Hormone-Like Effects of Bisphenol A on p53 and Estrogen Receptor Alpha in Breast Cancer Cells

Metabolic status is a key factor influencing proteomic changes in ewe granulosa cells induced by chronic BPS exposure

BACKGROUND

Bisphenol S (BPS) is the main substitute for bisphenol A (BPA), a well-known plasticiser and endocrine disruptor. BPS disrupts ovarian function in several species. Moreover, a few studies have reported that the effects of BPS might be modulated by the metabolic status, and none have characterised the granulosa cell (GC) proteome after chronic BPS exposure.

OBJECTIVES

This study aimed to decipher the mechanisms of action of chronic BPS exposure on the proteome of ewe GCs while considering the interaction between a deliberate contrasted metabolism and reproductive function.

METHODS

Forty ewes were split into two groups with contrasted diets: restricted (R, n = 20) and well-fed (WF, n = 20). The R and WF ewes were subdivided according to the dose of BPS administered through the diet (0-50 µg/kg/day), forming four groups: R0, R50, WF0 and WF50. After 3-month BPS daily exposure, GCs were recovered during the pre-ovulatory stage and proteins were analysed by nano-liquid chromatography coupled with tandem mass spectrometry.

RESULTS

Chronic exposure to BPS affected the GC proteome differently according to the ewe metabolic status. Fifty-nine out of 958 quantified proteins were differentially abundant between groups and are mainly involved in carbohydrate and lipid pathways. Unsupervised hierarchical clustering of differentially abundant proteins (DAPs) identified four clusters of 34, 6, 5 and 14 proteins according to the BPS exposure and diet interaction. Pairwise comparisons between groups also revealed a strong effect of BPS exposure and diet interaction. Functional analysis of DAPs highlighted that BPS upregulated β-glucuronidase (GUSB; p = 0.002), a protein especially able to deconjugate bisphenol glucuronides (BP-g). Moreover, among unexposed ewes, GUSB was detected only in well-fed ewes.

DISCUSSION

Conjugation of glucuronides inhibits the oestrogenic activity of bisphenols. Upregulation of GUSB in ewes dosed with BPS would prolong the oestrogenic effects of BPS by deconjugating BPS-g into free BPS. In addition, literature has reported an up-regulation of GUSB in people suffering from obesity. Therefore, people suffering from obesity could be subjected to prolonged and aggravated exposure to BPS. These data highlighted the deleterious effects of BPS and its interaction with metabolic status.

Predicting p53-dependent cell transitions from thermodynamic models

A cell's fate involves transitions among its various states, each defined by a distinct gene expression profile governed by the topology of gene regulatory networks, which are affected by 3D genome organization. Here, we develop thermodynamic models to determine the fate of a malignant cell as governed by the tumor suppressor p53 signaling network, taking into account long-range chromatin interactions in the mean-field approximation. The tumor suppressor p53 responds to stress by selectively triggering one of the potential transcription programs that influence many layers of cell signaling. These range from p53 phosphorylation to modulation of its DNA binding affinity, phase separation phenomena, and internal connectivity among cell fate genes. We use the minimum free energy of the system as a fundamental property of biological networks that influences the connection between the gene network topology and the state of the cell. We constructed models based on network topology and equilibrium thermodynamics. Our modeling shows that the binding of phosphorylated p53 to promoters of target genes can have properties of a first order phase transition. We apply our model to cancer cell lines ranging from breast cancer (MCF-7), colon cancer (HCT116), and leukemia (K562), with each one characterized by a specific network topology that determines the cell fate. Our results clarify the biological relevance of these mechanisms and suggest that they represent flexible network designs for switching between developmental decisions.

Bisphenol-A in Drinking Water Accelerates Mammary Cancerogenesis and Favors an Immunosuppressive Tumor Microenvironment in BALB-neuT Mice

Bisphenol-A (BPA), a synthetic compound ubiquitously present in the environment, can act as an endocrine disruptor by binding to both canonical and non-canonical estrogen receptors (ERs). Exposure to BPA has been linked to various cancers, in particular, those arising in hormone-targeted tissues such as the breast. In this study, we evaluated the effect of BPA intake through drinking water on ErbB2/neu-driven cancerogenesis in BALB-neuT mice, transgenic for a mutated ErbB2/neu receptor gene, which reproducibly develop carcinomas in all mammary glands. In this model, BPA accelerated mammary cancerogenesis with an increase in the number of tumors per mouse and a concurrent decrease in tumor-free and overall survival. As assessed by immunohistochemistry, BALB-neuT tumors were ER-negative but expressed high levels of the alternative estrogen receptor GPR30, regardless of BPA exposure. On the other hand, BPA exposure resulted in a marked upregulation of progesterone receptors in preinvasive tumors and of Ki67, CD31, and phosphorylated Akt in invasive tumors. Moreover, based on several infiltration markers of immune cells, BPA favored an immunosuppressive tumor microenvironment. Finally, in vitro cell survival studies performed on a cell line established from a BALB-neuT breast carcinoma confirmed that BPA's impact on cancer progression can be particularly relevant after chronic, low-dose exposure.

A cohort study investigating the role of Bisphenol A in the molecular pathogenesis of breast cancer

BACKGROUND

Breast cancer is an abnormal division of breast cells. Bisphenol A (BPA), an environmental toxicant, is identified as an emerging risk factor for breast cancer development. However, to the best of our knowledge, no previous study has investigated the BPA levels in breast cancer patients in Pakistan. The present study sought to explore the role of BPA in tumor growth among the Pakistani population.

METHODS

The levels of BPA were analyzed in the serum samples of breast cancer patients and controls by using HPLC. To elucidate the role of BPA to initiate tumorigenic events in breast tissue different biochemical assays along with expression analysis of tumor markers were performed.

RESULTS

The level of BPA in the serum samples of breast cancer patients was significantly higher than control. Histological analysis of breast cancer tissue samples revealed distinct subtypes of tumor, such as ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC). There was a significant increase in ROS level while a significant decrease in the levels of superoxide dismutase (SOD) and catalase (CAT) enzymes in malignant breast tissue samples as compared to control tissue samples. We found upregulated expression of p53, ZEB1 and WNT1 genes at mRNA level in malignant breast tissue samples by 17 folds, 328 folds and 35 folds, respectively. p53 protein expression in malignant breast tissue samples was also enhanced at the translational level.

CONCLUSION

Current findings suggest a relationship between BPA and the progression of breast cancer among the Pakistani population.

Toxicity of bisphenol A (BPA) and its derivatives in divers biological models with the assessment of molecular mechanisms of toxicity

The aim of the study was to determine totoxicity of bisphenol A (BPA) and its derivatives (bisphenol S (BPS), bisphenol F (BPF), and tetrabromobisphenol A (TBBPA)) due to its high accumulation in environment. The performed analysis revealed the toxicity of the BPA, BPF, and BPS against Kurthia gibsoni, Microbacterium sp., and Brevundimonas diminuta as the most sensitive, reaching microbial toxic concentrations in the range of 0.018-0.031 mg ∙ L^-1. Moreover, the genotoxicity assay shows the ability of all tested compounds to increase in the β-galactosidase level at the concentration range 7.81-500 µM (in Escherichia coli, PQ37). In turn, the matbolic activation of tested bishpenols has caused the enhacement of the genotoxicity and cytotoxicity effect. Interestingely, the highest phytotoxicity effect was pointed for BPA and TBBPA at the concentrations of 10 mg ∙ L^-1 and 50 mg ∙ L^-1, which cause the inhibition of root growth by 58% and 45%, respectively (especially for S. alba and S. saccharatum). Furthermore, the cytotoxicity analyses show the ability of BPA, BPS, and TBBPA to significantly decrease the metabolic activity of human keratynoctes in vitro after 24 h of treatment at the micromolar concentrations. Simialry, the impact of the certain bisphenols on proliferation-, apoptosis-, and inflammation-related mRNA expression was shown in tested cell line. Summarizing, the presented results have proved that BPA and its derrivatives are able to show high negative effect on certain living orgnisms such as bacteria, plants, and human cells, which is strict related to pro-apoptotic and genotoxic mechanism of action.

Dysregulation of P53 in breast cancer: Causative factors and treatment strategies

One of the most prevalent cancers impacting women worldwide is breast cancer. Although there are several risk factors for breast cancer, the p53 gene's function has recently received much attention. The "gatekeeper" gene, or p53, is sometimes referred to as such since it is crucial in controlling cell proliferation and preventing the development of malignant cells. By identifying DNA damage and initiating cellular repair processes, p53 usually functions as a tumor-suppressor. But p53 gene alterations can result in a lack of function, allowing cells to divide out of control and perhaps triggering the onset of cancer. Various factors, such as mutation genes, signaling pathways, and hormones, can dysregulate P53 proteins and cause breast cancer. A promising strategy for individualized cancer treatment involves focusing on p53 mutations in breast cancer. While numerous techniques, including gene therapy and small compounds, have shown promise, further study is required to create safe and efficient treatments to target p53 mutations in breast cancer successfully.

Repeated exposure to 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP) accelerates ligand-independent activation of estrogen receptors in long-term estradiol-deprived MCF-7 cells

It was previously identified that there may be an active metabolite of bisphenol A (BPA), 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP). An in vitro system was developed to detect MBP toxicity to the Michigan Cancer Foundation-7 (MCF-7) cells that had been repeatedly exposed to a low dose of the metabolite. MBP profoundly activated estrogen receptor (ER)-dependent transcription as a ligand, with an EC₅₀ of 2.8 nM. Women are continuously exposed to numerous estrogenic environmental chemicals; but their susceptibility to these chemicals may be significantly altered after menopause. Long-term estrogen-deprived (LTED) cells, which display ligand-independent ER activation, are a postmenopausal breast cancer model derived from MCF-7 cells. In this study, we investigated the estrogenic effects of MBP on LTED cells in a repeated exposure in vitro model. The results suggest that i) nanomolar levels of MBP reciprocally disrupt the balanced expression of ERα and ERβ proteins, leading to the dominant expression of ERβ, ii) MBP stimulates ERs-mediated transcription without acting as an ERβ ligand, and iii) MBP utilizes mitogen-activated protein kinase and phosphatidylinositol-3 kinase signaling to evoke its estrogenic action. Moreover, the repeated exposure strategy was effective for detecting low-dose estrogenic-like effects caused by MBP in LTED cells.

Bisphenol A and bisphenol S both disrupt ovine granulosa cell steroidogenesis but through different molecular pathways

BACKGROUND

Ovarian granulosa cells (GC) are essential for the development and maturation of a proper oocyte. GC are sensitive to endocrine disruptors, including bisphenol A (BPA) and its analogue bisphenol S (BPS), plasticisers present in everyday consumer products. BPA exhibits greater binding affinity for the membrane oestrogen receptor (GPER) than for the nuclear oestrogen receptors (ERα and ERβ). Here, we analysed the effects of BPA and BPS on the steroidogenesis of ovine GC in vitro, as well as their early mechanisms of action, the ovine being a relevant model to study human reproductive impairment. Disruption of GC steroidogenesis might alter oocyte quality and consequently fertility rate. In addition, we compared the effects of a specific GPER agonist (G-1) and antagonist (G-15) to those of BPA and BPS. Ewe GC were cultured with BPA or BPS (10 or 50 µM) or G-1 (1 µM) and/or G-15 (10 µM) for 48 h to study steroidogenesis.

RESULTS

Both BPA and BPS (10 µM) altered the secretion of progesterone, however, only BPS (10 µM) affected oestradiol secretion. RNA-seq was performed on GC after 1 h of culture with BPA or BPS (50 µM) or G-1 (10 µM), followed by real-time PCR analyses of differentially expressed genes after 12, 24 and 48 h of culture. The absence of induced GPER target genes showed that BPA and BPS did not activate GPER in GC after 1 h of treatment. These molecules exhibited mainly independent early mechanisms of action. Gene ontology analysis showed that after 1 h of treatment, BPA mainly disrupted the expression of the genes involved in metabolism and transcription, while BPS had a smaller effect and impaired cellular communications. BPA had a transient effect on the expression of CHAC1 (NOTCH signalling and oxidative balance), JUN (linked to MAPK pathway), NR4A1 (oestradiol secretion inhibition), ARRDC4 (endocytose of GPCR) and KLF10 (cell growth, differentiation and apoptosis), while expression changes were maintained over time for the genes LSMEM1 (linked to MAPK pathway), TXNIP (oxidative stress) and LIF (cell cycle regulation) after 12 and 48 h, respectively.

CONCLUSION

In conclusion, although they exhibited similar effects, BPA and BPS impaired different molecular pathways in GC in vitro. New investigations will be necessary to follow the temporal changes of these genes over time, as well as the biological processes involved.

Bisphenol S Alters the Steroidome in the Preovulatory Follicle, Oviduct Fluid and Plasma in Ewes With Contrasted Metabolic Status

Bisphenol A (BPA), a plasticizer and endocrine disruptor, has been substituted by bisphenol S (BPS), a structural analogue that had already shown adverse effects on granulosa cell steroidogenesis. The objective of this study was to assess the effect of chronic exposure to BPS, a possible endocrine disruptor, on steroid hormones in the ovary, oviduct and plasma using the ewe as a model. Given the interaction between steroidogenesis and the metabolic status, the BPS effect was tested according to two diet groups. Eighty adult ewes were allotted to restricted (R) and well-fed (WF) groups, that were further subdivided into two subgroups. Ewes were exposed to 50 µg BPS/kg/day in their diet (R50 and WF50 groups) or were unexposed controls (R0 and WF0 groups). After at least 3 months of BPS exposure, preovulatory follicular fluid, oviduct fluid and plasma were collected and steroid hormones were analyzed by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). A deleterious effect of restricted diet on the volume of oviduct fluid and numbers of pre-ovulatory follicles was observed. Exposure to BPS impaired estradiol concentrations in both follicular and oviduct fluids of well-fed ewes and progesterone, estradiol and estrone concentrations in plasma of restricted ewes. In addition, a significant interaction between metabolic status and BPS exposure was observed for seven steroids, including estradiol. In conclusion, BPS acts in ewes as an endocrine disruptor with differential actions according to metabolic status.

Effects of electrospun fiber curcumin on bisphenol A exposed Caco-2 cells

Curcumin; the major polyphenolic compound, isolated from Curcuma longa L.; loaded polyvinylpyrrolidone K90 fibers were prepared using electrospinning method. Effectiveness was tested on human colorectal adenocarcinoma cells with the presence of the endocrine disrupter Bisphenol A. Curcumin-loaded fibers were shown to have good physicochemical properties where excellent morphology of the electrospin fibers were formed. With the presence of 8 nM Bisphenol A, 17.37 mM fibers were found to inhibit proliferation in the cells in a dose-dependent manner. Fibers induced a significant increase in malondialdehyde by Thiobarbituric Acid Reactive Substances Assay compared to the control and this effect was supported by the presence of Bisphenol A. Western blot results indicate Super Oxide Dismutase-1 levels were increased by fiber, while Bisphenol A coincubated group resulted in a decrease. Fibers increased the expression of Estrogen Receptor 2, while Estrogen Receptor 1 expression did not change. Estrogen Receptor 2 expression was increased by coincubation with Bisphenol A; indicating a possible role of Estrogen Receptor 2 in the protective effects of fiber. This study presents that fiber had enhanced bioavailability and solubility with increased anticancer effect in human colon adenocarcinoma cells in presence of Bisphenol A; where involved mechanisms are antioxidant system and estrogen receptor expression.

Understanding the Mechanistic Link between Bisphenol A and Cancer Stem Cells: A Cancer Prevention Perspective

Endocrine disruptors, such as bisphenol A (BPA), have become more frequently present in the environment as contaminants, especially in industrialized countries. Long-term effects of these environmental contaminants in humans are elusive. With their structural similarity to estrogen, many environmental contaminants including BPA, have been shown to mimic the biological functions of estrogen, potentially contributing to the development of breast cancer. It has been well established that BPA exerts estrogenic activity in animal models and in vitro systems. There is a concern for adverse effects from the exposure to BPA in regard to developmental and reproductive toxicities. However, the mechanisms by which BPA promotes breast cancer development remain unknown. Understanding the role of endocrine disruptors and their key mechanisms of action is important for public health, especially by providing a foundation for a better intervention approach in cancer prevention.

Cadmium promotes breast cancer cell proliferation, migration and invasion by inhibiting ACSS2/ATG5-mediated autophagy

Cadmium (Cd), which is considered a carcinogenic metal, promotes breast cancer (BC) progression, but the precise mechanism remains unclear. Herein, MCF-7 and T47-D cells were treated with 0.1, 1, and 10 μM cadmium chloride (CdCl2) for 24, 48 and 72 h. In our study, Cd exposure significantly accelerated the proliferation, migration and invasion of MCF-7 and T47-D cells. Notably, Cd inhibited autophagic flux by suppressing ATG5-dependent autophagosome formation but had no significant effect on autophagosome-lysosome fusion and lysosomal function. The genetic enhancement of autophagy through ATG5 overexpression suppressed the Cd-mediated increases in proliferation, migration and invasion, which indicated a carcinogenic role of autophagy impairment in Cd-exposed BC cells. GSEA and GeneMANIA were utilized to demonstrate that the Cd-induced decrease in ACSS2 expression mechanistically inhibited ATG5-dependent autophagy in BC cells. Importantly, ACSS2 overexpression increased the level of H3K27 acetylation in the promoter region of ATG5, and this result maintained autophagic flux and abolished the Cd-induced increases in proliferation, migration and invasion. We also verified that the expression of ACSS2 in BC tissues was low and positively related to ATG5 expression. These findings indicated that the promoting effect of Cd on BC cell proliferation, migration and invasion through the impairment of ACSS2/ATG5-dependent autophagic flux suggests a new mechanism for BC cell proliferation and metastasis stimulated by Cd.

Bisphenols and Risk of Breast Cancer: A Narrative Review of the Impact of Diet and Bioactive Food Components

Data from preclinical studies suggest a link between increased risk of breast cancer and exposure to bisphenols at doses below what the United States Food and Drug Administration (FDA) considers as safe for consumption. Bisphenols exert estrogenic effects and are found in canned and plastic wrapped foods, food packaging, and plasticware. Mechanistically, bisphenols bind to the estrogen receptor (ER) and activate the expression of genes associated with cell proliferation and breast cancer. In this paper, we present a narrative literature review addressing bisphenol A and chemical analogs including bisphenol AF, bisphenol F, and bisphenol S selected as prototype xenoestrogens; then, we discuss biological mechanisms of action of these bisphenols in breast cells and potential impact of exposure at different stages of development (i.e., perinatal, peripubertal, and adult). Finally, we summarize studies detailing interactions, both preventative and promoting, of bisphenols with food components on breast cancer risk. We conclude the review with a discussion of current controversies in interpretation of the above research and future areas for investigation, including the impact of bisphenols and food components on breast tumor risk.

Oncogenic Potential of Bisphenol A and Common Environmental Contaminants in Human Mammary Epithelial Cells

There is an ample epidemiological evidence to support the role of environmental contaminants such as bisphenol A (BPA) in breast cancer development but the molecular mechanisms of their action are still not fully understood. Therefore, we sought to analyze the effects of three common contaminants (BPA; 4-tert-octylphenol, OP; hexabromocyclododecane, HBCD) on mammary epithelial cell (HME1) and MCF7 breast cancer cell line. We also supplied some data on methoxychlor, MXC; 4-nonylphenol, NP; and 2-amino-1-methyl-6-phenylimidazo [4-b] pyridine, PhIP. We focused on testing the prolonged (two months) exposure to low nano-molar concentrations (0.0015-0.0048 nM) presumed to be oncogenic and found that they induced DNA damage (evidenced by upregulation of pH2A.X, pCHK1, pCHK2, p-P53) and disrupted the cell cycle. Some agents induced epigenetic (methylation) changes of tumor suppressor genes TIMP3, CHFR, ESR1, IGSF4, CDH13, and GSTP1. Obviously, the accumulation of these molecular alterations is an essential base for cancer development. Consistent with this, we observed that these agents increased cellular invasiveness through collagen. Cellular abilities to form colonies in soft agar were increased for MCF7. Toxic agents induced phosphorylation of protein kinase such as EGFR, CREB, STAT6, c-Jun, STAT3, HSP6, HSP27, AMPKα1, FAK, p53, GSK-3α/β, and P70S6 in HME1. Most of these proteins are involved in potential oncogenic pathways. Overall, these data clarify the molecular alterations that can be induced by some common environmental contaminants in mammary epithelial cells which could be a foundation to understand environmental carcinogenesis.