Strong Estrogenic Activity Research Articles

Estrogenic activity of a Rhus verniciflua extract and its major components

Rhus verniciflua Stokes has been used as a traditional herbal medicine, a food additive, and a material for lacquer in Korea. In this study, hot water extracts of R. verniciflua Stokes xylem (RVE) and purified compounds were examined for estrogenic activity. RVE showed estrogenic activity mediated by estrogen receptors (ER) with a higher binding affinity and activity to ERβ than to ERα in ERα- or ERβ-transfected cells. It also exhibited estrogenic activity in a uterotrophic assay using rats. All of RVE compounds had high affinity to ERβ compared with ERα in reporter gene assay and ER binding assay. Among seven RVE compounds, butin, butein, sulfuretin, and garbanzol had a strong estrogenic activity in ERE-mediated reporter gene assay. Butein and sulfuretin had stronger ERβ binding affinity compared with others. Collectively, these results demonstrate an estrogenic activity of RVE and suggest its potential value for postmenopausal women.

Anti-osteoclastogenic, estrogenic, and antioxidant activities of cell suspension cultures and tuber root extracts from Pueraria mirifica

The flavonoid contents of intact tubers and cell culture media were determined and physiological activities of Pueraria mirifica extracts were investigated. The total flavonoid contents from cell culture media (PMC) were higher than from tubers (PMT). Results from in vivo estrogenic activity assays indicated that PMT had a strong estrogenic activity in ovariectomized rats. The same amount of PMC exhibited a weak activity. In vitro osteoclast suppression investigations indicated that both PMT and PMC extracts exhibited anti-osteoclastogenic activities with low toxicities in a standard test cell line. Determination of the antioxidant potential using the DPPH assay revealed that the IC50 value for PMT was lower than for PMC. P. mirifica cell cultures produce more flavonoids and exhibit a mild estrogenic and more antioxidant activities than tubers.

Determination of 17β-estradiol and 17α-ethinylestradiol in water at sub-ppt levels by liquid chromatography coupled to tandem mass spectrometry

Steroid estrogens are a group of endocrine disrupting compounds (EDCs) excreted in human urine mainly as glucuronide or sulfate conjugates, which might be converted back into the free estrogens in water. The natural estrogen 17β-estradiol (E2) and the synthetic one 17α-ethinylestradiol (EE2) are of particular concern due to their strong estrogenic activity. The main environmental source of estrogen exposure is treated wastewaters, with the associated risk of releasing these pollutants to surface waters and even reaching finished drinking waters. In this work, we have developed and validated (at 0.1 and 1 ng L−1 levels) a robust and sensitive method based on Ultra-High Performance Liquid Chromatography (UHPLC) coupled to MS/MS for the reliable identification and quantification of E2 and EE2 in surface waters. Several sulfate conjugates have been also included into the methodology. A pre-concentration step based on off-line solid-phase extraction with Oasis HLB cartridges has been optimized prior to the UHPLC-(ESI)MS/MS determination with a last-generation triple quadrupole analyzer. Two isotope-labelled analytes (E2-d4 and EE2-d4) have been used as surrogate standards to ensure an accurate quantification, achieving very low limits of detection for E2 (0.06 ng L−1) and EE2 (0.02 ng L−1). Several surface waters and influents and effluents from wastewater treatment plants have been analyzed to test the method applicability.

Danshen mediates through estrogen receptors to activate Akt and inhibit apoptosis effect of Leu27IGF-II-induced IGF-II receptor signaling activation in cardiomyoblasts

Post-menopausal women show dramatically increased cardiovascular disease morbidity (CVD). Danshen is used widely in China for the treatment of cardiovascular disorders, including coronary heart disease. Danshen possesses lipid-soluble biologically active components with a structure similar to 17β-estrodiol (E2). This study assesses whether the cardio-protection exerted by Danshen is mediated through the ERs within H9c2 cardiomyoblast cells. Cardiomyoblast cells pretreated with Fulvestrant (ICI 182,780), an estrogen receptor antagonist was applied to investigate the estrogenic activity of Danshen. The Danshen extract preventive effects on Leu27IGF-II-induced IGF-IIR signaling activator and H9c2 cell apoptosis were identified using TUNEL assay, JC-1 staining and Western blot assay. We found that Danshen extract treatments significantly enhanced phosphorylated Akt through estrogen receptor activation to inhibit Leu27IGF-II-induced calcineurin activation and block H9c2 cell apoptosis. Danshen extracts suppressed the IGF-IIR signaling proteins, pro-apoptotic proteins and reversed the mitochondrial membrane instability induced by Leu27IGF-II. However, the cardioprotective properties of Danshen to inhibit Leu27IGF-II-induced cell apoptosis and promote cell survival were attenuated by applying ICI, which suggests that the Danshen cardioprotective effect is mediated through estrogen receptors. All our data indicated that Danshen exerts strong estrogenic activity which can be considered a novel selective estrogen receptor modulator (SERM) against IGF2R signaling that blocks cardiac apoptosis.

Evaluation of the Estrogenic Activity of Pueraria (Kudzu) Flower Extract and Its Major Isoflavones Using ER-Binding and Uterotrophic Bioassays

Pueraria flower extract (PFE) is a hot water extract of the Kudzu flower (Pueraria thomsonii). Tea made from dried Kudzu flower is widely used inChina, and PFE is utilized as a nutritional supplement inJapan. PFE contains unique isoflavones such as 6-hydroxygenistein 6,7-di-O-glucoside (6HGDG), tectorigenin 7-O-xylosylglucoside (TGXG), and tectoridin. 6HGDG is known to be metabolized into 6-hydroxygenistein, and TGXG and tectoridin are known to be metabolized into tectorigenin in the digestive tract. Isoflavones typically mimic the effects β-estradiol has on estrogen receptors (ERs) and may influence the female genital system in the case of excessive intake. As a result, the upper limit of safe daily consumption of soy isoflavones has been enforced inJapan. In the present study, ER-binding assays were performed using the EnBio estrogen receptor/cofactor assay system to compare the estrogenic activity of 6-hydroxygenistein and tectorigenin to that of the soy isoflavone genistein. In addition, uterotrophic bioassays were performed to investigate the estrogenic effects of PFE in vivo. The ER-binding assays revealed that the ER-binding affinities of 6-hydroxygenistein and tectorigenin were approximately 0.01 - 0.04 that of genistein. Soy isoflavone products also induced an increase in uterine wet and blotted weight at doses of 500 mg/kg and 1000 mg/kg, whereas PFE did not cause adverse estrogenic effects, even at a dose of 1000 mg/kg. Based on these results, PFE does not appear to contain compounds with strong estrogenic activity or cause adverse estrogenic effects in vivo. Importantly, the results of this study confirm the safety of PFE as a food supplement.

Estrogenic/antiestrogenic activities of a Epimedium koreanum extract and its major components: in vitro and in vivo studies

The estrogenic and antiestrogenic activities of Epimedii Herba, which is a traditional medicinal herb used in Korea and China were investigated in this study. The in vitro estrogen receptor (ER) mediated estrogenic/antiestrogenic activities of an Epimedii Herba extract (Epi ext) and its major components were determined using an estrogen responsive element driven reporter gene assay in MCF-7/ERE and HEK293T cells. The Epi ext exhibited ERα- and ERβ-mediated estrogenic activity with an EC50 of 5.0 and 17.8μM in HEK293T cells, respectively. Prenylflavonoid glycosides such as icariin (ICA), epimedin A, B, and C did not show any in vitro estrogenic or antiestrogenic activities. Icaritin (ICT) and quercetin exhibited in vitro ER mediated estrogenic activity with a more potent interaction with ERβ. In vivo estrogenic activities of the Epi ext, ICA and ICT were compared using an uterotrophic assay. Although the potency of in vitro estrogenic activity was in the order of ICT>Epi ext>ICA, ICA had the strongest estrogenic activity and next ICT in ovariectomized rats. These results collectively suggest that phytoestrogens possess both estrogenic and antiestrogenic activity, and that the differential expression of these two compounds with opposing activities is dependent on the physiological environment in terms of estrogen level, which may be the case in humans.

Differential Estrogenic Actions of Endocrine-Disrupting Chemicals Bisphenol A, Bisphenol AF, and Zearalenone through Estrogen Receptor α and β in Vitro

Background: Endocrine-disrupting chemicals (EDCs) are widely found in the environment. Estrogen-like activity is attributed to EDCs, such as bisphenol A (BPA), bisphenol AF (BPAF), and zearalenone (Zea), but mechanisms of action and diversity of effects are poorly understood.Objectives: We used in vitro models to evaluate the mechanistic actions of BPA, BPAF, and Zea on estrogen receptor (ER) α and ERβ.Methods: We used three human cell lines (Ishikawa, HeLa, and HepG2) representing three cell types to evaluate the estrogen promoter activity of BPA, BPAF, and Zea on ERα and ERβ. Ishikawa/ERα stable cells were used to determine changes in estrogen response element (ERE)-mediated target gene expression or rapid action-mediated effects.Results: The three EDCs showed strong estrogenic activity as agonists for ERα in a dose-dependent manner. At lower concentrations, BPA acted as an antagonist for ERα in Ishikawa cells and BPAF acted as an antagonist for ERβ in HeLa cells, whereas Zea was only a partial antagonist for ERα. ERE-mediated activation by BPA and BPAF was via the AF-2 function of ERα, but Zea activated via both the AF-1 and AF-2 functions. Endogenous ERα target genes and rapid signaling via the p44/42 MAPK pathway were activated by BPA, BPAF, and Zea.Conclusion: BPA and BPAF can function as EDCs by acting as cell type–specific agonists (≥ 10 nM) or antagonists (≤ 10 nM) for ERα and ERβ. Zea had strong estrogenic activity and activated both the AF-1 and AF-2 functions of ERα. In addition, all three compounds induced the rapid action-mediated response for ERα.

Occurrence of androgens in sewage treatment plants influents is associated with antagonist activities on other steroid receptors

The occurrence of endocrine disrupting chemicals such as estrogens in raw urban sewage is well documented. By contrast, the presence of other steroidal activities in wastewater has been poorly studied, although they can cause undesirable biological responses in the environment. In this work, extracts of raw wastewater were tested for agonist and antagonist activities on estrogen, androgen, progesterone, mineralocorticoid and glucocorticoid receptors. We detected strong estrogenic activities that correlated well with the concentration of natural estrogens (estrone, estriol and 17β-estradiol) measured by chemical analysis. We also measured strong androgenic activities which were not due to estrogen receptor ligands based on the use of recombinant estrogen receptor α affinity columns. Several molecules with androgenic activities were identified in wastewater samples, testosterone, dihydrotestosterone and epiandrosterone being the most abundant. However, they explain only a small part of the detected androgenic activity, as indicated by the comparison of the detected biological responses with the results of the targeted chemical analysis. Finally, we found that our samples also contained strong antagonist activities on progesterone, glucocorticoid and mineralocorticoid receptors. Very interestingly, we identified pregnenolone (the precursor to all steroid hormones in humans) as a major endocrine disrupting chemical which accounts for most of the anti-mineralocorticoid activities present in raw wastewater. In conclusion, this study demonstrates the occurrence of androgen agonists as well as other steroid receptor antagonists such as pregnenolone in raw wastewater. Further research is needed to assess the fate of such compounds during sewage treatment and their potential effect on living organisms.

Use of oral contraceptives in the management of acne

The pathogenesis of acne (the most common disorder involving the sebaceous gland) originates from increased sebum production by the sebaceous gland followed by colonization of the hair follicle with Propionibacterium acnes, hyperkeratinization of the upper follicle, and release of inflammatory mediators into the skin. Androgens are the main stimulators of sebum production. Androgens originate from the gonads and adrenal glands, but can also be locally produced within the sebaceous gland from dehydroepiandrosterone sulfate. In the presence of high androgen levels, which can be either a normal pattern of adolescence or a consequence of gonadal or adrenal disease, overproduction of sebum triggers the pathogenesis of acne which, mainly in adolescent women, has deleterious psychological consequences. Estrogens exert the opposite action on sebum production, probably due to the reduction of androgen availability, a direct consequence of estrogen-related increased production of hepatic sex hormone-binding globulin (SHBG). The inhibition of the hypothalamus-pituitary axis induced by oral contra- ceptives is followed by reduced androgen production. Oral contraceptives containing ethinyl estradiol, which has strong estrogenic activity, amplify the hypoandrogenic effect via estrogen- related stimulation of SHBG. The hypoandrogenic effect of oral contraceptives is modulated by the progestin compound. Progestins derived from 19-nortestosterone bind androgenic receptors, whereas others exert antiandrogenic properties by antagonizing the binding of androgens to their receptors, reduce 5α-reductase, and do not bind SHBG. Through this last effect, SHBG is freely available to bind androgens, and the same progestin is totally free to exert its antian- drogenic properties. After correct evaluation of the cause of acne, appropriate management can be undertaken using oral contraceptives containing low daily doses of ethinyl estradiol (20 or 30 µg) associated with a progestin compound, such as cyproterone acetate, drospirenone, or chlormadinone acetate, the antiandrogenic activity of which has been demonstrated by many studies in animals and in humans.

Activation of transgenic estrogen receptor-beta by selected phytoestrogens in a stably transduced rat serotonergic cell line

Many flavonoids, a major group of phenolic plant-derived secondary metabolites, are known to possess estrogen-like bioactivities. However, little is known about their estrogenic properties in the central nervous system due to the lack of suitable cellular models expressing sufficient amounts of functional estrogen receptor β (ERβ). To overcome this deficit, we have created a cellular model, which is serotonergic in origin, to study properties of estrogenic substances by stably transducing RN46A-B14 cells derived from raphe nuclei region of the rat brain with a lentiviral vector encoding a human ERβ. We clearly showed that the transgenic human ERβ is a spontaneously expressed and a functional receptor. We have further assessed the estrogenicity of three different isoflavones and four different naringenin-type flavanones in this cell line utilizing a luciferase reporter gene assay. Genistein (GEN), Daidzein (DAI), Equol (EQ), Naringenin (NAR) and 8-prenylnaringenin (8-PN) showed strong estrogenic activity in a concentration-dependent manner as compared to 7-(O-prenyl)naringenin-4′-acetate (7-O-PN) which was only slightly estrogenic and 6-(1,1-dimethylallyl)naringenin (6-DMAN) that neither showed estrogenic nor anti-estrogenic activity in our model. All observed effects could be antagonized by the anti-estrogen fulvestrant. Moreover, co-treatment of cells with 17β-estradiol (E2) and either GEN or DAI showed a slight additive effect as compared to EQ. On the other hand, 8-PN in addition to 7-O-PN, but not NAR and 6-DMAN, were able to slightly antagonize the responses triggered by E2. Our newly established cellular model may prove to be a useful tool in explicating basic physiological properties of ERβ in the brain and may help unravel molecular and cellular mechanisms involved in serotonergic mood regulation by estrogen or potential plant-derived secondary metabolites.

Estrogenic Activity of Glyceollins Isolated from Soybean Elicited with Aspergillus sojae

Glyceollins, which are synthesized from daidzein in soybeans cultured with fungi, have been shown to have antifungal effects and cancer preventive properties. Several studies have proposed that isoflavones and their metabolites act as a mixed agonist/antagonist for estrogen. Although glyceollins were reported to suppress some cancer cells via anti-estrogenic activity, it is not clear whether the compounds possess estrogenic potential. In contrast to the anti-estrogenic action reported thus far, we observed estrogenic effects of glyceollins using E-screen assay and pS2 expression, whereas glyceollins showed higher affinity for estrogen receptor (ER) beta than ERalpha. We also found that glyceollins were more efficiently produced de novo in minced than in half-sliced soybean, following infection with Aspergillus sojae. In conclusion, glyceollins may be useful in the prevention or amelioration of postmenopausal complications because they had strong estrogenic activity, and their production could be variable depending upon processing prior to fungal inoculation.

Prenylation has a compound specific effect on the estrogenicity of naringenin and genistein

A variety of plant derived substances, so-called phytoestrogens (PEs), although structurally not related to steroids, produce effects similar to the mammalian estradiol. However, little is known so far about the structural requirements which determine PE activities. Taking into consideration that prenylation reactions are relatively common in plant secondary metabolism, the activity of a set of three PE derivatives of genistein and naringenin, namely genistein, 8-prenylgenistein (8PG), 6-(1,1-dimethylallyl)genistein (6DMAG), naringenin, 8-prenylnaringenin (8PN) and 6-(1,1-dimethylallyl)naringenin (6DMAN) was compared regarding structure–estrogenicity relationships in three functionally different estrogen receptor assays. Strong estrogenic activities were recorded for 6DMAN and 8PN in all assays used, while the parent compound naringenin showed only very weak estrogenicity. In contrast, in the case of genistein derivatives, only genistein itself exhibited estrogenic activity in a yeast based assay. In MVLN breast cancer cells, a bioluminescent MCF-7-derived cell line, the estrogenic activity of all three genistein derivatives was similar. Studying alkaline phosphatase activity in Ishikawa endometrial cancer cells as an estrogenic response marker revealed a similar pattern of estrogenicity of the genistein derivatives compared to the yeast based assay although a slight estrogenic effect of 6DMAG and 8PG was apparent. In summary, this study demonstrates that prenylation often found in plant secondary metabolism differentially modifies estrogenic properties of PEs depending on the basic structure of the respective PE.

Effects of Exposure Period and Dose of Diethylstilbestrol on Pregnancy in Rats

The aim of this study was to investigate the effect of exposure period and dose of diethylstilbestrol (DES), which has strong estrogenic activity, on pregnancy in rats. All rats with observed vaginal plugs or sperm in vaginal smear tests after mating were divided into 3 groups: those fed a normal diet, a diet mixed with DES throughout pregnancy and a diet mixed with DES from day 13 of pregnancy. DES was mixed into the diet at 0.1, 1, 10 and 100 ppm. All bred rats fed the normal diet and 0.1 ppm DES from day 13 of pregnancy delivered pups, while none of the rats treated with 1-100 ppm DES during pregnancy and 100 ppm DES from day 13 of pregnancy delivered any pups. The number of male and female pups born decreased in rats treated with 10 ppm DES from day 13 of pregnancy. These results suggest that DES could affect pregnancy and that the exposure period and dose may result in sterility, abortion, poor fetal growth and reduced number of pups born.

INTERACTION OF HYDROXYLATED POLYCYCLIC AROMATIC HYDROCARBONS TO ESTROGEN RECEPTOR

Binding activities and estrogenic/antiestrogenic activities of polycyclic aromatic hydrocarbons (PAHs) and hydroxylated PAHs (OHPAHs) having 2 to 6 rings were evaluated by competition assay and yeast two-hybrid assay expressing human estrogen receptor (hER), respectively. PAHs did not bind to hER and did not show any activity. On the other hand, OHPAHs bound to hER and several OHPAHs showed estrogenic or antiestrogenic activity. Relative estrogenic activity (REP E ) and antiestrogenic activity (REP AE ) were calculated from the values of E 2 and 4-hydroxytamoxyfen as positive controls, respectively. Several OHPAHs having 4 rings showed strongly estrogenic activity. 4-Hydroxybenzo[a]anthracene exhibited the strongest estrogenic activity (REP E = 7.5 × 10−3 ) followed by 3-hydroxybenzo[a]anthracene and 2-hydroxychrysene (REP E = 4.2 × 10−3 ). Several other 4-ring OHPAHs showed strongly antiestrogenic activity. 3-Hydroxybenzo[c]phenanthrene exhibited the strongest antiestrogenic activity (REP AE = 190) followed by 2-hydroxybenzo[c]phenanthrene (REP AE = 69) and 2- hydroxybenz [a]anthracene (REP AE = 0.42). The results suggested that there is a strong structure – activity relationship.

Suppression of estrogenic activity of 17β-estradiol by β-cyclodextrin

The suppressive effects of cyclodextrins (CDs) on the strong estrogenic activity of 17β-estradiol (E2) in water environments were investigated in this study. Cyclodextrins are doughnut-shaped molecules that possess a hydrophobic cavity and a hydrophilic exterior. The cavity can incorporate nonpolar molecules as guests to form inclusion complexes. β-CD and 2-hydroxypropyl-β-CD (HP-β-CD) were the most successful in forming a complex with E2 and improving its low aqueous solubility. The E2/CDs complexes bound to the estrogen receptor in a cell-free system as determined by ELISA and suppressed the hormone activities as measured by a yeast two-hybrid assay. These results indicate that hydrophobic E2 is easily transported through the lipid zone of the plasma membrane into the target cell and can bind to the nuclear receptor. However, the hydrophilic E2/β-CD and E2/HP-β-CD complexes do not penetrate the membrane. Therefore, these CDs are able to suppress the hormone activity of E2 through complex formation.

Identification of Vaginal Stains by Detection of 17 β-Estradiol

ABSTRACT17β-Estradiol (E2–17β), the female hormone with the strongest estrogenic activity, is thought to be present in high quantities in vaginal secretions because it is synthesized mainly in the ovaries and placenta. To clarify whether the detection of E2–17β is useful for identifying vaginal secretions among other body fluid stains, we quantified the amount of E2–17β in extracts from body fluid stains of approximately 4 cm in diameter using gas chromatography-mass spectrometry (GC-MS). The results showed that E2–17β was strongly detected in all of 6 extracts from vaginal stains (81–1,811 ng/mL), 1 of 10 extracts from semen stains (31 ng/mL), and 1 of 9 extracts from female saliva stains (37 ng/mL). All other samples tested were below the limit of quantification. In addition, E2–17β did not show significant degradation in stains kept for 2 days at room temperature. Then, the usefulness of a simple and rapid commercial enzyme-linked immunosorbent assay (ELISA) kit using E2–17β monoclonal antibody was examined. Although the ELISA results were consistent with those from GC-MS, the assay was prone to problems affecting the accuracy of quantification. This is a preliminary report that E2–17β is present at high concentrations in vaginal secretions and its detection might be useful to identify vaginal stains among other body fluid stains.

Toxicities induced in cultured cells exposed to zearalenone: Apoptosis or mutagenesis?

Zearalenone (ZEN) is a fusarotoxin produced mainly by Fusarium graminearum in temperate and warm countries. ZEN has several adverse effects on humans and animals. It has a strong estrogenic activity associated with hyperestrogenism and leads to several physiological alterations in the reproductive tract. Even though the mutagenic and genotoxic proprieties of ZEN have been described recently, its molecular mechanisms of action are not completely understood. The aim of this study was to determine the involvement of other possible mechanisms in ZEN-induced toxicities. Each of the following toxicities, cytotoxicity, cell cycle perturbation, genotoxicity, and mutagenicity, was monitored in Vero cells exposed to ZEN. Our results showed that ZEN-reduced cell viability correlated to cell cycle perturbation-induced DNA fragmentation, resulting in DNA-laddering patterns on agar gel electrophoresis. This observation is consistent with apoptosis, which was confirmed by induction of apoptotic bodies. Moreover, ZEN induced in a concentration-dependant manner the formation of micronuclei and chromosome aberrations. This apparent contradiction between the apoptotic and mutagenic effects of ZEN can be explained by the modification of normal cellular regulation inducing apoptotic or antiapoptotic factors resulting from a lack of or an incorrect DNA-reparation in relation to cell exposure to the toxin.

Degradation of Endocrine Disrupting Chemicals by Ozone/AOPs

The presence of endocrine-disrupting compounds (EDCs) in the aqueous environment is of increasing concern due to their adverse impact on aquatic life, and potential risk to human health. Among the EDCs of concern are steroidal estrogenic hormones such as estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethinylestradiol (EE2), which have a high environmental prevalence and strong estrogenic activity. In addition, the extensive use of alkylphenol ethoxylates (APnEOs), bisphenol A (BPA) and phthalate compounds have resulted in an environmental presence at significant concentrations, although they appear to have a lower estrogenic activity than the steroidal hormones. As water and wastewaters are some of the primary routes of exposure to EDCs, it is important to determine at what levels EDCs are found in these media and how these levels may be reduced. Hence, it is necessary to understand the fate of EDCs in conventional water and wastewater treatment plants, as well as the efficacy of more specialized treatment methods, such as adsorption and oxidation. This paper is a summary of the latest information on the degradation of prominent EDCs by ozone and ozone-based advanced oxidation processes (AOPs). From this review, it is clear that ozone and AOPs are effective in degrading these EDCs, with the possible exception of phthalates, which are relatively stable to ozone oxidation. Knowledge of the formation of reaction products from the treatment by ozone and AOPs is relatively poor at present, and particularly for the non-steroid compounds.

Biphasic effects of zeranol on the growth of estrogen receptor-positive human breast carcinoma cells

Zeranol (alpha-zearalanol) is a metabolite of the mycoestrogen zearalenone, and is used as a growth promoter of livestock due to its strong estrogenic activity. In the present study, we investigated the effects of zeranol on the growth of estrogen receptor (ER)-positive and -negative human breast carcinoma cells in vitro, and the molecules involved. At low concentrations, zeranol accelerated the growth of ER-positive MCF-7 and KPL-1 human breast carcinoma cells, but did not affect the growth of ER-negative MDA-MB-231 cells. At high concentrations, zeranol suppressed the growth of both ER-positive and -negative human breast carcinoma cells. The acceleration of ER-positive cell growth by low-dose zeranol involved the down-regulation of p21Cip1 (a cyclin-dependent kinase inhibitor), which resulted in cell cycle progression. High-dose zeranol induced the formation of a sub-G1 fraction and the up-regulation of the apoptosis stimulator p53, suggesting the induction of apoptosis. Thus, zeranol exerted dose-dependent biphasic effects on ER-positive human breast carcinoma cells, accelerating cell growth at low concentrations and inducing apoptosis at high concentrations.

Production Mechanism of Hydroxylated PCBs by Oxidative Degradation of Selected PCBs Using TiO2 in Water and Estrogenic Activity of Their Intermediates

The oxidative photodegradation behaviors of selected polychlorinated biphenyls (PCBs) [2,3,3',4'-tetraCB (BZ number: CB56), 2,3',4',5-tetraCB (CB70), and 3,4,4',5-tetraCB (CB81: coplanar PCB)] using titanium dioxide (TiO2) in water were investigated. The main purposes were to clarify the structural relation between the original PCBs and the intermediates derived by TiO2 oxidation and to evaluate the estrogenic activity in the treated PCBs during the oxidative reactions. Approximately 90% of the three tetraCBs decomposed within 120 min. Intermediates by decomposition of three tetraCBs, such as some OH-tetraCBs and OH-triCBs, carboxylic intermediates, phenolic intermediates, and other intermediates produced by the cleavage of a benzene ring were identified and quantified. In the degradation pathways, the produced amounts of OH-tetraCB and OH-triCB increased within 60 min of irradiation time. Estrogenic activities of the intermediates from the three tetraCBs in water were assessed by using a yeast two-hybrid assay system for human estrogen receptor alpha (hERalpha). The maximal estrogenic activities were induced by the solutions of decomposed CB81 with irradiation time at 60 min. We found that the solutions at an irradiation time of 60-120 min contained several 4-OH-tetraCBs and 4-OH-triCBs substituted with OH and Cl at para- and para'-positions. It is presumed that the chemical structures of the 4-OH-PCBs are similar to that of 17beta-estradiol (beta-E2); these intermediates present strong estrogenic activities. Moreover, we learned that there is a high possibility of conversion from some low toxic PCBs congeners to strong estrogenic OH-PCBs.