Estradiol metabolism in Ishikawa endometrial cancer cells

Manipulating Estrogenic/Anti-Estrogenic Activity of Triphenylethylenes towards Development of Novel Anti-Neoplastic SERMs

Selective estrogen receptor modulators (SERMs) act as estrogen receptor (ERα) agonists or antagonists depending on the target issue. Tamoxifen (TAM) (a non-steroidal triphenylethylene derivative) was the first SERM approved as anti-estrogen for the treatment of metastatic breast cancer. On the hunt for novel SERMs with potential growth inhibitory activity on breast cancer cell lines yet no potential to induce endometrial carcinoma, we designed and synthesized 28 novel TAM analogs. The novel analogs bear a triphenylethylene scaffold. Modifications on rings A, B, and C aim to attenuate estrogenic/anti-estrogenic activities of the novel compounds so they can potentially inhibit breast cancer and provide positive, beneficial estrogenic effects on other tissues with no risk of developing endometrial hyperplasia. Compound 12 (E/Z-1-(2-{4-[1-(4-Chloro-phenyl)-2-(4-methoxy-phenyl)-propenyl]-phenoxy}-ethyl)-piperidine) showed an appreciable relative ERα agonistic activity in a yeast estrogen screen (YES) assay. It successfully inhibited the growth of the MCF-7 cell line with GI₅₀ = 0.6 µM, and it was approximately three times more potent than TAM. It showed no potential estrogenicity on Ishikawa endometrial adenocarcinoma cell line via assaying alkaline phosphatase (AlkP) activity. Compound 12 was tested in vivo to assess its estrogenic properties in an uterotrophic assay in an ovariectomized rat model. Compared to TAM, it induced less increase in wet uterine wet weight and showed no uterotrophic effect. Compound 12 is a promising candidate for further development due to its inhibition activity on MCF-7 proliferation with moderate AlkP activity and no potential uterotrophic effects. The in vitro estrogenic activity encourages further investigations toward potential beneficial properties in cardiovascular, bone, and brain tissues.

DESIGNER Extracts as Tools to Balance Estrogenic and Chemopreventive Activities of Botanicals for Women's Health

Botanical dietary supplements contain multiple bioactive compounds that target numerous biological pathways. The lack of uniform standardization requirements is one reason that inconsistent clinical effects are reported frequently. The multifaceted biological interactions of active principles can be disentangled by a coupled pharmacological/phytochemical approach using specialized ("knock-out") extracts. This is demonstrated for hops, a botanical for menopausal symptom management. Employing targeted, adsorbent-free countercurrent separation, Humulus lupulus extracts were designed for pre- and postmenopausal women by containing various amounts of the phytoestrogen 8-prenylnaringenin (8-PN) and the chemopreventive constituent xanthohumol (XH). Analysis of their estrogenic (alkaline phosphatase), chemopreventive (NAD(P)H-quinone oxidoreductase 1 [NQO1]), and cytotoxic bioactivities revealed that the estrogenicity of hops is a function of 8-PN, whereas their NQO1 induction and cytotoxic properties depend on XH levels. Antagonization of the estrogenicity of 8-PN by elevated XH concentrations provided evidence for the interdependence of the biological effects. A designed postmenopausal hop extract was prepared to balance 8-PN and XH levels for both estrogenic and chemopreventive properties. An extract designed for premenopausal women contains reduced 8-PN levels and high XH concentrations to minimize estrogenic while retaining chemopreventive properties. This study demonstrates the feasibility of modulating the concentrations of bioactive compounds in botanical extracts for potentially improved efficacy and safety.

Androgens Upregulate Endometrial Epithelial Progesterone Receptor Expression: Potential Implications for Endometriosis

BACKGROUND

Androgenic compounds have been implicated in induction of endometrial atrophy yet the mechanisms of androgen effects on human endometrium have not been well studied. We hypothesized that androgens may promote their endometrial effects via modulation of progesterone receptor (PR) expression.

METHODS

Proliferative phase endometrial samples were collected at the time of hysterectomy. We evaluated the effect of the potent androgen 5α-dihydrotestosterone (DHT) on endometrial PR expression by treating human endometrial explants, endometrial stromal cells, and Ishikawa cells with DHT. Ishikawa cells were also treated with DHT ± the androgen receptor (AR) blocker flutamide. The PR-B, total PR messenger RNA (mRNA), and PR protein expression were assessed. Expression of cyclin D1 and D2 was checked as markers of cell proliferation.

RESULTS

As expected, estradiol induced PR expression in isolated stromal cells, endometrial epithelial cells, and tissue explants. The DHT treatment also resulted in increased PR expression in endometrial explants and Ishikawa cells but not in stromal cells. Further, protein levels of both nuclear PR isoforms (PR-A and PR-B) were induced with the DHT treatment. Although flutamide treatment alone did not affect PR expression, flutamide diminished androgen-induced upregulation of PR in both endometrial explants and Ishikawa cells. Although estradiol induced both cyclin D1 and cyclin D2 mRNA, DHT did not induce these markers of cell proliferation.

CONCLUSION

Androgens may mediate endometrial effects through upregulation of PR gene and protein expression. Endometrial PR upregulation by androgens is mediated, at least in part, through AR.

LeftyA sensitive cytosolic pH regulation and glycolytic flux in Ishikawa human endometrial cancer cells

OBJECTIVE

LeftyA, a powerful regulator of stemness, embryonic differentiation, and reprogramming of cancer cells, counteracts cell proliferation and tumor growth. Key properties of tumor cells include enhanced glycolytic flux, which is highly sensitive to cytosolic pH and thus requires export of H(+) and lactate. H(+) extrusion is in part accomplished by Na(+)/H(+) exchangers, such as NHE1. An effect of LeftyA on transport processes has, however, never been reported. The present study thus explored whether LeftyA modifies regulation of cytosolic pH (pHi) in Ishikawa cells, a well differentiated endometrial carcinoma cell model.

METHODS

NHE1 transcript levels were determined by qRT-PCR, NHE1 protein abundance quantified by Western blotting, pHi estimated utilizing (2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein [BCECF] fluorescence, Na(+)/H(+) exchanger activity from Na(+) dependent realkalinization after an ammonium pulse, and lactate concentration in the supernatant utilizing an enzymatic assay and subsequent colorimetry.

RESULTS

A 2 h treatment with LeftyA (8 ng/ml) significantly decreased NHE1 transcript levels (by 99.6%), NHE1 protein abundance (by 71%), Na(+)/H(+) exchanger activity (by 55%), pHi (from 7.22 ± 0.02 to 7.05 ± 0.02), and lactate release (by 41%).

CONCLUSIONS

LeftyA markedly down-regulates NHE1 expression, Na(+)/H(+) exchanger activity, pHi, and lactate release in Ishikawa cells. Those effects presumably contribute to cellular reprogramming and growth inhibition.

Evaluation of estrogenic activity of licorice species in comparison with hops used in botanicals for menopausal symptoms

The increased cancer risk associated with hormone therapies has encouraged many women to seek non-hormonal alternatives including botanical supplements such as hops (Humulus lupulus) and licorice (Glycyrrhiza spec.) to manage menopausal symptoms. Previous studies have shown estrogenic properties for hops, likely due to the presence of 8-prenylnarigenin, and chemopreventive effects mainly attributed to xanthohumol. Similarly, a combination of estrogenic and chemopreventive properties has been reported for various Glycyrrhiza species. The major goal of the current study was to evaluate the potential estrogenic effects of three licorice species (Glycyrrhiza glabra, G. uralensis, and G. inflata) in comparison with hops. Extracts of Glycyrrhiza species and spent hops induced estrogen responsive alkaline phosphatase activity in endometrial cancer cells, estrogen responsive element (ERE)-luciferase in MCF-7 cells, and Tff1 mRNA in T47D cells. The estrogenic activity decreased in the order H. lupulus > G. uralensis > G. inflata > G. glabra. Liquiritigenin was found to be the principle phytoestrogen of the licorice extracts; however, it exhibited lower estrogenic effects compared to 8-prenylnaringenin in functional assays. Isoliquiritigenin, the precursor chalcone of liquiritigenin, demonstrated significant estrogenic activities while xanthohumol, a metabolic precursor of 8-prenylnaringenin, was not estrogenic. Liquiritigenin showed ERβ selectivity in competitive binding assay and isoliquiritigenin was equipotent for ER subtypes. The estrogenic activity of isoliquiritigenin could be the result of its cyclization to liquiritigenin under physiological conditions. 8-Prenylnaringenin had nanomolar estrogenic potency without ER selectivity while xanthohumol did not bind ERs. These data demonstrated that Glycyrrhiza species with different contents of liquiritigenin have various levels of estrogenic activities, suggesting the importance of precise labeling of botanical supplements. Although hops shows strong estrogenic properties via ERα, licorice might have different estrogenic activities due to its ERβ selectivity, partial estrogen agonist activity, and non-enzymatic conversion of isoliquiritigenin to liquiritigenin.

Recent advances on the action of estrogens and progestogens in normal and pathological human endometrium

Hormonal control in the development of the normal endometrium is of the utmost importance. It is well established that the two main hormones involved in this process are estradiol and progesterone, which are also implicated in the pathological conditions concerning endometriosis and endometrial carcinoma. There are two types of endometrial carcinoma: type I which represents 80%–90% is hormone-dependent, whereas the remainder is type II and is hormone-independent. The endometrial tissue contains all the enzymatic systems in the formation and transformation of the various hormones, including aromatases, sulfatases, sulfotransferases, hydroxysteroid dehydrogenases, hydroxylases, and glucuronidases. It is interesting to note that increased sulfatase activity is correlated with severity of endometriosis. An increased sulfatase/sulfotransferase ratio represents a poor prognosis in patients with endometrial carcinoma. Treatment with hormone replacement therapy (estrogens+progestogens), as well as with tibolone, is most effective in protecting this tissue by climacteric alterations, owing to the significant decrease of ovarian hormones. In conclusion, enzymatic control can open appealing perspectives to protect this organ from possible pathological alterations.

Estrogen sulfotransferases in breast and endometrial cancers

Estrogen sulfotransferase is significantly more active in the normal breast cell (e.g., Human 7) than in the cancer cell (e.g., MCF-7). The data suggest that in breast cancer sulfoconjugated activity is carried out by another enzyme, the SULT1A, which acts at high concentration of the substrates. In breast cancer cells sulfotransferase (SULT) activity can be stimulated by various progestins: medrogestone, promegestone, and nomegestrol acetate, as well as by tibolone and its metabolites. SULT activities can also be controlled by other substances including phytoestrogens, celecoxib, flavonoids (e.g., quercetin, resveratrol), and isoflavones. SULT expression was localized in breast cancer cells, which can be stimulated by promegestone and correlated with the increase of the enzyme activity. The estrogen sulfotransferase (SULT1E1), which acts at nanomolar concentration of estradiol, can inactivate most of this hormone present in the normal breast; however, in the breast cancer cells, the sulfotransferase denoted as SULT1A1 is mainly present, and this acts at micromolar concentrations of E(2). A correlation was postulated among breast cancer cell proliferation, the effect of various progestins, and sulfotransferase stimulation. In conclusion, it is suggested that factors involved in the stimulation of the estrogen sulfotransferases could provide new possibilities for the treatment of patients with hormone-dependent breast and endometrial cancers.

Induction of apoptosis in endometrial cancer cells by psammaplysene A involves FOXO1

OBJECTIVE

Endometrial cancer is the most common type of gynecologic cancer in the United States. In this study, we propose that a marine sponge compound, psammaplysene A (PsA) induces apoptosis in endometrial cancer cells through forced nuclear expression of FOXO1.

METHODS

Ishikawa and ECC1 cells were treated with varying doses of PsA. FOXO1 protein localization was observed using immunofluorescent staining of cells. The effects of PsA on cell viability and proliferation were assessed using a cell viability assay and a BrdU incorporation assay respectively. Cell cycle analysis was performed using flow cytometry. To assess the role of FOXO1 in PsA-induced apoptosis, FOXO1 was silenced in ECC1 cells using siRNA technique, and overexpressed in Ishikawa cells using an adenovirus containing FOXO1 cDNAs. Western blots were used to measure levels of FOXO1 and cleaved PARP proteins.

RESULTS

Treatment of both ECC1 and Ishikawa cells with PsA caused an increase in nuclear FOXO1 protein, a dramatic decrease in cell viability of approximately 5-fold (p<0.05) and minimal effect on proliferation. Furthermore, treatment of cells with PsA doubled the percentage of cells in the G2/M phase (p<0.05). PsA induced apoptosis in endometrial cancer cells. When FOXO1 was silenced in ECC1 cells and treated with PsA, the incidence of apoptosis decreased. In addition, overexpression of FOXO1 with PsA treatment increased apoptosis.

CONCLUSIONS

Increasing nuclear FOXO1 function is important for the induction of apoptosis of endometrial cancer cells by PsA.

ECC-1 Cells: A Well-Differentiated Steroid-Responsive Endometrial Cell Line with Characteristics of Luminal Epithelium1

Endometrial cancer cell lines have provided a valuable model to study endometrial epithelial cells in vitro. Since the first development of HEC1B over 35 yr ago, many different cell lines have been isolated and described. One valuable cell line that maintains hormone responsiveness and unique stability over time is the ECC-1 cell line, developed originally by the late P.G. Satyaswaroop. In this study, we investigated some of the properties of these cells and present their salient characteristics. Like Ishikawa cells, ECC-1 cells maintain both estrogen receptors (ESR1 [ER alpha] and ESR2 [ER beta]), progesterone receptors (PR A and B; PGRs), and androgen receptors (ARs), along with the p160 steroid receptor coactivators NCOA1 (formerly SRC1), NCOA2 (formerly TIF2), and NCOA3 (formerly AIB1). The karyotype of these cells is abnormal, with multiple structural rearrangements in all cells analyzed. Unlike Ishikawa cells that express glandular epithelial antigens, ECC-1 cells maintain a luminal phenotype, with expression of KRT13 (cytokeratin 13) and KRT18 (cytokeratin 18). Apparent differences in the regulation of ESR2 also were evident in ECC-1 cells compared to Ishikawa cells. Like other endometrial cell lines, ECC-1 cells express the steroid receptor coactivators and exhibit epidermal growth factor-stimulated expression of known luminal proteins thought to be involved in implantation, including the hyaluronate receptor CD44 and SPP1 (formerly osteopontin) and CD55 (decay-accelerating factor). These characteristics appear to be stable and persistent over multiple cell passages, making this well-differentiated cell line an excellent choice to study endocrine and paracrine regulation of endometrial epithelium in vitro.

Regulation of MCF-7 breast cancer cell growth by beta-estradiol sulfation

Estrogen stimulation is an important factor in human breast cancer cell growth and development. Metabolism of beta-estradiol (E2), the major endogenous human estrogen, is important in regulating both the level and activity of the hormone in breast tissues. Conjugation of E2 with a sulfonate moiety is an inactivation process since the sulfate ester formed by this reaction can not bind and activate the estrogen receptor. In human tissues including the breast, estrogen sulfotransferase (EST, SULT1E1) is responsible for high affinity E2 sulfation activity. EST is expressed in human mammary epithelial (HME) cells but not in most cultured breast cancer cell lines, including estrogen responsive MCF-7 cells. Stable expression of EST in MCF-7 cells at levels similar to those detected in HME cells significantly inhibits cell growth at physiologically relevant E2 concentrations. The mechanism of cell growth inhibition involves the abrogation of responses observed in growth factor expression in MCF-7 cells following E2 stimulation. MCF-7 cells expressing EST activity did not show a decrease in estrogen receptor-alpha levels, nor a characteristic increase in progesterone receptor or decrease in transforming growth factor-beta expression upon exposure to 100 pM or 1 nM E2. The lack of response in these MCF-7 cells is apparently due to the rapid sulfation and inactivation of free E2 by EST. These results suggest that loss of EST expression in the transformation of normal breast tissues to breast cancer may be an important factor in increasing the growth responsiveness of preneoplastic or tumor cells to estrogen stimulation.

HEC-1 cells

HEC-1 cell line was the first in vitro cell line of a human endometrial adenocarcinoma which enabled us to perform research work on the endometrium and endometrial carcinoma at a simplified cellular system, contributing cell and molecular biological studies on endometrial carcinoma. Once a cell line is established, it provides a stable experimental system that facilitates and progresses in the study of the tissues and/or neoplasias from which they are derived. In this article we report how HEC-1 cells have been established and cleared the proposed requirements to characterize the established cell line. Also to show the usefulness of the cell line for research work, once it was established, we illustrate these concepts by recalling results obtained with HEC-1 cells and reviewing the literature on what has been achieved by using these cells.

Assessment of oestrogenic potency of chemicals used as growth promoter by in-vitro methods

Three in-vitro bioassays were used to compare the oestrogenic potency of chemicals used as growth promoter in beef cattle in certain non-European Union countries (17beta-oestradiol, alpha-zearalanol, testosterone, trenbolone, trenbolone acetate, melengestrol acetate) or found as food contaminant such as the mycotoxin zearalenone and some of their metabolites (17alpha-oestradiol, oestrone, 17alpha-epitestosterone, 19-nortestosterone, androstendione, zearalanone, alpha-zearalanol, beta-zearalanol, alpha-zearalenol, beta-zearalenol). The strong oestrogens 17alpha-ethinyl oestradiol and diethylstilboestrol were used as standards. The first bioassay was based on the activation of a reporter gene by oestrogens in recombinant yeast expressing human or rainbow trout oestrogen receptor. In the second bioassay, the vitellogenin gene induction of rainbow trout hepatocyte cultures was used as a biomarker for the exposure to oestrogens. The third bioassay was based on the alkaline phosphatase gene induction by oestrogens in the human endometrial Ishikawa cell line. The assessment of oestrogenic potency of these chemicals clearly demonstrates the strong oestrogenicity of the mycotoxin zearalenone and its metabolites and particularly alpha-zearalenol which was as potent as ethinyl oestradiol and diethylstilboestrol in the human endometrial Ishikawa cell line.

Steroid sulphotransferase and 17beta-hydroxysteroid dehydrogenase activities in Ishikawa human endometrial adenocarcinoma cells

The present studies concern sulphotransferase activities for estrogens and other steroids, and 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activities for estrogens in Ishikawa endometrial adenocarcinoma cells. When physiological concentrations of various estrogens (estrone, estradiol, estriol) are incubated, most of the transformation product is the respective sulphate. The sulphotransferase activity is very rapid, and 2 h after incubation 70-95% are converted to the sulphated form. Sulphates are found exclusively in the culture medium, which suggests that as soon as the sulphate is biosynthesized it is secreted to the medium. Comparative data using neutral steroids (dehydroepiandrosterone, testosterone, and pregnenolone) show that sulphotransferase activity for these compounds is very limited. In another series of studies, 17beta-HSD activity was explored for the interconversion estrone estradiol. At low concentrations (5 x 10(-9)-5 x 10(-8) M), when estradiol (E2) is incubated, most of the unconjugated material remains as E2 in the cellular compartment, but at high concentrations (5 x 10(-7)-5 x 10(-6) M) a great proportion (70-80%) of the E2 is converted to estrone (E1). On the other hand, after incubation of E1 at all concentrations most remained as unchanged E1. It is suggested that, in Ishikawa cells, at very low concentrations of E1 or E2, sulphotransferases are predominant, but when this enzyme is saturated 17beta-HSD activity is orientated to the oxidative form.

17 beta-Hydroxysteroid dehydrogenase activity in endometrial cancer cells: different metabolic pathways of estradiol in hormone-responsive and non-responsive intact cells

In this paper we report that two human long-term endometrial cancer cell lines, Ishikawa and HEC-1A, exhibit quite different abilities in metabolizing estrogens. As a matter of fact, incubation of Ishikawa cells with close-to-physiological concentrations of estradiol (E2) as precursor resulted in: (1) elevated formation (up to 90%) of E2-sulphate (E2-S), using lower precursor concentrations; (2) very limited conversion to estrone (E1) (< 10% at 24 h incubation), as either free or sulphate; and (3) low but consistent production of other estrogen derivatives, such as 2-hydroxy-estrogens and estriol. Conversely, scant amounts (if any) of E2-S were found in HEC-1A cells, while no detectable formation of other estrogen metabolites could be observed after 24 h. On the other hand, E1 production was significantly greater (nearly 60% at 24 h) than in Ishikawa cells, a large proportion of E1 (over 50% of the total) being formed after only 6 h incubation using time-course experiments. The hypothesis that E2 metabolism could be minor in Ishikawa cells as a consequence of the high rate of E2-S formation encountered is contradicted by the evidence that conversion to E1 also remains limited in the presence of much lower E2-S amounts, seen using higher molar concentrations of precursor. Overall, we observe that 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity diverges significantly in intact Ishikawa and HEC-1A endometrial cancer cells. This difference could not merely be accounted for by the diverse amounts of substrate (E2) available to the cells, nor may it be imputed to different levels of endogenous estrogens. It should rather be sought in different mechanisms controlling 17 beta-HSD activity or, alternatively, in the presence of distinct isoenzymes in the two different cell types.

Metabolism of E1 and E2 in Ishikawa endometrium carcinoma cells: influence of TNF alpha

The metabolism of estrone (E1) and estradiol (E2) by Ishikawa endometrial carcinoma cells and its alteration by TNF alpha treatment was studied. Whereas this cell line practically does not respond to estrogens, it is very sensitive to TNF with respect to growth inhibition and other parameters. E2 and E1 were found to be metabolized by this cell line whereby the main metabolite for both estrogens was estriol. TNF significantly increased the rate of E1 and E2 conversion.

Estrogenic action of estriol fatty acid esters

Recent studies suggest that, estriol, like estradiol, is biosynthetically esterified with fatty acids. We have synthesized the stearate estriol, at C-16 alpha, C-17 beta and the diester, C-16 alpha,17 beta and tested these D-ring esters for their estrogenic action both in vivo and in vitro, comparing them to estradiol, estriol and estradiol-17-stearate. None of the estriol esters bind to the estrogen receptor. They are only weakly estrogenic in a microtiter plate estrogen bioassay: stimulation of alkaline phosphatase in the Ishikawa endometrial cells. However, both estriol monoesters are extremely potent estrogens when injected subcutaneously (in aqueous alcohol) into ovariectomized mice. Compared to the free steroids, they produced a dramatically increased uterine weight with a greatly prolonged duration of stimulation. The 16 alpha,17 beta-diester also induced a protracted uterotrophic response, but the stimulation of uterine weight was comparatively low. Since the esters of estradiol and estriol do not bind to the estrogen receptor, their estrogenic signal must be generated through the action of esterase enzymes. These naturally occurring esters have the potential of being extremely useful pharmacological agents for long-lived estrogenic stimulation.

Steroid patterns of benign breast disease

We briefly review some biochemical aspects of benign breast disease (BBD), mainly focusing on free and conjugate estrogen content of breast cyst fluid (BCF), also in relation to cyst type. Evidence is reported that high K(+)-type I-cysts clearly associate with low Cl- levels and accumulate significantly higher quantities of dehydroepiandrosterone sulfate (DHAS) and estrone-3-sulfate (E1S). In spite of the limited number of cases, both increasing DHAS and E1S levels correlate with the increment of K+ to Na+ ratio. A positive correlation was also found between DHAS and E1S. Using electrochemical detection (ECD) on-line to high performance liquid chromatography (HPLC) in the reverse phase mode, we also studied the free estrogen profile. We observed that in type I BCF there are significantly increased amounts of free estrone (E1). The E1S to E1 ratio was significantly different in the two cyst subpopulations; again, a positive correlation was found between free and sulfated E1 (r = 0.820, p less than 10(-6). This last, together with other experimental observations, allows us to hypothesize that in BCF a main pathway of steroids should be E1S----E1. Besides, high specific activity of sulfatase, as well as beta-glucuronidase enzymes, has been demonstrated for BBD. Preliminary information is also reported concerning the BCF pattern of free estrogens, including the highly polar ones, i.e., catecholestrogens (CCE) and the parent methoxy (MeO) conjugates, which represent, in BCF, a predominant portion of all free estrogens. Both CCE levels and ratios appear unevenly distributed in the two different cyst types. In addition, some BCFs show very high concentrations of 16 alpha-OH-E1. Further studies are needed to answer the main question: whether estrogen patterns could represent additive parameters to further categorize breast cystic disease (BCD) or whether they are of minor interest to determine patients' risk of developing breast cancer.