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

Steroid-Modulated Transcription Synergistically Forms DNA Double-Strand Breaks With Topoisomerase II Inhibitor

The synergistic effects of drug combinations have emerged as a promising approach for achieving efficient cancer treatment. Through our exploration of drug combinations, we found that medroxyprogesterone acetate (MPA), a steroid, induced a synergistic antitumor effect in combination with the topoisomerase II inhibitor etoposide (ETP). In this study, we investigated the mechanisms underlying this synergistic effect for potential clinical applications. To elucidate the relevant mechanisms, we performed a cell viability assay, cell cycle analysis, DNA repair assays, detection of DNA double-strand breaks (DSBs) and the nuclear localization of topoisomerase II (Top2), and genome-wide detection of DSBs. MPA synergistically increased ETP-induced DSBs, resulting in cell cycle arrest in the G2/M phase. Interestingly, this effect was not due to the inhibition of DSB repair but to a specific increase in the Top2-DNA covalent complex formed by ETP. A genome-wide search for DSB locations revealed that DSB formation was promoted near promoter regions, suggesting the involvement of MPA transcriptional modulation in this mechanism. We also found that various steroids promoted DSB formation when combined with ETP, strongly supporting our synergistic model. Therefore, this synergistic effect is based on an innovative mechanism that differs from conventional strategies targeting the DNA damage response and is expected to contribute toward novel therapeutic options.

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.

Retrospective study on the effectiveness of medroxyprogesterone acetate in the treatment of ER-positive/HER2-negative post-menopausal advanced breast cancer: an additional analysis of the JBCRG-C06 Safari study

BACKGROUND

Only old evidence exists to back up the use of medroxyprogesterone acetate. Therefore, this study aimed to explore the factors that influence the time to treatment failure of medroxyprogesterone acetate in real-world settings as late-line treatment.

METHODS

This was a cohort study that used the database of the Safari study on oestrogen receptor-positive post-menopausal advanced breast cancer (UMIN000015168). We created Kaplan-Meier curves for time to treatment failure with medroxyprogesterone acetate. Further, univariate and multivariate analyses were performed using a Cox hazard model of the clinicopathological factors involved in the time to treatment failure of medroxyprogesterone acetate.

RESULTS

From the 1031 patients in the Safari study, 279 patients were selected as the population for the analysis of effectiveness of medroxyprogesterone acetate monotherapy. In the analysis of medroxyprogesterone acetate by treatment line, the median time to treatment failure was 3.0 months for third-line treatment and 4.1 months for fourth and subsequent treatment lines. In cases where medroxyprogesterone acetate was used as a third-line or later endocrine treatment, multivariate analysis showed that the length of the disease-free interval was correlated with the length of time to treatment failure of medroxyprogesterone acetate (P = 0.004). With medroxyprogesterone acetate monotherapy as the fourth-line or later treatment, 20% of the patients achieved a time to treatment failure of 12 months or longer.

CONCLUSION

In actual clinical practice, patients treated with medroxyprogesterone acetate alone as the fourth or subsequent treatment lines showed a time to treatment failure of 4 months, suggesting that there is merit in using medroxyprogesterone acetate even in late treatment lines, especially in patients with long disease-free interval and those who are difficult to treat using other antineoplastic agents.

Modeling hormonal contraception in female rats: A framework for studies in behavioral neurobiology

Research on hormonal contraceptives (HC) in animal models is lacking, and as a result, so is our understanding of the impact of HC on the brain and behavior. Here, we provide a review of the pharmacology of HC, as well as the methodology and best practices for designing a model of HC in female rats. We outline specific methodological considerations regarding dosing, route of administration, exposure time/timing, and selecting a control group. We also provide a framework outlining important levels of analysis for thinking about the impact of HC on behavioral and neurobiological outcomes. The purpose of this review is to equip researchers with foundational knowledge, and some basic elements of experimental design for future studies investigating the impact of HC on the brain and behavior of female rats.

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.

Growth regulation by estrogen in breast cancer 1 (GREB1) is a novel progesterone-responsive gene required for human endometrial stromal decidualization

STUDY QUESTION

Is Growth Regulation by Estrogen in Breast Cancer 1 (GREB1) required for progesterone-driven endometrial stromal cell decidualization?

SUMMARY ANSWER

GREB1 is a novel progesterone-responsive gene required for progesterone-driven human endometrial stromal cell (HESC) decidualization.

WHAT IS KNOWN ALREADY

Successful establishment of pregnancy requires HESCs to transform from fibroblastic to epithelioid cells in a process called decidualization. This process depends on the hormone progesterone, but the molecular mechanisms by which it occurs have not been determined.

STUDY DESIGN, SIZE, DURATION

Primary and transformed HESCs in which GREB1 expression was knocked down were decidualized in culture for up to 6 days. Wild-type and progesterone receptor (PR) knockout mice were treated with progesterone, and their uteri were assessed for levels of GREB1 expression.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Analysis of previous data included data mining of expression profile data sets and in silico transcription factor-binding analysis. Endometrial biopsies obtained from healthy women of reproductive age during the proliferative phase (Days 8-12) of their menstrual cycle were used for isolating HESCs. Experiments were carried out with early passage (no more than four passages) HESCs isolated from at least three subjects. Transcript levels of decidualization markers prolactin (PRL) and insulin-like growth factor-binding protein-1 (IGFBP-1) were detected by quantitative RT-PCR as readouts for HESC decidualization. Cells were also imaged by phase-contrast microscopy. To assess the requirement for GREB1, PR and SRC-2, cells were transfected with specifically targeted small interfering RNAs. Results are shown as mean and SE from three replicates of one representative patient-derived primary endometrial cell line. Experiments were also conducted with transformed HESCs.

MAIN RESULTS AND THE ROLE OF CHANCE

Progesterone treatment of mice and transformed HESCs led to an ~5-fold (5.6 ± 0.81, P < 0.05, and 5.2 ± 0.26, P < 0.01, respectively) increase in GREB1 transcript levels. This increase was significantly reduced in the uteri of PR knock-out mice (P < 0.01), in HESCs treated with the PR antagonist RU486 (P < 0.01), or in HESCs in which PR expression was knocked down (P < 0.05). When GREB1 expression was knocked down, progesterone-driven decidualization markers in both immortalized and primary HESCs was significantly reduced (P < 0.05 and P < 0.01). Finally, GREB1 knock down signficantly reduced expression of the PR target genes WNT4 and FOXOA1 (P < 0.05 and P < 0.01, respectively).

LARGE SCALE DATA

This study used the Nuclear Receptor Signaling Atlas.

LIMITATIONS, REASONS FOR CAUTION

Although in vitro cell culture studies indicate that GREB1 is required for endoemtrial decidualization, the in vivo role of GREB1 in endometrial function and dysfunction should be assessed by using knock-out mouse models.

WIDER IMPLICATIONS OF THE FINDINGS

Identification and functional analysis of GREB1 as a key molecular mediator of decidualization may lead to improved diagnosis and clinical management of women with peri-implantation loss due to inadequate endometrial decidualization.

STUDY FUNDING AND COMPETING INTEREST(S)

This research was funded in part by: a National Institutes of Health (NIH)/ National Institute of Child Health and Human Development (NICHD) grant (R00 HD080742) and Washington University School of Medicine start-up funds to R.K., an NIH/NICHD grant (RO1 HD-07857) to B.W.O.M., and a NIH/NICHD grant (R01 HD-042311) to J.P.L. The authors declare no conflicts of interests.

The effects of progesterones on blood lipids in hormone replacement therapy

The safety of progestogens as a class has drawn much attention after the publication of data from the Women’s Health Initiative (WHI) trial, particularly with respect to cardiovascular disease. Depending on the chemical structure, pharmacokinetics, receptor affinity and potency of action, progestogens have a divergent range of properties that may translate to very different clinical effects. The purpose of this review is to describe the role of varied progestogens in hormone replacement therapy (HRT), especially focusing on blood lipids, which are the most important parameters for assessing cardiovascular disease risk.

Metabolism of megestrol acetate in vitro and the role of oxidative metabolites

1. There is limited knowledge regarding the metabolism of megestrol acetate (MA), as it was approved by FDA in 1971, prior to the availability of modern tools for identifying specific drug-metabolizing enzymes. We determined the cytochrome P450s (P450s) and UDP-glucuronosyltransferases (UGTs) that metabolize MA, identified oxidative metabolites and determined pharmacologic activity at the progesterone, androgen and glucocorticoid receptors (PR, AR and GR, respectively). 2. Oxidative metabolites were produced using human liver microsomes (HLMs), and isolated for mass spectral (MS) and nuclear magnetic resonance (NMR) analyses. We screened recombinant P450s using MA at 62 μM (HLM K_m for metabolite 1; M1) and 28 μM (HLM K_m for metabolite 2; M2). UGT isoforms were simultaneously incubated with UDPGA, nicotinamide adenine dinucleotide phosphate (NADPH), CYP3A4 and MA. Metabolites were evaluated for pharmacologic activity on the PR, AR and GR. CYP3A4 and CYP3A5 are responsible for oxidative metabolism of 62 μM MA. 3. At 28 μM substrate concentration, CYP3A4 was the only contributing enzyme. Mass spectral and NMR data suggest metabolism of MA to two alcohols. After oxidation, MA is converted into two secondary glucuronides by UGT2B17 among other UGTs. MA, M1 and M2 had significant pharmacologic activity on the PR while only MA showed activity on the AR and GR.

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.

Intracrine Androgens Enhance Decidualization and Modulate Expression of Human Endometrial Receptivity Genes

The endometrium is a complex, steroid-dependent tissue that undergoes dynamic cyclical remodelling. Transformation of stromal fibroblasts (ESC) into specialised secretory cells (decidualization) is fundamental to the establishment of a receptive endometrial microenvironment which can support and maintain pregnancy. Androgen receptors (AR) are present in ESC; in other tissues local metabolism of ovarian and adrenal-derived androgens regulate AR-dependent gene expression. We hypothesised that altered expression/activity of androgen biosynthetic enzymes would regulate tissue availability of bioactive androgens and the process of decidualization. Primary human ESC were treated in vitro for 1–8 days with progesterone and cAMP (decidualized) in the presence or absence of the AR antagonist flutamide. Time and treatment-dependent changes in genes essential for a) intra-tissue biosynthesis of androgens (5α-reductase/SRD5A1, aldo-keto reductase family 1 member C3/AKR1C3), b) establishment of endometrial decidualization (IGFBP1, prolactin) and c) endometrial receptivity (SPP1, MAOA, EDNRB) were measured. Decidualization of ESC resulted in significant time-dependent changes in expression of AKR1C3 and SRD5A1 and secretion of T/DHT. Addition of flutamide significantly reduced secretion of IGFBP1 and prolactin and altered the expression of endometrial receptivity markers. Intracrine biosynthesis of endometrial androgens during decidualization may play a key role in endometrial receptivity and offer a novel target for fertility treatment.

Reprint of "Use of medroxyprogesterone acetate for hormone therapy in postmenopausal women: Is it safe?"

Medroxyprogesterone acetate (MPA) has been in clinical use for over 30 years, and was generally considered to be safe until the results of long-term studies of postmenopausal hormone therapy (HT) using treatment with conjugated equine estrogens (CEE) combined with MPA and CEE alone suggested that MPA, and perhaps other progestogens, may play a role in the increased risk of breast cancer and cardiovascular diseases. This review examines critically the safety of MPA in terms of breast cancer and cardiovascular disease risk, and its effects on brain function. Research into mechanisms by which MPA might cause adverse effects in these areas, combined with the available clinical evidence, suggests a small increase in relative risk for breast cancer and stroke, and a decline in cognitive function, in older women using MPA with an estrogen for postmenopausal HT. However, short-term (less than 5 years) use of MPA with an estrogen in the years immediately after the onset of menopause for the management of vasomotor symptoms does not appear to be associated with any increased risk of these disorders.

Agonist-Dependent Downregulation of Progesterone Receptors in Human Cervical Stromal Fibroblasts

Progesterone (P(4)) maintains uterine quiescence during the majority of pregnancy, whereas diminished progesterone receptor (PR) expression and/or activity (ie, functional P(4) withdrawal) promotes parturition. To investigate the regulation of PR expression in cervical stroma, fibroblasts from premenopausal hysterectomy specimens were prepared. Greater than 99% of the cultures were vimentin positive (mesenchymal cell marker) with only occasional cytokeratin-8 positivity (epithelial cell marker) and no evidence of CD31-positive (endothelial cell marker) cells. Cells were immunolabeled with antibodies directed against PRs (PR-A and PR-B), estrogen receptor α (ER-α), and glucocorticoid receptor-α/β (GR-α/β). All cells were uniformly immunopositive for ER-α and GR-α/β but did not express PRs. Incubation of cells with 10(-8) mol/L 17β-estradiol induced a time-dependent increase in PR-A and PR-B messenger RNAs (mRNAs) by quantitative real-time polymerase chain reactions and proteins by immunoblotting and immunofluorescence. Incubation of cervical fibroblasts with PR ligands (medroxyprogesterone acetate or Org-2058) downregulated PR-A and PR-B levels. Coincubation of cells with PR ligands plus RU-486, a PR antagonist, partially abrogated agonist-induced receptor downregulation. Dexamethasone, a pure glucocorticoid, had no inhibitory effect on PR expression. These results indicate that progestins and estrogens regulate PR expression in cervical fibroblasts. We postulate that hormonal regulation of PR expression in the cervical stroma may contribute to functional P(4) withdrawal in preparation for parturition.

Progesterone receptor modulates ERα action in breast cancer

Progesterone receptor (PR) expression is used as a biomarker of oestrogen receptor-α (ERα) function and breast cancer prognosis. Here we show that PR is not merely an ERα-induced gene target, but is also an ERα-associated protein that modulates its behaviour. In the presence of agonist ligands, PR associates with ERα to direct ERα chromatin binding events within breast cancer cells, resulting in a unique gene expression programme that is associated with good clinical outcome. Progesterone inhibited oestrogen-mediated growth of ERα(+) cell line xenografts and primary ERα(+) breast tumour explants, and had increased anti-proliferative effects when coupled with an ERα antagonist. Copy number loss of PGR, the gene coding for PR, is a common feature in ERα(+) breast cancers, explaining lower PR levels in a subset of cases. Our findings indicate that PR functions as a molecular rheostat to control ERα chromatin binding and transcriptional activity, which has important implications for prognosis and therapeutic interventions.

Steroid induction of therapy-resistant cytokeratin-5-positive cells in estrogen receptor-positive breast cancer through a BCL6-dependent mechanism

Therapy resistance remains a major problem in estrogen receptor-α (ERα)-positive breast cancer. A subgroup of ERα-positive breast cancer is characterized by mosaic presence of a minor population of ERα-negative cancer cells expressing the basal cytokeratin-5 (CK5). These CK5-positive cells are therapy resistant and have increased tumor-initiating potential. Although a series of reports document induction of the CK5-positive cells by progestins, it is unknown if other 3-ketosteroids share this ability. We now report that glucocorticoids and mineralocorticoids effectively expand the CK5-positive cell population. CK5-positive cells induced by 3-ketosteroids lacked ERα and progesterone receptors, expressed stem cell marker, CD44, and displayed increased clonogenicity in soft agar and broad drug-resistance in vitro and in vivo. Upregulation of CK5-positive cells by 3-ketosteroids required induction of the transcriptional repressor BCL6 based on suppression of BCL6 by two independent BCL6 small hairpin RNAs or by prolactin. Prolactin also suppressed 3-ketosteroid induction of CK5+ cells in T47D xenografts in vivo. Survival analysis with recursive partitioning in node-negative ERα-positive breast cancer using quantitative CK5 and BCL6 mRNA or protein expression data identified patients at high or low risk for tumor recurrence in two independent patient cohorts. The data provide a mechanism by which common pathophysiological or pharmacologic elevations in glucocorticoids or other 3-ketosteroids may adversely affect patients with mixed ERα+/CK5+ breast cancer. The observations further suggest a cooperative diagnostic utility of CK5 and BCL6 expression levels and justify exploring efficacy of inhibitors of BCL6 and 3-ketosteroid receptors for a subset of ERα-positive breast cancers.

Steroid hormones, steroid receptors, and breast cancer stem cells

The ovarian hormones progesterone and estrogen play important roles in breast cancer etiology, proliferation, and treatment. Androgens may also contribute to breast cancer risk and progression. In recent years, significant advances have been made in defining the roles of these steroid hormones in stem cell homeostasis in the breast. Stem cells are potential origins of breast cancer and may dictate tumor phenotype. At least a portion of breast cancers are proposed to be driven by cancer stem cells (CSCs), cells that mimic the self-renewing and repopulating properties of normal stem cells, and can confer drug resistance. Progesterone has been identified as the critical hormone regulating normal murine mammary stem cell (MaSC) populations and normal human breast stem cells. Synthetic progestins increase human breast cancer risk; one theory speculates that this occurs through increased stem cells. Progesterone treatment also increases breast CSCs in established breast cancer cell lines. This is mediated in part through progesterone regulation of transcription factors, signal transduction pathways, and microRNAs. There is also emerging evidence that estrogens and androgens can regulate breast CSC numbers. The evolving concept that a breast CSC phenotype is dynamic and can be influenced by cell signaling and external cues emphasizes that steroid hormones could be crucial players in controlling CSC number and function. Here we review recent studies on steroid hormone regulation of breast CSCs, and discuss mechanisms by which this occurs.

A comparative study of the androgenic properties of progesterone and the progestins, medroxyprogesterone acetate (MPA) and norethisterone acetate (NET-A)

The importance of investigating the molecular mechanism of action of medroxyprogesterone acetate (MPA) and norethisterone acetate (NET-A), two clinically important progestins used in hormone therapy (HT), has been highlighted by clinical evidence showing that MPA and norethisterone (NET) increase the risk of the development of breast cancer in HRT users, and that MPA may increase susceptibility to- and transmission of HIV-1. The aim of this study was to compare the molecular mechanisms of action of MPA, NET-A and progesterone (Prog) via the androgen receptor (AR) in a cell line model that can minimize confounding factors such as the presence of other steroid receptors. This study is the first to determine accurate apparent Ki values for Prog, MPA and NET-A toward the human AR in COS-1 cells. The results reveal that these ligands have a similar binding affinity for the AR to that of the natural androgen 5α-dihydrotestosterone (DHT) (Ki's for DHT, Prog, MPA and NET-A are 29.4, 36.6, 19.4 and 21.9 nM, respectively). Moreover, in both transactivation and transrepression transcriptional assays we demonstrate that, unlike Prog, MPA and NET-A are efficacious AR agonists, with activities comparable to DHT. One of the most novel findings of our study is that NET-A, like DHT, induces the ligand-dependent interaction between the NH2- and COOH-terminal domains (N/C-interaction) of the AR independent of promoter-context, while MPA does not induce the N/C interaction on a classical ARE and does so only weakly on an AR-selective ARE. This suggests that MPA and NET-A may exert differential promoter-specific actions via the AR in vivo. Consistent with this, molecular modeling suggests that MPA and NET-A induce subtle differences in the structure of the AR ligand binding domain. Taken together, the results from this study suggest that unlike Prog, both MPA and NET-A used in hormonal therapy are likely to compete with DHT and exert significant and promoter-specific off-target transcriptional effects via the AR, possibly contributing to some of the observed side-effects with the clinical use of MPA and NET-A.

Use of medroxyprogesterone acetate for hormone therapy in postmenopausal women: is it safe?

Medroxyprogesterone acetate (MPA) has been in clinical use for over 30 years, and was generally considered to be safe until the results of long-term studies of postmenopausal hormone therapy (HT) using treatment with conjugated equine estrogens (CEE) combined with MPA and CEE alone suggested that MPA, and perhaps other progestogens, may play a role in the increased risk of breast cancer and cardiovascular diseases. This review examines critically the safety of MPA in terms of breast cancer and cardiovascular disease risk, and its effects on brain function. Research into mechanisms by which MPA might cause adverse effects in these areas, combined with the available clinical evidence, suggests a small increase in relative risk for breast cancer and stroke, and a decline in cognitive function, in older women using MPA with an estrogen for postmenopausal HT. However, short-term (less than 5 years) use of MPA with an estrogen in the years immediately after the onset of menopause for the management of vasomotor symptoms does not appear to be associated with any increased risk of these disorders.

Androgen receptor expression in early triple-negative breast cancer: clinical significance and prognostic associations

BACKGROUND

Triple-negative breast cancers (TNBC) are characterized by aggressive tumour biology resulting in a poor prognosis. Androgen receptor (AR) is one of newly emerging biomarker in TNBC. In recent years, ARs have been demonstrated to play an important role in the genesis and in the development of breast cancer, although their prognostic role is still debated. In the present study, we explored the correlation of AR expression with clinical, pathological and molecular features and its impact on prognosis in early TNBC.

PATIENTS AND METHODS

ARs were considered positive in case of tumors with >10% nuclear-stained. Survival distribution was estimated by the Kaplan Meier method. The univariate and multivariate analyses were performed. The difference among variables were calculated by chi-square test.

RESULTS

81 TNBC patients diagnosed between January 2006 and December 2011 were included in the analysis. Slides were stained immunohistochemically for estrogen and progesterone receptors, HER-2, Ki-67, ALDH1, e-cadherin and AR. Of the 81 TNBC samples, 18.8% showed positive immunostaining for AR, 23.5% and 44.4% of patients were negative for e-cadherin and ALDH1, respectively. Positive AR immunostaining was inversely correlated with a higher Ki-67 (p < 0.0001) and a lympho-vascular invasion (p = 0.01), but no other variables. Univariate survival analysis revealed that AR expression was not associated with disease-free survival (p = 0.72) or overall survival (p = 0.93).

CONCLUSIONS

The expression of AR is associated with some biological features of TNBC, such as Ki-67 and lympho-vascular invasion; nevertheless the prognostic significance of AR was not documented in our analysis. However, since ARs are expressed in a significant number of TNBC, prospective studies in order to determine the biological mechanisms and their potential role as novel treatment target.

Androgenic pathways in the progression of triple-negative breast carcinoma: a comparison between aggressive and non-aggressive subtypes

One of the active intracellular pathways/networks in triple-negative breast carcinoma (TNBC) is that of the androgen receptor (AR). In this study, we examined AR and androgen-metabolising enzyme immunoreactivity in subcategories of TNBC to further elucidate the roles of androgenic pathways in TNBC. We utilised formalin-fixed paraffin-embedded breast cancer samples from ductal carcinoma in situ (DCIS) and invasive ductal carcinoma patient cohorts. We then used immunohistochemistry to classify these samples into basal-like and non-basal samples and to assess interactions between AR, androgen-metabolising enzymes and proliferation. To further substantiate our hypothesis and provide mechanistic insights, we also looked at the expression and regulation of these factors in publically available microarray data and in a panel of TNBC AR-positive cell lines. DCIS was associated with higher levels of AR and enzymes (p < 0.02), although a similar difference was not noticed in basal and non-basal samples. AR and enzymes were correlated in all states. In TNBC cell lines (MDA-MD-453, MFM-223 and SUM185-PE), we found that DHT treatment up-regulated 5αR1 and 17βHSD5 suggesting a mechanistic explanation for the correlations observed in the histological samples. Publicly available microarray data in TNBC cases suggested similar patterns to those observed in histological samples. In the majority of settings, including publically available microarray data, an inverse association between AR and proliferation was detected. These findings suggest that decreases in AR and androgen-metabolising enzymes may be involved in the increased biological aggressiveness in TNBC development.

Molecular and structural basis of androgen receptor responses to dihydrotestosterone, medroxyprogesterone acetate and Δ(4)-tibolone

Medroxyprogesterone acetate (MPA) has widely been used in hormone replacement therapy (HRT), and is associated with an increased risk of breast cancer, possibly due to disruption of androgen receptor (AR) signaling. In contrast, the synthetic HRT Tibolone does not increase breast density, and is rapidly metabolized to estrogenic 3α-OH-tibolone and 3β-OH-tibolone, and a delta-4 isomer (Δ(4)-TIB) that has both androgenic and progestagenic properties. Here, we show that 5α-dihydrotestosterone (DHT) and Δ(4)-TIB, but not MPA, stabilize AR protein levels, initiate specific AR intramolecular interactions critical for AR transcriptional regulation, and increase proliferation of AR positive MDA-MB-453 breast cancer cells. Structural modeling and molecular dynamic simulation indicate that Δ(4)-TIB induces a more stable AR structure than does DHT, and MPA a less stable one. Microarray expression analyses confirms that the molecular actions of Δ(4)-TIB more closely resembles DHT in breast cancer cells than either ligand does to MPA.

Tissue-specific bioconcentration of the synthetic steroid hormone medroxyprogesterone acetate in the common carp (Cyprinus carpio)

The steroid hormone medroxyprogesterone acetate (MPA), commonly used in oral and injectable contraceptives, has been detected in surface and wastewaters near urban and agricultural areas in several rivers of the world. The objectives of this study were to examine the accumulative potential and tissue distribution of MPA in fish. A freshwater species, the common carp (Cyprinus carpio), was exposed to 100 μg/L of MPA for a 7-day period followed by a depuration phase in which fish were maintained in dechlorinated tap water for an additional 7 days. Tissues (muscle, brain, plasma, and liver) were sampled during the uptake (days 1, 3, and 7) and depuration (day 14) phases of the experiment. Tissue-specific bioconcentration factors (BCF) ranged from 4.3 to 37.8 and uptake was greatest in the liver>brain>plasma and lowest in the muscle. From a regulatory standpoint, MPA shows little tendency to bioaccumulate in fish.

Progestogens used in postmenopausal hormone therapy: differences in their pharmacological properties, intracellular actions, and clinical effects

The safety of progestogens as a class has come under increased scrutiny after the publication of data from the Women's Health Initiative trial, particularly with respect to breast cancer and cardiovascular disease risk, despite the fact that only one progestogen, medroxyprogesterone acetate, was used in this study. Inconsistency in nomenclature has also caused confusion between synthetic progestogens, defined here by the term progestin, and natural progesterone. Although all progestogens by definition have progestational activity, they also have a divergent range of other properties that can translate to very different clinical effects. Endometrial protection is the primary reason for prescribing a progestogen concomitantly with postmenopausal estrogen therapy in women with a uterus, but several progestogens are known to have a range of other potentially beneficial effects, for example on the nervous and cardiovascular systems. Because women remain suspicious of the progestogen component of postmenopausal hormone therapy in the light of the Women's Health Initiative trial, practitioners should not ignore the potential benefits to their patients of some progestogens by considering them to be a single pharmacological class. There is a lack of understanding of the differences between progestins and progesterone and between individual progestins differing in their effects on the cardiovascular and nervous systems, the breast, and bone. This review elucidates the differences between the substantial number of individual progestogens employed in postmenopausal hormone therapy, including both progestins and progesterone. We conclude that these differences in chemical structure, metabolism, pharmacokinetics, affinity, potency, and efficacy via steroid receptors, intracellular action, and biological and clinical effects confirm the absence of a class effect of progestogens.

Androgenic pathway in triple negative invasive ductal tumors: its correlation with tumor cell proliferation

Triple negative breast cancer (TNBC) is defined by estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 negativity. Patients with TNBC frequently undergo an aggressive clinical course due to the unavailability of specific targeted therapies. Androgen receptor (AR) was reported to be expressed in up to 60% of TNBC cases but there have been controversies as to the roles of androgen signaling through AR in TNBC. Therefore, in this study, we analyzed the status of AR in combination with androgen synthesizing enzymes (5α-reductase type 1 (5αR1) and 17β-hydroxysteroid dehydrogenase type 5 (17βHSD5)] in order to further understand androgenic actions in TNBC. Androgen receptor, 5αR1, and 17βHSD5 were immunolocalized in a cohort of 203 TNBC patients from Thailand and Japan. We then correlated the findings with clinicopathological characteristics (age, stage, tumor diameter, lymph node invasion, metastatic spread, Ki-67 labeling index, disease-free survival, and overall survival) of the patients. Univariate analysis revealed that AR+/enzyme+ cases were associated with a significantly lower Ki-67 labeling index than AR-/enzyme- samples. Multivariate analysis indicated the presence of significant positive correlations between AR and enzyme status in tumor cells, and between tumor diameter, lymph node invasion, and distant metastasis. Significant negative correlations were also detected between Ki-67 labeling index and AR status (P = 0.04) or 5αR1 (P < 0.001). Cox proportional hazards analysis showed that Ki-67 labeling index and stage were the only factors predicting disease-free and overall survival of the patients, although univariate Kaplan-Meier analysis revealed AR/5αR1 negativity suggested a more adverse clinical course up to 80 months after surgery. These results suggest that the presence of androgen synthesizing pathways in addition to AR expression in tumor cells could confer a better clinical outcome through suppression of cell proliferation.

The contraceptive depot medroxyprogesterone acetate impairs mycobacterial control and inhibits cytokine secretion in mice infected with Mycobacterium tuberculosis

The contraceptive depot medroxyprogesterone acetate (DMPA), with progestin as the single active compound, possesses selective glucocorticoid activity and can alter the expression of glucocorticoid receptor-regulated genes. We therefore propose that pharmacological doses of DMPA used for endocrine therapy could have significant immune modulatory effects and impact on susceptibility to, as well as clinical manifestation and outcome of, infectious diseases. We investigated the effect of contraceptive doses of DMPA in two different murine Mycobacterium tuberculosis models. Multiplex bead array analysis revealed that DMPA altered serum cytokine levels of tumor necrosis factor alpha (TNF-α), granulocyte colony-stimulating factor (G-CSF), and interleukin 10 (IL-10) in C57BL/6 mice and gamma interferon (IFN-γ) in BALB/c mice. DMPA also suppressed antigen-specific production of TNF-α, G-CSF, IL-10, and IL-6 and induced the production of IP-10 in C57BL/6 mice. In BALB/c mice, DMPA altered the antigen-specific secretion of IFN-γ, IL-17, granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-6, and monocyte chemotactic protein 1 (MCP-1). Furthermore, we show that C57BL/6 mice treated with doses of DMPA, which result in serum concentrations similar to those observed in contraceptive users, have a significantly higher bacterial load in their lungs. Our data show for the first time that DMPA impacts tuberculosis (TB) disease severity in a mouse model and that the effects of this contraceptive are not confined to infections of the genital tract. This could have major implications for the contraceptive policies not only in developing countries like South Africa but also worldwide.

Androgen receptor in triple negative breast cancer

The clinical management of triple negative breast cancer (TNBC) is challenging due to the relatively aggressive biological behaviour and paucity of specific targeted therapy. A subset of TNBC patients has been reported to express androgen receptor (AR) in carcinoma cells and the manipulation of androgen signalling or AR targeted therapies have been proposed. However, the biological significance of AR in TNBC has remained relatively unknown. Therefore, this review aims to summarise the reported studies assessing the rates of AR positivity in TNBC patients and androgenic effects in TNBC cell lines. The rates of AR positivity among TNBC cases varied depending on the study population (0-53% of all TNBC patients). This difference among the reported studies may be largely due to the methodological differences of analysing AR. While the majority of cell line studies suggest that androgen increase proliferation and preliminary clinical studies suggest that AR antagonists improve the prognosis of AR positive TNBC patients, cell line transfection experiments and survival analyses of histological samples suggest that the presence of AR in tumour is either benign or predicts better survival. Therefore further translational investigations regarding the mechanisms of androgen action in TNBC are required to explain this discrepancy between clinical and basic studies.

An androgen receptor mutation in the MDA-MB-453 cell line model of molecular apocrine breast cancer compromises receptor activity

Recent evidence indicates that the estrogen receptor-α-negative, androgen receptor (AR)-positive molecular apocrine subtype of breast cancer is driven by AR signaling. The MDA-MB-453 cell line is the prototypical model of this breast cancer subtype; its proliferation is stimulated by androgens such as 5α-dihydrotestosterone (DHT) but inhibited by the progestin medroxyprogesterone acetate (MPA) via AR-mediated mechanisms. We report here that the AR gene in MDA-MB-453 cells contains a G-T transversion in exon 7, resulting in a receptor variant with a glutamine to histidine substitution at amino acid 865 (Q865H) in the ligand binding domain. Compared with wild-type AR, the Q865H variant exhibited reduced sensitivity to DHT and MPA in transactivation assays in MDA-MB-453 and PC-3 cells but did not respond to non-androgenic ligands or receptor antagonists. Ligand binding, molecular modeling, mammalian two-hybrid and immunoblot assays revealed effects of the Q865H mutation on ligand dissociation, AR intramolecular interactions, and receptor stability. Microarray expression profiling demonstrated that DHT and MPA regulate distinct transcriptional programs in MDA-MB-453 cells. Gene Set Enrichment Analysis revealed that DHT- but not MPA-regulated genes were associated with estrogen-responsive transcriptomes from MCF-7 cells and the Wnt signaling pathway. These findings suggest that the divergent proliferative responses of MDA-MB-453 cells to DHT and MPA result from the different genetic programs elicited by these two ligands through the AR-Q865H variant. This work highlights the necessity to characterize additional models of molecular apocrine breast cancer to determine the precise role of AR signaling in this breast cancer subtype.

Male breast cancer: A retrospective study comparing survival with female breast cancer

Male breast cancer is a rare disease. The aim of this study was to compare overall survival (OS) and disease-free survival (DFS) in a group of matched males and females with breast cancer. The clinical data and survival status of 42 operable male breast cancer (MBC) cases treated at the Central Hospital of Tai'an from 1982 to 2006 were collected. Each MBC patient recorded in the database was matched with two female breast cancer (FBC) patients. Matching was conducted based on age, year of diagnosis, stage and pathology. SPSS 16.0 software was used for statistical analysis. The Chi-square test was used for the categorical data, the Kaplan-Meier method was applied to analyze survival and the log-rank test was used to compare curves between the groups. P<0.05 was considered to indicate a statistically significant difference. The 42 MBC patients were matched with 84 FBC patients. The mean age at diagnosis was 58.0±11.3 years for males and 57.1±10.6 years for females, and the median follow-up time was 64 months (range, 5-262 months) for males and 71 months (range, 29-283 months) for females. Significant differences were identified for tumor location, hormone receptor status, adjuvant chemotherapy and hormone therapy between the two groups. Monofactorial analysis demonstrated that tumor size, lymph node status and AJCC stage were prognostic factors in MBC patients. The 5- and 10-year DFS rates were 61.2 and 40.7% for males, and 68.7 and 43.0% for females, respectively. The 5-and 10-year OS rates were 75.3 and 52.3% for males, and 82.9 and 63.2% for females, respectively. In our study, male breast carcinoma patients had a worse prognosis compared to female breast carcinoma patients which may be due to the deficiency of adjuvant chemotherapy and endocrine therapy.

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.

Progesterone and levonorgestrel regulate expression of 17βHSD-enzymes in progesterone receptor positive breast cancer cell line T47D

The use of combined hormone replacement therapy (HRT) with oestrogens and progestins in postmenopausal women has been associated with an increased risk for developing breast cancer. The reasons are not fully understood, but influence of HRT on endogenous conversion of female sex hormones may be involved. The expression of 17β hydroxysteroid dehydrogenases (17βHSD), which are enzymes catalysing the conversion between more or less potent oestrogens, may partly be regulated by progestins. The breast cancer cell lines T47D, MCF7 and ZR75-1 were treated with progesterone, medroxyprogesterone acetate (MPA) or levonorgestrel for 48 and 72 h at 10(-7) and 10(-9)M to investigate influence on 17βHSD1, 17βHSD2 and 17βHSD5 mRNA expression measured by real time PCR. The expression of 17βHSD1 increased in progesterone and levonorgestrel treated T47D cells (48 h 10(-7)M P=0.002; P<0.001) and 17βHSD5 increased after progesterone treatment (48 h 10(-7)M P=0.003), whereas the expression of 17βHSD2 decreased after the (48 h 10(-7)M P=0.003; P<0.001). Similar, but less prominent effects were seen in MCF7 and ZR75-1. The progestin effects on 17βHSD-expression were lost when T47D cells were co-treated with progestins and the progesterone receptor (PgR) inhibitor mifprestone. We show that both reductive (17βHSD1 and 17βHSD5) and oxidative (17βHSD2) members of the 17βHSD-family are under control of progesterone and progestins in breast cancer cell lines. This is most clear in T47D cells which have high PgR expression. 17βHSD-enzymes are important players in the regulation of sex steroids locally in breast tumours and tumoural expression of various 17βHSD-enzymes have prognostic and treatment predictive relevance. We propose a mechanism for increased breast cancer risk after HRT in which hormone replacement affects the expression of 17βHSD-enzymes, favouring the expression of reductive enzymes, which in turn could increase levels of bioactive and mitogenic estrogens in local tissue, e.g. breast tissue.

The growth response to androgen receptor signaling in ERα-negative human breast cells is dependent on p21 and mediated by MAPK activation

Introduction

Although a high frequency of androgen receptor (AR) expression in human breast cancers has been described, exploiting this knowledge for therapy has been challenging. This is in part because androgens can either inhibit or stimulate cell proliferation in pre-clinical models of breast cancer. In addition, many breast cancers co-express other steroid hormone receptors that can affect AR signaling, further obfuscating the effects of androgens on breast cancer cells.

Methods

To create better-defined models of AR signaling in human breast epithelial cells, we took estrogen receptor (ER)-α-negative and progesterone receptor (PR)-negative human breast epithelial cell lines, both cancerous and non-cancerous, and engineered them to express AR, thus allowing the unambiguous study of AR signaling. We cloned a full-length cDNA of human AR, and expressed this transgene in MCF-10A non-tumorigenic human breast epithelial cells and MDA-MB-231 human breast-cancer cells. We characterized the responses to AR ligand binding using various assays, and used isogenic MCF-10A p21 knock-out cell lines expressing AR to demonstrate the requirement for p21 in mediating the proliferative responses to AR signaling in human breast epithelial cells.

Results

We found that hyperactivation of the mitogen-activated protein kinase (MAPK) pathway from both AR and epidermal growth factor receptor (EGFR) signaling resulted in a growth-inhibitory response, whereas MAPK signaling from either AR or EGFR activation resulted in cellular proliferation. Additionally, p21 gene knock-out studies confirmed that AR signaling/activation of the MAPK pathway is dependent on p21.

Conclusions

These studies present a new model for the analysis of AR signaling in human breast epithelial cells lacking ERα/PR expression, providing an experimental system without the potential confounding effects of ERα/PR crosstalk. Using this system, we provide a mechanistic explanation for previous observations ascribing a dual role for AR signaling in human breast cancer cells. As previous reports have shown that approximately 40% of breast cancers can lack p21 expression, our data also identify potential new caveats for exploiting AR as a target for breast cancer therapy.

Estradiol and thermoregulation in adult endotoxemic rats exposed to lipopolysaccharide in neonatal life

AIMS

Early life immune challenge has been considered an adaptive defense strategy against potential pathogens when the innate immune system is not completely developed. This study assesses whether neonatal endotoxin challenge alters body temperature response in adult female rats during endotoxemic shock and also, whether ovarian hormones may participate in this response.

METHODS

Rats were intraperitoneally injected with lipopolysacharide (LPS) or saline at post-natal day 14, then as adults they were submitted to endotoxemic shock.

RESULTS

The LPS injection in adult neonatal Saline rats caused an initial hypothermia, followed by a febrile response. However, neonatal LPS showed an increased hypothermic response and an attenuation of fever. The bilateral ovariectomy abolished the difference in body temperature between the neonatal LPS and saline rats. To determine the dependence of ovarian hormones, ovariectomized rats treated with estradiol cypionate (ECP) restored hypothermia and the suppressed febrile response. However, the same results were not obtained when the animals were supplemented with ECP and medroxyprogesterone acetate (MPA). The neonatal LPS rats displayed a significant reduction in TNF-α levels and an increase in IL-10 levels when compared with saline animals. The ECP injection significantly enhanced IL-10 and suppressed TNF-α in neonatal LPS, but it did not change the inflammatory response in the saline rats. The ECP + MPA regiment in the neonatal LPS rats reduced TNF-α, but eliminated IL-10 stimulation in comparison with the saline group.

CONCLUSION

The present investigation shows that neonatal LPS challenge alters the thermoregulatory response during endotoxemic shock in adulthood and the mechanism for this difference could be mediated by sex hormones, especially estradiol.

Differential regulation of endogenous pro-inflammatory cytokine genes by medroxyprogesterone acetate and norethisterone acetate in cell lines of the female genital tract

BACKGROUND

Medroxyprogesterone acetate (MPA) and norethisterone (NET) and its derivatives are widely used in female reproductive therapy, but little is known about their mechanisms of action via steroid receptors in the female genital tract. MPA used as a contraceptive has been implicated in effects on local immune function. However, the relative effects of progesterone (Prog), MPA and norethisterone acetate (NET-A) on cytokine gene expression in the female genital tract are unknown.

STUDY DESIGN

Using two epithelial cell lines generated from normal human vaginal (Vk2/E6E7) and ectocervical (Ect1/E6E7) cells as in vitro cell culture model systems for mucosal immunity of the female cervicovaginal environment, we investigated steroid receptor expression and activity as well as regulation of cytokine/chemokine genes by MPA and NET-A, as compared to the endogenous hormone Prog.

RESULTS

We show that the Prog, androgen, glucocorticoid and estrogen receptors (PR, AR, GR and ER, respectively) are expressed in both the Vk2/E6E7 and Ect1/E6E7 cell lines, and that the GR and AR are transcriptionally active. This study is the first to show ligand-, promoter- and cell-specific regulation of IL-6, IL-8 and RANTES (regulated-upon-activation, normal T cell expressed and secreted) gene expression by Prog, MPA and NET-A in these cell lines. Moreover, we show that the repression of the TNF-α-induced RANTES gene by MPA in the Ect1/E6E7 cell line is mediated by the AR.

CONCLUSION

Collectively, these data demonstrate that cell lines from different anatomical sites of the female genital tract respond differently to Prog and the synthetic progestins, most likely due to differential actions via different steroid receptors. The results highlight the importance of choice of progestins for immune function in the cervicovaginal environment. They further suggest that choice of progestins in endocrine therapy may have implications for women's risk of susceptibility to infections due to differential actions on genes involved in inflammation and immune function.

Intestinal tumorigenesis is not affected by progesterone signaling in rodent models

Clinical data suggest that progestins have chemopreventive properties in the development of colorectal cancer. We set out to examine a potential protective effect of progestins and progesterone signaling on colon cancer development. In normal and neoplastic intestinal tissue, we found that the progesterone receptor (PR) is not expressed. Expression was confined to sporadic mesenchymal cells. To analyze the influence of systemic progesterone receptor signaling, we crossed mice that lacked the progesterone receptor (PRKO) to the Apc^Min/+ mouse, a model for spontaneous intestinal polyposis. PRKO-Apc^Min/+mice exhibited no change in polyp number, size or localization compared to Apc^Min/+. To examine effects of progestins on the intestinal epithelium that are independent of the PR, we treated mice with MPA. We found no effects of either progesterone or MPA on gross intestinal morphology or epithelial proliferation. Also, in rats treated with MPA, injection with the carcinogen azoxymethane did not result in a difference in the number or size of aberrant crypt foci, a surrogate end-point for adenoma development. We conclude that expression of the progesterone receptor is limited to cells in the intestinal mesenchyme. We did not observe any effect of progesterone receptor signaling or of progestin treatment in rodent models of intestinal tumorigenesis.

Molecular mechanisms of steroid receptor-mediated actions by synthetic progestins used in HRT and contraception

Synthetic progestins are used by millions of women as contraceptives and in hormone replacement therapy (HRT), although their molecular mechanisms of action are not well understood. The importance of investigating these mechanisms, as compared to those of progesterone, has been highlighted by clinical evidence showing that medroxyprogesterone acetate (MPA), a first generation progestin, increases the risk of breast cancer and coronary heart disease in HRT users. A diverse range of later generation progestins with varying structures and pharmacological properties is available for therapeutic use and it is becoming clear that different progestins elicit beneficial and adverse effects to different extents. These differences in biological activity are likely to be due to many factors including variations in dose, metabolism, pharmacokinetics, bioavailability, and regulation of, and/or binding, to serum-binding proteins and steroidogenic enzymes. Since the intracellular effects on gene expression and cell signaling of steroids are mediated via intracellular steroid receptors, differential actions via the progesterone and other steroid receptors and their isoforms, are likely to be the major cause of differential intracellular actions of progestins. Since many progestins bind not only to the progesterone receptor, but also to the glucocorticoid, androgen, mineralocorticoid, and possibly the estrogen receptors, it is plausible that synthetic progestins exert therapeutic actions as well as side-effects via some of these receptors. Here we review the molecular mechanisms of intracellular actions of old (MPA, norethisterone, levonorgestrel, gestodene) vs. new (drospirenone, dienogest, trimegestone) generation progestins, via steroid receptors.

QSAR models for anti-androgenic effect--a preliminary study

Three modelling systems (MultiCase®, LeadScope® and MDL® QSAR) were used for construction of androgenic receptor antagonist models. There were 923-942 chemicals in the training sets. The models were cross-validated (leave-groups-out) with concordances of 77-81%, specificity of 78-91% and sensitivity of 51-76%. The specificity was highest in the MultiCase® model and the sensitivity was highest in the MDL® QSAR model. A complementary use of the models may be a valuable tool when optimizing the prediction of chemicals for androgenic receptor antagonism. When evaluating the fitness of the model for a particular application, balance of training sets, domain definition, and cut-offs for prediction interpretation should also be taken into account. Different descriptors in the modelling systems are illustrated with hydroxyflutamide and dexamethasone as examples (a non-steroid and a steroid anti-androgen, respectively). More research concerning the mechanism of anti-androgens would increase the possibility for further optimization of the QSAR models. Further expansion of the basis for the models is in progress, including the addition of more drugs.

Mnemonic effects of progesterone to mice require formation of 3alpha,5alpha-THP

Ovarian hormones organize and activate neural circuits for reproduction and may also mediate cognition. Research has focused on estradiol's mnemonic effects, albeit progesterone covaries with estradiol and its mechanisms for cognition require attention. Studies tested the hypothesis that cognitive effects of progesterone occur subsequent to its metabolism to 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP), which does not bind progestin receptors. Cognitive performance and progestogen levels in plasma, hippocampus, and cortex were determined in ovariectomized mice administered vehicle, or progestins that differentially form 3alpha,5alpha-THP and bind progestin receptors (progesterone, 3alpha,5alpha-THP, and/or medroxyprogesterone acetate). Only treatments that increased 3alpha,5alpha-THP levels during memory consolidation (progesterone, 3alpha,5alpha-THP, 3alpha-5alpha-THP plus medroxyprogesterone acetate, but not progesterone plus medroxyprogesterone acetate) improved cognitive performance. Thus, formation of 3alpha,5alpha-THP may be required for progesterone's cognitive-enhancing effects.

Androgen receptor overexpression induces tamoxifen resistance in human breast cancer cells

Although the androgen receptor (AR) is a known clinical target in prostate cancer, little is known about its possible role in breast cancer. We have investigated the role of AR expression in human breast cancer in response to treatment with the antiestrogen tamoxifen. Resistance to tamoxifen is a major problem in treating women with breast cancer. By gene expression profiling, we found elevated AR and reduced estrogen receptor (ER) alpha mRNA in tamoxifen-resistant tumors. Exogenous overexpression of AR rendered ERalpha-positive MCF-7 breast cancer cells resistant to the growth-inhibitory effects of tamoxifen in anchorage-independent growth assays and in xenograft studies in athymic nude mice. AR-overexpressing cells remained sensitive to growth stimulation with dihydrotestosterone. Treatment with the AR antagonist Casodex (bicalutamide) reversed this resistance, demonstrating the involvement of AR signaling in tamoxifen resistance. In AR-overexpressing cells, tamoxifen induced transcriptional activation by ERalpha that could be blocked by Casodex, suggesting that AR overexpression enhances tamoxifen's agonistic properties. Our data suggest a role for AR overexpression as a novel mechanism of hormone resistance, so that AR may offer a new clinical therapeutic target in human breast cancers.

Curcumin inhibits MPA-induced secretion of VEGF from T47-D human breast cancer cells

OBJECTIVE

Recent clinical trials show that women who receive combined estrogen and progestin hormone therapy (HT) have a higher risk of breast cancer than women who receive estrogen alone or placebo. We have shown that progestins stimulate expression of vascular endothelial growth factor (VEGF), a potent angiogenic factor, in human breast cancer cells that express the progesterone receptors and mutant p53 protein. Because increased levels of VEGF promote tumor progression, compounds that prevent progestin-induced expression of VEGF could be clinically useful. The objective of this study was to examine whether the polyphenol compound curcumin has the capacity to block progestin-induced secretion of VEGF from T47-D human breast cancer cells.

DESIGN

The estrogen and progesterone receptor containing T47-D human breast cancer cells was exposed to 10 nM progesterone or synthetic progestins and varying concentrations of curcumin to determine whether curcumin blocks progestin-dependent production of VEGF from tumor cells.

RESULTS

Curcumin (0.001-10 microM for 18 h) reduced medroxyprogesterone acetate (MPA)-induced secretion of VEGF from T47-D cells in a dose-dependent manner. Secretion of VEGF from cells treated with progesterone or progestins other than MPA was unaffected by curcumin.

CONCLUSIONS

MPA is the most widely used progestin in HT. Curcumin may therefore provide a clinically useful tool for the suppression of MPA-induced elaboration of VEGF by tumor cells. We propose therefore that clinical trials to assess the beneficial effects of curcumin in postmenopausal women are warranted.

Male breast cancer: is the scenario changing

Background

The overall incidence of male breast cancer is around 1% of all breast cancers and is on the rise. In this review we aim to present various aspects of male breast cancer with particular emphasis on incidence, risk factors, patho-physiology, treatment, prognostic factors, and outcome.

Methods

Information on all aspects of male breast cancer was gathered from available relevant literature on male breast cancer from the MEDLINE database over the past 32 years from 1975 to 2007. Various reported studies were scrutinized for emerging evidence. Incidence data were also obtained from the IARC, Cancer Mondial database.

Conclusion

There is a scenario of rising incidence, particularly in urban US, Canada and UK. Even though more data on risk factors is emerging about this disease, more multi-institutional efforts to pool data with large randomized trials to show treatment and survival benefits are needed to support the existing vast emerging knowledge about the disease.

Antiproliferative actions of the synthetic androgen, mibolerone, in breast cancer cells are mediated by both androgen and progesterone receptors

Androgen signaling, mediated by the androgen receptor (AR), is a critical factor influencing growth of normal and malignant breast cells. Given the increasing use of exogenous androgens in women, a better understanding of androgen action in the breast is essential. This study compared the effects of 5alpha-dihydrotestosterone (DHT) and a synthetic androgen, mibolerone, on estradiol (E(2))-induced proliferation of breast cancer cells. DHT modestly inhibited E(2)-induced proliferation and mibolerone significantly inhibited proliferation in T-47D cells. The effects of both androgens could be reversed by an AR antagonist, suggesting that their actions were mediated, in part, by AR. Whereas high physiological doses (10-100nM) of DHT reduced E(2)-mediated induction of the estrogen-regulated gene progesterone receptor (PR) to basal levels, mibolerone at lower doses (1nM) eliminated PR expression, suggesting that mibolerone may also act via the PR. In the AR positive, PR-negative MCF-7 cells, mibolerone had modest effects on E(2)-induced proliferation, but was a potent inhibitor of proliferation in the AR positive, PR positive MCF-7M11 PRA cells. The effects of mibolerone in breast cancer cells were similar to those of the progestin, medroxyprogesterone acetate. Our results demonstrate that mibolerone can have both androgenic and progestagenic actions in breast cancer cells.

Disruption of androgen receptor signaling by synthetic progestins may increase risk of developing breast cancer

There is now considerable evidence that using a combination of synthetic progestins and estrogens in hormone replacement therapy (HRT) increases the risk of breast cancer compared with estrogen alone. Furthermore, the World Health Organization has recently cited combination contraceptives, which contain synthetic progestins, as potentially carcinogenic to humans, particularly for increased breast cancer risk. Given the above observations and the current trend toward progestin-only contraception, it is important that we have a comprehensive understanding of how progestins act in the millions of women worldwide who regularly take these medications. While synthetic progestins, such as medroxyprogesterone acetate (MPA), which are currently used in both HRT and oral contraceptives were designed to act exclusively through the progesterone receptor, it is clear from both clinical and experimental settings that their effects may be mediated, in part, by binding to the androgen receptor (AR). Disruption of androgen action by synthetic progestins may have serious deleterious side effects in the breast, where the balance between estrogen signaling and androgen signaling plays a critical role in breast homeostasis. Here, we review the role of androgen signaling in the normal breast and in breast cancer and present new data demonstrating that androgen receptor function can be perturbed by low doses of MPA, similar to doses achieved in serum of women taking HRT. We propose that the observed excess of breast malignancies associated with combined HRT may be explained, in part, by synthetic progestins such as MPA acting as endocrine disruptors to negate the protective effects of androgen signaling in the breast. Understanding the role of androgen signaling in the breast and how this is modulated by synthetic progestins is necessary to determine how combined HRT alters breast cancer risk, and to inform the development of optimal preventive and treatment strategies for this disease.

The effects of sex steroid hormones and interleukin-1-beta on MUC1 expression in endometrial epithelial cell lines

Oestrogen, progesterone and paracrine signals from the embryo have been associated with the overall control of implantation. Changes in the expression of the heavily glycosylated transmembrane glycoprotein MUC1 mucin on the endometrial epithelium are also thought to be important for embryo attachment. Increased MUC1 expression has been correlated with elevated progesterone levels in the secretory phase of the menstrual cycle. Embryonic control of endometrial receptivity through changes in MUC1 expression could be achieved through the interleukin-1 system. Four endometrial epithelial cell lines (HEC1A, HEC1B, Ishikawa and RL592) were treated with oestrogen and progesterone (with or without interleukin-1-beta) and were subjected to immunocytochemistry and flow cytometric analysis to determine MUC1 production using MUC1 antibodies. HEC1A (oestrogen receptor (ER) and progesterone receptor (PR) positive) and HEC1B (ER positive and PR negative) were transfected with the MUC1 promoter, underwent similar treatment regimes and the activity of the MUC1 promoter relative to their untreated controls was determined using a chloramphenicol acetyltransferase (CAT) enzyme-linked immunoassay. Using the cell lines, we determined that endometrial MUC1 expression is up-regulated by progesterone, consistent with the in vivo increases in MUC1 related to high progesterone levels. We also revealed that neither oestrogen, nor interleukin-1-beta, appear to modulate MUC1. Progesterone-dependent regulation of MUC1 is likely to be an important factor in determining endometrial receptivity.

Reduced metabolites mediate neuroprotective effects of progesterone in the adult rat hippocampus. The synthetic progestin medroxyprogesterone acetate (Provera) is not neuroprotective

The ovarian hormone progesterone is neuroprotective in different experimental models of neurodegeneration. In the nervous system, progesterone is metabolized to 5alpha-dihydroprogesterone (DHP) by the enzyme 5alpha-reductase. DHP is subsequently reduced to 3alpha,5alpha-tetrahydroprogesterone (THP) by a reversible reaction catalyzed by the enzyme 3alpha-hydroxysteroid dehydrogenase. In this study we have analyzed whether progesterone metabolism is involved in the neuroprotective effect of the hormone in the hilus of the hippocampus of ovariectomized rats injected with kainic acid, an experimental model of excitotoxic cell death. Progesterone increased the levels of DHP and THP in plasma and hippocampus and prevented kainic-acid-induced neuronal loss. In contrast to progesterone, the synthetic progestin medroxyprogesterone acetate (MPA, Provera) did not increase DHP and THP levels and did not prevent kainic-acid-induced neuronal loss. The administration of the 5alpha-reductase inhibitor finasteride prevented the increase in the levels of DHP and THP in plasma and hippocampus as a result of progesterone administration and abolished the neuroprotective effect of progesterone. Both DHP and THP were neuroprotective against kainic acid. However, the administration of indomethacin, a 3alpha-hydroxysteroid dehydrogenase inhibitor, blocked the neuroprotective effect of both DHP and THP, suggesting that both metabolites are necessary for the neuroprotective effect of progesterone. In conclusion, our findings indicate that progesterone is neuroprotective against kainic acid excitotoxicity in vivo while the synthetic progestin MPA is not and suggest that progesterone metabolism to its reduced derivatives DHP and THP is necessary for the neuroprotective effect of the hormone.

Effects of long-term hormone treatment and of tibolone on monoamines and monoamine metabolites in the brains of ovariectomised, Cynomologous monkeys

The effects of long-term hormone treatment on monoamines and monoamine metabolites in different regions of the primate brain were examined and compared. Ovariectomised Cynomologous monkeys received daily oral administration of either conjugated equine oestrogens (CEE), CEE + medroxyprogesterone acetate (MPA), or a low or high dose of tibolone, for a period of 2 years. Tissue punches collected from frozen sections through various regions of the forebrain, midbrain, and hindbrain were assayed for levels of dopamine, dihydroxyphenylacetic acid (DOPAC), serotonin, 5-hydroxyindole acetic acid (5-HIAA), and norepinephrine by high-performance liquid chromatography. Few differences between hormone-treated animals and ovariectomised controls were observed. No statistically significant effects of CEE relative to controls were detected in any of the seven brain regions analysed. Animals treated with CEE + MPA showed significant reductions in 5-HIAA in the dorsal raphe nucleus, a significant reduction in dopamine in the hypothalamus, and a significant reduction in serotonin (5-HT) levels in area 8AD of the frontal cortex. Similar to CEE, no significant effects of tibolone relative to controls were detected; however, animals treated with high-dose tibolone showed a decrease in 5-HT levels in the frontal cortex that approached significance and was similar to the effect of CEE + MPA. Collectively, the findings suggest that long-term oral administration of these compounds has relatively few effects on the levels of dopamine, serotonin, and their primary metabolites in the primate brain. This differs from the significant effects on serotonergic and dopaminergic systems detected following parenteral treatment with oestradiol and progesterone, and likely reflects differences between the effects of treating with CEE + MPA versus oestradiol and progesterone on brain monoaminergic systems.