitro work, we have compared the effect of these different estrogenic compounds and the different treatment regimens on breast cancer risk. Human breast cancer cells (ZR75-1 and HCC1500) were incubated with equimolar concentrations of estradiol or ethinylestradiol combined with various progestogens, dienogest, drospirenone, keto-desogestrel, levonorgestrel, and nomegestrel. Usual and extended cycle was mimicked by incubation periods of 3 days with 1 day hormones off and 4 days, respectively. Molecular markers for proliferation and apoptosis were investigated by Western blot. In both cell lines estradiol and ethinylestradiol elicited a significant increase in the proliferation rate without difference between the 2 estrogens. The effect in the long-term cycle tended to be more pronounced than in the intermitted cycle. Progestogen addition most significantly reduced the estrogen-induced proliferation rate. The molecular markers were influenced by the progestogens mostly in the same manner, reducing the proliferation/apoptosis rate. Our results indicate that both estrogenic based combinations with progestogens may not increase breast cancer risk independent from the regimen, intermitted or long-term cycle. However clinical studies are necessary to prove these in vitro results.

Breast cancer risk during hormone therapy: experimental versus clinical data

Evidence is increasing suggesting that adding progestogens to estrogens can increase the risk of breast cancer. However, our experimental data as a result of scientific collaboration between university of Tuebingen, Germany, and university of Beijing, China, comparing all available progestogens used in hormone therapy and hormonal contraception present high evidence that there may be differences regarding breast cancer risk. Especially of concern may be to differentiate between primary and secondary risk i.e. between the effect of on benign and malignant breast epithelial cells suggesting differences in primary risk and risk in patients after breast cancer. Of importance also is that in contrast to natural progesterone the apocrine impact of stromal growth factors and also certain cell components of breast epithelial cells can strongly increase proliferation rates of some (but not all. synthetic progestogens which can lead to clinical cancer before (in contrast to estrogen-only therapy. carcinoprotective mechanisms can work. Regarding clinical data, epidemiological studies and especially the Women's Health Initiative, so far the only prospective placebo-controlled study, demonstrate an increased risk under combined estrogen/progestogen-, but not under estrogen-only therapy. However, up to now the clinical studies cannot discriminate between the various progestogens mostly due to too small patient numbers in the subgroups, and in most studies either medroxyprogesterone acetate or norethisterone have been used. However, there is evidence that the natural progesterone and dydrogesterone, possibly also the transdermal usage of synthetic progestogens, may have less risks, but this must be proven in further clinical trials.

Progestogens and membrane-initiated effects on the proliferation of human breast cancer cells

OBJECTIVES

Evidence is accumulating that progestogens may play a crucial role in the development of breast cancer under contraception and hormone therapy in reproductive and menopausal women. Progesterone receptor membrane component 1 (PGRMC1) expressed in breast cancer may be important in tumorigenesis and thus may increase breast cancer risk. The aim of this project was to investigate the influence of progesterone and nine synthetic progestins on MCF-7 breast cancer cells overexpressing PGRMC1.

METHODS

MCF-7 cells were stably transfected with PGRMC1 expression plasmid (WT-12). To test the effects of progestogerone (P) and the synthetic progestins chlormadinone acetate (CMA), desogestrel (DSG), drospirenone (DRSP), dydrogesterone (DYD), levonorgestrel (LNG), medroxyprogesterone acetate (MPA), nomegestrol (NOM) and norethisterone (NET) on cell proliferation, MCF-7 and WT-12 cells were stimulated with different concentrations (0.01-1 µmol/l).

RESULTS

In MCF-7 cells, DRSP, DSG, DYD, LNG and NET increased the proliferation at 1 µmol/l, the effect being highest for NET with about 20%. In WT-12 cells, the same progestins, but additionally MPA, showed a significant increase, which was much higher (30-245%) than in MCF-7 cells. Here again, NET showed the highest proliferative effect. No effect was found for CMA, NOM and P.

CONCLUSION

Some synthetic progestins trigger a proliferative response of PGRMC1-overexpressed MCF-7 cancer cells. The effect of progestogens on breast cancer tumorigenesis may clearly depend on the specific pharmacology of the various synthetic progestins.

2-Methoxyestradiol--biology and mechanism of action

In the last decade the endogenous estradiol metabolite, 2-methoxyestradiol (2ME), has gained more and more interest due to its marked anticancerogenic properties and possible cardiovascular benefits, as shown in numerous animal and experimental investigations. Some promising results in terms of the usage of 2ME as a therapeutic agent were obtained by various clinical studies in patients with breast cancer and prostate cancer. However, one main problem appears to be the bioavailability of 2ME, therefore new formulations are now in the test phase. In this review, the most important aspects of the biology and molecular mechanisms of 2ME are summarized.

Membrane-initiated effects of progesterone on proliferation and activation of VEGF in breast cancer cells

OBJECTIVE

Progesterone influences mammary gland development and probably breast cancer tumorigenesis and functions by regulating a broad spectrum of physiological processes. We investigated receptor membrane-initiated actions of progesterone in MCF-7 breast cancer cells via progesterone receptor membrane component 1 (PGRMC1).

DESIGN AND METHOD

The expression of PGRMC1 in breast cancer was verified by immune fluorescent analysis of paraffin sections. MCF-7 cells were transfected with PGRMC1 (wild type) or PGRMC1 variants. These cells were stimulated with a membrane-impermeable progesterone (P4) conjugate (P4-BSA-fluorescein isothiocyanate, P4-BSA-FITC, 10(-6) mol/l) or unconjugated progesterone (P4, 10(-6) mol/l) in the presence or absence of the progesterone receptor blocker RU-486 (10(-6) mol/l). Additionally, the effects on the expression of vascular endothelial growth factor A (VEGF-A) were determined using quantitative real-time polymerase chain reaction.

RESULTS

PGRMC1 is perinuclearly localized in breast cancer cells. Western Blot analysis suggests that PGRMC1 is phosphorylated at serine 180. MCF-7-PGRMC1 (S180A) cells show an approximately 35% increase in proliferation after incubation with P4-BSA-FITC compared to MCF-7 control and MCF-7-PGRMC1 (wild type) cells. This effect cannot be blocked by RU-486. P4 reduced proliferation of MCF-7-PGRMC1 cells by approximately 10% compared to untreated controls. P4-BSA-FITC treatment led to a roughly three-fold activation of VEGF-A gene expression compared to MCF-7 cells.

CONCLUSION

PGRMC1 is expressed in breast cancer tissue and mediates an RU-486-independent proliferative signal. It might also contribute to VEGF-induced neovascularization in tumor tissue. Thus, screening for PGRMC1 expression might be of interest to identify women with a higher expression of PGRMC1 and who might thus be susceptible for breast cancer development under hormone replacement therapy.

Urinary cGMP excretion after hormone replacement therapy in postmenopausal women

It is well established that estrogens and progestogens are able to influence the vasotonus in postmenopausal women. The present study was undertaken to find out if the NO/cGMP-system is involved in this hormone action. Urinary cGMP excretion which can reflect intracellular cGMP production elicited by NO (EDRF) was investigated in 20 postmenopausal women. In an open cross-over study design norethisterone acetate was administered orally for 8 days, estradiol valerate orally for 9 days and a combination of both substances for 12 days. After all three treatment phases urinary cGMP expressed as percentage of the pretreatment value was increased at a statistically significant level. Due to high individual variations no significant differences could be found among the values after the three treatment phases. It was concluded that the NO/cGMP-system may play a role in maintaining vasotonus in postmenopausal women under hormone replacement therapy.

Breast cancer: are estrogen metabolites carcinogenic?

Certain estrogen metabolites can act as carcinogens in in vitro and animal experiments. The clinical relevance remains unclear. However, in the presence of factors that could influence estradiol metabolism, such as smoking or genetic polymorphisms, it seems prudent to prefer transdermal therapy to minimize the production of possible toxic metabolites. In addition, various defense mechanisms operate in the physiologic human body that prevent the formation of possible toxic intermediate products of estradiol metabolism, especially during oxidative stress. Only under rare special conditions is it conceivable that the human body cannot react sufficiently.