Androgen and glucocorticoid receptor-mediated inhibition of cell proliferation by medroxyprogesterone acetate in ZR-75-1 human breast cancer cells

Estrogens and breast cancer

Estrogens have been associated with an increase in breast cancer risk. Yet emerging clinical and experimental evidence points to progestogens [endogenous progesterone or synthetic progesterone (progestin)] as the primary hormonal driver underlying seemingly estrogen-associated breast cancer risk. Estrogens may contribute to breast cancer risk indirectly by induction of the progesterone receptor and thus amplifying progesterone signaling. Large studies of hormonal contraceptives suggest that the small increase in breast cancer risk from hormonal contraceptives is mainly attributable to progestins, not estrogens. Estrogen-plus-progestin hormone replacement therapy (HRT) has consistently shown an increase in breast cancer risk among postmenopausal women, whereas estrogen-alone HRT has little impact on breast cancer risk in naturally or surgically menopausal women. In particular, the long-term follow-up of the Women's Health Initiative (WHI) randomized trials suggests a benefit of estrogen alone. Recent data further indicate that endogenously elevated estrogen during assisted reproductive technology (ART) exhibits little adverse effect on or potentially a reduction in breast cancer risk and recurrence. Also, accumulating evidence suggests that inhibition of progesterone signaling is a critical mechanism underlying the risk-reducing and therapeutic effects of antiestrogens. Estrogen HRT has shown an array of proven benefits, including ameliorating menopausal symptoms and improving bone health. Collective evidence thus suggests that estrogen HRT is likely to offer health benefits to perimenopausal or postmenopausal women, including breast cancer survivors, as well as young BRCA1/2 carriers with prophylactic oophorectomy for ovarian cancer prevention.

Steroid hormone receptors, exome sequencing and treatment responsiveness of breast cancer patient-derived xenografts originated in a South American country

Breast cancer (BC) patient-derived xenografts (PDX) are relevant models for precision medicine. However, there are no collections derived from South American BC patients. Since ethnicity significantly impacts clinical outcomes, it is necessary to develop PDX models from different lineages. Our goals were to a) develop BC PDX from our population; b) characterize the expression of estrogen (ER), progesterone (PR), androgen (AR) and glucocorticoid (GR) receptors, basal and luminal cytokeratins, EGFR and HER2; c) identify PDX mutations; d) evaluate the response to treatments selected based on their biological and genetic features, and e) perform BC tissue cultures (BCTC) from PDX tissues and compare in vivo and ex vivo results. Surgical fragments were maintained in a culture medium and inoculated subcutaneously into untreated NSG female mice, or treated with estradiol pellets. Other fragments were fixed in formalin for diagnosis and immunohistochemistry, and a third piece was frozen at -80°C for molecular studies or whole exome-sequencing. Tumors were serially transplanted into NSG mice. Once the PDX was established, in vivo and ex vivo drug responses were evaluated. Eight PDX were established: two ER + [BC-AR685 (PR +) and BC-AR707 (PR-)], one from a triple-negative (TN) recurrence whose primary tumor was ER + (BC-AR485), one HER2 + (BC-AR474) and four TN primary tumors (BC-AR553, BC-AR546, BC-AR631 and BC-AR687). BC-AR685 had higher levels of PR isoform A than isoform B and was sensitive to mifepristone, tamoxifen, and palbociclib. BC-AR707 was inhibited by tamoxifen and testosterone. BC-AR474 was inhibited by trastuzumab and trastuzumab emtansine. BC-AR485 was sensitive to doxorubicin and resistant to paclitaxel in vivo and ex vivo. BC-AR687 carried a PIK3CA (C420R) mutation and was sensitive to alpelisib and mTOR inhibitors. All PDX expressed AR with varying intensities. GR and AR were co-expressed in the ER + tumors and in 3 TN PDX. We report the first PDX originated from South American countries that were genetically and biologically characterized and may be used in precision medicine studies. PDX expressing AR and/or GR are powerful tools to evaluate different endocrine treatment combinations even in TN tumors.

Exploring the utility of zinc finger protein-related genes in predicting hepatocellular carcinoma prognosis, immune responses, and drug efficacy

BackgroundHepatocellular carcinoma (LIHC), a prevalent liver cancer with a grim prognosis due to high recurrence rates, is under scrutiny for its association with zinc finger proteins (ZNFs) in tumorigenesis. This study aims to create a prognostic model for LIHC incorporating ZNF-related genes.MethodsBy analyzing TCGA data, we identified differentially expressed genes (DEGs) between normal and LIHC samples, focusing on ZNF-related genes through univariate Cox and LASSO Cox regression. A multivariate Cox regression model was built, categorizing LIHC patients into high- and low-ZNFRS groups based on ZNF-related risk scores. Model performance was evaluated using ROC curves, with a nomogram integrating clinical data and ZNFRS. Immune microenvironment, enrichment analysis, mutations, and drug responses in LIHC were also explored.ResultsA prognostic model utilizing 10 ZNF-related genes accurately predicted LIHC survival. The low-risk group exhibited enhanced immune cell infiltration, contrasting with cell cycle and DNA replication enrichment in the high-risk group, which also displayed increased mutation rates. Promising drug candidates like SNS-314 and Decitabine warrant further investigation in LIHC treatment.ConclusionThis study introduces impactful prognostic markers for LIHC management, emphasizing the significance of ZNFs in predicting patient outcomes and guiding treatment strategies.

Diagnostic and therapeutic use of oral micronized progesterone in endocrinology

Progesterone is a natural steroid hormone, while progestins are synthetic molecules. In the female reproductive system, progesterone contributes to the control of luteinizing hormone and follicle-stimulating hormone secretion and their pulsatility, via its receptors on the kisspeptin, neurokinin B, and dynorphin neurons in the hypothalamus. Progesterone together with estradiol controls the cyclic changes of proliferation and decidualization of the endometrium; exerts anti-mitogenic actions on endometrial epithelial cells; regulates normal menstrual bleeding; contributes to fertilization and pregnancy maintenance; participates in the onset of labor. In addition, it exerts numerous effects on other endocrine systems. Micronized progesterone (MP) is natural progesterone with increased bioavailability, due to its pharmacotechnical micronized structure, which makes it an attractive diagnostic and therapeutic tool. This critical literature review aims to summarize and put forward the potential diagnostic and therapeutic uses of MP in the field of endocrinology. During reproductive life, MP is used for diagnostic purposes in the evaluation of primary or secondary amenorrhea as a challenge test. Moreover, it can be prescribed to women presenting with amenorrhea or oligomenorrhea for induction of withdrawal bleeding, in order to time blood-sampling for diagnostic purposes in early follicular phase. Therapeutically, MP, alone or combined with estrogens, is a useful tool in various endocrine disorders including primary amenorrhea, abnormal uterine bleeding due to disordered ovulation, luteal phase deficiency, premenstrual syndrome, polycystic ovary syndrome, secondary amenorrhea [functional hypothalamic amenorrhea, premature ovarian insufficiency], perimenopause and menopause. When administrated per os, acting as a neurosteroid directly or through its metabolites, it exerts beneficial effects on brain function such as alleviation of symptoms of anxiety and depression, asw well as of sleep problems, while it improves working memory in peri- and menopausal women. Micronized progesterone preserves full potential of progesterone activity, without presenting many of the side-effects of progestins. Although it has been associated with more frequent drowsiness and dizziness, it can be well tolerated with nocturnal administration. Because of its better safety profile, especially with regard to metabolic ailments, breast cancer risk and veno-thromboembolism risk, MP is the preferred option for individuals with an increased risk of cardiovascular and metabolic diseases and of all-cause mortality.

Progestins and breast cancer hallmarks: The role of the ERK1/2 and JNK pathways in estrogen receptor positive breast cancer cells

Progestins used in hormonal contraceptives and menopausal hormone therapy (MHT) have been linked to increased breast cancer risk. Whether the association holds for all progestins is unclear and the underlying mechanisms remain poorly understood. We directly compared the effects of four progestins (medroxyprogesterone acetate (MPA), norethisterone acetate (NET-A), levonorgestrel (LNG) and drospirenone (DRSP)) to each other and the natural progestogen progesterone (P4) on selected cancer hallmarks. To provide mechanistic insight into these effects, we assessed the role of the progesterone receptor (PR), and the extracellular signal-related kinase (ERK1/2) and c-Jun N terminal (JNK) signaling pathways. We showed that the increased proliferation of the luminal T47D breast cancer cell line by P4 and all progestins, albeit to different extents, was inhibited by PR knockdown and inhibition of both the ERK1/2 and JNK pathways. While knockdown of the PR also blocked the upregulation of MKI67 and CCND1 mRNA expression by selected progestogens, only a role for the ERK1/2 pathway could be established in these effects. Similarly, only a role for the ERK1/2 pathway could be confirmed for progestogen-induced colony formation, whereas both the ERK1/2 and JNK pathways were required for cell migration in response to the three older progestins implicated in the etiology of breast cancer, MPA, NET-A and LNG. Together our results show that all the progestins elicit their effects on cell proliferation via a mechanism requiring the PR, ERK1/2 and JNK pathways. While the ERK1/2 and JNK pathways are also required for increased cell migration by the older progestins, only a role for the ERK1/2 pathway could be established in their effects on colony formation. Notably, the cytoplasmic PR was not needed for activation of the ERK1/2 pathway by the progestogens. Given that DRSP showed significantly lower proliferation than MPA and NET-A, and that it had no effect on breast cancer cell migration and colony formation, hormonal formulations containing the newer generation progestin DRSP may provide a better benefit/risk profile towards breast cancer than those containing the older generation progestins.

Anti-proliferative transcriptional effects of medroxyprogesterone acetate in estrogen receptor positive breast cancer cells are predominantly mediated by the progesterone receptor

Medroxyprogesterone acetate (MPA) is a first generation progestin that has been in clinical use for various hormonal conditions in women since the 1960s. Although developed as a progesterone receptor (PR) agonist, MPA also has strong binding affinity for other steroid receptors. This promiscuity confounds the mechanistic action of MPA in target cells that express multiple steroid receptors. This study is the first to assess the relative contribution of progesterone, androgen and glucocorticoid receptors in mediating the transcriptional activity of MPA on endogenous targets in breast cancer cells that endogenously express all three receptors at comparable levels. Gene expression profiling in estrogen receptor positive (ER+) ZR-75-1 breast cancer cells demonstrated that although the MPA-regulated transcriptome strongly overlapped with that of Progesterone (PROG), 5α-dihydrotestosterone (DHT) and Dexamethasone (DEX), it clustered most strongly with that of PROG, suggesting that MPA predominantly acts via the progesterone receptor (PR) rather than androgen receptor (AR) or glucocorticoid receptor (GR). Subsequent experiments manipulating levels of these receptors, either through specific culture conditions or with lentiviral shRNAs targeting individual receptors, also revealed a stronger contribution of PR compared to AR and GR on the expression of endogenous target genes that are either commonly regulated by all ligands or specifically regulated only by MPA. A predominant contribution of PR to MPA action in ER+ T-47D breast cancer cells was also observed, although a stronger role for AR was evident in T-47D compared to that observed in ZR-75-1 cells. Network analysis of ligand-specific and commonly regulated genes demonstrated that MPA utilises different transcription factors and signalling pathways to inhibit proliferation compared with PROG. This study reaffirms the importance of PR in mediating MPA action in an endogenous breast cancer context where multiple steroid receptors are co-expressed and has potential implications for PR-targeting therapeutic strategies in ER+ breast cancer.

Medroxyprogesterone Acetate in Gender-Affirming Therapy for Transwomen: Results From a Retrospective Study

CONTEXT

Medroxyprogesterone acetate (MPA) is a widely used progestin in feminizing hormone therapy. However, the side effects and hormonal changes elicited by this drug have never been investigated in the transgender population.

OBJECTIVE

We evaluated the incidence of self-reported effects among transwomen using MPA and this drug's impact on hormonal and metabolic parameters.

DESIGN, SETTING, AND PARTICIPANTS

We retrospectively collected data from 290 follow-up visits (FUVs) of transwomen treated at Rhode Island Hospital from January 2011 to July 2018 (mean duration of therapy 3.4 ± 1.7 years). FUVs followed regimens of estradiol (E) and spironolactone, with MPA (n = 102) or without MPA (n = 188).

MAIN OUTCOME MEASURES

We assessed the incidence of self-reported effects after MPA treatment. We also compared blood levels of E, testosterone, and various laboratory parameters between MPA and non-MPA groups.

RESULTS

Mean weighted E level was 211 ± 57 pg/mL after MPA treatment and 210 ± 31 pg/mL otherwise; this difference was nonsignificant [t(274) = 0.143, P = 0.886]. Mean weighted testosterone level was 79 ± 18 ng/dL after MPA treatment and 215 ± 29 ng/dL otherwise; testosterone levels were significantly lower in the MPA group [t(122) = 32.4, P < 0.001]. There were minimal changes in other laboratory parameters. Of 39 patients receiving MPA, 26 reported improved breast development and 11 reported decreased facial hair. Five patients experienced mood swings on MPA.

CONCLUSIONS

In our cohort of transwomen, we found minimal side effects, unchanged E levels, and a decline in testosterone associated with MPA, outcomes consistent with feminization. Prospective studies are needed to confirm our findings.

Androgen receptor: A promising therapeutic target in breast cancer

Breast cancer (BCa) is the second most common cancer worldwide and the most prevalent cancer in women. The majority of BCa cases are positive (+) for the estrogen receptor (ER⁺, 80%) and progesterone receptor (PR⁺, 65%). Estrogen and progesterone hormones are known to be involved in cancer progression, and thus hormonal deprivation is used as an effective treatment for ER⁺PR⁺ BCa subtypes. However, some ER⁺PR⁺ BCa patients develop resistance to such therapies. Meanwhile, chemotherapy is the only available treatment for ER^-PR^- BCa tumors. Another hormone receptor known as the androgen receptor (AR) has also been found to be widely expressed in human breast carcinomas. However, the mechanisms of AR and its endogenous androgen ligands is not well-understood in BCa and its biological role in this hormone-related disease remains unclear. In this review, we aim to address the importance of the AR in BCa diagnosis and prognosis, current AR-targeting approaches in BCa, and the potential for AR-downstream molecules to serve as therapeutic targets.

Deciphering the divergent roles of progestogens in breast cancer

Most breast cancers are driven by oestrogen receptor-α. Anti-oestrogenic drugs are the standard treatment for these breast cancers; however, treatment resistance is common, necessitating new therapeutic strategies. Recent preclinical and historical clinical studies support the use of progestogens to activate the progesterone receptor (PR) in breast cancers. However, widespread controversy exists regarding the role of progestogens in this disease, hindering the clinical implementation of PR-targeted therapies. Herein, we present and discuss data at the root of this controversy and clarify the confusion and misinterpretations that have consequently arisen. We then present our view on how progestogens may be safely and effectively used in treating breast cancer.

Endometrial Stromal Decidualization Responds Reversibly to Hormone Stimulation and Withdrawal

Human endometrial stromal decidualization is required for embryo receptivity, angiogenesis, and placentation. Previous studies from our laboratories established that connexin (Cx)-43 critically regulates endometrial stromal cell (ESC) differentiation, whereas gap junction blockade prevents it. The current study evaluated the plasticity of ESC morphology and Cx43 expression, as well as other biochemical markers of cell differentiation, in response to decidualizing hormones. Primary human ESC cultures were exposed to 10 nM estradiol, 100 nM progesterone, and 0.5 mM cAMP for up to 14 days, followed by hormone withdrawal for 14 days, mimicking a biphasic ovulatory cycle. Reversible differentiation was documented by characteristic changes in cell shape. Cx43 was reversibly up- and down-regulated after the estradiol, progesterone, and cAMP treatment and withdrawal, respectively, paralleled by fluctuations in prolactin, vascular endothelial growth factor, IL-11, and glycodelin secretion. Markers of mesenchymal-epithelial transition (MET), and its counterpart epithelial-mesenchymal transition, followed reciprocal patterns corresponding to the morphological changes. Incubation in the presence of 18α-glycyrrhetinic acid, an inhibitor of gap junctions, partially reversed the expression of decidualization and MET markers. In the absence of hormones, Cx43 overexpression promoted increases in vascular endothelial growth factor and IL-11 secretion, up-regulated MET markers, and reduced N-cadherin, an epithelial-mesenchymal transition marker. The combined results support the hypothesis that Cx43-containing gap junctions and endocrine factors cooperate to regulate selected biomarkers of stromal decidualization and MET and suggest roles for both phenomena in endometrial preparation for embryonic receptivity.

Progesterone and related compounds in hepatocellular carcinoma: basic and clinical aspects

Primary liver cancer is the fifth most common cancer worldwide and the third most common cause of cancer mortality. Hepatocellular carcinoma (HCC) accounts for 85% to 90% of primary liver cancers. Major risk factors for HCC include infection with HBV or HCV, alcoholic liver disease, and most probably nonalcoholic fatty liver disease. In general, men are two to four times more often associated with HCC than women. It can be suggested that sex hormones including progesterone may play some roles in HCC. Rather, very limited information discusses its potential involvement in HCC. This paper thus collects some recent studies of the potential involvement of progesterone and related compounds in HCC from basic and clinical aspects. In addition, two synthetic progestins, megestrol acetate (MA) and medroxyprogesterone acetate (MPA), will be discussed thoroughly. It is noted that progesterone can also serve as the precursor for androgens and estrogens produced by the gonadal and adrenal cortical tissues, while men have a higher incidence of HCC than women might be due to the stimulatory effects of androgen and the protective effects of estrogen. Eventually, this paper suggests a new insight on the associations of progesterone and related compounds with HCC development and treatment.

The safety of postmenopausal testosterone therapy

Testosterone is increasingly used as part of postmenopausal HRT regimens. Unfortunately, few androgenic preparations designed specifically for use in women have been approved by regulatory authorities. Ongoing concerns exist surrounding the potential long-term effects of testosterone therapy. Here, we review the most recent data on postmenopausal testosterone therapy, focusing particularly on the effects of testosterone on breast, endometrium and cardiovascular health.

Multiple nuclear receptor signaling pathways mediate the actions of synthetic progestins in target cells

Synthetic progestins are used clinically to treat a variety of women's health issues. Although progestins are designed to signal through the progesterone receptor (PR) to elicit specific pharmacological effects, they can also variably bind to and influence the activity of other nuclear receptors within target tissues, particularly the androgen and glucocorticoid receptors and, in some cases, they regulate mineralocorticoid and estrogen receptors. This article reviews current knowledge on progestin cross-talk to nuclear receptors other than PR, their resultant effect on receptor function in different in vitro models and the potential consequences of this activity for breast, ovarian and endometrial cancer. The impact of cell and tissue context, assay type, steroid metabolism and hormonal milieu in determining progestin-mediated activity are also presented. Collectively this review highlights the complexity of progestin action and the need for consideration of multiple mechanisms that act in concert to influence their ultimate biological activity.

Differential effects of medroxyprogesterone acetate on thrombosis and atherosclerosis in mice

BACKGROUND AND PURPOSE

The risk for cardiovascular events including venous and arterial disease and stroke is elevated after treatment with estrogen and medroxyprogesterone acetate (MPA) in postmenopausal women. Here, we have investigated the effect of MPA on arterial thrombosis and atherosclerosis in a murine model of atherosclerosis.

EXPERIMENTAL APPROACH

Apolipoprotein E (ApoE)-/- mice were bilaterally ovariectomized and treated with placebo, MPA (27.7 microg day(-1)) and MPA + 17-beta-oestradiol (E2; 1.1 microg day(-1)) for 90 days, on a Western-type diet. Thrombotic response was measured in a photothrombosis model, platelet activation by fluorescence activated cell sorting (FACS) analysis (CD62P) and thrombin generation by the endogenous thrombin potential (ETP). Furthermore, aortic plaque burden and aortic root plaque composition were determined.

KEY RESULTS

MPA and MPA + E2-treated animals showed an aggravated thrombotic response shown by significantly reduced time to stable occlusion. The pro-thrombotic effect of MPA was paralleled by increased ETP whereas platelet activation was not affected. Furthermore, MPA + E2 reduced the number of cells positive for alpha-smooth muscle actin and increased hyaluronan in the plaque matrix. Interestingly, total plaque burden was reduced by MPA but unchanged by MPA + E2.

CONCLUSION AND IMPLICATIONS

Long-term treatment with MPA and MPA + E2 increased arterial thrombosis despite inhibitory effects of MPA on atherosclerosis in ApoE-deficient mice. Increased thrombin formation, reduced smooth muscle content and remodelling of non-collagenous plaque matrix may be involved in the pro-thrombotic effects. Thus, MPA exhibits differential effects on arterial thrombosis and on atherosclerosis.

Usage of megestrol acetate in the treatment of anorexia-cachexia syndrome in the elderly

The aim of this review is to assess the efficacy and safety of megestrol acetate (MA) in geriatric cachexia. The paper presented here reviews a previously published study of MA use in 69 patients in a randomized double blind placebo-controlled trial. This paper will also address the underlying pathogenesis of cachexia (specifically, the role of cytokines) along with the use of MA, its mechanism of action and its side effects.

OBJECTIVE

To compare the effects of MA oral suspension (O.S.), 800 mg/day, versus placebo on weight in geriatric nursing home patients with weight loss or low body weight.

DESIGN

Twelve weeks, randomized, double-blind, placebo-controlled trial with a 13-week follow-up period.

PATIENTS

Northport VAMC Nursing home patients with weight loss of * 5% of usual body weight over the past 3 months, or body weight 20% below their ideal body weight.

INTERVENTIONS

Patients were randomly assigned to receive placebo or MA 800 mg/d for 12 weeks and were then followed for 13 weeks off treatment and mortality 4 years post treatment.

MEASUREMENTS

Primary outcome- weight and appetite change. Secondary outcome-sense of well being, enjoyment of life, change in depression scale, laboratory nutrition parameters, energy intake counts, body composition, and adverse events.

RESULTS

At 12 weeks there were no significant differences in weight gain between treatment groups, while MA-treated patients reported significantly greater improvement in appetite, enjoyment of life, and well being. At week 25 (3 months after treatment), 61.9% of MA-treated patients had gained * 1.82 kg (4 lbs) compared to 21.7% of placebo patients. There was no difference in survival between MA and placebo groups. Considering possible confounders, higher initial IL-6, initial TNFR-p75 levels, and final neutrophil percentage were associated with elevated mortality, whereas higher initial pre-albumin, initial albumin, final pre-albumin, final albumin and final weight gain were associated with decreased death.

Estrogens and age-related memory decline in rodents: what have we learned and where do we go from here?

The question of whether ovarian hormone therapy can prevent or reduce age-related memory decline in menopausal women has been the subject of much recent debate. Although numerous studies have demonstrated a beneficial effect of estrogen and/or progestin therapy for certain types of memory in menopausal women, recent clinical trials suggest that such therapy actually increases the risk of cognitive decline and dementia. Because rodent models have been frequently used to examine the effects of age and/or ovarian hormone deficiency on mnemonic function, rodent models of age-related hormone and memory decline may be useful in helping to resolve this issue. This review will focus on evidence suggesting that estradiol modulates memory, particularly hippocampal-dependent memory, in young and aging female rats and mice. Various factors affecting the mnemonic response to estradiol in aging females will be highlighted to illustrate the complications inherent to studies of estrogen therapy in aging females. Avenues for future development of estradiol-based therapies will also be discussed, and it is argued that an approach to drug development based on identifying the molecular mechanisms underlying estrogenic modulation of memory may lead to promising future treatments for reducing age-related mnemonic decline.

Pharmacological Treatment of Geriatric Cachexia: Evidence and Safety in Perspective

Anticachexic or antisarcopenic medications are prescribed worldwide for geriatric patients with poor appetite and associated weight loss. They represent a valuable treatment option for managing cachexia. However, the well-publicized adverse reports about these medications in acquired immunodeficiency syndrome (AIDS) and in the cancer population has led to some concern and much subsequent discussion over the safety of these medications being used in geriatric population. This review looks at the evidence in relation to the benefits and risks of these medications and discusses what we know about their use in the geriatric population.

Dehydroepiandrosterone, androgens and the mammary gland

Mainly through the transformation of dehydroepiandrosterone (DHEA) into androgens in peripheral tissues by intracrine mechanisms, women synthesize at least two-thirds of the androgens found in men. Such data strongly suggest that androgens exert very important but so far underestimated physiological functions in women, including in the breast. In fact, the mammary gland possesses all the enzymatic machinery required to transform DHEA into both androgens and estrogens, although androgens are the predominant steroids synthesized from DHEA in the mammary gland. Early clinical studies have shown beneficial effects of androgens on breast cancer which are comparable to those observed with other hormonal therapies. In fact, a long series of preclinical and clinical data clearly indicate that proliferation of both the normal mammary gland and breast cancer results from the balance between the stimulatory effect of estrogens and the inhibitory effect of androgens. Moreover, the data showing the additive inhibitory effects of antiestrogens and androgens suggest that taking advantage of the inhibitory effect of androgens on breast cancer proliferation could well improve the efficacy of the currently used estrogen deprivation therapies for the treatment and prevention of breast cancer, the best and most physiological candidate being DHEA that limits the androgenic exposure to the tissues which possess the required enzymatic intracrine machinery.

The progestational and androgenic properties of medroxyprogesterone acetate: gene regulatory overlap with dihydrotestosterone in breast cancer cells

Introduction

Medroxyprogesterone acetate (MPA), the major progestin used for oral contraception and hormone replacement therapy, has been implicated in increased breast cancer risk. Is this risk due to its progestational or androgenic properties? To address this, we assessed the transcriptional effects of MPA as compared with those of progesterone and dihydrotestosterone (DHT) in human breast cancer cells.

Method

A new progesterone receptor-negative, androgen receptor-positive human breast cancer cell line, designated Y-AR, was engineered and characterized. Transcription assays using a synthetic promoter/reporter construct, as well as endogenous gene expression profiling comparing progesterone, MPA and DHT, were performed in cells either lacking or containing progesterone receptor and/or androgen receptor.

Results

In progesterone receptor-positive cells, MPA was found to be an effective progestin through both progesterone receptor isoforms in transient transcription assays. Interestingly, DHT signaled through progesterone receptor type B. Expression profiling of endogenous progesterone receptor-regulated genes comparing progesterone and MPA suggested that although MPA may be a somewhat more potent progestin than progesterone, it is qualitatively similar to progesterone. To address effects of MPA through androgen receptor, expression profiling was performed comparing progesterone, MPA and DHT using Y-AR cells. These studies showed extensive gene regulatory overlap between DHT and MPA through androgen receptor and none with progesterone. Interestingly, there was no difference between pharmacological MPA and physiological MPA, suggesting that high-dose therapeutic MPA may be superfluous.

Conclusion

Our comparison of the gene regulatory profiles of MPA and progesterone suggests that, for physiologic hormone replacement therapy, the actions of MPA do not mimic those of endogenous progesterone alone. Clinically, the complex pharmacology of MPA not only influences its side-effect profile; but it is also possible that the increased breast cancer risk and/or the therapeutic efficacy of MPA in cancer treatment is in part mediated by androgen receptor.

The effect of megestrol acetate on growth of HepG2 cells in vitro and in vivo

PURPOSE

Hepatocellular carcinoma (HCC) is generally considered as a sex hormone-dependent tumor, and hormonal therapy has been proposed as a strategy for the treatment of HCC. The aim of the study is to investigate the effect of megestrol acetate, a synthetic progesteronal agent, on growth of HepG2 cells in vitro and in vivo.

EXPERIMENTAL DESIGN

Cell growth in vitro was assessed by a colormetric method, and cell growth in vivo was assessed by tumor volumetrics.

RESULTS

Megestrol acetate was shown to inhibit the growth of HepG2 cells in vitro in dose- and time-dependent manners with an IC (50) of 260 microm (24-h incubation). The growth of HepG2 cell-transplanted tumors in nude mice was also inhibited by i.p. injection of megestrol acetate (10 mg/kg/day). The tumor volumes of the megestrol acetate-treated group regressed to 59% of controls by week 6 and to 41% of controls by week 13. Apoptosis following G(1) arrest was observed in megestrol acetate-treated cells and may be a mechanism through which megestrol acetate inhibits HepG2 cells. Megestrol acetate was also demonstrated to have a beneficial effect on the weight gain of tumor-bearing nude mice, and the mean weight of the megestrol acetate-treated animals was higher than that of controls from week 4 of the treatment period, and the differences were statistically significant in week 5 and 6 (P < 0.05, compared with controls). No significant survival advantage was, however, demonstrated in the treatment group.

CONCLUSIONS

This study showed that megestrol acetate inhibited the growth of HepG2 cells grown in vitro and in vivo. These data provide useful information for clinical study of megestrol acetate for the treatment of HCC.

Lessons to be learned from clinical studies on hormones and the breast

Estrogen is a well-known mitogen in human breast epithelium but the action of progestogen is complex and incompletely understood. During the last years, accumulating data from animal, clinical and observational studies suggest a proliferative effect in breast tissue when progestogen is added to estrogen. Findings in surrogate markers like breast density add to clinical and epidemiological reports indicating that continuous combined HRT may carry a higher risk of breast cancer than treatment with estrogen alone. Whether the results are valid for all progestogens remains to elucidated. It is also clear that not all women respond in the same way to the same treatment and the biological basis for the marked individual variation in breast response has to be clarified. Further knowledge about the role of androgens and of the impact of different treatment regimens is important and prospective randomized clinical studies are needed.

Polymorphism in the Androgen Receptor and Mammographic Density in Women Taking and Not Taking Estrogen and Progestin Therapy

There is some evidence that women with a higher number of CAG repeat lengths on the androgen receptor (AR) gene have increased breast cancer risk. We evaluated the association between AR-CAG repeat length and mammographic density, a strong breast cancer risk factor, in 404 African-American and Caucasian breast cancer patients. In postmenopausal estrogen progestin therapy users, carriers of the less active AR-CAG had statistically significantly higher mean percentage of density (41.4%) than carriers of the more active AR-CAG (25.7%; P = 0.04). Our results raise the question of whether the number of AR-CAG repeats predicts breast cancer risk in estrogen progestin therapy users.

Endocrine and intracrine sources of androgens in women: inhibition of breast cancer and other roles of androgens and their precursor dehydroepiandrosterone

Serum androgens as well as their precursors and metabolites decrease from the age of 30-40 yr in women, thus suggesting that a more physiological hormone replacement therapy at menopause should contain an androgenic compound. It is important to consider, however, that most of the androgens in women, especially after menopause, are synthesized in peripheral intracrine tissues from the inactive precursors dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEA-S) of adrenal origin. Much progress in this new area of endocrine physiology called intracrinology has followed the cloning and characterization of most of the enzymes responsible for the transformation of DHEA and DHEA-S into androgens and estrogens in peripheral target tissues, where the locally produced sex steroids are exerting their action in the same cells in which their synthesis takes place without significant diffusion into the circulation, thus seriously limiting the interpretation of serum levels of active sex steroids. The sex steroids made in peripheral tissues are then inactivated locally into more water-soluble compounds that diffuse into the general circulation where they can be measured. In a series of animal models, androgens and DHEA have been found to inhibit breast cancer development and growth and to stimulate bone formation. In clinical studies, DHEA has been found to increase bone mineral density and to stimulate vaginal maturation without affecting the endometrium, while improving well-being and libido with no significant side effects. The advantage of DHEA over other androgenic compounds is that DHEA, at physiological doses, is converted into androgens and/or estrogens only in the specific intracrine target tissues that possess the appropriate physiological enzymatic machinery, thus limiting the action of the sex steroids to those tissues possessing the tissue-specific profile of expression of the genes responsible for their formation, while leaving the other tissues unaffected and thus minimizing the potential side effects observed with androgens or estrogens administered systemically.

Medroxyprogesterone acetate decreases secretion of interleukin-6 and parathyroid hormone-related protein in a new anaplastic thyroid cancer cell line, KTC-2

A new thyroid cancer cell line, KTC-2, was established from the malignant pleural effusion of a patient with recurrent thyroid cancer associated with anaplastic transformation from thyroid papillary cancer. Karyotype analysis showed a mode of 109 chromosomes. Subcutaneous cell injections produced small regressing tumors in athymic or severe combined immunodeficiency disorders (SCID) mice. Histologic examination showed anaplastic tumor cells surrounded by prominent mononuclear cells. An expression of thyroglobulin, thyroid transcription factor-1, and PAX-8 but not thyroid peroxidase and thyrotropin (TSH) receptor was detected. Biochemical analysis revealed secretion of interleukin (IL)-6, parathyroid hormone-related protein (PTHrP), and granulocyte-macrophage colony-stimulating factor. All the cytokines are known to induce paraneoplastic syndromes in patients with anaplastic thyroid cancer. Our previous studies revealed that medroxyprogesterone acetate (MPA) reduces secretion of IL-6 and PTHrP from human breast cancer cells. To investigate the regulatory mechanisms of secretion of these cytokines, MPA was administered to the KTC-2 cells. MPA dose-dependently decreased the secretion and mRNA expression of IL-6 and PTHrP. Expression of androgen receptor and glucocorticoid receptor (GR) but not progesterone receptor was detected. Dexamethasone but not dihydrotestosterone and progesterone decreased IL-6 and PTHrP secretion. These findings suggest that MPA decreases IL-6 and PTHrP secretion as a glucocorticoid mediated by GR in the KTC-2 cells. This KTC-2 cell line may be a suitable model for developing new strategies against paraneoplastic syndromes caused by anaplastic thyroid cancer.

Regulation of interleukin-6 secretion from breast cancer cells and its clinical implications

Interleukin (IL)-6 may play possible roles in the proliferation and metastasis of cancer cells, in the development of osteolysis and humoral hypercalcemia, and in the regulation of estrogen production in breast cancer tissues. IL-6 is also suggested to be a cachectic factor in cancer patients. A decrease in serum IL-6 levels induced by medroxyprogesterone acetate (MPA) has been reported to correlate with a reversion of body weight loss in patients with advanced breast cancer. To elucidate the mechanisms of action of the anti-cachectic effect of MPA its effects on IL-6 secretion from the KPL-4 cell line, the first human breast cancer cell line to secrete IL-6 and to induce cachexia, were explored. It has been suggested that an inhibitory effect of MPA on IL-6 secretion from breast cancer cells causes the anti-cachectic effect of MPA. Our other studies have revealed that 5'-fluorouridine (5'-DFUR) inhibits the growth of KPL-4 tumors and decreases IL-6 levels in both serum and tumor tissues. Decreasing serum IL-6 levels resulted in alleviation of body weight loss. Docetaxel increased IL-6 levels in both serum and KPL-4 tumors, but combined treatment with docetaxel and 5'-DFUR resulted not only in a potent antitumor effect but also in a drastic decrease of serum IL-6 levels. In the present paper the possible roles of IL-6 in the development and progression of breast cancer are reviewed, and the regulatory mechanisms of IL-6 secretion from breast cancer cells and the possible clinical implications of decreasing IL-6 secretion by therapeutic agents are discussed.

Analysis and characteristics of multiple types of human 17beta-hydroxysteroid dehydrogenase

Androgens and estrogens are not only synthesized in the gonads but also in peripheral target tissues. Accordingly, recent molecular cloning has allowed us to identify multiple types of 17beta-hydroxysteroid dehydrogenases (17beta-HSD), the key and exclusive enzymes involved in the formation and inactivation of sex steroids. However, only one form, namely, type 3 17beta-HSD, is responsible for pseudohermaphroditism in deficient boys. To date, seven human 17beta-HSDs have been isolated and characterized. Although they catalyze substrates having a similar structure, 17beta-HSDs have very low homology. In intact cells in culture, these enzymes catalyze the reaction in a unidirectional way - types 1, 3, 5 and 7 catalyze the reductive reaction, while types 2, 4 and 8 catalyze the oxidative reaction. It is noteworthy that rat type 6 17beta-HSD also catalyzes the reaction in the oxidative direction. In this report, we analyze the different characteristics of the multiple types of human 17beta-HSD.

Effect of medroxyprogesterone acetate on thyrotropin secretion in adult and old female rats

Steroid hormones have been implicated in the modulation of TSH secretion; however, there are few and controversial data regarding the effect of progesterone (Pg) on TSH secretion. Medroxyprogesterone acetate (MPA) is a synthetic alpha-hydroxyprogesterone analog that has been extensively employed in therapeutics for its Pg-like actions, but that also has some glucocorticoid and androgen activity. Both hormones have been shown to interfere with TSH secretion. The objective of the present study was to investigate the effects of MPA or Pg administration to ovariectomized (OVX) rats on in vivo and in vitro TSH release and pituitary TSH content. The treatment of adult OVX rats with MPA (0. 25 mg/100 g body weight, sc, daily for 9 days) induced a significant (P<0.05) increase in the pituitary TSH content, which was not observed when the same treatment was used with a 10 times higher MPA dose or with Pg doses similar to those of MPA. Serum TSH was similar for all groups. MPA administered to OVX rats at the lower dose also had a stimulatory effect on the in vitro basal and TRH-induced TSH release. The in vitro basal and TRH-stimulated TSH release was not significantly affected by Pg treatment. Conversely, MPA had no effect on old OVX rats. However, in these old rats, ovariectomy alone significantly reduced (P<0.05) basal and TRH-stimulated TSH release in vitro, as well as pituitary TSH content. The results suggest that in adult, but not in old OVX rats, MPA but not Pg has a stimulatory effect on TSH stores and on the response to TRH in vitro.

Androgen receptor agonist activity of the synthetic progestin, medroxyprogesterone acetate, in human breast cancer cells

Medroxyprogesterone acetate (MPA), which is frequently used as second line hormonal therapy for the treatment of metastatic breast cancer, binds with high affinity to the progesterone receptor (PR). However, the androgenic side-effects of MPA suggest that it may also activate androgen receptor (AR) regulated pathways. Treatment of the human breast cancer cell lines MDA-MB-453, ZR-75-1 and T47-D with high dose (100 nM) MPA resulted in 26-30% inhibition of cell growth, which was partially reversed by co-treatment with a 10-fold excess of the synthetic antiandrogen, anandron. Scatchard analysis demonstrated specific, high affinity (non-PR) binding of [3H]MPA to cytosols prepared from the PR-/AR+ MDA-MB-453 and PR+/AR+ ZR-75-1, but not the PR-/AR- BT-20 breast cancer cell lines. Competition of [3H]MPA binding to MDA-MB-453 cytosols by equimolar concentrations of androgens (5alpha-dihydrotestosterone (DHT), R1881) and the antiandrogen, anandron was consistent with binding of MPA to the AR. In ZR-75-1 cell cytosol fractions, DHT, R1881 and anandron only partially competed out [3H]MPA binding, suggesting that androgens displace [3H]MPA binding to AR but not to PR. Induction by MPA of AR transactivation was demonstrated in MDA-MB-453 and ZR-75-1 cells, and in the CV-1 cell line transfected with a full-length AR. In these cell lines the increased activity of the androgen responsive reporter gene (MMTV-CAT) by 1 nM MPA was fully (MDA-MB-453, CV-1) or partially (ZR-75-1) inhibited by co-culture with 1 microM anandron. These findings indicate that MPA is an AR agonist and suggest that the in vivo effects of MPA in breast cancer patients may in part be mediated by the AR.

EM-652 (SCH 57068), a third generation SERM acting as pure antiestrogen in the mammary gland and endometrium

Breast cancer is the most frequent cancer in women while it is the second cause of cancer death. Estrogens are well recognized to play the predominant role in breast cancer development and growth and much efforts have been devoted to the blockade of estrogen formation and action. The most widely used therapy of breast cancer which has shown benefits at all stages of the disease is the use of the antiestrogen Tamoxifen. This compound, however, possesses mixed agonist and antagonist activity and major efforts have been devoted to the development of compounds having pure antiestrogenic activity in the mammary gland and endometrium. Such a compound would avoid the problem of stimulation of the endometrium and the risk of endometrial carcinoma. We have thus synthesized an orally active non-steroidal antiestrogen, EM-652 (SCH 57068) and the prodrug EM-800 (SCH57050) which are the most potent of the known antiestrogens. EM-652 is the compound having the highest affinity for the estrogen receptor, including estradiol. It has higher affinity for the ER than ICI 182780, hydroxytamoxifen, raloxifene, droloxifene and hydroxytoremifene. EM-652 has the most potent inhibitory activity on both ER alpha and ER beta compared to any of the other antiestrogens tested. An important aspect of EM-652 is that it inhibits both the AF1 and AF2 functions of both ER alpha and ER beta while the inhibitory action of hydroxytamoxifen is limited to AF2, the ligand-dependent function of the estrogen receptors. AF1 activity is constitutive, ligand-independent and is responsible for mediation of the activity of growth factors and of the ras oncogene and MAP-kinase pathway. EM-652 inhibits Ras-induced transcriptional activity of ER alpha and ER beta and blocks SRC-1-stimulated activity of the two receptors. EM-652 was also found to block the recruitment of SRC-1 at AF1 of ER beta, this ligand-independent activation of AF1 being closely related to phosphorylation of the steroid receptors by protein kinase. Most importantly, the antiestrogen hydroxytamoxifen has no inhibitory effect on the SRC-1-induced ER beta activity while the pure antiestrogen EM-652 completely abolishes this effect, thus strengthening the need to use pure antiestrogens in breast cancer therapy in order to control all known aspects of ER-regulated gene expression. In fact, the absence of blockade of AF2 by hydroxytamoxifen could explain why the benefits of tamoxifen observed up to 5 years become negative at longer time intervals and why resistance develops to tamoxifen. EM-800, the prodrug of EM-652, has been shown to prevent the development of dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma in the rat, a well-recognized model of human breast cancer. It is of interest that the addition of dehydroepiandrosterone, a precursor of androgens, to EM-800, led to complete inhibition of tumor development in this model. Not only the development, but also the growth of established DMBA-induced mammary carcinoma was inhibited by treatment with EM-800. An inhibitory effect was also observed when medroxyprogesterone was added to treatment with EM-800. Uterine size was reduced to castration levels in the groups of animals treated with EM-800. An almost complete disappearance of estrogen receptors was observed in the uterus, vaginum and tumors in nude mice treated with EM-800. EM-652 was the most potent antiestrogen to inhibit the growth of human breast cancer ZR-75-1, MCF-7 and T-47D cells in vitro when compared with ICI 182780, ICI 164384, hydroxytamoxifen, and droloxifene. Moreover, EM-652 and EM-800 have no stimulatory effect on the basal levels of cell proliferation in the absence of E2 while hydroxytamoxifen and droloxifene had a stimulatory effect on the basal growth of T-47D and ZR-75-1 cells. EM-652 was also the most potent inhibitor of the percentage of cycling cancer cells. (ABSTRACT TRUNCATED)

Medroxyprogesterone acetate inhibits interleukin 6 secretion from KPL-4 human breast cancer cells both in vitro and in vivo: a possible mechanism of the anticachectic effect

Interleukin 6 (IL-6) is a multifunctional cytokine. Recent reports suggest that circulating IL-6 secreted from tumour cells plays an important role in cancer-induced cachexia. Medroxyprogesterone acetate (MPA) has been used as an endocrine therapeutic agent for patients with breast cancer. It has been suggested that MPA decreases serum IL-6 levels and preserves the bodyweight of patients with advanced breast cancer. However, the mechanisms of action responsible for the anticachectic effect of MPA have not been elucidated. Therefore, the effects of MPA on IL-6 secretion were studied both in vitro and in vivo using a human breast cancer cell line, KPL-4, which secretes IL-6 into medium and induces cachexia when injected into female nude mice. MPA (10-1000 nM) dose-dependently decreased basal IL-6 secretion into medium, and also suppressed tumour necrosis factor (TNF-alpha)-induced IL-6 secretion. Both basal and TNF-alpha-induced IL-6 mRNA levels were dose-dependently lowered by MPA. Moreover, intramuscular injections of MPA (100 mg kg(-1) twice a week) into nude mice bearing KPL-4 transplanted tumours significantly decreased serum IL-6 levels without affecting tumour growth and preserved the bodyweight of recipient mice. These findings suggest that suppression of IL-6 secretion from tumour cells, at least in part, causes the anticachectic effect of MPA.

Role of the androgen receptor in human breast cancer

Although the androgen receptor (AR)3 is often co-expressed with the estrogen receptor (ER) and progesterone receptor (PR) in human breast tumors, its role in breast cancer is poorly understood. Specific growth stimulatory and inhibitory actions of androgens have been described in human breast cancer cell lines. The mechanisms by which androgens exert these contrasting growth effects are unknown. A commonly utilized second line therapy for the treatment of advanced breast cancer is high dose medroxyprogesterone acetate (MPA). Although MPA, a synthetic progestin, was thought to act exclusively through the PR, the androgenic side-effects observed in women taking MPA suggest that its action may also be mediated in part by the AR. In support of this hypothesis, the level of AR measured by radioligand binding in primary breast tumors was correlated with the duration of response to MPA treatment following failure of tamoxifen therapy. Recent data suggest that the presence of structurally altered AR in breast cancers may account for unresponsiveness to MPA in some of these cases. Further studies are warranted to determine the role of AR mediated pathways in regulating breast tumor growth. In particular, identification of androgen-regulated genes may lead to new possibilities for the hormonal treatment of breast cancer.

Inhibitory effect of the novel anti-estrogen EM-800 and medroxyprogesterone acetate on estrone-stimulated growth of dimethylbenz[a]anthracene-induced mammary carcinoma in rats

The novel anti-estrogen EM-800 and medroxyprogesterone acetate (MPA) inhibit estrone (E1)-stimulated growth of dimethylbenz[a]anthracene (DMBA)-induced mammary tumors in a rat model. After 65 days, ovariectomy (OVX) decreased total tumor area to 9.6 +/- 3.9% of initial size, while E1 (1.0 microg, s.c., twice daily) stimulated tumor growth to 225 +/- 40.9% of initial size. Daily oral administration of 2.5 mg/kg body weight of EM-800 completely abolished E1-stimulated tumor growth. A low daily dose of EM-800 (0.25 mg/kg body weight) or MPA (1 mg, s.c., twice daily) used alone partially reversed the stimulatory effect of E1 on the growth of DMBA-induced tumors. The combination of both compounds, however, caused a more potent inhibitory effect than each compound used alone. A high dose of EM-800 completely or almost completely inhibited the E1-stimulated vaginal and uterine weights, respectively. The same dose of EM-800 completely reversed the inhibitory effect of E1 on serum luteinizing hormone levels. Uterine, vaginal and tumoral estrogen and progesterone receptor levels were reduced markedly following treatment with EM-800. Our data show that the combination of the pure anti-estrogen EM-800 with the androgenic compound MPA achieves greater inhibition of the growth of DMBA-induced mammary carcinoma than that achieved by each compound used alone.

Predictive value of serum medroxyprogesterone acetate concentration for response in advanced or recurrent breast cancer

Medroxyprogesterone acetate (MPA) is one of the most commonly prescribed drugs for endocrine therapy of metastatic breast cancer. In this study, the serum MPA concentration was measured by high-performance liquid chromatography (HPLC) and evaluated for its usefulness in predicting the response in 79 cases of advanced or recurrent breast cancers. Overall, 29 patients (37%) achieved an objective response. The response rate correlated significantly with the oestrogen receptor (ER) status (P = 0.03), proliferative activity determined by DNA polymerase alpha (P = 0.04), the disease-free interval (DFI) (P = 0.05) and the serum MPA concentration (P < 0.001). Patients with ER-positive tumours, lower proliferative activity, a longer (DFI) or a higher serum MPA concentration responded more frequently. The mean serum MPA concentration in the responders with ER-positive tumours (P = 0.01) or tumours with a lower proliferative activity (P = 0.008) were significantly lower than in cases with ER-negative tumours or tumours with a higher proliferative activity, respectively. Cases with soft tissue metastases showed responses at significantly lower MPA concentrations (P = 0.003) than those with bone or visceral metastases. Furthermore, there was a dramatic decrease in the MPA concentration when a responder with a high concentration became unresponsive to the therapy. Thus, the serum MPA concentration is a determining factor for the response to treatment.

Effects of sex- and glucocorticoid steroids on breast cancer cells grown as either multicellular tumor spheroids or monolayers

The effects of estradiol, medroxyprogesterone acetate (MPA) dexamethasone, dihydrotestosterone and the antihormones 4-OH tamoxifen and RU 38486 were studied in two established breast carcinoma cell lines, the estrogen-sensitive ZR-75-1 and the estrogen-independent BT 20 cells applying two different in vitro systems, spheroid and monolayer cell culture in steroid deprived medium. Growth of ZR-75-1 spheroids was dramatically stimulated by the addition of estradiol, an effect which was neutralized by the simultaneous addition of 4-OH tamoxifen. The antiestrogen alone as well as dihydrotestosterone and MPA reduced ZR-75-1 spheroid growth significantly. While growth of BT 20 spheroids was only transiently inhibited by tamoxifen and dihydrotestosterone, a persistent increase in BT 20 spheroid growth was observed under MPA treatment in a concentration of 1 microM. This effect, although statistically significant, was very moderate. With the exception of this finding, growth effects of the different test compounds were similar in both in vitro systems, tumor spheroids and monolayer cell cultures.

Effect of medroxyprogesterone acetate (MPA) and serum factors on cell proliferation in primary cultures of an MPA-induced mammary adenocarcinoma

The effect of progesterone (Pg), medroxyprogesterone acetate (MPA), estradiol (E2), dihydrotestosterone (DHT) and dexamethasone (DEXA) was studied on the in vitro growth rate of a progestin-dependent (PD), estrogen-sensitive mammary tumor line originated in an MPA-treated BALB/c mouse (C4-HD), and on its estrogen-resistant variant (C4-HDR). The specificity of hormone action was further investigated using the anti-hormones RU-486 and hydroxyflutamide (FLU). Cell growth was evaluated in epithelial and fibroblast-enriched cultures using 3H-thymidine and/or autoradiography and immunocytochemistry. The results indicate that cell growth is directly stimulated by MPA and Pg at concentrations ranging from 10(-11) to 10(-7) M. RU486 prevented MPA-induced stimulation in concentrations 10 to 100 fold lower than those of MPA. When used alone, it inhibited cell proliferation only in concentrations higher than 10(-11) M. At nM concentrations, neither DEXA nor DHT stimulated 3H-thymidine uptake except DEXA at 100 nM. MPA-induced stimulation was not reverted by micromolar concentrations of FLU. As for E2 (10(-7)-10(-9) M) it prevented MPA stimulation only in cultures of estrogen-sensitive tumors. Progesterone receptors (PR) (475 +/- 115 fmoles/10(5) cells, n = 5) and estrogen receptors (ER) (ND-115 fmoles/10(5) cells, n = 5) were detected only in epithelial-enriched cultures. Serum from 7 day-MPA-treated mice induced a significant increase of 3H-thymidine uptake; an increase was also obtained with serum from untreated ovariectomized animals to which 1 nM-100 nM concentrations of MPA had been added. The stimulatory effect of the exogenous MPA was much lower than that of the serum obtained from MPA-treated animals. It is concluded that MPA stimulates cell growth of primary cultures of MPA-induced PD tumors via PR. The results provide support for a direct effect of MPA which may be mediated or potentiated by serum factors.

Inhibitory effects of medroxyprogesterone acetate (MPA) and the pure antiestrogen EM-219 on estrone (E1)-stimulated growth of dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma in the rat

Estrogens are well known to play a predominant role in promoting the growth of DMBA-induced mammary tumors in the rat. Estrone (E1), a steroid having weak estrogenic activity, is one of most important estrogens in post-menopausal women, where it is converted into the potent estrogen estradiol (E2) by 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) in many peripheral tissues, including the mammary gland. In this report, we have studied the effect of a new antiestrogen (EM-219) (N-butyl, N-methyl-11-(3', 17'beta-dihydroxy-17'alpha-ethinyl-estra-1'3'5'(10'), 14'-tetraen-7'alpha-yl) undecanamide) on E1-stimulated growth of DMBA-induced mammary tumors and compared its effect with that of medroxyprogesterone acetate (MPA) alone or in combination. After 18 days, ovariectomy (OVX) reduced total tumor area to 29.6 +/- 7.1% of the original size, while E1 (1.0 microgram, twice daily) caused a 139 +/- 21% increase in tumor size in OVX animals. MPA (1.5 mg, twice daily) partially reversed the stimulatory effect of E1 to 66.0 +/- 9.0%, while the antiestrogen EM-219 (40 micrograms, twice daily) decreased tumor size to 70.0 +/- 10%. Combination of these two compounds led to a further inhibition of tumor size to 30.7 +/- 7.4% of the value found in OVX animals treated with E1. Tumor E2 levels decreased from 1688 +/- 155 pmoles/kg tissue in OVX animals receiving E1 to 709 +/- 92, 1347 +/- 98, and 184 +/- 11 pmoles/kg tissue in MPA-, EM-219-, and MPA+EM-219-treated OVX-E1 animals, respectively. Treatment of OVX animals with E1 increased by 69% the reductive activity of 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) while MPA abolished completely this effect of E1. In the oxidative direction, treatment with E1, E1 + MPA, or E1 + EM-219 had minimal or no significant effect on the activity of 17 beta-HSD (vs OVX), while the combined treatment with MPA+EM-219 induced a 2-fold increase in 17 beta-HSD activity, thus leading to an increased conversion of E2 into E1. The present data show that combination of the pure antiestrogen EM-219 with MPA exerts a greater reduction in DMBA-induced mammary tumor growth and intratumoral E2 levels stimulated by E1 than either compound used alone. This interactive effect of the antiestrogen and MPA could at least partially be related to the increased inactivation of E2 into E1.(ABSTRACT TRUNCATED AT 400 WORDS)

Structure, regulation and role of 3 beta-hydroxysteroid dehydrogenase, 17 beta-hydroxysteroid dehydrogenase and aromatase enzymes in the formation of sex steroids in classical and peripheral intracrine tissues

In addition to the classical steroidogenic tissues, namely the ovaries, testes, adrenals and placenta, a large series of human peripheral tissues possess all the enzymatic systems required for the formation of active androgens and oestrogens from a relatively large supply of precursor steroids provided by the adrenals. This chapter describes the structure, function, tissue-specific expression and regulation of the 3 beta-HSD and 17 beta-HSD gene families as well as some information about the aromatase gene. While, so far, most therapeutic approaches have been aimed and limited at controlling steroid formation by the classical steroidogenic tissues, it is clear that major efforts should now be turned towards intracrinology in order to understand better the physiological mechanisms controlling local steroid formation in peripheral target tissues and thus be in a position to develop novel therapeutic approaches that take into account the high proportion of steroids that are made locally and are responsible for the growth and function of normal as well as cancerous tissue.

Prevention by dehydroepiandrosterone of the development of mammary carcinoma induced by 7,12-dimethylbenz(a)anthracene (DMBA) in the rat

The concentration of serum dehydroepiandrosterone sulfate (DHEA-S) and DHEA decreases markedly during aging, and low circulating levels of DHEA have been associated with a higher incidence of breast cancer in women. Using 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma in the rat as model, we have studied the effect of increasing serum levels of DHEA released from Silastic implants on the incidence of these tumors in the rat. Treatment with increasing doses of DHEA leading to serum DHEA levels comparable to those observed in normal adult women (7.1 +/- 0.6 nM and 17.5 +/- 1.1 nM) caused a progressive inhibition of tumor development from 68% bearing tumors in control animals to 22% and 11%, respectively. The average tumor area per rat decreased from 2.81 cm2 in intact control animals to 0.96 and 0.09 cm2 in the groups treated with the same doses of DHEA, respectively. The present data indicate that circulating levels of DHEA similar to those found in normal adult premenopausal women exert a potent inhibitory effect on the development of DMBA-induced mammary tumors in the rat, thus suggesting the possibility of a new and more physiological approach for the prevention of breast cancer in women.

Glucocorticoids and androgens up-regulate the Zn-alpha 2-glycoprotein messenger RNA in human breast cancer cells

We have studied the hormonal regulation of the gene encoding Zn-alpha 2-glycoprotein (Zn-alpha 2-gp), a human protein with a high degree of amino acid sequence similarity to class I histocompatibility antigens that is produced by a specific subset of breast carcinomas. Northern blot analysis revealed that dexamethasone and 5 alpha-dihydrotestosterone strongly induced the accumulation of Zn-alpha 2-gp mRNA in T-47D human breast cancer cells. Furthermore, the effect of these two hormones was shown to be additive, since the combination of both hormones produced a stimulation of Zn-alpha 2-gp mRNA of at least 3-fold over that produced by either hormone alone. By contrast, the addition of 5 beta-dihydrotestosterone, 17 beta-estradiol, or progesterone failed to induce the expression of Zn-alpha 2-gp. The stimulatory effect of glucocorticoids and androgens on Zn-alpha 2-gp expression was produced in a time and dose dependent manner, without significantly affecting the cell proliferation rate. A time-course study demonstrated that the induction of Zn-alpha 2-gp mRNA by androgens and glucocorticoids reached a level of 4 or 3.2-fold over the untreated control after seven days of incubation in the presence of a 10(-7) M concentration of 5 alpha-dihydrotestosterone or dexamethasone, respectively. A dose-response study showed that as little as 10(-11) M of 5 alpha-dihydrotestosterone or dexamethasone produced an accumulation of Zn-alpha 2-gp mRNA of 2.4 or 2.1-fold over the control, respectively. On the basis of these results, we propose that Zn-alpha2-gp may be useful as a biochemical marker of breast carcinomas with a specific pattern of hormone responsiveness in whose development glucocorticoids and/or androgens may play a significant role.

Controlled release low dose medroxyprogesterone acetate (MPA) inhibits the development of mammary tumors induced by dimethyl-benz(a) anthracene in the rat

Medroxyprogesterone acetate (MPA) is well recognized to have beneficial effects for the treatment of advanced breast cancer which are comparable to those achieved with other forms of endocrine therapy. Using mammary tumors induced in the rat by dimethylbenz(a)anthracene (DMBA) as a model, we have studied the possibility that low dose MPA could prevent the development of these tumors. Single subcutaneous injection of Depo-Provera (crystalline suspension of MPA) or MPA encapsulated in biodegradable microspheres of 50:50 poly[DL-lactide-co-glycolide] was given 7 days before oral DMBA. While 63% of intact animals developed palpable mammary tumors within 85 days after DMBA administration, tumor incidence decreased to 28% and 23% in animals who had received 30 mg and 100 mg of Depo-Provera, respectively. The same amounts of MPA delivered in microspheres caused a further decrease in tumor incidence to respective values of 7% and 6%. Average tumor area, on the other hand, decreased from 4.89 cm2 in intact rats to about 0.75 (0.57-0.88) cm2 and approximately 0.20 (0.14-0.22) cm2 in the Depo-Provera and microsphere-treated groups, respectively. Using the 50:50 formulation of poly[DL-lactide-co-glycolide] designed to release MPA at a constant rate for a 4-month period, the serum MPA concentration at 3 months was measured at 4.99 +/- 0.43 ng/ml. Such data suggest that administration of a low dose controlled-release formulation of MPA in 50:50 poly[DL-lactide-co-glycolide] microspheres could well be an efficient and well tolerated approach for the prevention of breast cancer in women.

Medroxyprogesterone acetate inhibits the proliferation of estrogen- and progesterone-receptor negative MFM-223 human mammary cancer cells via the androgen receptor

This study demonstrates for the first time, that medroxyprogesterone acetate (MPA) inhibits the proliferation of the estrogen and progesterone receptor negative mammary cancer cell line MFM-223 via the androgen receptor. MPA is a progestin, which is used in the hormonal treatment of disseminated breast cancer. It binds to the progesterone, androgen, and glucocorticoid receptor and may exert its antiproliferative effects via different receptors. MFM-223 human mammary cancer cells contain a very high level of androgen receptors (160 fmol/mg protein) and low levels of estrogen, progesterone, and glucocorticoid receptors (< 20 fmol/mg protein). This cell line provides therefore a good model system to analyze the possible role of the androgen receptor in the action of MPA avoiding interference with other steroid hormone receptors. Effective inhibition of proliferation is achieved by 10 nM MPA or 1 nM of the androgen dihydrotestosterone, corresponding well to the binding affinities of both compounds (3.6 and 0.18 nM, respectively). The involvement of the androgen receptor was confirmed by competition experiments with antiandrogens. Furthermore, MFM-DHT cells, which are an androgen resistant subline of MFM-223 cells, are also resistant to MPA. This data supports the involvement of the androgen receptor in the action of MPA and additionally rules out direct hormone-independent cytotoxic effects of MPA.

The relationship between affinity of progestins and antiprogestins for the progesterone receptor in breast cancer cells (ZR-PR-LT) and ability to down-regulate the receptor: evidence for heterospecific receptor modulation via the glucocorticoid receptor

In a human breast cancer cell line (ZR-PR-LT) we have found a poor overall correlation between affinity of progestins and anti-progestins for the progesterone receptor (PGR), concentration required for receptor down-regulation and anti-proliferative potency. Medroxyprogesterone acetate (MPA) and the anti-progestin RU 38.486, which possess glucocorticoid and antiglucocorticoid activity, respectively, cause receptor down-regulation at lower concentrations than their Kdi for [3H] ORG 2058 binding sites. In addition dexamethasone markedly down-regulates PGR at concentrations which fail to interact with PGR suggesting that heterospecific modulation of PGR occurs via the glucocorticoid receptor. In contrast the progestin ORG2058 and the anti-progestin ZK 98.299 caused 50% PGR down-regulation at a concentration (EC50) 50-fold higher than their Kdi values. ZK 112.993 was 500-fold more potent at PGR down-regulation than ZK 98.299 but had only a 5-fold higher affinity for PGR. Anti-proliferative concentrations of progestins/anti-progestins showing were generally higher than either Kdi values or EC50 values.