Low concentrations of bisphenol A induce mouse spermatogonial cell proliferation by G protein-coupled receptor 30 and estrogen receptor-α

Disruption of gonadotropin hormone biosynthesis by parabens: A potential development and reproduction-associated adverse outcome pathway

Parabens are widely used as antibacterial preservatives in foods and personal care products. The knowledge about the modes of toxic action of parabens on development and reproduction remain very limited. The present study attempted to establish a development and reproduction-associated adverse outcome pathway (AOP) by evaluating the effects of methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP) on the biosynthesis of gonadotropins, which are key hormones for development and reproduction. MP and BP significantly upregulated the mRNA and protein levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH) in pituitary gonadotropic cells in a concentration-dependent manner. Activation of gonadotropin-releasing hormone receptor (GnRHR) was required for gonadotropin biosynthesis induced by BP, but not MP. Molecular docking data further demonstrated the higher binding efficiency of BP to human GnRHR than that of MP, suggesting GnRHR as a potential molecular initiative event (MIE) for BP-induced gonadotropin production. L-type voltage-gated calcium channels (VGCCs) were found to be another candidate for MIE in gonadotropic cells response to both MP and BP exposure. The calcium-dependent activation of extracellular signal-regulated kinase 1 (ERK1) and ERK2 was subsequently required for MP- and BP-induced activation of GnRHR and L-type VGCCs pathways. In summary, MP and BP promoted gonadotropin biosynthesis through their interactions with cellular macromolecules GnRHR, L-type VGCCs, and subsequent key event ERK1/2. This is the first study to report the direct interference of parabens with gonadotropin biosynthesis and establish a potential AOP based on pathway-specific mechanism, which contributes to the effective screening of environmental chemicals with developmental and reproductive health risks.

Rapamycin protects Sertoli cells against BPA-induced autophagy disorders

Bisphenol A (BPA) is a well-known environmental contaminant that can negatively impact reproductive function. Disruption of autophagy is implicated in BPA-induced cell injury, the specific molecular mechanisms through which BPA affects autophagy in Sertoli cells are still unknown. In the present study, TM4 cells were exposed to various doses of BPA (10, 100, and 200 μM), and the results indicated that BPA exposure led to the accumulation of autophagosomes, this change was accompanied by increased expression of p-mTOR and decreased expression of Atg12, a protein involved in regulating autophagy initiation. Additionally, BPA exposure upregulated the expression levels of p62, a protein involved in autophagic degradation. The inhibition of autophagy initiation and autophagic degradation contributes to the accumulation of autophagosomes. Further studies showed that BPA exposure didn't affect the expression of the lysosome protein LAMP1; however, decreased cytoplasmic retention of acridine orange in TM4 cells may explain the disruption of autophagy. The role of rapamycin and chloroquine (CQ), an autophagy inhibitor that impairs lysosomal degradation also confirmed the effect of BPA on autophagy regulation. Specifically, rapamycin can protect Sertoli cells against BPA-induced cell injury by promoting autophagy. These findings contribute to our understanding of the mechanisms underlying reproductive toxicity caused by BPA.

Alternatives Exert Higher Health Risks than Bisphenol A on Indo-Pacific Humpback Dolphins

The detrimental effects of bisphenol (BP) exposure are a concern for vulnerable species, Indo-Pacific humpback dolphins (Sousa chinensis). To investigate the characteristics of BP profiles and their adverse impact on humpback dolphins, we assessed the concentrations of six BPs, including bisphenol A (BPA), bisphenol S (BPS), bisphenol F (BPF), bisphenol AF (BPAF), bisphenol B (BPB), and bisphenol P (BPP) in blubber (n = 26) and kidney (n = 12) of humpback dolphins stranded in the Pearl River Estuary, China. BPS accounted for the largest proportion of the total bisphenols (∑BPs) in blubber (55%) and kidney (69%). The concentration of ∑BP in blubber was significantly higher than that in the kidney and liver. The EC50 values of five BPA alternatives were lower than those of BPA in humpback dolphin skin fibroblasts (ScSF) and human skin fibroblasts (HSF). ScSF was more sensitive to BPS, BPAF, BPB, and BPP than HSF. The enrichment pathway of BPA was found to be associated with inflammation and immune dysregulation, while BPP and BPS demonstrated a preference for genotoxicity. BPA, BPP, and BPS, which had risk quotients (RQs) > 1, were found to contribute to subhealth and chronic disease in humpback dolphins. According to the EC50-based risk assessment, BPS poses a higher health risk than BPA for humpback dolphins. This study successfully evaluated the risks of bisphenols in rare and endangered cetacean cell lines using a noninvasive method. More in vivo and in field observations are necessary to know whether the BPA alternatives are likely to be regrettable substitutions.

Transcriptomic Integration Analyses Uncover Common Bisphenol A Effects Across Species and Tissues Primarily Mediated by Disruption of JUN/FOS, EGFR, ER, PPARG, and P53 Pathways

Bisphenol A (BPA) is a common endocrine disruptor widely used in the production of electronic, sports, and medical equipment, as well as consumer products like milk bottles, dental sealants, and thermal paper. Despite its widespread use, current assessments of BPA exposure risks remain limited due to the lack of comprehensive cross-species comparative analyses. To address this gap, we conducted a study aimed at identifying genes and fundamental molecular processes consistently affected by BPA in various species and tissues, employing an effective data integration method and bioinformatic analyses. Our findings revealed that exposure to BPA led to significant changes in processes like lipid metabolism, proliferation, and apoptosis in the tissues/cells of mammals, fish, and nematodes. These processes were found to be commonly affected in adipose, liver, mammary, uterus, testes, and ovary tissues. Additionally, through an in-depth analysis of signaling pathways influenced by BPA in different species and tissues, we observed that the JUN/FOS, EGFR, ER, PPARG, and P53 pathways, along with their downstream key transcription factors and kinases, were all impacted by BPA. Our study provides compelling evidence that BPA indeed induces similar toxic effects across different species and tissues. Furthermore, our investigation sheds light on the underlying molecular mechanisms responsible for these toxic effects. By uncovering these mechanisms, we gain valuable insights into the potential health implications associated with BPA exposure, highlighting the importance of comprehensive assessments and awareness of this widespread endocrine disruptor.

Seasonal variations of testis anatomy and of G-coupled oestrogen receptor 1 expression in Gerbillus gerbillus

The gerbil, Gerbillus gerbillus, a nocturnal desert rodent of northern Africa, exhibits a seasonal reproductive cycle with marked anatomical and behavioural shifts between breeding season and resting season. The aim of this study is to investigate key elements involved in these seasonal changes, specifically in males: the histology of the testis as well as the expression of the G-protein-coupled oestrogen receptor 1 (GPER1) in the testis. During the breeding season, the seminiferous tubules were full of spermatozoa, and their epithelium contained germinal cells embedded in Sertoli cells. Amidst tubules, well-developed Leydig cells were observed around blood vessels, with peritubular myoid cells providing structural and dynamic support to the tubules. GPER1 was largely expressed throughout the testis. Notably, Leydig cells, spermatogonia and spermatocytes showed strong immunohistochemical signals. Sertoli cells, spermatozoa and peritubular myoid cells were moderately stained. During the resting season, spermatogenesis was blocked at the spermatocyte stage, spermatids and spermatozoa were absent and the interstitial space was reduced. The weight of the testis decreased significantly. At this stage, GPER1 was found in Leydig cells, spermatocytes and peritubular myoid cells. Sertoli cells and spermatogonia were not marked. Overall, the testis of the gerbil, Gerbillus gerbillus, has undergone noticeable histological, cellular and weight changes between seasons. In addition, the seasonal expression pattern of GPER1, with pronounced differences between resting season and breeding season, indicates that this receptor is involved in the regulation of the reproductive cycle.

BDE-209 disturbed proliferation and differentiation of spermatogonia during mitotic process through estrogen receptor α

Deca-bromodiphenyl ether (BDE-209) exposure caused spermatogenesis disorder resulting in poor sperm quality has become a public concern in recent years. Spermatogenesis refers to the process by which the division of spermatogonia stem cells (SSCs) produces haploid spermatozoa, including mitosis, meiosis, and spermiogenesis. However, the mechanism of mitosis including proliferation and differentiation of spermatogonia dysfunction induced by BDE-209 remains largely unclear. Here, our data showed that BDE-209 exposure caused a decline in sperm quality with seminiferous tubule structure disorder in rats. In addition, BDE-209 exposure damage spermatogonia proliferation and differentiation with decreasing level of PLZF and cKit in testis. Moreover, rats exposed to BDE-209 decreased the expression of ERα, whereas an elevated expression of Wnt3a and Wnt5a. Mechanistically, supplementation with propipyrazole triol (PPT, a selective ERα pathway agonist) rescued sperm quality and attenuated impairment of proliferation and differentiation of spermatogonia in BDE-209-induced rats. Therefore, ERα plays a crucial role in the proliferation and differentiation of spermatogonia during mitotic process. In conclusion, our study clarified the role of ERα in BDE-209-induced spermatogonia proliferation and differentiation in rats and provides a potential therapeutic application on poor sperm quality caused by BDE-209 exposure.

Estrogen Receptors-Mediated Apoptosis in Hormone-Dependent Cancers

It is known that estrogen stimulates growth and inhibits apoptosis through estrogen receptor(ER)-mediated mechanisms in many cancer cell types. Interestingly, there is strong evidence that estrogens can also induce apoptosis, activating different ER isoforms in cancer cells. It has been observed that E2/ERα complex activates multiple pathways involved in both cell cycle progression and apoptotic cascade prevention, while E2/ERβ complex in many cases directs the cells to apoptosis. However, the exact mechanism of estrogen-induced tumor regression is not completely known. Nevertheless, ERs expression levels of specific splice variants and their cellular localization differentially affect outcome of estrogen-dependent tumors. The goal of this review is to provide a general overview of current knowledge on ERs-mediated apoptosis that occurs in main hormone dependent-cancers. Understanding the molecular mechanisms underlying the induction of ER-mediated cell death will be useful for the development of specific ligands capable of triggering apoptosis to counteract estrogen-dependent tumor growth.

Physiologically detectable bisphenol A impairs human sperm functions by reducing protein-tyrosine phosphorylation

BACKGROUND

Bisphenol A (BPA), a widely used plastic monomer and plasticizer, is detectable in blood, urine and semen of a healthy people, with concentrations ranging from 0.1 nM to 10 nM. It has been shown that in vitro exposure of BPA as low as 0.001 nM could significantly inhibited mouse sperm motility and acrosome reaction. However, it is still unclear whether BPA at those physiologically detectable concentration affects human sperm.

METHODS

The effects of different concentrations of BPA (0, 10^-3, 10^-2, 10^-1, 10, 10³ nM) on sperm functions were examined, including human sperm viability, kinematic parameters, hyperactivation and capacitation.

RESULTS

BPA caused a remarkable decline in human sperm viability, motility and progressive motility, hyperactivation, capacitation and progesterone-induced acrosome reaction. Mechanism studies showed that BPA could suppress the protein tyrosine phosphorylation level of human sperm, but had no effect on sperm calcium signaling.

CONCLUSIONS

Physiologically detectable concentrations of BPA may impair human sperm functions via suppressing protein tyrosine phosphorylation of human sperm, implying that environmental pollution of BPA might be a factor contributing to male infertility.

Biomarker responses induced by bisphenol A on spermatogenesis in a Neotropical teleost fish are temperature-dependent

Bisphenol A (BPA) is an organic synthetic compound used in the plastic industry with endocrine disrupting activity. Although it is frequently found in surface waters, few studies have investigated its impact on fish gametogenesis, particularly when associated with natural stressors. In this regard, the present study evaluated BPA toxicity on spermatogenesis in the lambari Astyanax bimaculatus under controlled conditions and its interactive effects with water temperature. Adult specimens were exposed in duplicate to 40 μg/L and 400 μg/L BPA at 23 °C and 28 °C for 21 days; the control group did not receive BPA. Testicular samples were collected and analyzed using different cellular and molecular techniques. The results showed a significant reduction in the gonadosomatic index in the BPA-treated groups at both temperatures. A decrease in the testicular levels of 11-ketotestosterone was observed in the 400 μg/L BPA group at 23 °C, 17β-estradiol increased significantly in the treated groups at 28 °C, and vitellogenin showed no difference between the treatments. The morphometric analysis of spermatogenesis revealed a significant increase in the proportion of spermatogonia, spermatocytes, and Sertoli cells in the treated groups, with a higher proportion at 23 °C than at 28 °C. Otherwise, the proportion of spermatozoa was significantly lower in the BPA-treated groups, with a greater reduction at 23 °C. In addition, BPA also stimulated spermatogonial proliferation in the treated groups, but apoptosis was significantly increased in spermatids at 23 °C. Testis-ova, cell degeneration, and chromatin alterations in spermatids and Sertoli cells were observed in the germinal epithelium of the BPA-treated groups. The integrated biomarker response (IBR) index revealed that the analyzed endpoints are suitable for assessing estrogenic contamination. Taken together, our results indicate that the interactive effects of BPA and temperature contribute to the impairment of spermatogenesis in A. bimaculatus with more severe effects observed on sperm production at 23 °C than at 28 °C.

Perfluorooctane sulfonate and bisphenol A induce a similar level of mast cell activation via a common signaling pathway, Fyn-Lyn-Syk activation

Perfluoroalkyl compounds (PFCs) as food contaminants are widely distributed persistent organic pollutants (POPs) and have been suggested to induce immune dysfunction. However, their effects on immune function are not conclusive. Mast cells play a central role in allergic and non-allergic inflammatory responses. Therefore, we have examined the effects of PFCs (PFHxS, PFOA, PFOS) on mast cell-mediated inflammatory responses using in vitro mouse bone marrow-derived mast cells (BMMCs) and human mast cells (HMC-1) and in vivo mice model. The effects of PFCs were compared with those of bisphenol A (BPA), a well-studied environmental pollutant. Among PFCs tested, PFOS had the highest effects. Both PFOS and BPA increased degranulation and production of inflammatory eicosanoids in mast cells at a similar level, which subsequently led to increased skin edema and serum LTC₄ and PGD₂ in mice. Both PFOS and BPA increased not only downstream signaling (PLCγ1, AKT, ERK), but also upstream signaling (Fyn, Lyn, Syk/LAT) in mast cells. Taken together, PFOS and BPA induce mast cell-mediated inflammatory responses via a common signaling pathways. Our results may help establish the scientific basis for understanding the etiology of mast cell-mediated inflammatory responses and improve the immune dysfunction risk assessment for emerging POPs such as PFCs.

Molecular mechanism study of BPAF-induced proliferation of ERα-negative SKBR-3 human breast cancer cells in vitro/in vivo

Bisphenol AF (BPAF) is a known estrogen disruptor of the ERα pathway. The aim of the present study was to characterize the proliferation effects of BPAF on ERα-negative SKBR-3 breast cancer cells with mechanistic insights. BPAF at low concentrations (0.001-0.1 μM) significantly induced the proliferation of SKBR-3 cells. In a SKBR-3 tumor model in BALB/c nude mice, BPAF at 100 mg/kg body weight/day also significantly promoted the growth of SKBR-3 tumors. Low concentrations of BPAF markedly increased the expression of G protein-coupled estrogen receptor (GPER1), c-Myc, CyclinD1 and c-Fos proteins, and enhanced phosphorylation of extracellular signal-regulated kinase (Erk) and protein kinase B (Akt) in SKBR-3 cells. Further, BPAF significantly upregulated mRNA levels of related target genes in SKBR-3 cells and SKBR-3 tumor tissues in nude mice. The GPER1 inhibitor G15 and phosphatidylinositide 3-kinase (PI3K) inhibitor wortmannin (WM) inhibited phosphorylation of Erk and Akt. The specific signal inhibitors also markedly decreased the expression of target genes and weakened the cell proliferation induced by low-concentration BPAF. The findings showed that GPER1 could independently regulate BPAF-induced proliferation of SKBR-3 cells without requiring ERα. These results provide mechanistic insights into the effects of BPAF regarding ERα-negative human breast cancer development.

Insight into the mechanism of tetrachlorobisphenol A (TCBPA)-induced proliferation of breast cancer cells by GPER-mediated signaling pathways

Tetrachlorobisphenol A (TCBPA), a chlorinated derivative of bisphenol A, is an endocrine disruptor based on interaction with nuclear estrogen receptor alpha (ERα). However, there is only limited data on the mechanisms through which TCBPA-associated estrogenic activity is related to the membrane G protein-coupled estrogen receptor (GPER) pathway. In this study, three human breast cancer cell lines-MCF-7, SKBR3, and MDA-MB-231 cells were used to evaluate whether, as well as how, TCBPA at concentration range of 0.001-50 μM affect cell proliferation. The role of GPER signaling in TCBPA-induced cell proliferation was studied by analyzing the protein expression and mRNA levels of relevant signal targets. The results showed that low concentrations of TCBPA significantly induced the proliferation of MCF-7, SKBR3, and MDA-MB-231 cells, with MCF-7 cells being the most sensitive to TCBPA exposure. Low-concentration TCBPA also upregulated the expression of GPER, CyclinD1, c-Myc, and c-Fos proteins, as well as increased the phosphorylation of extracellular signal-regulated-kinase 1/2 (Erk1/2) and protein kinase B (Akt). Additionally, the mRNA levels of genes associated with estrogen signaling pathways also increased upon exposure to TCBPA. However, the phosphorylation of Erk1/2 and Akt decreased when the cells were treated with GPER inhibitor G15 and phosphatidylinositide 3-kinase (PI3K) inhibitor wortmannin (WM) prior to TCBPA exposure. Besides, the increased proliferation of breast cancer cells induced by TCBPA were also inhibited. In ERα-positive MCF-7 cells, TCBPA also upregulated ERα expression, and ERα was found to interact with GPER-mediated signaling. The results indicate that GPER activates the PI3K/Akt and Erk1/2 signal cascades to drive the cell proliferation observed for low concentrations of TCBPA. The presented results suggest a new mechanism by which TCBPA exerts estrogenic action in breast cancer cells, namely, GPER signaling in an ERα-independent manner, and also highlights the potential risks to human health of the usage of TCBPA.

The proliferation effects of fluoxetine and amitriptyline on human breast cancer cells and the underlying molecular mechanisms

Some studies have suggested possible estrogen actions for antidepressants such as fluoxetine. However, the specific molecular mechanisms remain unclear. In this study, the molecular mechanism of fluoxetine-induced the proliferation of breast cancer SKBR3 and MCF-7 cells was evaluated by detecting ERα and GPR30-mediated ERK and PI3K/AKT signals. We found that low concentrations of fluoxetine upregulated the expression of GPR30, ERα, CyclinD1, and C-MYC proteins, as well as elevated the phosphorylation of ERK and AKT. The phosphorylation of ERK and AKT decreased when the cells were pretreated with ERα inhibitor ICI, GPR30 inhibitor G15, and PI3K inhibitor WM prior to fluoxetine exposure. The addition of these inhibitors also attenuated the fluoxetine-induced cell proliferation. These findings indicated that fluoxetine activated the PI3K/AKT and ERK signaling cascades via GPR30 to derive the cell proliferation. It suggests that fluoxetine has the potential to exert estrogen actions via GPR30.

Characterization of Estrogenic Activity and Site-Specific Accumulation of Bisphenol-A in Epididymal Fat Pad: Interfering Effects on the Endocannabinoid System and Temporal Progression of Germ Cells

The objective of this work has been to characterize the estrogenic activity of bisphenol-A (BPA) and the adverse effects on the endocannabinoid system (ECS) in modulating germ cell progression. Male offspring exposed to BPA during the foetal-perinatal period at doses below the no-observed-adverse-effect-level were used to investigate the exposure effects in adulthood. Results showed that BPA accumulates specifically in epididymal fat rather than in abdominal fat and targets testicular expression of 3β-hydroxysteroid dehydrogenase and cytochrome P450 aromatase, thus promoting sustained increase of estrogens and a decrease of testosterone. The exposure to BPA affects the expression levels of some ECS components, namely type-1 (CB1) and type-2 cannabinoid (CB2) receptor and monoacylglycerol-lipase (MAGL). Furthermore, it affects the temporal progression of germ cells reported to be responsive to ECS and promotes epithelial germ cell exfoliation. In particular, it increases the germ cell content (i.e., spermatogonia while reducing spermatocytes and spermatids), accelerates progression of spermatocytes and spermatids, promotes epithelial detachment of round and condensed spermatids and interferes with expression of cell–cell junction genes (i.e., zonula occcludens protein-1, vimentin and β-catenin). Altogether, our study provides evidence that early exposure to BPA produces in adulthood sustained and site-specific BPA accumulation in epididymal fat, becoming a risk factor for the reproductive endocrine pathways associated to ECS.

Bioinformatics analysis and quantitative weight of evidence assessment to map the potential mode of actions of bisphenol A

Bisphenol A (BPA) is a classical chemical contaminant in food, and the mode of action (MOA) of BPA remains unclear, constraining the progress of risk assessment. This study aims to assess the potential MOAs of BPA regarding reproductive/developmental toxicity, neurological toxicity, and proliferative effects on the mammary gland and the prostate potentially related to carcinogenesis by using the Comparative Toxicogenomics Database (CTD)-based bioinformatics analysis and the quantitative weight of evidence (QWOE) approach on the basis of the principles of Toxicity Testing in the 21st Century. The CTD-based bioinformatics analysis results showed that estrogen receptor 1, estrogen receptor 2, mitogen-activated protein kinase (MAPK) 1, MAPK3, BCL2 apoptosis regulator, caspase 3, BAX, androgen receptor, and AKT serine/threonine kinase 1 could be the common target genes, and the apoptotic process, cell proliferation, testosterone biosynthetic process, and estrogen biosynthetic process might be the shared phenotypes for different target organs. In addition, the KEGG pathways of the BPA-induced action might involve the estrogen signaling pathway and pathways in cancer. After the QWOE evaluation, two potential estrogen receptor-related MOAs of BPA-induced testis dysfunction and learning-memory deficit were proposed. However, the confidence and the human relevance of the two MOAs were moderate, prompting studies to improve the MOA-based risk assessment of BPA.

Detrimental Effects of Bisphenol Compounds on Physiology and Reproduction in Fish: A Literature Review

Bisphenol-A is one of the most studied endocrine-chemicals, which is widely used all over the world in plastic manufacture. Because of its extensive use, it has become one of the most abundant chemical environmental pollutants, especially in aquatic environments. BPA is known to affect fish reproduction via estrogen receptors but many studies advocate that BPA affects almost all aspects of fish physiology. The possible modes of action include genomic, as well as and non-genomic mechanisms, estrogen, androgen, and thyroid receptor-mediated effects. Due to the high detrimental effects of BPA, various analogs of BPA are being used as alternatives. Recent evidence suggests that the analogs of BPA have similar modes of action, with accompanying effects on fish physiology and reproduction. In this review, a detailed comparison of effects produced by BPA and analogs and their mode of action is discussed.

Lei-gong-gen formula granule attenuates hyperlipidemia in rats via cGMP-PKG signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Lei-gong-gen formula granule (LFG) is a folk prescription derived from Zhuang nationality, the largest ethnic minority among the 56 nationalities in China. It is composed of three herbs, namely Centella asiatica (L.) Urb., Eclipta prostrata (L.) L., Smilax glabra Roxb. It has been widely used as health protection tea for many years to prevent cardiovascular and cerebrovascular diseases such as hyperlipidemia and hypertension.

AIM OF THE STUDY

This study validated the lipid-lowering effect of LFG in a hyperlipidemia rat model. Then we employed network pharmacology and molecular biological approach to identify the active ingredients of LFG, corresponding targets, and its anti-hyperlipidemia mechanisms.

MATERIALS AND METHODS

Hyperlipidemia rat model was established by feeding male Sprague-Dawley rats with high-fat diet for two weeks. LFG (two doses of 10 and 20 g/kg) was administered orally to hyperlipidemia rat model for 4 weeks, twice per day. Serum levels of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) were monitored in rats pre and post-treatment. Hematoxylin-eosin staining was applied to observe the pathology and lipid accumulation of liver. We then performed network pharmacology analysis to predict the ingredients, their associated targets, and hyperlipidemia associated targets. Pathway analysis with significant genes was carried out using KEGG pathway. These genes and proteins intersectioned between compound targets and hyperlipidemia targets were further verified with samples from hyperlipidemia rats treated with LFG using Real-time RT-PCR and Western Blot.

RESULTS

LFG attenuated hyperlipidemia in rat model, and this was characterized with decreased serum levels of TC, LDL-C, liver wet weight, and liver index. LFG alleviated the hepatic steatosis in hyperlipidemia rats. Network pharmacology analysis identified 53 bioactive ingredients from LFG formula (three herbs), which link to 765 potential targets. 53 hyperlipidemia associated genes were retrieved from public databases. There were 10 common genes between ingredients-targets and hyperlipidemia associated genes, which linked to 20 bioactive ingredients. Among these 10 genes, 3 of them were validated to be involved in LFG's anti-hyperlipidemia effect using Real-time RT-PCR, namely ADRB2 encoding beta-2 adrenergic receptor, NOS3 encoding nitric oxide synthase 3, LDLR encoding low-density lipoprotein receptor. The cGMP-PKG signaling pathway was enriched for hyperlipidemia after pharmacology network analysis with ADRB2, NOS3, and LDLR. Interestingly, expression of cGMP-dependent protein kinase (PKG) was downregulated in hyperlipidemia rat after LFG treatment. Molecular docking study further supported that ferulic acid, histidine, p-hydroxybenzoic acid, and linalool were potential active ingredients for LFG's anti-hyperlipidemia effect. LC-MS/MS analysis confirmed that ferulic acid and p-hydroxybenzoic acid were active ingredients of LFG.

CONCLUSION

LFG exhibited the lipid-lowering effect, which might be attributed to downregulating ADRB2 and NOS3, and upregulating LDLR through the cGMP-PKG signaling pathway in hyperlipidemia rat. Ferulic acid and p-hydroxybenzoic acid might be the underlying active ingredients which affect the potential targets for their anti-hyperlipidemia effect.

Role of GPER-Mediated Signaling in Testicular Functions and Tumorigenesis

Estrogen signaling plays important roles in testicular functions and tumorigenesis. Fifteen years ago, it was discovered that a member of the G protein-coupled receptor family, GPR30, which binds also with high affinity to estradiol and is responsible, in part, for the rapid non-genomic actions of estrogens. GPR30, renamed as GPER, was detected in several tissues including germ cells (spermatogonia, spermatocytes, spermatids) and somatic cells (Sertoli and Leydig cells). In our previous review published in 2014, we summarized studies that evidenced a role of GPER signaling in mediating estrogen action during spermatogenesis and testis development. In addition, we evidenced that GPER seems to be involved in modulating estrogen-dependent testicular cancer cell growth; however, the effects on cell survival and proliferation depend on specific cell type. In this review, we update the knowledge obtained in the last years on GPER roles in regulating physiological functions of testicular cells and its involvement in neoplastic transformation of both germ and somatic cells. In particular, we will focus our attention on crosstalk among GPER signaling, classical estrogen receptors and other nuclear receptors involved in testis physiology regulation.

Tricresyl phosphate isomers exert estrogenic effects via G protein-coupled estrogen receptor-mediated pathways

Tricresyl phosphates (TCPs), as representative aromatic organophosphate flame retardants (OPFRs), have received much attention due to their potential neurotoxicity and endocrine-disrupting effects. However, the role of estrogen receptor α (ERα) and G protein-coupled estrogen receptor (GPER) in their estrogen disrupting effects remains poorly understood. Therefore, in this study, three TCP isomers, tri-o-cresyl phosphate (ToCP), tri-m-cresyl phosphate (TmCP) and tri-p-cresyl phosphate (TpCP), were examined for their activities on ERα by using two-hybrid yeast assay, and action on GPER by using Boyden chamber assay, cAMP production assay, calcium mobilization assay and molecular docking analysis. The results showed that three TCP isomers were found to act as ERα antagonists. Conversely, they had agonistic activity on GPER to promote GPER-mediated cell migration of MCF7 cells and SKBR3 cells. Both ToCP and TpCP activated GPER-mediated cAMP production and calcium mobilization, whereas TmCP had different mode of action, it only triggered GPER-mediated calcium mobilization, as evidenced by using the specific GPER inhibitor (G15) and GPER overexpressing experiments. Molecular docking further revealed that the way of interaction of TmCP and TpCP with GPER was different from that of ToCP with GPER, and higher activity of ToCP in activating GPER-mediated pathways might be associated with the alkyl substitution at the ortho position of the aromatic ring. Our results, for the first time, found a new target, GPER, for TCPs exerting their estrogen-disrupting effects, and demonstrated complex estrogen-disrupting effects of three TCP isomers involved their opposite activities toward ERα and GPER.

Impacts of bisphenol A analogues on zebrafish post-embryonic brain

Bisphenol A (BPA) is a widely studied and well-recognised endocrine-disrupting chemical, and one of the current issues is its safe replacement by various analogues. Using larva zebrafish as a model, the present study reveals that moderate and chronic exposure to BPA analogues such as bisphenol S, bisphenol F and bisphenol AF may also affect vertebrate neurodevelopment and locomotor activity. Several parameters of embryo-larval development were investigated, such as mortality, hatching, number of mitotically active cell, as defined by 5-bromo-2'-deoxyuridine incorporation and proliferative cell nuclear antigen labelling, aromatase B protein expression in radial glial cell and locomotor activity. Our results show that exposure to several bisphenol analogues induced an acceleration of embryo hatching rate. At the level of the developing brain, a strong up-regulation of the oestrogen-sensitive Aromatase B was also detected in the hypothalamic region. This up-regulation was not associated with effects on the numbers of mitotically active progenitors nor differentiated neurones in the preoptic area and in the nuclear recessus posterior of the hypothalamus zebrafish larvae. Furthermore, using a high-throughput video tracking system to monitor locomotor activity in zebrafish larvae, we show that some bisphenol analogues, such as bisphenol AF, significantly reduced locomotor activity following 6 days of exposure. Taken together, our study provides evidence that BPA analogues can also affect the neurobehavioural development of zebrafish.

Putative adverse outcome pathways for female reproductive disorders to improve testing and regulation of chemicals

Modern living challenges female reproductive health. We are witnessing a rise in reproductive disorders and drop in birth rates across the world. The reasons for these manifestations are multifaceted and most likely include continuous exposure to an ever-increasing number of chemicals. The cause–effect relationships between chemical exposure and female reproductive disorders, however, have proven problematic to determine. This has made it difficult to assess the risks chemical exposures pose to a woman’s reproductive development and function. To address this challenge, this review uses the adverse outcome pathway (AOP) concept to summarize current knowledge about how chemical exposure can affect female reproductive health. We have a special focus on effects on the ovaries, since they are essential for lifelong reproductive health in women, being the source of both oocytes and several reproductive hormones, including sex steroids. The AOP framework is widely accepted as a new tool for toxicological safety assessment that enables better use of mechanistic knowledge for regulatory purposes. AOPs equip assessors and regulators with a pragmatic network of linear cause–effect relationships, enabling the use of a wider range of test method data in chemical risk assessment and regulation. Based on current knowledge, we propose ten putative AOPs relevant for female reproductive disorders that can be further elaborated and potentially be included in the AOPwiki. This effort is an important step towards better safeguarding the reproductive health of all girls and women.

The Interaction Test of Binary Mixtures of Endocrine-Disrupting Chemicals Using In Vitro Bioassays

Typical environmental endocrine-disrupting chemicals (EDCs) such as estradiol valerate (EV), diethylstilbestrol (DES), di-2-ethylhexyl phthalate (DEHP), mono-2-ethylhexyl phthalate (MEHP), and bisphenol A (BPA) have a strong reproductive and developmental toxicity at low concentrations. However, information on their joint toxicity is scarce. In this study, we evaluated the combined effects of EV and other four EDCs (DES, DEHP, MEHP, and BPA) on the human breast MCF-7 cells by detecting the cell proliferation, intracellular reactive oxygen species (ROS) levels, and estrogen receptor alpha (ERα) protein expression using equal concentration ratio method. The results showed that, after exposure for 24, 48, and 72 h, single EV, DES, and BPA can promote the proliferation of MCF-7 human breast cancer cells, and EV has the strongest effect in inducing cell proliferation. DEHP and MEHP cannot induce MCF-7 cell proliferation for all exposure time, while cell proliferation induced by EV was significantly attenuated by DES, BPA, DEHP, and MEHP when they mixed with EV. For intracellular ROS, single EV, BPA, DES, DEHP, and MEHP elevated intracellular ROS levels for different exposure time. Similar to the cell proliferation, DES and BPA decreased intracellular ROS levels induced by EV when they mixed with EV for 24 h. EV, DES, and BPA exposed alone or combined with EV upregulated the ERα protein expression. However, DEHP and MEHP exposed alone or combined with EV had no effect on ERα protein expression, indicating that DEHP or MEHP could attenuate ERα protein expression upregulated by EV. These results showed that the joint toxicity of binary mixtures of EV and other EDCs do not interact in a synergistic fashion in inducing cell proliferation, intracellular ROS levels, and ERα protein expression. These findings have important implications in the human risk assessments of EV mixed with other EDCs in the environment.

Bisphenol A triggers the malignancy of nasopharyngeal carcinoma cells via activation of Wnt/β-catenin pathway

It is critical to understand the risk factors responsible for the tumorigenesis and progression of nasopharyngeal carcinoma (NPC). Bisphenol A (BPA) can regulate the estrogenic signals to modulate cancer progression, while its roles in NC were not investigated. Our present study revealed that the BPA can increase proliferation and migration of NPC cells while decrease the chemosensitivity to doxorubicin (Dox). The inhibitor of GSK-3β/β-catenin (LiCl) can restore BPA-induced cell proliferation of NPC cells, which is due to that BPA can decrease phosphorylation while increase expression and nucleus localization of β-catenin. Mechanistically, BPA can increase the mRNA stability of β-catenin (encoded by CTNNB1) via suppressing the expression of miR-214-3p, which can direct target the 3'UTR of β-catenin mRNA. Further, BPA can decrease phosphorylation of β-catenin via repressing the expression of CK1α. Collectively, our data showed that BPA can trigger the proliferation and malignancy of NPC cells via activation of Wnt/β-catenin pathway. It indicated that body accumulation and inhalation exposure of BPA might be a risk factor for NPC development.

GPER as a Receptor for Endocrine-Disrupting Chemicals (EDCs)

Endocrine-disrupting chemicals (EDCs) are exogenous chemicals that interfere with endogenous hormonal systems at various levels, resulting in adverse health effects. EDCs belong to diverse chemical families and can accumulate in the environment, diet and body fluids, with different levels of persistence. Their action can be mediated by several receptors, including members of the nuclear receptor family, such as estrogen and androgen receptors. The G protein-coupled estrogen receptor (GPER), a seven-transmembrane domain receptor, has also attracted attention as a potential target of EDCs. This review summarizes our current knowledge concerning GPER as a mediator of EDCs' effects.

A Cell-Based Method to Detect Agonist and Antagonist Activities of Endocrine-Disrupting Chemicals on GPER

Endocrine-disrupting chemicals (EDCs) are exogenous compounds that impact endogenous hormonal systems, resulting in adverse health effects. These chemicals can exert their actions by interfering with several pathways. Simple biological systems to determine whether EDCs act positively or negatively on a given receptor are often lacking. Here we describe a low-to-middle throughput method to screen the agonist/antagonist potential of EDCs specifically on the GPER membrane estrogen receptor. Application of this assay to 23 candidate EDCs from different chemical families reveals the existence of six agonists and six antagonists.

Immunotoxic Potential of Bisphenol F Mediated through Lipid Signaling Pathways on Macrophages

As a bisphenol A (BPA) alternative, bisphenol F (BPF) has been detected in various products, such as paper products, personal care products, and food. More importantly, the toxicity of BPF remains underexplored. We reported an integrated method to study the immunotoxic potentials and the underlying mechanisms of BPF on cell apoptosis, macrophage polarization, reactive oxygen species generation, expression and secretion of immune-related cytokines, and reprogramming of lipid signaling. More serious to BPA, BPF induced apoptosis in macrophages. The apoptosis was induced by activating both sphingomyelin-ceramide signaling pathway and oxidative stress, which included intrinsic (bax and caspase-9) and extrinsic apoptotic pathways (tumor necrosis factor receptor 1, caspase-8, and caspase-3). BPF exposure also induced the proinflammatory phenotype of the macrophage. This alternation was shown to be closely correlated with the modulation of biosynthesis and degradation of glycerophospholipids. This study demonstrated novel evidence that BPF as a substituent of BPA induced immunotoxic effects at environmentally relevant concentrations. We also showed that the reprogramming of lipidome plays a key role in the regulation of macrophage polarization and the induction of immunotoxicity of the BPA analogue.

Neurotoxicity of BPA, BPS, and BPB for the hippocampal cell line (HT-22): An implication for the replacement of BPA in plastics

Bisphenol A (BPA), a plastic additive, is ubiquitous in the environment and has endocrine disrupting effects. As many countries have prohibited the manufacture and sale of plastic products with BPA, BPA analogs have been used to replace BPA during production, including bisphenol S (BPS) and bisphenol B (BPB). To investigate the toxicities of BPA and its analogs on neurons, reactive oxygen species (ROS) assay, Annexin V-FITC (fluorescein) apoptosis detection assay, lactate dehydrogenase (LDH) cytotoxicity assay, and Cell Counting Kit-8 assay were conducted to comprehensively assess the influence of different concentrations of BPA, BPB, and BPS on ROS, apoptosis, damage, and proliferation for hippocampal HT-22 cells, respectively. Results showed that 6 h of exposure to bisphenols (BPs) could increase the ROS levels, 24 h and 48 h of exposure could induce higher apoptosis and LDH leakage rates for HT-22 cells, and 7 d of exposure could inhibit the cell proliferations. In addition, non-monotonic dose-response relationships were observed between the concentrations of bisphenols and the toxic effects mentioned above. The neurotoxic effects of BPA, BPB and BPS on HT-22 cells were in the increasing order of BPS, BPA, and BPB. In conclusion, these results showed that exposure to BPA and its analogs may result in adverse effects on hippocampal neuronal cell lines. BPS is a surrogate with lower neurotoxicity to replace BPA in production of plastic utensils.

Bisphenol AF exerts estrogenic activity in MCF-7 cells through activation of Erk and PI3K/Akt signals via GPER signaling pathway

The negative health effects of bisphenol A (BPA) due to its estrogenic activity result in the increasing usage of alternative bisphenols (BPs) including bisphenol AF (BPAF). To comprehensive understand health effects of BPAF, the MCF-7 cells were used to investigate the effects of BPAF on cell proliferation, intracellular reactive oxygen species (ROS) formation, and calcium ion (Ca²⁺) level. The molecular mechanisms of cell biological responses caused by BPAF were investigated by analyzing target protein expression. The results showed that low-concentration BPAF induces significant effects on MCF-7 cells, including promoting cell proliferation and elevating intracellular ROS and Ca²⁺ levels. BPAF in low concentration significantly enhances the protein expression of estrogen receptor α (ERα), G protein-coupled receptor (GPER), c-Myc, and Cyclin D1, as well as increases phosphorylation levels of protein kinase B (Akt) and extracellular signal-regulated kinase (Erk) in MCF-7 cells. After the addition of ERα, GPER, and phosphatidylinositide 3-kinase (PI3K) inhibitors, phosphorylations of Erk and Akt were both inhibited. In addition, specific signal inhibitors significantly attenuated the effects of BPAF. Silencing of GPER also markedly decreased BPAF induced cell proliferation. The present results suggested that BPAF can activate PI3K/Akt and Erk signals via GPER, which, in turn, stimulate cellular biological effects induced by BPAF. ERα also plays a critical role in BPAF induced cellular biological effects.

Molecular mechanism of endocrine-disruptive effects induced by Bisphenol A: The role of transmembrane G-protein estrogen receptor 1 and integrin αvβ3

Bisphenol A (BPA) is one of the highest volume industrial products worldwide and has been widely used to make various products as the intermediates of polycarbonate plastics and epoxy resins. Inevitably, general population has been widely exposed to BPA due to extensive use of BPA-containing products. BPA has similar chemical structure with the natural estrogen and has been shown to induce a variety of estrogen-like endocrine effects on organism in vivo or in vitro. High doses of BPA tend to act as antagonist of estrogen receptors (ERs) by directly regulating the genomic transcription. However, BPA at environmentally relevant low-dose always disrupt the biological function via a non-genomic manner mediated by membrane receptors, rather than ERs. Although some studies had investigated the non-genomic effects of low-dose BPA, the exact molecular mechanism still remains unclear. Recently, we found that membrane G protein-coupled estrogen receptor 1 and integrin αvβ3 and its relative signal pathways participate in the induction of male germ cell proliferation and thyroid transcription disruption by the low-dose BPA. A profound understanding for the mechanism of action of the environmentally relevant BPA exposure not only contributes to objectively evaluate and predict the potential influence to human health, but also provides theoretical basis and methodological support for assessing health effects trigged by other estrogen-like environmental endocrine disruptors. Based mainly on our recent findings, this review outlines the research progress of molecular mechanism on endocrine disrupting effects of environmental low-dose BPA, existing problems and some consideration for future studies.

Low-concentration BPF induced cell biological responses by the ERα and GPER1-mediated signaling pathways in MCF-7 breast cancer cells

Bisphenol F (BPF), one of the alternatives to bisphenol A (BPA), can induce proliferation through the nuclear estrogen receptor ERα (estrogen receptor alpha) pathway in human breast cancer MCF-7 cells. However, the roles of membrane estrogen receptor GPER1 (G-protein-coupled receptor 1)-mediated signaling pathways in MCF-7 cell proliferation caused by BPF are unclear. The influence of BPF on MCF-7 cells was evaluated in terms of cell proliferation, intracellular calcium (Ca²⁺) fluctuations, and reactive oxygen species (ROS) generation. The molecular mechanisms of the cellular responses to low doses of BPF were studied through detecting the activations of ERα and GPER1-regulated PI3K/PKB or AKT (phosphatidylinotidol 3-kinase/protein kinase B) and ERK1/2 (extracellular-signa1-regulated kinase 1/2) signals. At 0.01-1 μM, BPF significantly promoted cell proliferation and elevated the levels of intracellular ROS and Ca²⁺. At these concentrations, BPF also significantly upregulated protein expressions of ERα, GPER1, c-myc, and cyclin D and phosphorylations of PKB and ERK1/2. Specific signal inhibitors decreased PKB and ERK1/2 phosphorylations and attenuated the effects of BPF. Silencing of GPER1 also significantly decreased BPF-induced cell proliferation. These results indicate that activating the GPER1-PI3K/PKB and ERK1/2 signals by low doses of BPF can regulate the response of MCF-7 cells and that ERα also influences the effects of exposure to BPF on the cells. The present study suggests a new mechanism by which BPF exerts relevant estrogenic action in cancer cells and also highlights the potential risks in using BPF as an alternative to BPA.

CLARITY-BPA academic laboratory studies identify consistent low-dose Bisphenol A effects on multiple organ systems

Bisphenol A (BPA) is a high-production chemical used in a variety of applications worldwide. While BPA has been documented as an endocrine-disrupting chemical (EDC) having adverse health-related outcomes in multiple studies, risk assessment for BPA has lagged due to reliance on guideline toxicology studies over academic ones with end-points considered more sensitive and appropriate. To address current controversies on BPA safety, the United States National Institute of Environmental Health Sciences (NIEHS), the National Toxicology Program (NTP) and the Food and Drug Administration (FDA) established the Consortium Linking Academic and Regulatory Insights on BPA Toxicity (CLARITY-BPA) using the NCTR Sprague-Dawley rats. The goal of CLARITY-BPA is to perform a traditional regulatory toxicology study (Core study) in conjunction with multiple behavioural, molecular and cellular studies by academic laboratories focused on previously identified BPA-sensitive organ systems (Academic studies). Combined analysis of the data from both study types will be undertaken by the NTP with the aim of resolving uncertainties on BPA toxicity. To date, the Core study has been completed and a draft report released. Most of the academic studies have also been finalized and published in peer-reviewed journals. In light of this important milestone, the PPTOX-VI meeting held in the Faroe Islands, 27-30 May 2018 devoted a plenary session to CLARITY-BPA with presentations by multiple investigators with the purpose of highlighting key outcome. This MiniReview synthesizes the results of three academic studies presented at this plenary session, evaluates recently published findings by other CLARITY-BPA academic studies to provide an early combined overview of this emerging data and places this in the context of the Core study findings. This co-ordinated effort revealed a plethora of significant BPA effects across multiple organ systems and BPA doses with non-monotonic responses across the dose range utilized. Remarkably consistent across most studies, including the Core study, are low-dose effects (2.5, 25 and 250 μg BPA/kg body-weight). Collectively, the findings highlighted herein corroborate a significant body of evidence that documents adverse effects of BPA at doses relevant to human exposures and emphasizes the need for updated risk assessment analysis.

Bisphenol A affects trophoblast invasion by inhibiting CXCL8 expression in decidual stromal cells

Bisphenol A (BPA), an environmental endocrine-disrupting organic chemical, has been positively associated with the rate of implantation failure of in vitro fertilization. However, the underlying mechanisms remain unclear. To reveal the impact and the underlying mechanism of BPA on the crosstalk between trophoblast and decidual stromal cells (DSCs), we determined whether BPA was able to affect trophoblast invasion in vitro. We found that BPA significantly inhibited CXCL8 expression in DSCs, which hindered trophoblast invasion, and activated the phosphorylation of ERK in DSCs. U0126, an inhibitor of ERK activation, remarkably rescued trophoblast invasion and the inhibition of CXCL8 expression caused by BPA treatment. Moreover, the nuclear estrogen receptor antagonist ICI 182,780 and transmembrane G protein-coupled receptor GPR30 (membrane estrogen receptor) antagonist G15 significantly blocked the phosphorylation of ERK and reversed the reduction of trophoblast invasion. In brief, BPA activated ERK through nuclear and membrane estrogen receptors and inhibited CXCL8 expression in DSCs, thereby affecting their regulation of trophoblast invasion.

Differential responses of GC‑1 spermatogonia cells to high and low doses of bisphenol A

Bisphenol A (BPA) is an environmental endocrine disruptor. The exact effect of BPA on spermatogenesis and the specific epigenetic effects on mouse spermatogonia remain to be elucidated. The present study exposed the GC‑1 spermatogonial cell line to a series of differing BPA concentrations and examined the subsequent effects on cell proliferation, mitogen activated protein kinase (MAPK) signaling, DNA and histone methylation. A Cell Counting Kit‑8 assay revealed that BPA significantly inhibited cell growth at the concentration of 10 µg/ml, however no significant alterations were detected at lower BPA doses. The global DNA methylation levels were reduced at the dose of 10 µg/ml of BPA, via detection of 5‑methylcytosine using a dot blot. The protein and mRNA expression levels of DNA methyltransferase (DNMT) 1 were decreased at 10 and 1 µg/ml of BPA, detected via western blotting and reverse transcription‑quantitative polymerase chain reaction, respectively. The global levels of H3K27me3 was decreased at 10 µg/ml BPA, detected via western blotting. Increased phosphorylation of p38 and decreased phosphorylation of extracellular signal‑regulated kinases 1/2 were observed at 10 and 1 µg/ml BPA. The results demonstrated that high and low doses of BPA exposure exhibit differential effects on cell growth, global DNA methylation, histone H3K9Me3 and H3K27Me3 levels and additionally affect the MAPK signaling pathways.

Acute effect of bisphenol A: Signaling pathways on calcium influx in immature rat testes

We investigated the acute effect of low concentrations of BPA on calcium influx and the mechanism of action of BPA in this rapid response in the rat testis. BPA increased calcium influx at 1 pM and 1 nM at 300 s of incubation, in a similar manner to that of estradiol. At 1 pM, BPA stimulated calcium influx independently of classical estrogen receptors, consistent with a G-protein coupled receptor. This effect also involves the modulation of ionic channels, such as K⁺, TRPV1 and Cl^- channels. Furthermore, BPA is able to modulate calcium from intracellular storages by inhibiting SERCA and activating IP₃ receptor/Ca²⁺ channels at the endoplasmic reticulum and activate kinase proteins, such as PKA and PKC. The rapid responses of BPA on calcium influx could, in turn, trigger a cross talk by MEK and p38^MAPK activation and also mediate genomic responses.

Low-concentration BPAF- and BPF-induced cell biological effects are mediated by ROS in MCF-7 breast cancer cells

Reactive oxygen species (ROS) induced by bisphenol A (BPA) have been implicated in cellular oxidative damage and carcinogenesis. It is not known whether the potential alternatives of BPA, bisphenol AF (BPAF), and bisphenol F (BPF) can also induce ROS involved in mediating biological responses. This study evaluated the toxicity of BPAF and BPF on cell proliferation, DNA damage, intracellular calcium homeostasis, and ROS generation in MCF-7 human breast cancer cells. The results showed that BPAF at 0.001-1 μM and BPF at 0.01-1 μM significantly increased cell viability and at 25 and 50 μM, both compounds decreased cell viability. At 0.01-10 μM, both BPAF and BPF increased DNA damage and significantly elevated ROS and intracellular Ca²⁺ levels in MCF-7 cells. These biological effects were attenuated by the ROS scavenger N-acetylcysteine (NAC), indicating that ROS played a key role in the observed biological effects of BPAF and BPF on MCF-7 cells. These findings can deepen our understanding on the toxicity of BPAF and BPF, and provide basis data to further evaluate the potential health harm and establish environmental standard of BPAF and BPF.

Melatonin inhibits the proliferation of breast cancer cells induced by bisphenol A via targeting estrogen receptor-related pathways

BACKGROUND

Background: Bisphenol A (BPA) is an estrogen-like chemical widely contained in daily supplies. There is evidence that environmental exposure to BPA could contribute to the development of hormone-related cancers. As is reported in numerous studies, melatonin, an endogenous hormone secreted by the pineal gland, could markedly inhibit estrogen-induced proliferation of breast cancer (BC) cells. In this study, we intended to reveal the effects of melatonin on BPA-induced proliferation of estrogen receptor-positive BC cells.

METHODS

Methods: We used methyl thiazolyl tetrazolium, luciferase reporter gene and western blotting assays to testify the effect of melatonin on BPA-mediated proliferation of MCF-7 and T47D cells.

RESULTS

Methyl thiazolyl tetrazolium and colony formation assays showed that melatonin could significantly abolish BPA-elevated cell proliferation. Meanwhile, BPA-upregulated phosphorylation of ERK and AKT was decreased by melatonin treatment. Mechanistically, we found that BPA was capable of upregulating the protein levels of steroid receptor coactivators (SRC-1, SRC-3), as well as promoting the estrogen response element activity. However, the addition of melatonin could remarkably block the elevation of steroid receptor coactivators expression and estrogen response element activity triggered by BPA.

CONCLUSION

Conclusions: Therefore, these results demonstrated that melatonin could abrogate BPA-induced proliferation of BC cells. Therapeutically, melatonin could be regarded as a potential medication for BPA-associated BC.

Diethylstilbestrol regulates mouse gubernaculum testis cell proliferation via PLC-Ca2+ -CREB pathway

Recent evidence suggested a positive correlation between environmental estrogens (EEs) and high incidence of abnormalities in male urogenital system, but the mechanism remains unclear. Diethylstilbestrol (DES) is a nonsteroidal synthetic estrogen that disrupts the morphology and proliferation of gubernaculum testis cells, but the underlying mechanism is unclear. In this study, mouse gubernaculum testis cells were pretreated with phospholipase C (PLC) inhibitor U-73122 and then treated with DES. The results demonstrated that U-73122 impaired DES-evoked intracellular Ca2+ mobilization in gubernaculum testis cells and inhibited DES-induced proliferation of gubernaculum testis cells. Mechanistically, we found that U-73122 inhibited DES-induced activation of cAMP-response element binding protein (CREB) in gubernaculum testis cells. In conclusion, these data suggest that the effects of DES on mouse gubernaculum testis cells are mediated by PLC-Ca²⁺ -CREB pathway.

SIGNIFICANCE OF THE STUDY

Environmental estrogens remain a serious threat to male reproductive health, and it is important to understand the mechanism by which EEs affect the male productive system. Here we explore potential mechanisms how the proliferation and contractility of gubernaculum testis cells are regulated by diethylstilbestrol. Our findings provide the first evidence that PLC-Ca²⁺ -CREB signalling pathway mediates the nongenomic effects of diethylstilbestrol on gubernaculum testis cells. These findings provide new insight into the role of diethylstilbestrol in the aetiology of male reproductive dysfunction and will help develop better approaches for the prevention and therapy of male reproductive malformation.

Bisphenol A induces proliferative effects on both breast cancer cells and vascular endothelial cells through a shared GPER-dependent pathway in hypoxia

Based on the breast cancer cells and the vascular endothelial cells are both estrogen-sensitive, we proposed a close reciprocity existed between them in the tumor microenvironment, via shared molecular mechanism affected by environmental endocrine disruptors (EDCs). In this study, bisphenol A (BPA), via triggering G-protein estrogen receptor (GPER), stimulated cell proliferation and migration of bovine vascular endothelial cells (BVECs) and breast cancer cells (SkBr-3 and MDA-MB-231) and enhanced tumor growth in vivo. Moreover, the expression of both hypoxia inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF) were up-regulated in a GPER-dependent manner by BPA treatment under hypoxic condition, and the activated GPER induced the HIF-1α expression by competitively binding to caveolin-1 (Cav-1) and facilitating the release of heat shock protein 90 (HSP90). These findings show that in a hypoxic microenvironment, BPA promotes HIF-1α and VEGF expressions through a shared GPER/Cav-1/HSP90 signaling cascade. Our observations provide a probable hypothesis that the effects of BPA on tumor development are copromoting relevant biological responses in both vascular endothelial and breast cancer cells.

Submicromolar bisphenol A induces proliferation and DNA damage in human hepatocyte cell lines in vitro and in juvenile rats in vivo

An association between bisphenol A (BPA) exposure and hepatic tumors was suggested, but the employment of high-dose levels raises questions about its relevance to human health. Here, we demonstrate that submicromolar concentrations of BPA induce the proliferation and DNA damage in human hepatocyte cell lines. In HepG2 and NKNT-3, undifferentiated and differentiated hepatocyte cell lines, respectively, submicromolar BPA concentrations promoted the cell proliferation, as indicated by enhanced DNA synthesis and elevated expression of cell-cycle proteins. At concentrations higher than 10 μM, these effects disappeared, reflecting a non-monotonic dose-response relationship. Notably, histone H2AX was activated following exposure to BPA, which is a sensitive marker of DNA damage. Importantly, proliferative foci and DNA damage were also observed in liver tissue of rats orally exposed to BPA at 0.5 mg/kg for 90 days, from juvenile age (postnatal day 9) through adulthood. Reactive oxygen species appeared to play a role in the BPA-induced proliferation and DNA damage, as evidenced by a partial reversal of both processes upon pretreatment with an antioxidant, N-acetylcysteine. Collectively, these results demonstrate that submicromolar BPA concentrations induce the DNA damage and promote the cell proliferation in the liver, which may support its role as a risk factor for hepatocarcinogenicity.

Calycosin inhibits the in vitro and in vivo growth of breast cancer cells through WDR7-7-GPR30 Signaling

BACKGROUND

Clinically, breast cancer is generally classified into estrogen receptor-positive (ER+) or estrogen receptor-negative (ER-) subtypes. The phytoestrogen calycosin has been shown to inhibit the proliferation of ER+ cells, which may be mediated by a feedback loop that involves miR-375, RAS dexamethasone-induced 1 (RASD1), and ERα. However, how calycosin acts on ER- breast cancer cells remains unclear.

RESULTS

Here, we show that calycosin inhibited the proliferation of both ER- (MDA-MB-468 and SKBR3) and ER+ breast cancer cells (MCF-7 and T47D) and that these inhibitory effects were associated with the up-regulation of the long non-coding RNA (lncRNA) WDR7-7. For the first time, we demonstrate that the expression of WDR7-7 is reduced in breast cancer cell lines and that the overexpression of WDR7-7 inhibits growth through a mechanism that involves G-protein coupled estrogen receptor 30 (GPR30). Meanwhile, we show that calycosin stimulated the WDR7-7-GPR30 signaling pathway in MCF-7, T47D, MDA-MB-468, and SKBR3 breast cancer cells. In contrast, in MCF10A and GPR30-deficient MDA-MB-231 cells, due to a lack of WDR7-7-GPR30 for activation, calycosin failed to inhibit cell growth. Additionally, in all four GPR30-positive breast cancer lines, calycosin decreased the phosphorylation levels of SRC, EGFR, ERK1/2 and Akt, but the inhibition of WDR7-7 blocked these changes and increased proliferation. In mice bearing MCF-7 or SKBR3 xenografts, tumor growth was inhibited by calycosin, and changes in expression the levels of WDR7-7 and GPR30 in tumor tissues were similar to those in cultured MCF-7 and SKBR3 cells.

CONCLUSIONS

These results suggest the possibility that calycosin inhibited the proliferation of breast cancer cells, at least partially, through WDR7-7-GPR30 signaling, which may explain why calycosin can exert inhibitory effects on ER- breast cancer.

Bisphenol AF and Bisphenol B Exert Higher Estrogenic Effects than Bisphenol A via G Protein-Coupled Estrogen Receptor Pathway

Numerous studies have indicated estrogenic disruption effects of bisphenol A (BPA) analogues. Previous mechanistic studies were mainly focused on their genomic activities on nuclear estrogen receptor pathway. However, their nongenomic effects through G protein-coupled estrogen receptor (GPER) pathway remain poorly understood. Here, using a SKBR3 cell-based fluorescence competitive binding assay, we found six BPA analogues bound to GPER directly, with bisphenol AF (BPAF) and bisphenol B (BPB) displaying much higher (∼9-fold) binding affinity than BPA. Molecular docking also demonstrated the binding of these BPA analogues to GPER. By measuring calcium mobilization and cAMP production in SKBR3 cells, we found the binding of these BPA analogues to GPER lead to the activation of subsequent signaling pathways. Consistent with the binding results, BPAF and BPB presented higher agonistic activity than BPA with the lowest effective concentration (LOEC) of 10 nM. Moreover, based on the results of Boyden chamber and wound-healing assays, BPAF and BPB displayed higher activity in promoting GPER mediated SKBR3 cell migration than BPA with the LOEC of 100 nM. Overall, we found two BPA analogues BPAF and BPB could exert higher estrogenic effects than BPA via GPER pathway at nanomolar concentrations.

Bisphenol A affects cell viability involved in autophagy and apoptosis in goat testis sertoli cell

Bisphenol A (BPA) is shown to be the endocrine disruptor that induces reproductive dysfunction in male animals. In this study, we aim to probe the effects of BPA exposure on induction of autophagy in goat Sertoli Cells (gSCs), as well as the relationship between autophagy and apoptosis. Results indicated that exposure to BPA (100, 200, 300, 400, 500 and 600μM) decreased the cell viability in a concentration-dependent manner. Exposure of gSCs to 500μM BPA for 12h resulted in in vitro triggered loss of mitochondrial membrane potential (ΔΨm) and increased reactive oxygen species (ROS) production. Apoptosis with an increase in Bax:Bcl-2 ratio and higher rates of autophagy, such as autophagosome formation and increased expression of autophagy-related markers were also induced in gSCs exposed to 500μM BPA. Furthermore, treatment with 350nM Rapamycin (Rap, autophagy activator) alleviated a decrease in cell viability, intracellular ROS production, and reduction of ΔΨm, as well as decreasing apoptosis. Collectively, our results indicated that gSCs viability was disrupted after BPA treatment through affecting ROS production, mitochondrial membrane potential and inducing autophagy/apoptosis.

Bisphenol A Affects on the Functional Properties and Proteome of Testicular Germ Cells and Spermatogonial Stem Cells in vitro Culture Model

The endocrine disruptor bisphenol A (BPA) is well known for its adverse effect on male fertility. Growing evidence suggests that BPA may interact with testicular germ cells and cause infertility as a result of its estrogenic activity. Objective of current in vitro study was to investigate the proliferation, survivability and stemness properties of mouse testicular germ cells exposed to BPA, and to evaluate possible expression of cellular proteome. Our results showed that germ cell viability and proliferation were not affected by low concentrations (0.01, 0.1, 1, and 10 µM) although significant reduction observed at 100 µM BPA. Germ cell self-renewal and differentiation related marker proteins expression found unchanged at those concentrations. When BPA-exposed germ cells were transplanted into recipient testes, we observed fewer colonies at higher concentrations (10 and 100 µM). Additionally, a significant frequency of recombination failure during meiosis was observed in 10 µM BPA-exposed germ cell transplanted recipient. Moreover, experiment on continuous BPA-exposed and 100 µM BPA-recovered germ cells suggested that spermatogonial stem cells are more potential to survive in adverse environment. Finally, scrutinizing differentially expressed cellular proteins resulted from our proteomic analysis, we conclude that BPA exposure might be associated with several health risks and infertility.

Bisphenol S exposure modulate macrophage phenotype as defined by cytokines profiling, global metabolomics and lipidomics analysis

As an important structural analogue of bisphenol A (BPA), bisphenol S (BPS) has been used as alternatives to BPA in industrialized production. However, the immunotoxicity of BPS remains poorly understood. As a critical model in inflammatory responses, macrophages are used to explore the immunotoxic potential and mechanisms of BPS at environmentally relevant concentrations in our study. Here, we are combining molecular toxicology and mass spectrometry (MS)-based global metabolomics and lipidomics study together to estimate the variation of cytokines profiling and metabolism characteristic following BPS exposure. Our results demonstrated that BPS exposure induced pro-inflammatory phenotype by activating the immuno-related cytokines which include TNF-α, IL-1β and IL-6, modulating metabolic pathways which include glycolytic, glutathione (GSH), sphingomyelin (SM)-ceramide (Cer), glycerophospholipids (GPs) and glycerolipids (GLs). These toxicological mechanisms are providing us with a deeper understanding of the critical role of metabolites and lipids reprogramming in immunotoxicity of BPS.