Synergistic control of sex hormones by 17β-HSD type 7: a novel target for estrogen-dependent breast cancer

Synthesis and characterization of targeted 17β-hydroxysteroid dehydrogenase type 7 inhibitors

Sex steroid hormones such as estrogen estradiol (E2) and androgen dihydrotestosterone (DHT) are involved in the development of hormone-dependent cancers. Blockade of 17β-hydroxysteroid dehydrogenase type 7 (17β-HSD7), a member of the short chain dehydrogenase/reductase superfamily, is thought to decrease E2 levels while increasing those of DHT. Therefore, its unique double action makes this enzyme as an interesting drug target for treatment of breast cancer. The chemical synthesis, molecular characterization, and preliminary biological evaluation as 17β-HSD7 inhibitors of novel carbamate derivatives 3 and 4 are described. Like previous 17β-HSD7 inhibitors 1 and 2, compounds 3 and 4 bear a hydrophobic nonyl side chain at the C-17β position of a 4-aza-5α-androstane nucleus, but compound 3 has an oxygen atom replacing the CH2 in the steroid A-ring C-2 position, while compound 4 has a C17-spiranic E-ring containing a carbamate function. They both inhibited the in vitro transformation of estrone (E1) into E2 by 17β-HSD7, but the introduction of a (17 R)-spirocarbamate is preferable to replacing C-2 methylene with an oxygen atom since compound 4 (IC50 = 63 nM) is an inhibitor 14 times more powerful than compound 3 (IC50 = 900 nM). Furthermore, when compared to the reference inhibitor 1 (IC50 = 111 nM), the use of a C17-spiranic E-ring made it possible to introduce differently the hydrophobic nonyl side chain, without reducing the inhibitory activity.

Computational prediction and analysis of targeting 17-beta-hydroxysteroid dehydrogenase (17-beta-HSD1) with natural products for colorectal cancer treatment

Colorectal cancer (CRC) is a type of cancer that occurs in the colon or rectum and kills millions of people each year. Steroid hormones are interconverted between their potent, high-affinity forms by using 17-beta hydroxysteroid dehydrogenase for their respective receptors in these tissues, with a high probability of random genetic errors. Currently, 17-beta-HSD1 studies have revealed the role of steroid metabolism in the development and proliferation of colorectal cancer. However, there is little information on how to target this enzyme with either modern medicine or natural products. In this study, we looked at 17-beta-HSD1 as a target for treating CRC development and proliferation using selected plant metabolites from previous studies. Plants are used to produce medicinal and novel bioactive compounds that are used to treat different infection. They primarily demonstrated anti-cancer effects through the regulation of cancer-related proteins, epigenetic factors and reactive oxygenase species. The study utilized Avogadro, ADMET lab 2.0, SWISS-MODEL, AutoDock, and Gromacs. Five lead molecules were chosen from a pool of plant metabolites based on their affinity for the 17-beta-HSD1 enzyme. Furthermore, two bind with high affinity are resveratrol (DG 11.29 kcal/mol) and folate (DG 12.23 kcal/mol) with low Ki values, while the rest binds with moderate affinity. Molecular dynamic simulation results also revealed that the folate-17-beta-HSD complex and reserverol- 17-beta-HSD1 complex maintained a stable conformation until the end of 100 ns. As a result, reserverol and folate could be used as lead molecules to target 17-beta-HSD1 and provide a promising starting point for further in vivo research.Communicated by Ramaswamy H. Sarma.

Targeting macrophagic 17β-HSD7 by fenretinide for the treatment of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide and macrophage polarization plays an important role in its pathogenesis. However, which molecule regulates macrophage polarization in NAFLD remains unclear. Herein, we showed NAFLD mice exhibited increased 17β-hydroxysteroid dehydrogenase type 7 (17β-HSD7) expression in hepatic macrophages concomitantly with elevated M1 polarization. Single-cell RNA sequencing on hepatic non-parenchymal cells isolated from wild-type littermates and macrophage-17β-HSD7 knockout mice fed with high fat diet (HFD) for 6 weeks revealed that lipid metabolism pathways were notably changed. Furthermore, 17β-HSD7 deficiency in macrophages attenuated HFD-induced hepatic steatosis, insulin resistance and liver injury. Mechanistically, 17β-HSD7 triggered NLRP3 inflammasome activation by increasing free cholesterol content, thereby promoting M1 polarization of macrophages and the secretion of pro-inflammatory cytokines. In addition, to help demonstrate that 17β-HSD7 is a potential drug target for NAFLD, fenretinide was screened out from an FDA-approved drug library based on its 17β-HSD7 dehydrogenase inhibitory activity. Fenretinide dose-dependently abrogated macrophage polarization and pro-inflammatory cytokines production, and subsequently inhibited fat deposition in hepatocytes co-cultured with macrophages. In conclusion, our findings suggest that blockade of 17β-HSD7 signaling by fenretinide would be a drug repurposing strategy for NAFLD treatment.

An unprecedented endocrine target for ovarian cancer: inhibiting 17β-HSD7 supresses cancer cell proliferation and arrests G2/M cycle

Epithelial ovarian cancer, widely suggested as endocrine-related cancer, yields a low survival rate among patients. Despite intensive research for nearly a century, there have been no fundamental advances in treatment. The reductive 17β-HSD7 is a special enzyme possessing a remarkable dual activity in both the biosynthesis of the most potent estrogen estradiol and the inactivation of the most active androgen dihydrotestosterone. In the present study, we observed over-expression of 17β-HSD7 in EOC cells such as OVCAR-3 and SKOV-3, in agreement with integrative data analysis demonstrating overexpression of 17β-HSD7 in EOC tissues. After knocking down 17β-HSD7, SKOV-3 cell proliferation decreased by 29%, cell arrest in the G2/M phase increased by 25% with cyclin B1/Cdk1 inhibition. Inhibition of 17β-HSD7 in EOC cells triggered negative feedback of its expression, which further decreased the estradiol level to more than 60% under the experimental condition. Such inhibition increased the dihydrotestosterone level to many times higher and suppressed cell proliferation. Thus, 17β-HSD7 is demonstrated to be a promising target for the endeavor against the malignant ovarian cancer, a menace in human life. The targeting of such an enzyme thus provides exceptional scientific importance.

The multi-specific human 17 beta-hydroxysteroid dehydrogenase type 7: Non-competitive inhibitors can target different catalyses to facilitate breast cancer treatment

Human 17β-hydroxysteroid dehydrogenase type 7 (17β-HSD7), a special multifunctional enzyme, activates the estrogen estrone while inactivating the potent androgen dihydrotestosterone. Thus, this enzyme has become an ideal target for hormone-dependent breast cancer treatment, as its inhibition leads to estradiol reduction and dihydrotestosterone restoration. However, a particular concern has arisen related to an additional role in cholesterol biosynthesis, as inhibition of the enzyme may lead to undesirable side effects. Our findings demonstrate that the available enzyme inhibitors are non-competitive. Among these, many such as INH81, are specific toward sex-hormone conversion, whereas others represented by 4-bromo-ethynylestradiol, are more specific for zymosterone reduction occurring during cholesterol biosynthesis. The binding of non-competitive inhibitors does not affect the substrate binding on the enzyme. This is the first demonstration of non-competitive inhibitors acting selectively on different catalyses, thereby facilitating inhibitor uses for breast cancer treatment. We aim to quickly communicate the novel results.

Antiproliferative and antimetastatic characterization of an exo-heterocyclic androstane derivative against human breast cancer cell lines

Cancer in general, and specifically gynaecological neoplasms, represents a major public health issue worldwide. Based on the effect of sex hormones on breast tumorigenesis and prognosis, as well as on the development of breast cancer metastases, modification of the steroid skeleton is a hotspot of research for novel anticancer agents. Numerous recent studies support that minor modifications of the androstane skeleton yield potent antiproliferative and antimetastatic drug candidates. The aim of the present study was to assess the antitumor and antimetastatic properties, as well as the mechanism of action of a D-ring-modified exo-heterocyclic androstadiene derivative named 17APAD. The test compound was found to be highly selective towards human breast cancer-derived cell lines (MCF-7, T47D, MDA-MB-361, MDA-MB-231) compared to non-cancerous fibroblast cells (NIH/3T3), and exerted superior effect compared to the clinically applied reference drug cisplatin. Changes in MCF-7- and MDA-MB-231 cell morphology and membrane integrity induced by the test substance were assessed by fluorescent double staining. Cell cycle disturbances were analyzed by flow cytometry, and concentration-dependent alterations were detected on breast cancer cell lines. Mitochondrial apoptosis induced by the test compound was demonstrated by JC-1 staining. Inhibitory effects on metastasis formation, including the inhibition of migration, invasion and intravasation were investigated in 2D and 3D models. Significant anti-migratory and anti-invasive effects on MCF-7 and MDA-MB-231 cells were detected after 24 h exposure in 2D wound healing and Boyden-chamber assays. The anti-intravasative properties of 17APAD were evident after 4 h of incubation in a co-culture 3D circular chemorepellent-induced defects (CCID) assay, and the level of inhibition at concentrations ≥2 µM was comparable to that exerted by the focal adhesion kinase inhibitor defactinib. Single cell mass cytometry revealed that chemosensitive subpopulations of MDA-MB-231 cells engaged to apoptosis were less positive for EGFR, CD274, and CD326, while the percentage of cells positive for GLUT1, MCT4, Pan-Keratin, CD66(a,c,e), Galectin-3 and TMEM45A increased in response to 17APAD treatment. Finally, the novel androstane analogue 17APAD had an outstanding inhibitory effect on tumour growth in the 4T1 orthotopic murine breast cancer model in vivo after 2 weeks of intraperitoneal administration. These findings support that substitution of the androsta-5,16-diene framework with a N-containing heterocyclic moiety at C17 position yields a molecular entity rational to be considered for design and synthesis of novel, effective antitumor agents, and 17APAD is worth further investigation as a promising anticancer drug candidate.

Steroid enzyme and receptor expression and regulations in breast tumor samples - A statistical evaluation of public data

In spite of the significant progress of estrogen-dependent breast cancer (BC) treatment, aromatase inhibitor resistance is a major problem limiting the clinical benefit of this frontier endocrine-therapy. The aim of this study was to determine the differential expression of steroid-converting enzymes between tumor and adjacent normal tissues, as well as their correlation in modulating intratumoral steroid-hormone levels in post-menopausal estrogen-dependent BC. RNA sequencing dataset (n = 1097) of The-Cancer-Genome-Atlas (Breast Invasive Carcinoma) retrieved through the data portal of Genomic Data Commons was used for differential expressions and expression correlation analyses by Mann-Whitney U and Spearman's rank test, respectively. The results showed significant up-regulation of 17β-HSD7 (2.50-fold, p < 0.0001) in BC, supporting its effect in sex-hormone control. Besides, suppression of 11β-HSD1 expression (-8.29-fold, p < 0.0001) and elevation of 11β-HSD2 expression (2.04-fold, p < 0.0001) provide a low glucocorticoid environment diminishing BC anti-proliferation. Furthermore, 3α-HSDs were down-regulated (-1.59-fold, p < 0.01; -8.18-fold, p < 0.0001; -33.96-fold, p < 0.0001; -31.85-fold, p < 0.0001 for type 1-4, respectively), while 5α-reductases were up-regulated (1.41-fold, p < 0.0001; 2.85-fold, p < 0.0001; 1.70-fold, p < 0.0001 for type 1-3, respectively) in BC, reducing cell proliferation suppressers 4-pregnenes, increasing cell proliferation stimulators 5α-pregnanes. Expression analysis indicates significant correlations between 11β-HSD1 with 3α-HSD4 (r = 0.605, p < 0.0001) and 3α-HSD3 (r = 0.537, p < 0.0001). Significant expression correlations between 3α-HSDs were also observed. Our results systematically present the regulation of steroid-converting enzymes and their roles in modulating the intratumoral steroid-hormone levels in BC with a vivid 3D-schema, supporting novel therapy targeting the reductive 17β-HSD7 and proposing a new combined therapy targeting 11β-HSD2 and 17β-HSD7.

Comparison of the roles of estrogens and androgens in breast cancer and prostate cancer

Breast cancer (BC) and prostate cancer (PC) are the second most common malignant tumors in women and men in western countries, respectively. The risks of death are 14% for BC and 9% for PC. Abnormal estrogen and androgen levels are related to carcinogenesis of the breast and prostate. Estradiol stimulates cancer development in BC. The effect of estrogen on PC is concentration-dependent, and estrogen can regulate androgen production, further affecting PC. Estrogen can also increase the risk of androgen-induced PC. Androgen has dual effects on BC via different metabolic pathways, and the role of the androgen receptor (AR) in BC also depends on cell subtype and downstream target genes. Androgen and AR can stimulate both primary PC and castration-resistant PC. Understanding the mechanisms of the effects of estrogen and androgen on BC and PC may help us to improve curative BC and PC treatment strategies.

Mutual regulations and breast cancer cell control by steroidogenic enzymes: Dual sex-hormone receptor modulation upon 17β-HSD7 inhibition

Reductive 17β-hydroxysteroid dehydrogenases (17β-HSDs) and 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2) play crucial roles in respectively regulating steroids and glucocorticoids for the progression of hormone-dependent breast cancer. Most studies focused on the function and individual regulation of these enzymes. However, mutual regulation of these enzymes and the induced modulation on the estrogen and androgen receptors for breast cancer promotion are not yet clear. In this study, MCF-7 and T47D cells were treated with inhibitors of 17β-HSD1, 17β-HSD7, aromatase or steroid sulfatase (STS), then mRNA levels of 17β-HSD7, STS, 11β-HSD 2, estrogen receptors α (ERα) and androgen receptor (AR) were determined by Q-PCR. ER negative cell line MDA-MB-231 was used as a negative control. Our results demonstrate that 17β-HSD7, STS and 11β-HSD2 are all regulated by the same estrogen estradiol via ERα. When the gene of ERα (ESR1) was knocked down, there was no longer significant mutual regulation of these enzymes. Our results demonstrate that important steroidogenic enzymes transcriptionally regulated by ERα, can be mutually closely correlated. Inhibition of one of them can reduce the expression of another, thereby amplifying the role of the inhibition. Furthermore, inhibition of 17β-HSD7 increases the expression of AR gene which is considered as a marker for better prognosis in ER + breast cancer, while maintaining ERα level. Thus, our mechanistic finding provides a base for further improving the endocrine therapy of ER + breast cancer, e.g., for selecting the target steroid enzymes, and for the combined targeting of human 17β-HSD7 and ERα.

The role of 17βHSDs in breast tissue and breast cancers

The family of seventeen beta hydroxysteroid dehydrogenase enzymes has a long and diverse history in breast and breast cancer research. Given the known dependence of the breast on steroid signalling and intracrine steroid metabolism these enzymes are considered to be essential local fine tuners of overall steroid balance in the tissue. This review will cover the current state of knowledge regarding the expression, clinical effect and biological regulation of enzymes in both cancerous and normal states. In addition we will also cover the current state of knowledge regarding 17βHSD actions in the often neglected adipose and stromal components of tumours.

The dual sex hormone specificity for human reductive 17β-hydroxysteroid dehydrogenase type 7: Synergistic function in estrogen and androgen control

Human 17β-hydroxysteroid dehydrogenase (17β-HSD) type 1 and 7 catalyze the final step of estrogen activation and the first step in androgen inactivation. It has been shown in breast cancer cells that DHT has a suppression effect on cell proliferation, counteracting the estrogen growth effect. However, the exact kinetic function of 17β-HSD7 in steroidogenesis was not determined. Here we report the steady-state kinetics and binding study for 17β-HSD7 with estrone or DHT as substrates and NADPH as cofactor. 17β-HSD7 has been overexpressed in E. coli and purified. For both substrates, kinetics of 17β-HSD7 demonstrates positive cooperativity. The K_0.5 value is 5.2 ± 0.4 μM and 14.4 ± 0.8 μM and the k_cat is 0.0063 ± 0.0003 s^-1 and 0.0153 ± 0.0007 s^-1 for the reduction of E1 and DHT, respectively. The binding study shows a similar affinity with a dissociation constant of 5.2 ± 0.5 μM and 11 ± 1 μM for E1 and DHT, respectively. Our kinetic and binding results reveal a positive cooperativity for 17β-HSD7 to both the E1 and DHT with a similar affinity, while 17β-HSD1 demonstrated a significantly higher affinity toward E1 than DHT, but with a strong E1 substrate inhibition. These results strongly support that the inhibition of 17β-HSD7 constitutes the basis of breast cancer cell proliferation decreasing that led to the shrinkage of xenograft ER + breast tumor mice model.

Steroid sulfatase inhibition success and limitation in breast cancer clinical assays: An underlying mechanism

Steroid sulfatase is detectable in most hormone-dependent breast cancers. STX64, an STS inhibitor, induced tumor reduction in animal assay. Despite success in phase І clinical trial, the results of phase II trial were not that significant. Breast Cancer epithelial cells (MCF-7 and T47D) were treated with two STS inhibitors (STX64 and EM1913). Cell proliferation, cell cycle, and the concentrations of estradiol and 5α-dihydrotestosterone were measured to determine the endocrinological mechanism of sulfatase inhibition. Comparisons were made with inhibitions of reductive 17β-hydroxysteroid dehydrogenases (17β-HSDs). Proliferation studies showed that DNA synthesis in cancer cells was modestly decreased (approximately 20%), accompanied by an up to 6.5% in cells in the G0/G1 phase and cyclin D1 expression reduction. The concentrations of estradiol and 5α-dihydrotestosterone were decreased by 26% and 3% respectively. However, supplementation of 5α-dihydrotestosterone produced a significant increase (approximately 35.6%) in the anti-proliferative effect of sulfatase inhibition. This study has clarified sex-hormone control by sulfatase in BC, suggesting that the different roles of estradiol and 5α-dihydrotestosterone can lead to a reduction in the effect of sulfatase inhibition when compared with 17β-HSD7 inhibition. This suggests that combined treatment of sulfatase inhibitors with 17β-HSD inhibitors such as the type7 inhibitor could hold promise for hormone-dependent breast cancer.

Deficiency of Gpr1 improves steroid hormone abnormality in hyperandrogenized mice

BACKGROUND

Polycystic ovary syndrome (PCOS) is a complex genetic disease with multifarious phenotypes. Many researches use dehydroepiandrosterone (DHEA) to induce PCOS in pubertal mouse models. The aim of this study was to investigate the role of GPR1 in dehydroepiandrosterone (DHEA)-induced hyperandrogenized mice.

METHODS

Prepubertal C57BL/6 mice (25 days of age) and Gpr1-deficient mice were each divided into two groups and injected daily with sesame oil with or without DHEA (6 mg/100 g) for 21 consecutive days. Hematoxylin and eosin (H&E) staining was performed to determine the characteristics of the DHEA-treated ovaries. Real-time PCR was used to examine steroid synthesis enzymes gene expression. Granulosa cell was cultured to explore the mechanism of DHEA-induced, GPR1-mediated estradiol secretion.

RESULTS

DHEA treatment induced some aspects of PCOS in wild-type mice, such as increased body weight, elevated serum testosterone, increased number of small, cystic, atretic follicles, and absence of corpus luteum in ovaries. However, Gpr1 deficiency significantly attenuated the DHEA-induced weight gain and ovarian phenotype, improving steroidogenesis in ovaries and estradiol synthesis in cultured granulosa cells, partially through mTOR signaling.

CONCLUSIONS

In conclusion, Gpr1 deficiency leads to the improvement of steroid synthesis in mice hyperandrogenized with DHEA, indicating that GPR1 may be a therapeutic target for DHEA-induced hyperandrogenism.

Estrogen Activation by Steroid Sulfatase Increases Colorectal Cancer Proliferation via GPER

CONTEXT

Estrogens affect the incidence and progression of colorectal cancer (CRC), although the precise molecular mechanisms remain ill-defined.

OBJECTIVE

The present study investigated prereceptor estrogen metabolism through steroid sulphatase (STS) and 17β-hydroxysteroid dehydrogenase activity and subsequent nongenomic estrogen signaling in human CRC tissue, in The Cancer Genome Atlas colon adenocarcinoma data set, and in in vitro and in vivo CRC models. We aimed to define and therapeutically target pathways through which estrogens alter CRC proliferation and progression.

DESIGN, SETTING, PATIENTS, AND INTERVENTIONS

Human CRC samples with normal tissue-matched controls were collected from postmenopausal female and age-matched male patients. Estrogen metabolism enzymes and nongenomic downstream signaling pathways were determined. CRC cell lines were transfected with STS and cultured for in vitro and in vivo analysis. Estrogen metabolism was determined using an ultra-performance liquid chromatography-tandem mass spectrometry method.

PRIMARY OUTCOME MEASURE

The proliferative effects of estrogen metabolism were evaluated using 5-bromo-2'-deoxyuridine assays and CRC mouse xenograft studies.

RESULTS

Human CRC exhibits dysregulated estrogen metabolism, favoring estradiol synthesis. The activity of STS, the fundamental enzyme that activates conjugated estrogens, is significantly (P < 0.001) elevated in human CRC compared with matched controls. STS overexpression accelerates CRC proliferation in in vitro and in vivo models, with STS inhibition an effective treatment. We defined a G-protein-coupled estrogen receptor (GPER) proproliferative pathway potentially through increased expression of connective tissue growth factor in CRC.

CONCLUSION

Human CRC favors estradiol synthesis to augment proliferation via GPER stimulation. Further research is required regarding whether estrogen replacement therapy should be used with caution in patients at high risk of developing CRC.

Substrate inhibition of 17β-HSD1 in living cells and regulation of 17β-HSD7 by 17β-HSD1 knockdown

This study addresses first the role of human 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1) in breast cancer (BC) cells. The enzyme has a high estrone-activating activity that is subject to strong substrate inhibition as shown by enzyme kinetics at the molecular level. We used BC cells to verify this phenomenon in living cells: estrone concentration increase did reduce the reaction with 0.025 to 4μM substrate. Moreover, 5α-dihydrotestosterone (DHT) demonstrated some inhibition of estrogen activation at both the molecular and cellular levels. The presence of DHT did not change the tendency toward substrate inhibition for estrone conversion, but shifted the inhibition toward higher substrate concentrations. Moreover, a binding study demonstrated that both DHT and dehydroepiandrosterone (DHEA) can be bound to the enzyme, thereby supporting the multi-specificity of 17β-HSD1. We then followed the concentrations of estradiol and performed q-RT-PCR measurements of reductive 17β-HSDs after 17β-HSD1 inhibition. The estradiol decrease by the 17β-HSD1 inhibition was demonstrated lending support to this observation. Knockdown and inhibition of 17β-HSD1 produced reduction in estradiol levels and the down-regulation of another reductive enzyme 17β-HSD7, thus "amplifying" the reduction of estradiol by the 17β-HSD1 modulation itself. The critical positioning of 17β-HSD7 in sex-hormone-regulation as well as the mutual regulation of steroid enzymes via estradiol in BC, are clearly demonstrated. Our study demonstrates that fundamental enzymological mechanisms are relevant in living cells. Moreover, further enzyme study in cells is merited to advance biological and medical research. We also demonstrated the central role of 17β-HSD7 in sex-hormone conversion and regulation, supporting it as a novel target for estrogen-dependent (ER+) BC.

Inhibition of 17beta-hydroxysteroid dehydrogenase type 7 modulates breast cancer protein profile and enhances apoptosis by down-regulating GRP78

17beta-hydroxysteroid dehydrogenase type 7 (17β-HSD7) promotes breast cancer cell growth via dual-catalytic activity by modulating estradiol and DHT. Here, we clarified the expression pattern of 17β-HSD7 in postmenopausal luminal A type breast cancer with The Cancer Genome Atlas (TCGA) cohort. The impact of 17β-HSD7 inhibition on the proteome of MCF-7 cells was investigated and on cell apoptosis was revealed. MCF-7 cells were treated with an efficient inhibitor of 17β-HSD7 (INH7) or with vehicle, and a differential proteomics study was performed using two-dimensional (2D) gel electrophoresis followed by mass spectrometry and ingenuity pathway analysis (IPA). Cell apoptosis was analyzed by flow cytometry, followed by reverse transcription quantitative real-time PCR (RT-qPCR) and Western blot to investigate the expression of apoptosis-related genes. Our data showed 17β-HSD7 is amplified in primary and progressive breast cancer, inhibition of 17β-HSD7 in MCF-7 cells modulated 104 proteins primarily involved in cell death/survival, cell growth and DNA processing. The expression of 78kDa glucose-regulated protein (GRP78) and anti-apoptosis factor Bcl-2 were significantly suppressed via 17β-HSD7 inhibition with INH7, consequently induced MCF-7 cell apoptosis. However, INH7 treatment of T47D, another widely used epithelial ER+ breast cancer cell line, led to an up-regulation of GRP78 expression, resulting in a limited increase in apoptosis. These results suggest cell-specific effects of INH7 in the breast cancer, which is interesting for further study. An combinatory effect on apoptosis by INH7 and Letrozole (aromatase inhibitor) was further demonstrated in MCF-7. Down-regulation of GRP78 via 17β-HSD7 inhibition enhances cell apoptosis in response to Letrozole. This study highlights GRP78 as a key regulator related to 17β-HSD7 inhibition and effect. Taken together, results from the present study suggest a hypothesis that inhibition of 17β-HSD7 would be a complementary strategy to Letrozole by suppression of GRP78 in ER+ breast cancer. However, from a research perspective, further studies have to be carried out with more breast cancer cell lines as well as in vivo model to assess the efficacy of inhibitor combination.

MiR-203 inhibits estrogen-induced viability, migration and invasion of estrogen receptor α-positive breast cancer cells

Breast cancer is common in females, and accounts for a large proportion of cancer-related cases of mortality. MicroRNAs (miRs) have been found to be involved in the progression of breast cancer via mediation of tumor suppressor genes or oncogenes. Previously, miR-203 has been reported to play a suppressive role in breast cancer. In the present study, the effects of miR-203 on the malignant phenotypes of estrogen receptor α (ERα)-positive breast cancer cells were investigated. It was found that treatment with estradiol (E2) significantly enhanced the viability, migration and invasion of ERα-positive breast cancer MCF-7 cells, accompanied by the significant downregulation of miR-203 in a dose-dependent manner. Furthermore, MCF-7 cells were transfected with miR-203 mimics, resulting in a significant increase in miR-203 levels. Upregulation of miR-203 was found to significantly inhibit E2-induced upregulation of MCF-7 cell viability, migration and invasion. Upregulation of miR-203 also led to a significant decrease in the protein expression of ERα in MCF-7 cells. Using a luciferase reporter assay, ERα was identified as a direct target of miR-203 in MCF-7 cells. Finally, it was demonstrated that miR-203 was significantly downregulated in ERα-positive breast cancer tissues compared to their matched normal adjacent tissues. The expression levels of miR-203 were inversely correlated to the ERα levels in ERα-positive breast cancer tissues. Based on these results, it is proposed that miR-203 inhibits E2-induced viability, migration and invasion of ERα-positive breast cancer cells, and that this may be via direct targeting of ERα. Therefore, the present study highlights the importance of miR-203 and ERα in breast cancer progression.

Increased levels of enzymes involved in local estradiol synthesis in chronic obstructive pulmonary disease

INTRODUCTION

Steroid hormones are involved in lung development, pulmonary inflammation, and lung cancer. Estrogen signaling and exposure may play a role in pulmonary disorders, including COPD. In both genders, estrogens can be generated locally in the lungs and this contributes importantly to the tissue exposure to these steroids.

OBJECTIVE

To characterize and assess differences in localization of estrogen receptors and enzymes involved in the local generation of estrogens in COPD.

METHODS

Estrogen Receptor alpha (ERα/ESR1), Estrogen Receptor beta (ERβ/ESR2) and G-protein-coupled estrogen receptor 1 (GPER) were explored by real-time (RT)-PCR analysis (mRNA expression), immunohistochemistry and western blotting in controls and COPD patients. mRNA expression of the enzymes involved in the local estrogen generation - i.e. aromatase (CYP19A1), 17beta-hydroxysteroid dehydrogenases (17β-HSDs) 1, 2, 4, 5, 7 and 12, steroid sulfatase (STS) and sulfotransferase (SULT1E1) - were analyzed by RT-PCR.

RESULTS

ERα, ERβ and GPER were expressed in lung tissue, but no differences were observed between patients and controls. The main enzymes involved in local estrogen generation were also present in both normal and COPD lung tissue. In lungs of COPD patients compared with controls, we observed increased expression of the enzymes 17β-HSD type 1 and aromatase (positive association), both involved in the local synthesis of active estrogens.

CONCLUSION

All ER subtypes are present in the lung. The shift in local mRNA level of estrogen metabolic enzymes suggests that exposure to estrogens is involved in the pathogenesis of COPD.

Androgen-metabolizing enzymes: A structural perspective

Androgen-metabolizing enzymes convert cholesterol, a relatively inert molecule, into some of the most potent chemical messengers in vertebrates. This conversion involves thermodynamically challenging reactions catalyzed by P450 enzymes and redox reactions catalyzed by Aldo-Keto Reductases (AKRs). This review covers the structures of these enzymes with a focus on active site interactions and proposed mechanisms. Due to their role in a number of diseases, particularly in cancer, androgen-metabolizing enzymes have been targets of drug design. Hence we will also highlight how existing knowledge of structure is being used to this end.

Steroid sulfatase activity in subcutaneous and visceral adipose tissue: a comparison between pre- and postmenopausal women

OBJECTIVE

Adipose tissue is an important extragonadal site for steroid hormone biosynthesis. After menopause, estrogens are synthesized exclusively in peripheral tissues from circulating steroid precursors, of which the most abundant is dehydroepiandrosterone sulfate (DHEAS). Our aim was to study activity of steroid sulfatase, an enzyme hydrolyzing DHEAS, and expression of steroid-converting enzyme genes in subcutaneous and visceral adipose tissue derived from pre- and postmenopausal women.

DESIGN

Serum and paired abdominal subcutaneous and visceral adipose tissue samples were obtained from 18 premenopausal and seven postmenopausal women undergoing elective surgery for non-malignant reasons in Helsinki University Central Hospital.

METHODS

To assess steroid sulfatase activity, radiolabeled DHEAS was incubated in the presence of adipose tissue homogenate and the liberated dehydroepiandrosterone (DHEA) was measured. Gene mRNA expressions were analyzed by quantitative RT-PCR. Serum DHEAS, DHEA, and estrogen concentrations were determined by liquid chromatography-tandem mass spectrometry.

RESULTS

Steroid sulfatase activity was higher in postmenopausal compared to premenopausal women in subcutaneous (median 379 vs 257 pmol/kg tissue per hour; P=0.006) and visceral (545 vs 360 pmol/kg per hour; P=0.004) adipose tissue. Visceral fat showed higher sulfatase activity than subcutaneous fat in premenopausal (P=0.035) and all (P=0.010) women. The mRNA expression levels of two estradiol-producing enzymes, aromatase and 17β-hydroxysteroid dehydrogenase type 12, were higher in postmenopausal than in premenopausal subcutaneous adipose tissue.

CONCLUSIONS

Steroid sulfatase activity in adipose tissue was higher in postmenopausal than in premenopausal women suggesting that DHEAS, derived from the circulation, could be more efficiently utilized in postmenopausal adipose tissue for the formation of biologically active sex hormones.

5α-Dihydrotestosterone regulates the expression of L-type calcium channels and calcium-binding protein regucalcin in human breast cancer cells with suppression of cell growth

Androgens have been associated with the development of normal breast, and their role in mammary gland carcinogenesis has also been described. Several studies reported that androgens inhibit breast cancer cell growth, whereas others linked their action with the modulation of calcium (Ca(2+)) pumps, Ca(2+) channels and Ca(2+)-binding proteins. Also, it is known that deregulated Ca(2+) homeostasis has been implicated in the pathophysiology of breast. The L-type Ca(2+) channels (LTCCs) were found to be up-regulated in colon, colorectal and prostate cancer, but their presence in breast tissues remains uncharacterized. On the other hand, regucalcin (RGN) is a Ca(2+)-binding protein involved in the control of mammary gland cell proliferation, which has been identified as an androgen target gene in distinct tissues except breast. This study aimed to confirm the expression and activity of LTCCs in human breast cancer cells and investigate the effect of androgens in regulating the expression of α1C subunit (Cav1.2) of LTCCs and Ca(2+)-binding protein RGN. PCR, Western blot, immunofluorescence and electrophysiological experiments demonstrated the expression and activity of Cav1.2 subunit in MCF-7 cells. The MCF-7 cells were treated with 1, 10 or 100 nM of 5α-dihydrotestosterone (DHT) for 24-72 h. The obtained results showed that 1 nM DHT up-regulated the expression of Cav1.2 subunit while diminishing RGN protein levels, which was underpinned by reduced cell viability. These findings first confirmed the presence of LTCCs in breast cancer cells and opened new perspectives for the development of therapeutic approaches targeting Ca(2+) signaling.