Kaisa Huhtinen

The Androgen and Progesterone Receptors Regulate Distinct Gene Networks and Cellular Functions in Decidualizing Endometrium

Progesterone is indispensable for differentiation of human endometrial stromal cells (HESCs) into decidual cells, a process that critically controls embryo implantation. We now show an important role for androgen receptor (AR) signaling in this differentiation process. Decreased posttranslational modification of the AR by small ubiquitin-like modifier (SUMO)-1 in decidualizing cells accounted for increased responsiveness to androgen. By combining small interfering RNA technology with genome-wide expression profiling, we found that AR and progesterone receptor (PR) regulate the expression of distinct decidual gene networks. Ingenuity pathway analysis implicated a preponderance of AR-induced genes in cytoskeletal organization and cell motility, whereas analysis of AR-repressed genes suggested involvement in cell cycle regulation. Functionally, AR depletion prevented differentiation-dependent stress fiber formation and promoted motility and proliferation of decidualizing cells. In comparison, PR depletion perturbed the expression of many more genes, underscoring the importance of this nuclear receptor in diverse cellular functions. However, several PR-dependent genes encode for signaling intermediates, and knockdown of PR, but not AR, compromised activation of WNT/beta-catenin, TGFbeta/SMAD, and signal transducer and activator of transcription (STAT) pathways in decidualizing cells. Thus, the nonredundant function of the AR in decidualizing HESCs, centered on cytoskeletal organization and cell cycle regulation, implies an important role for androgens in modulating fetal-maternal interactions. Moreover, we show that PR regulates HESC differentiation, at least in part, by reprogramming growth factor and cytokine signal transduction.

Endometrial and Endometriotic Concentrations of Estrone and Estradiol Are Determined by Local Metabolism Rather than Circulating Levels

CONTEXT Aberrant estrogen synthesis and metabolism have been suggested to increase local estradiol (E2) concentration in endometriosis and thus to promote the growth of the lesions. However, tissue estrogen concentrations within the endometrium and different types of endometriosis lesions have not been described. OBJECTIVE The aim of the study was to evaluate local E2 and estrone (E1) concentrations in the endometrium and different types of endometriosis lesions, and to correlate them with the expression of estrogen-metabolizing enzymes. PATIENTS Patients with endometriosis (n = 60) and healthy controls (n = 16) participated in the study. MAIN OUTCOME MEASURES We measured serum and tissue concentrations of E2 and E1 as well as mRNA expression of the estrogen-metabolizing enzymes. RESULTS Endometrial or endometriotic intratissue E2 concentrations did not reflect the corresponding serum levels. In the proliferative phase, endometrial E2 concentration was five to eight times higher than in the serum, whereas in the secretory phase the E2 concentration was about half of that in the serum. Accordingly, a markedly higher E2/E1 ratio was observed in the endometrium at the proliferative phase compared with the secretory phase. In the endometriosis lesions, E2 levels were predominating over those of E1 throughout the menstrual cycle. Among the hydroxysteroid (17β) dehydrogenase (HSD17B) enzymes analyzed, HSD17B2 negatively correlated with the E2 concentration in the endometrium, and HSD17B6 was strongly expressed, especially in the deep lesions. CONCLUSIONS Endometrial or endometriotic tissue E2 concentrations are actively regulated by local estrogen metabolism in the tissue. Thus, the inhibition of local E2 synthesis is a valid, novel approach to reduce local E2-dependent growth of endometriotic tissue.

Fast and sensitive liquid chromatography–mass spectrometry assay for seven androgenic and progestagenic steroids in human serum

A fast and sensitive LC-MS/MS method for the quantitative analysis of seven steroid hormones in 150 μl of human serum was developed and validated. The following compounds were included: 17α-hydroxypregnenolone, 17α-hydroxyprogesterone, androstenedione, dehydroepiandrosterone, testosterone, pregnenolone, and progesterone. Individual stable isotope-labeled analogues were used as internal standards. Sample preparation was performed by liquid-liquid extraction, followed by oxime derivatization to improve the ionization efficiency of the analytes. In contrast to the common derivatization-based methods, the reaction was incorporated into the sample preparation process and the only additional step due to the derivatization was a short heating of the autosampler vials before the sample injection. Chromatographic separation was achieved on a reversed-phase column using a methanol-water gradient. For the analyte detection, a triple quadrupole instrument with electrospray ionization was used. Total run time was 7.0 min and the lower limits of quantification were in the range of 0.03-0.34 nM (0.01-0.10 ng/ml), depending on the analyte. The method was validated using human serum samples from both sexes and applied for the serum steroid profiling of endometriosis patients.

Evaluation of inhibitors for 17β-hydroxysteroid dehydrogenase type 1 in vivo in immunodeficient mice inoculated with MCF-7 cells stably expressing the recombinant human enzyme

17Beta-hydroxysteroid dehydrogenase (17HSD1) is an enzyme activating estrone (E1) to estradiol (E2). In the present study, a mechanistic animal model was set up for evaluating putative inhibitors for the human enzyme in vivo. Estrogen-dependent MCF-7 human breast carcinoma cells were stably transfected with a plasmid expressing human 17HSD1. These cells formed estrogen-dependent tumors in immunodeficient mice. In the optimized model, tumor sizes were decreased in both ovariectomized and intact vehicle-treated mice, whereas they were maintained or slightly increased in mice supplemented 2 weeks with an appropriate dose of the 17HSD1-substrate E1. Tumor sizes in mice treated with 0.1 micromol/kg/d of E1 were reduced by administering 5 micromol/kg/d of different 17HSD1-inhibitors and a 86% reduction in size was detected with the most potent inhibitor. A dose-response relationship in the inhibitory effect of this compound further confirmed the validity of the model for testing the drug candidates in vivo.

Estrogen biosynthesis and signaling in endometriosis

Endometriosis is an estrogen-dependent gynecological disease where endometrium-like tissue grows outside uterine cavity. Endometriotic cell proliferation is stimulated by estrogens acting predominantly via their nuclear receptors. Estrogen receptors (ESR1, ESR2) are ligand activated transcription factors whose activation is dependent on the cell-specific dynamic expression of the receptors, on the interacting proteins and on the ligand availability. The different types of endometriotic lesions, peritoneal, deep, and ovarian endometriosis, may respond to estrogens differentially due to differences in the expression of the receptors and interacting proteins, and due to potential differences in the ligand availability regulated by the local estrogen synthesis. This review summarizes the current knowledge of estrogen synthesizing enzymes and estrogen receptors in different types of endometriosis lesions. Further studies are still needed to define the possible differences in steroid metabolism in different types of endometriotic lesions.

Serum HE4 concentration is not dependent on menstrual cycle or hormonal treatment among endometriosis patients and healthy premenopausal women

OBJECTIVE Human epididymal secretory protein E4 (HE4) is a new promising tumor marker developed for the diagnostics and follow up of ovarian cancer. It has yet to become widely accepted in clinical practice, and its biological properties have not been inclusively studied. The aim of this study was to investigate whether serum HE4 concentration varies within the normal menstrual cycle and whether common gynecological hormonal treatments have an effect on HE4 values. METHODS Our study population consisted of 180 women, including 126 endometriosis patients and 54 healthy women. We measured their serum HE4 and CA125 concentrations and evaluated the effect of the menstrual cycle and the possible hormonal medication on these marker concentrations. RESULTS We found no significant variation in serum HE4 concentrations in samples taken at different phases of the menstrual cycle. The median HE4 concentrations in proliferative, secretory and menstrual phase were 41.5, 45.1 and 35.3 pM in healthy women, and 43.4, 44.3 and 43.0 pM in endometriosis patients, respectively. The use of combined estrogen and progestin contraceptives did not affect serum HE4 levels significantly. CONCLUSIONS The present study shows that the HE4 measurement in healthy premenopausal women as well as in women with endometriosis can be carried out at any phase of the menstrual cycle, and irrespective of hormonal medication, extending the benefits of HE4 use in clinical practice.

Intra-Tissue Steroid Profiling Indicates Differential Progesterone and Testosterone Metabolism in the Endometrium and Endometriosis Lesions

CONTEXT Aberrant sex steroid signaling is suggested to promote endometriosis growth by several mechanisms, and the tissue concentrations of sex steroids are key determinants of the hormone action. However, their concentrations are only superficially known in the endometrium and endometriosis lesions. OBJECTIVE This study sought to evaluate whether the tissue steroid hormone concentrations in endometriosis differ from the endometrium or serum. MAIN OUTCOME MEASURES Steroid analysis of serum and tissue specimens of women with endometriosis (n = 60) and healthy controls (n=16) was measured, and supporting data from quantitative RT-PCR for steroidogenic enzymes and explant cultures of a subset of specimens is provided. RESULTS Endometrial tissue progesterone (P4) concentrations reflected the serum P4 levels during the menstrual cycle, whereas in endometriosis lesions, the cycle-dependent change was missing. Remarkably high tissue T concentrations were measured in endometriosis lesions independent of the cycle phase, being 5-19 times higher than the corresponding serum levels. Tissue/serum ratio of T was further increased in patients with contraceptive medication. The altered tissue steroid concentrations in endometriosis were in line with the expression of various steroidogenic enzymes in the lesions, of which HSD3B2 showed constantly high expression, whereas CYP11A1 expression was low. Furthermore, the high concentration of sex steroids detected in the ovarian lesions involves their production by the lesion and by the adjacent ovarian tissue. CONCLUSIONS Endometriosis lesions present with progestin and androgen metabolism, which are different from that of the endometrium, and the lesions are characterized by high tissue T and a loss of cyclical changes in tissue P4 concentration.

LC-MS analysis of estradiol in human serum and endometrial tissue: Comparison of electrospray ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization

Accurate measurement of estradiol (E2) is important in clinical diagnostics and research. High sensitivity methods are critical for specimens with E2 concentrations at low picomolar levels, such as serum of men, postmenopausal women and children. Achieving the required assay performance with LC-MS is challenging due to the non-polar structure and low proton affinity of E2. Previous studies suggest that ionization has a major role for the performance of E2 measurement, but comparisons of different ionization techniques for the analysis of clinical samples are not available. In this study, female serum and endometrium tissue samples were used to compare electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) in both polarities. APPI was found to have the most potential for E2 analysis, with a quantification limit of 1 fmol on-column. APCI and ESI could be employed in negative polarity, although being slightly less sensitive than APPI. In the presence of biological background, ESI was found to be highly susceptible to ion suppression, while APCI and APPI were largely unaffected by the sample matrix. Irrespective of the ionization technique, background interferences were observed when using the multiple reaction monitoring transitions commonly employed for E2 (m/z 271 > 159; m/z 255 > 145). These unidentified interferences were most severe in serum samples, varied in intensity between ionization techniques and required efficient chromatographic separation in order to achieve specificity for E2.

Interactions between inflammatory signals and the progesterone receptor in regulating gene expression in pregnant human uterine myocytes.

The absence of a fall in circulating progesterone levels has led to the concept that human labour is associated with ‘functional progesterone withdrawal’ caused through changes in the expression or function of progesterone receptor (PR). At the time of labour, the human uterus is heavily infiltrated with inflammatory cells, which release cytokines to create a ‘myometrial inflammation’ via NF‐κB activation. The negative interaction between NF‐κB and PR, may represent a mechanism to account for ‘functional progesterone withdrawal’ at term. Conversely, PR may act to inhibit NF‐κB function and so play a role in inhibition of myometrial inflammation during pregnancy. To model this inter‐relationship, we have used small interfering (si) RNA‐mediated knock‐down of PR in human pregnant myocytes and whole genome microarray analysis to identify genes regulated through PR. We then activated myometrial inflammation using IL‐1β stimulation to determine the role of PR in myometrial inflammation regulation. Through PR‐knock‐down, we found that PR regulates gene networks involved in myometrial quiescence and extracellular matrix integrity. Activation of myometrial inflammation was found to antagonize PR‐induced gene expression, of genes normally upregulated via PR. We found that PR does not play a role in repression of pro‐inflammatory gene networks induced by IL‐1β and that only MMP10 was significantly regulated in opposite directions by IL‐1β and PR. We conclude that progesterone acting through PR does not generally inhibit myometrial inflammation. Activation of myometrial inflammation does cause ‘functional progesterone withdrawal’ but only in the context of genes normally upregulated via PR.

Resampling reveals sample-level differential expression in clinical genome-wide studies.

Genome-scale molecular profiling of clinical sample material often results in heterogeneous datasets beyond the capability of standard statistical procedures. Statistical tests for differential expression, in particular, rely upon the assumption that the sample groups being compared are relatively homogeneous. Such assumption rarely holds in clinical materials, which leads to detection of secondary findings (false positives) or loss of significant targets (false negatives). Here, we introduce a resampling-based procedure, named ReScore, which aggregates individual changes across all the samples while preserving their clinical classes, and thereby provides multiple sets of markers that can effectively characterize distinct sample subsets. When applied to a public leukemia microarray study, the procedure could accurately reveal hidden subgroup structures associated with underlying genotypic abnormalities. The procedure improved both the sensitivity and specificity of the findings, as well as helped us to identify several disease subtype-specific genes that have remained undetected in the conventional analyses. In our endometriosis study, we were able to accurately distinguish between various sources of systematic variation, linked, for example, to tissue-specificity and disease-related factors, many of which would have been missed with standard approaches. The generic procedure should benefit also other global profiling experiments such as those based on mass spectrometry-based proteomic assays.