A novel shift in estrogen receptor expression occurs as estradiol suppresses inflammation-associated colon tumor formation

Estrogen Alleviates Oxidative Bowel Injury and Neuroinflammation in Necrotizing Enterocolitis

INTRODUCTION

High mortality and morbidity of neonates with necrotizing enterocolitis (NEC) necessitates the investigation of novel therapies to improve outcomes. It was aimed to elucidate the potential therapeutic effect of estrogen receptor agonists on NEC-induced intestinal and brain injury in rats.

METHODS

Sprague-Dawley pups of both sexes were separated from their mothers at postnatal 5th d. Feeding with formula along with a single session of hypoxia was applied to induce NEC, while control pups were kept with their mothers. The NEC rats received either vehicle, estrogen receptor α (ERα) agonist propyl pyrazole triol (1 mg/kg/day), ERβ agonist diarylpropionitrile (1 mg/kg/day), or 17β-estradiol (1 mg/kg/day) during maternal separation. All pups were decapitated on postnatal 9th d to collect intestinal and brain tissue samples.

RESULTS

Elevation in proinflammatory cytokines, apoptosis, and microscopically and biochemically evident oxidative injury in both the intestinal and brain tissues were observed in NEC-induced pups. In both the intestinal and brain tissues, nerve growth factor and brain-derived neurotrophic factor protein levels were depleted, expressions of both the ESR1 and ESR2 genes were downregulated, while treatment with 17β-estradiol or ER agonists alleviated extent of oxidative injury of the intestines and brain tissue, upregulated nerve growth factor, brain-derived neurotrophic factor, and ER gene expressions, abolished NEC-induced decrease in claudin-3 expression, increased the survival rates, improved the clinical states of the survived pups at varying degrees.

CONCLUSIONS

Activation of estrogen signaling by receptor agonists alleviated NEC-induced intestinal and cerebral injury, implicating that estrogen agonists could be regarded as promising preventive/therapeutic agents for NEC.

17β-estradiol in colorectal cancer: friend or foe?

Colorectal cancer (CRC) is a common gastrointestinal malignancy with higher incidence and mortality rates in men compared to women, potentially due to the effects of estrogen signaling. There is substantial evidence supporting the significant role of 17β-Estradiol (E2) in reducing CRC risk in females, although this perspective remains debated. E2 has been demonstrated to inhibit CRC cell proliferation and migration at the cellular level by enhancing DNA mismatch repair, modulating key gene expression, triggering cell cycle arrest, and reducing activity of migration factors. Furthermore, E2 contributes to promote a tumor microenvironment unfavorable for CRC growth by stimulating ERβ expression, reducing inflammatory responses, reversing immunosuppression, and altering the gut microbiome composition. Conversely, under conditions of high oxidative stress, hypoxia, and nutritional deficiencies, E2 may facilitate CRC development through GPER-mediated non-genomic signaling. E2's influence on CRC involves the genomic and non-genomic signals mediated by ERβ and GPER, respectively, leading to its dual roles in anticancer activity and carcinogenesis. This review aims to summarize the potential mechanisms by which E2 directly or indirectly impacts CRC development, providing insights into the phenomenon of sexual dimorphism in CRC and suggesting potential strategies for prevention and treatment.

Delineating the role of nuclear receptors in colorectal cancer, a focused review

Colorectal cancer (CRC) stands as one of the most prevalent form of cancer globally, causing a significant number of deaths, surpassing 0.9 million in the year 2020. According to GLOBOCAN 2020, CRC ranks third in incidence and second in mortality in both males and females. Despite extensive studies over the years, there is still a need to establish novel therapeutic targets to enhance the patients' survival rate in CRC. Nuclear receptors (NRs) are ligand-activated transcription factors (TFs) that regulate numerous essential biological processes such as differentiation, development, physiology, reproduction, and cellular metabolism. Dysregulation and anomalous expression of different NRs has led to multiple alterations, such as impaired signaling cascades, mutations, and epigenetic changes, leading to various diseases, including cancer. It has been observed that differential expression of various NRs might lead to the initiation and progression of CRC, and are correlated with poor survival outcomes in CRC patients. Despite numerous studies on the mechanism and role of NRs in this cancer, it remains of significant scientific interest primarily due to the diverse functions that various NRs exhibit in regulating key hallmarks of this cancer. Thus, modulating the expression of NRs with their agonists and antagonists, based on their expression levels, holds an immense prospect in the diagnosis, prognosis, and therapeutical modalities of CRC. In this review, we primarily focus on the role and mechanism of NRs in the pathogenesis of CRC and emphasized the significance of targeting these NRs using a variety of agents, which may represent a novel and effective strategy for the prevention and treatment of this cancer.

Sex differences in colonic gene expression and fecal microbiota composition in a mouse model of obesity-associated colorectal cancer

This study investigated the sex-specific correlation between obesity and colorectal cancer emphasizing a more pronounced association in males. Estrogen, chromosomal genes, and gut bacteria were assessed in C57BL6/J male, female and ovariectomized (OVX) female mice, subjected to either a low-fat diet (LFD) or high-fat diet (HFD) for 14 weeks. Induction of colon tumor involved azoxymethane (10 mg/kg) administration, followed by three cycles of dextran sulfate sodium. Male mice on HFD exhibited higher final body weight and increased colon tumors compared to females. Colonic mucin 2 expression was significantly higher in females. HFD-modulated differentially expressed genes numbered 290 for males, 64 for females, and 137 for OVX females. Only one up-regulated gene (Gfra3) overlapped between females and OVX females, while two down-regulated genes (Thrsp and Gbp11) overlapped between males and OVX females. Genes up-regulated by HFD in males were linked to cytokine-cytokine interaction, HIF-1 signaling pathway, central carbon metabolism in cancer. Sex-specific changes in gut microbial composition in response to HFD were observed. These findings suggest a male-specific vulnerability to HFD-induced colon tumor formation, implicating key genes and colonic bacteria in colon tumorigenesis.

Profiling estrogen, progesterone, and androgen receptors in colorectal cancer in relation to gender, menopausal status, clinical stage, and tumour sidedness

BACKGROUND

Although estrogen (ERα/ERβ), progesterone (PGR), and androgen (AR) receptors are pathologically altered in colorectal cancer (CRC), their simultaneous expression within the same cohort of patients was not previously measured.

METHODS

ERα/ERβ/PGR/AR proteins were measured in archived paired normal and malignant colon specimens (n =120 patients) by immunohistochemistry, and results were analyzed by gender, age (≤50 vs. ≥60 years), clinical stages (early-stage I/II vs. late-stage III/IV), and anatomical location (right; RSCs vs. left; LSCs). Effects of 17β-estradiol (E2), progesterone (P4), and testosterone alone or combined with the specific blockers of ERα (MPP dihydrochloride), ERβ (PHTPP), PGR (mifepristone), and AR (bicalutamide) on cell cycle and apoptosis were also measured in the SW480 male and HT29 female CRC cell lines.

RESULTS

ERα and AR proteins increased, whilst ERβ and PGR declined markedly in malignant specimens. Moreover, male neoplastic tissues showed highest AR expression, whilst ERβ and PGR weakest alongside ERα strongest expression was seen in cancerous tissues from women aged ≥60 years. Late-stage neoplasms also revealed maximal alterations in the expression of sex steroid receptors. By tumor location, LSCs disclosed significant elevations in ERα with marked declines in PGR compared with RSCs, and ERα strongest alongside PGR weakest expression was detected in advanced LSCs from women aged ≥60 years. Late-stage LSCs from females aged ≥60 years also showed weakest ERβ and strongest AR expression. In contrast, male RSC and LSC tissues exhibited equal ERβ and AR expression in all clinical stages. ERα and AR proteins also correlated positively, whereas ERβ and PGR inversely, with tumor characteristics. Concomitantly, E2 and P4 monotherapies triggered cell cycle arrest and apoptosis in the SW480 and HT29 cells, and while pre-treatment with ERα-blocker enhanced the effects of E2, ERβ-blocker and PGR-blocker suppressed the E2 and P4 anti-cancer actions, respectively. In contrast, treatment with the AR-blocker induced apoptosis, whilst co-treatment with testosterone hindered the effects.

CONCLUSIONS

This study advocates that protein expression of sex steroid receptors in malignant tissues could represent prognostic markers, as well as hormonal therapy could provide an alternative strategy against CRC, and their efficacies could be dependent on gender, clinical stage, and tumor location.

Sex-Dependent Differences in Colorectal Cancer: With a Focus on Obesity

Colorectal cancer (CRC) is the third most common cancer and has the second highest cancer-related mortality in the world. The incident rates of CRC vary country-wise; however, population studies and data from different countries show a general increase in the CRC rate in young adults, males, and females ≥65 years. CRC incidence is affected by age, sex, environmental, dietary, hormonal, and lifestyle factors. Obesity is a known disease that is spreading rapidly throughout the world. A large body of literature indicates that, among many conditions, obesity is the increasing cause of CRC. Even though obesity is one of the known factors for CRC development, limited studies are available that explain the mechanistic link between obesity, sex hormones, and CRC development. Thus, this review summarizes the literature and aims to understand sex-dependent differences in CRC, especially in the context of obesity.

Integration of multi-omics data reveals cis-regulatory variants that are associated with phenotypic differentiation of eastern from western pigs

Background

The genetic mechanisms that underlie phenotypic differentiation in breeding animals have important implications in evolutionary biology and agriculture. However, the contribution of cis-regulatory variants to pig phenotypes is poorly understood. Therefore, our aim was to elucidate the molecular mechanisms by which non-coding variants cause phenotypic differences in pigs by combining evolutionary biology analyses and functional genomics.

Results

We obtained a high-resolution phased chromosome-scale reference genome with a contig N50 of 18.03 Mb for the Luchuan pig breed (a representative eastern breed) and profiled potential selective sweeps in eastern and western pigs by resequencing the genomes of 234 pigs. Multi-tissue transcriptome and chromatin accessibility analyses of these regions suggest that tissue-specific selection pressure is mediated by promoters and distal cis-regulatory elements. Promoter variants that are associated with increased expression of the lysozyme (LYZ) gene in the small intestine might enhance the immunity of the gastrointestinal tract and roughage tolerance in pigs. In skeletal muscle, an enhancer-modulating single-nucleotide polymorphism that is associated with up-regulation of the expression of the troponin C1, slow skeletal and cardiac type (TNNC1) gene might increase the proportion of slow muscle fibers and affect meat quality.

Conclusions

Our work sheds light on the molecular mechanisms by which non-coding variants shape phenotypic differences in pigs and provides valuable resources and novel perspectives to dissect the role of gene regulatory evolution in animal domestication and breeding.

Estrogen receptor actions in colitis

In recent years, researchers have demonstrated that estrogen and its receptors, aside from their role in regulating several biological functions, contribute to the development and progression/severity of inflammatory bowel diseases (IBDs). IBDs include both ulcerative colitis (UC) and Crohn's disease (CD). Epidemiological data indicate a clear difference in the incidence, severity, and complications of IBDs between sexes. Men present a higher risk of developing colitis than women and a higher risk of developing colorectal cancer, a common complication of this condition. However, fluctuations of estrogen levels have yielded inconsistent data, where oral contraceptives and hormone replacement therapy have been associated with an increased risk of IBDs in premenopausal women but significantly reduce disease activity after menopause. Likewise, improvement of symptoms related to CD has been reported during pregnancy, but not in UC, who often experience worsening symptoms. In the colonic epithelium, estrogen receptor β (ERβ) is the predominant form of the protein expressed, and it helps maintain normal epithelial function and organization. Preclinical data suggest that ER expression and activation via estrogen confers different responses on disease severity depending on the model used to induce colitis, which may reflect what is observed in patients with IBDs. Hence, this review aims to provide an overview of estrogen and its receptors, particularly ERβ, in the pathophysiology of IBDs.

Disruptive Selection of Human Immunostimulatory and Immunosuppressive Genes Both Provokes and Prevents Rheumatoid Arthritis, Respectively, as a Self-Domestication Syndrome

Using our previously published Web service SNP_TATA_Comparator, we conducted a genome-wide study of single-nucleotide polymorphisms (SNPs) within core promoters of 68 human rheumatoid arthritis (RA)-related genes. Using 603 SNPs within 25 genes clinically associated with RA-comorbid disorders, we predicted 84 and 70 candidate SNP markers for overexpression and underexpression of these genes, respectively, among which 58 and 96 candidate SNP markers, respectively, can relieve and worsen RA as if there is a neutral drift toward susceptibility to RA. Similarly, we predicted natural selection toward susceptibility to RA for 8 immunostimulatory genes (e.g., IL9R) and 10 genes most often associated with RA (e.g., NPY). On the contrary, using 25 immunosuppressive genes, we predicted 70 and 109 candidate SNP markers aggravating and relieving RA, respectively (e.g., IL1R2 and TGFB2), suggesting that natural selection can simultaneously additionally yield resistance to RA. We concluded that disruptive natural selection of human immunostimulatory and immunosuppressive genes is concurrently elevating and reducing the risk of RA, respectively. So, we hypothesize that RA in human could be a self-domestication syndrome referring to evolution patterns in domestic animals. We tested this hypothesis by means of public RNA-Seq data on 1740 differentially expressed genes (DEGs) of pets vs. wild animals (e.g., dogs vs. wolves). The number of DEGs in the domestic animals corresponding to worsened RA condition in humans was significantly larger than that in the related wild animals (10 vs. 3). Moreover, much less DEGs in the domestic animals were accordant to relieved RA condition in humans than those in the wild animals (1 vs. 8 genes). This indicates that the anthropogenic environment, in contrast to a natural one, affects gene expression across the whole genome (e.g., immunostimulatory and immunosuppressive genes) in a manner that likely contributes to RA. The difference in gene numbers is statistically significant as confirmed by binomial distribution (p < 0.01), Pearson's χ² (p < 0.01), and Fisher's exact test (p < 0.05). This allows us to propose RA as a candidate symptom within a self-domestication syndrome. Such syndrome might be considered as a human's payment with health for the benefits received during evolution.

Estrogen Receptor Beta: The Promising Biomarker and Potential Target in Metastases

The discovery of the Estrogen Receptor Beta (ERβ) in 1996 opened new perspectives in the diagnostics and therapy of different types of cancer. Here, we present a review of the present research knowledge about its role in endocrine-related cancers: breast, prostate, and thyroid, and colorectal cancers. We also discuss the reasons for the controversy of its role in carcinogenesis and why it is still not in use as a biomarker in clinical practice. Given that the diagnostics and therapy would benefit from the introduction of new biomarkers, we suggest ways to overcome the contradictions in elucidating the role of ERβ.

Soy isoflavones ameliorate experimental colitis by targeting ERα/NLRP3 inflammasome pathways

Soy isoflavones (SIFs) are selective estrogen receptor modulators (SERMs) that have anti-inflammatory activities. Our previous study found that estrogen receptor α (ERα) directly regulates the NLRP3 transcription and NLRP3 inflammasome assembly. Therefore, we hypothesized that SIFs alleviate colitis via an ERα-dependent mechanism by targeting the NLRP3 inflammasome. The influence of SIFs on colitis and the potential mechanisms were thoroughly determined in this study. The results suggested that SIFs ameliorated dextran sodium sulfate (DSS)-induced body weight loss, reduced disease activity index and promoted the recovery of colon pathological damage in mice. Moreover, expression of the NLRP3 inflammasome was significantly inhibited, and the release of IL-1β and IL-18 was suppressed by SIFs. Furthermore, ERα blockade ameliorated DSS-induced inflammatory responses in the intestine, and SIFs markedly suppressed the expression of ERα in a dose-dependent manner. Our study demonstrated that the protective therapeutic action of SIFs on DSS-induced colitis depended on inhibition of ERα and subsequent NLRP3 inflammasome activation, and SIFs are promising therapeutic agents for the treatment of colitis.

Targeting estrogen receptors in colorectal cancer

Hormones have become a useful therapeutic aspect of clinical endocrinology but how to use them to optimize the health benefits and avoid adverse effects is a major challenge. Estrogen is an indispensable hormone for proper biological functioning but is also implicated with the pathology of both the reproductive and non-reproductive tissues. Abnormal estrogen receptor signaling may increase the risk of development of a variety of diseases including colorectal cancer (CRC). Estrogen receptor beta (ERβ) is the predominant subtype in the colonic epithelium and confers the anti-tumor effect through various mechanisms. Many investigators have embarked on the search for the biological mechanisms by which estrogen and estrogen-like compounds may influence the pathogenesis of CRC. This review explores the recent findings on the therapeutic role of ERβ in the colonic epithelium as a prospective candidate for targeted endocrine therapy in CRC.

Prognostic value of estrogen receptor-α and progesterone receptor in curatively resected colorectal cancer: a retrospective analysis with independent validations

Background

Prognostic assessment is crucial for optimal treatment. The aim of our study was to investigate the potential impact of estrogen receptor-α (ER-α) and progesterone receptor (PR) on the prognosis of colorectal cancer (CRC) patients who received curative resection.

Methods

Retrospective evaluation of two independent cohorts of CRC patients maintained prospectively in 2009–2010 (training set) (n = 148) and 2007–2009 (internal validation set) (n = 485). Furthermore, we used an external independent CRC cohort from The Cancer Genome Atlas (TCGA) (n = 511) for further validation. ER-α and PR expression as well as other potential prognostic factors were retrospectively evaluated in training set with respect to overall survival (OS), local relapse free survival (LRFS) and distant metastasis free survival (DMFS). The prognostic factors found in training set will be validated in two validation cohorts.

Results

On univariate analysis for the training set, OS, LRFS and DMFS were not associated with PR expression. While patients with ER-αexpression were found to have poor prognosis. In addition, multivariate analysis showed that ER-αexpression maintained significance with respect to OS (HR, 5.06; p = 0.002), LRFS (HR, 8.81; p = 0.002) and DMFS (HR, 8.07; p = 0.004). Similarly, ER-α expression showed prognostic significance with respect to OS with hazard ratios (HRs) of 1.572 (95% CI: 1.001–2.467, p = 0.049) and 1.624 (95% CI: 1.047–2.520, p = 0.031) for the internal and external validation cohort, respectively.

Conclusion

ER-α expression was a biomarker of poor prognosis and it might inform treatment decision for high risk CRC patients. However, PR expression was not associated with survival outcomes.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5918-4) contains supplementary material, which is available to authorized users.

Estrogen receptor alpha regulates the Wnt/β-catenin signaling pathway in colon cancer by targeting the NOD-like receptors

It has been reported that estrogen receptors (ERs) participate in carcinogenesis by directly regulating NOD-like receptors (NLRs). However, the expression profiles of ERs and NLRs in tumor and the ER-NLR regulated signaling pathway are not clear. In this study, we summarized gene expression profiles of ERs and NLRs across normal and tumor tissue by comprehensive data mining. Then we explored the ER-NLR regulated signaling pathway by RNA sequencing (RNA-seq). The results showed that the NLRs and ERs were differentially expressed in different neoplasm tissues. Such expression discrepancies might influence inflammatory regulation and tumorigenesis. Importantly, we identified that ER-NLR regulate Wnt/β-catenin pathway in colon cancer. Taking colon adenocarcinoma (COAD) as example, we found that Wnt2b/LRP8/Dvl1/Axin2/GSK3a/APC/β-catenin genes were differentially expressed in ER^-/- mouse colon tissue and colon cancer cells. The selective ERα antagonist could significantly decrease Wnt2b/LRP8/Dvl1 expression, increase destruction complex (Axin2/GSK3a/APC) expression, and promote degradation of β-catenin in colon carcinoma cell by inhibited NLRP3 expression. In short, the research demonstrates that NLRs are potential biomarkers for cancer, and ERs can regulate the Wnt/β-catenin signaling pathway in cancer by targeting the NLRs. Our results provide a possible signaling pathway in which ER-NLR is correlated with Wnt/β-catenin.

Estradiol and progesterone regulate proliferation and apoptosis in colon cancer

Epidemiological studies describe estrogens as protectors in the development of colon cancer in postmenopausal women treated with hormone replacement therapy. However, the role of progesterone in colon cancer has been minimally studied and the results are controversial. For the above, the objective of this work was to determine the hormonal regulation exerted by natural ovarian steroids on proliferation and apoptosis in an experimental model of colon cancer in ovariectomized rats treated with 17-beta estradiol and progesterone. Sprague-Dawley rats were exposed to the carcinogen 1,2-dimethylhydrazine to induce colon tumors. Thirty days later, the rats were ovariectomized and treated with estradiol (60 μg/kg), progesterone (10 mg/kg), estradiol plus progesterone (60 μg/kg and 10 mg/kg) or vehicle. We observed no significant differences in colon cancer incidence and tumor multiplicity between the groups. Nevertheless, we observed a decrease in PCNA expression and a greater number of apoptotic index, higher expression of caspase 3, cleaved PARP and cleaved caspase 8 in tumors, confirming the activation of the extrinsic pathway of apoptosis by the combined treatment. In addition, we observed a higher expression of estrogen receptor beta in these tumors. We conclude that the action of both hormones, estradiol and progesterone, is necessary to reduce proliferation and increase apoptosis in colon tumors, probably through estrogen receptor beta activation.

Bisphenol-A alters microbiota metabolites derived from aromatic amino acids and worsens disease activity during colitis

Inflammatory bowel disease is a complex collection of disorders. Microbial dysbiosis as well as exposure to toxins including xenoestrogens are thought to be risk factors for inflammatory bowel disease development and relapse. Bisphenol-A has been shown to exert estrogenic activity in the colon and alter intestinal function, but the role that xenoestrogens, such as bisphenol-A , play in colonic inflammation has been previously described but with conflicting results. We investigated the ability of bisphenol-A to exacerbate colonic inflammation and alter microbiota metabolites derived from aromatic amino acids in an acute dextran sulfate sodium-induced colitis model. Female C57BL/6 mice were ovariectomized and exposed to bisphenol-A daily for 15 days. Disease activity measures include body weight, fecal consistency, and rectal bleeding. Colons were scored for inflammation, injury, and nodularity. Alterations in the levels of microbiota metabolites derived from aromatic amino acids known to reflect phenotypic changes in the gut microbiome were analyzed. Bisphenol-A exposure increased mortality and worsened disease activity as well as inflammation and nodularity scores in the middle colon region following dextran sulfate sodium exposure. Unique patterns of metabolites were associated with bisphenol-A consumption. Regardless of dextran sulfate sodium treatment, bisphenol-A reduced levels of tryptophan and several metabolites associated with decreased inflammation in the colon. This is the first study to show that bisphenol-A treatment alone can reduce microbiota metabolites derived from aromatic amino acids in the colon which may be associated with increased colonic inflammation and inflammatory bowel disease. Impact statement As rates of inflammatory bowel disease rise, discovery of the mechanisms related to the development of these conditions is important. Environmental exposure is hypothesized to play a role in etiology of the disease, as are alterations in the gut microbiome and the metabolites they produce. This study is the first to show that bisphenol-A alone alters tryptophan and microbiota metabolites derived from aromatic amino acids in a manner consistent with autoimmune diseases, specifically inflammatory bowel diseases, regardless of dextran sulfate sodium treatment. These findings indicate a potential mechanism by which bisphenol-A negatively affects gut physiology to exacerbate inflammation.

Bone Remodeling and the Microbiome

Exposed surfaces of mammals are colonized with 100 trillion indigenous bacteria, fungi, and viruses, creating a diverse ecosystem known as the microbiome. The gastrointestinal tract harbors the greatest numbers of these microorganisms, which regulate human nutrition, metabolism, and immune system function. Moreover, the intestinal microbiota contains pro- and anti-inflammatory products that modulate immune responses and may play a role in maintaining gut barrier function. Therefore, the community composition of the microbiota has profound effects on the immune status of the host and impacts the development and/or progression of inflammatory diseases. Accordingly, numerous studies have shown differences in the microbiota of patients with and without a given inflammatory condition. There is now strong evidence that the gut microbiome regulates bone homeostasis in health and disease, and that prebiotic and probiotics protect against bone loss. Herein, the evidence supporting the role of the microbiota and the effects of prebiotic and probiotics will be reviewed.

Effects of Estrogen on the Gastrointestinal Tract

Estrogen is a kind of steroid compound that has extensive biologic activities. The effect of estrogen is pleiotropic, affecting multiple systems in the body. There is accumulating evidence that estrogen has important effects on the gastrointestinal tract. Longer exposure to estrogen may decrease the risk of gastric cancer. Use of the anti-estrogen drug tamoxifen might increase the risk of gastric adenocarcinoma. Estrogen receptor β may serve as a target for colorectal cancer prevention. In addition, estrogen has been reported to be closely related to the mucosal barrier, gastrointestinal function and intestinal inflammation. However, the role of estrogen in the gastrointestinal tract has not been systematically summarized. In this review, we aim to provide an overview of the role of estrogen in the gastrointestinal tract and evaluate it from various aspects, including estrogen receptors, the mucosal barrier, intestinal inflammation and gastrointestinal tract tumors, which may provide the basis for the development of therapeutic strategies to manage gastrointestinal diseases.

Estradiol Has Differential Effects on Acute Colonic Inflammation in the Presence and Absence of Estrogen Receptor β Expression

BACKGROUND

Inflammatory bowel disease (IBD) increases the risk of developing colon cancer. This risk is higher in men compared to women, implicating a role for female hormones in the protection against this disease. Studies from our laboratory demonstrated that estradiol (E₂) protects against inflammation-associated colon tumor formation when administered following chemical carcinogen and induction of chronic colitis.

AIM

This study seeks to better understand the effect of E₂ on acute colitis in the presence and absence of estrogen receptor β (ERβ).

METHODS

Inflammation was induced by 2,4,6-trinitrobenzenesulfonic acid in wild-type (WT) and ERβ knockout (ERβKO) mice implanted with a control or E₂-containing pellet and killed 5 days later. Inflammation and injury were scored by a pathologist. Apoptosis and proliferation were assessed by immunohistochemistry. Cytokines were measured by multiplex analysis.

RESULTS

E₂ treatment reduced inflammation in the middle colon in WT mice and the distal colon in ERβKO mice compared to control mice. WT mice had reduced IL-6, IL-12, IL-17, GM-CSF, IFN-γ, MCP-1, MIP-1α, and TNF-α, and ERβKO had reduced IL-6 and IFN-γ expression in response to E₂. Injury scores were lower in E₂-treated ERβKO mice compared to control ERβKO mice. ERβKO mice had increased proliferation in the basal third of crypts in the distal colon and decreased apoptosis in the proximal colon.

CONCLUSIONS

These data suggest that E₂ has differential protective effects against acute colitis in the presence or absence of ERβ and provide insight into how E₂ may protect against IBD.

Bisphenol A (BPA) Exposure In Utero Leads to Immunoregulatory Cytokine Dysregulation in the Mouse Mammary Gland: A Potential Mechanism Programming Breast Cancer Risk

Bisphenol-A (BPA) is a ubiquitous estrogen-like endocrine disrupting compound (EDC). BPA exposure in utero has been linked to breast cancer and abnormal mammary gland development in mice. The recent rise in incidence of human breast cancer and decreased age of first detection suggests a possible environmental etiology. We hypothesized that developmental programming of carcinogenesis may involve an aberrant immune response. Both innate and adaptive immunity play a role in tumor suppression through cytolytic CD8, NK, and Th1 T-cells. We hypothesized that BPA exposure in utero would lead to dysregulation of both innate and adaptive immunity in the mammary gland. CD1 mice were exposed to BPA in utero during gestation (days 9-21) via osmotic minipump. At 6 weeks, the female offspring were ovariectomized and estradiol was given at 8 weeks. RNA and protein were extracted from the posterior mammary glands, and the mRNA and protein levels were measured by PCR array, qRT-PCR, and western blot. In mouse mammary tissue, BPA exposure in utero significantly decreased the expression of members of the chemokine CXC family (Cxcl2, Cxcl4, Cxcl14, and Ccl20), interleukin 1 (Il1) gene family (Il1β and Il1rn), interleukin 2 gene family (Il7 receptor), and interferon gene family (interferon regulatory factor 9 (Irf9), as well as immune response gene 1 (Irg1). Additionally, BPA exposure in utero decreased Esr1 receptor gene expression and increased Esr2 receptor gene expression. In utero exposure of BPA resulted in significant changes to inflammatory modulators within mammary tissue. We suggest that dysregulation of inflammatory cytokines, both pro-inflammatory and anti-inflammatory, leads to a microenvironment that may promote disordered cell growth through inhibition of the immune response that targets cancer cells.

Evaluation of 99m Tc-resveratrol as a colon cancer targeting probe

The study aimed to evaluate cancer-targeting potential of a newly synthesised radiopharmaceutical, ^99m Tc-resveratrol in vivo, using colon cancer model. Colon cancer was induced in 20 male Sprague-Dawley rats by subcutaneous administration of 1,2-dimethylhydrazine (DMH), dissolved in 1 mM EDTA-normal saline, at a dose of 30 mg/kg body weight twice a week for first 4 weeks and once a week for next 12 weeks. A control group containing normal rats was used for result comparison. Colon cancer in DMH-treated group was confirmed by gross analysis of the colon, by histopathological analysis and molecular marker study in tumour tissue. At the end of the treatment period, the animals from the two groups were used for bio-distribution evaluation of ^99m Tc-resveratrol at different time intervals. High uptake of ^99m Tc-resveratrol was recorded in rat liver, spleen and kidneys, and the ratio of colon tumour uptake to normal colon uptake in DMH-treated rats increased significantly (P ≤ 0.01) with time, to reach a maximum value at 2 h but decreased thereafter. High uptake at the tumour site as compared to normal colon tissue was observed; however, the uptake by cancer cells at the target site was limited by high reticulo-endothelial uptake and rapid metabolism.

Sex steroid deficiency-associated bone loss is microbiota dependent and prevented by probiotics

A eubiotic microbiota influences many physiological processes in the metazoan host, including development and intestinal homeostasis. Here, we have shown that the intestinal microbiota modulates inflammatory responses caused by sex steroid deficiency, leading to trabecular bone loss. In murine models, sex steroid deficiency increased gut permeability, expanded Th17 cells, and upregulated the osteoclastogenic cytokines TNFα (TNF), RANKL, and IL-17 in the small intestine and the BM. In germ-free (GF) mice, sex steroid deficiency failed to increase osteoclastogenic cytokine production, stimulate bone resorption, and cause trabecular bone loss, demonstrating that the gut microbiota is central in sex steroid deficiency-induced trabecular bone loss. Furthermore, we demonstrated that twice-weekly treatment of sex steroid-deficient mice with the probiotics Lactobacillus rhamnosus GG (LGG) or the commercially available probiotic supplement VSL#3 reduces gut permeability, dampens intestinal and BM inflammation, and completely protects against bone loss. In contrast, supplementation with a nonprobiotic strain of E. coli or a mutant LGG was not protective. Together, these data highlight the role that the gut luminal microbiota and increased gut permeability play in triggering inflammatory pathways that are critical for inducing bone loss in sex steroid-deficient mice. Our data further suggest that probiotics that decrease gut permeability have potential as a therapeutic strategy for postmenopausal osteoporosis.

Estrogen receptor beta as target for colorectal cancer prevention

Colorectal cancer (CRC) is a leading cause of death in the United States. Despite its slow development and the capacity for early diagnosis, current preventive approaches are not sufficient. However, a role for estrogen has been demonstrated in multiple epidemiologic studies, which may benefit CRC prevention. A large body of evidence from preclinical studies indicates that expression of the estrogen receptor beta (ERβ/ESR2) demonstrates an inverse relationship with the presence of colorectal polyps and stage of tumors, and can mediate a protective response. Natural compounds, including phytoestrogens, or synthetic ERβ selective agonists, can activate or upregulate ERβ in the colon and promote apoptosis in preclinical models and in clinical experience. Importantly, this activity has been associated with a reduction in polyp formation and, in rodent models of CRC, has been shown to lower incidence of colon adenocarcinoma. Collectively, these findings indicate that targeted activation of ERβ may represent a novel clinical approach for management of colorectal adenomatous polyps and prevention of colorectal carcinoma in patients at risk for this condition. In this review, we discuss the potential of new chemopreventive or dietary approaches based on estrogen signaling.

The sharp decline of beta estrogen receptors expression in long-lasting ulcerative-associated carcinoma

OBJECTIVE

Colorectal carcinoma is an important cause of death in inflammatory bowel diseases, thus requiring surveillance for dysplasia in long-standing ulcerative colitis (UC). Females show a lower incidence probably related to hormonal factors; therefore, a role of estrogen receptors (ERs) has been supposed in carcinoma-associated colitis (CAC) development. Our aim was to identify ER beta/alpha expression in long-lasting pancolitis through each grade of dysplasia to carcinoma and, furthermore, to investigate the simultaneous epithelial apoptosis/proliferation.

MATERIALS AND METHODS

Forty-eight patients affected by long-lasting pancolitis were retrospectively investigated. Samples were divided into four groups: UC, low-grade dysplasia/high-grade dysplasia (UC-HGD), and CAC. Normal colon samples were used as controls. ER-beta, ER-alpha, Ki-67, and TUNEL expression (labeling/H index) were evaluated by immunohistochemistry.

RESULTS

ER-beta expression revealed an impressive reduction in CAC (10.4 ± 5.1; p < 0.001) compared to controls and UC (34.3 ± 3.1 and 26.8 ± 7.8, respectively), meanwhile ER-beta level in LGD (29.4 ± 3.7) was comparable to UC. As far ER-beta/ER-alpha mean value ratio revealed a progressive reduction. Ki67 demonstrated a progressive significant increase from UC until CAC (37.9 ± 6.4 < 45.7 ± 6.2 < 60.6 ± 5.2 < 71.1 ± 5.1; p < 0.001). Apoptotic index (TUNEL) revealed a strong fall in UC-HGD and CAC.

CONCLUSIONS

ER-beta fall could be considered as a biomarker of UC-dysplasia progression. It occurs in HGD and overt neoplasia, while in LGD shows a normal expression. At the moment, we are unable to use this tool in the clinical practice to predict tumor progression, but it would be appropriate to encourage ER expression investigations in large samples for the interesting perspectives of application.

Estrogen receptors and their implications in colorectal carcinogenesis

Upon binding their cognate receptors, ERα (ESR1) and ERβ (ESR2), estrogens activate intracellular signaling cascades that have important consequences for cellular behavior. Historically linked to carcinogenesis in reproductive organs, estrogens have also been implicated in the pathogenesis of different cancer types of non-reproductive tissues including the colon. ERβ is the predominant estrogen receptor expressed in both normal and malignant colonic epithelium. However, during colon cancer progression, ERβ expression is lost, suggesting that estrogen signaling may play a role in disease progression. Estrogens may in fact exert an anti-tumor effect through selective activation of pro-apoptotic signaling mediated by ERβ, inhibition of inflammatory signals and modulation of the tumor microenvironment. In this review, we analyze the estrogen pathway as a possible therapeutic avenue in colorectal cancer, we report the most recent experimental evidence to explain the cellular and molecular mechanisms of estrogen-mediated protection against colorectal tumorigenesis, and we discuss future challenges and potential avenues for targeted therapy.

Impact of the Mdm2(SNP309-G) allele on a murine model of colorectal cancer

A single-nucleotide polymorphism (SNP) in the promoter of the Mdm2 gene (Mdm2(SNP309-G)) results in an increased Mdm2 expression, partial attenuation of the p53 pathway and accelerated tumor development. Clinical case-control studies indicate the Mdm2(SNP309-)(G) allele associates with a significant increase in colorectal cancer (CRC) risk that is heightened in women, but the biological significance of this polymorphism has never been directly evaluated. To examine whether the Mdm2(SNP309-)(G) allele contributes to colorectal cancer, we generated cohorts of mice harboring either the G (minor allelic variant) or T (major allelic variant) allele and treated them with azoxymethane (AOM), a carcinogen that induces sporadic colorectal cancer. Mdm2(SNP309-G/G) mice displayed a significant reduction in survival following AOM treatment with more colonic lesions in a wider distribution throughout the lower and upper colon and an attenuated apoptotic response following exposure. AOM did not significantly induce stabilization of wild-type p53 or activate p53 downstream targets following AOM treatment, regardless of the genotype. Instead, Mdm2(SNP309-G/G) colons had significant changes in the expression of genes that regulate Mdm2 transcription (ERα and Sp1) as well as downstream targets of Mdm2. Together these results suggest the Mdm2(SNP309-)(G) allele significantly impacts CRC through mechanisms outside the p53 pathway.

CYP19A1 single nucleotide polymorphism associations with CYP19A1, NFκB1, and IL6 gene expression in human normal colon and normal liver samples

Background

Estrogen is known to decrease the risk of colon cancer in postmenopausal women, and may exert its actions by decreasing interleukin-6 (IL6) production via stabilization of the transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB). Estrogens are biosynthesized by CYP19A1 (aromatase), so it is possible that genetic variations in CYP19A1 influences the risk of colon cancer by altering expression of CYP19A1. Further, studies on gene-gene interactions suggest that single nucleotide polymorphisms in one gene may affect expression of other genes. The current study aims to explore the role of CYP19A1 single nucleotide polymorphisms on CYP19A1, NFκB1 and IL6 gene expression.

Methods

Phenotype–genotype associations, cross-associations between genes, and haplotype analyses were performed in both normal human colon (n=82) and liver (n=238) samples.

Results

CYP19A1 rs10459592, rs1961177, and rs6493497 were associated with CYP19A1 expression in colon samples (P=0.042, P=0.041, and P=0.013, respectively). CYP19A1 single nucleotide polymorphisms (rs12908960, rs730154, rs8025191, and rs17523880) were correlated with NFκB1 expression (P=0.047, P=0.04, P=0.05, and P=0.03, respectively), and CYP19A1 rs11856927, rs2470152, and rs2470144 (P=0.049, P=0.025, P=0.047, respectively) were associated with IL6 expression in the colon. While rs730154 and rs17523880 could not be analyzed in the liver samples, none of the other associations with the colon were replicated in the liver samples. Haplotype analysis revealed three separate haplotypes of the CYP19A1 single nucleotide polymorphism that were significantly associated with CYP19A1, NFκB1, and IL6 gene expression.

Conclusion

CYP19A1 single nucleotide polymorphisms are associated not only with CYP19A1 expression but also with NFκB1 and IL6 expression. These data demonstrate the possible functional consequences of genetic variation within the CYP19A1 gene on other genes in a biologically plausible pathway.

Insight into the mechanisms of action of estrogen receptor β in the breast, prostate, colon, and CNS

Estrogen and its receptors (ERs) influence many biological processes in physiology and pathology in men and women. ERs are involved in the etiology and/or progression of cancers of the prostate, breast, uterus, ovary, colon, lung, stomach, and malignancies of the immune system. In estrogen-sensitive malignancies, ERβ usually is a tumor suppressor and ERα is an oncogene. ERβ regulates genes in several key pathways including tumor suppression (p53, PTEN); metabolism (PI3K); survival (Akt); proliferation pathways (p45(Skp2), cMyc, and cyclin E); cell-cycle arresting factors (p21(WAF1), cyclin-dependent kinase inhibitor 1 (CDKN1A)), p27(Kip1), and cyclin-dependent kinases (CDKs); protection from reactive oxygen species, glutathione peroxidase. Because they are activated by small molecules, ERs are excellent targets for pharmaceuticals. ERα antagonists have been used for many years in the treatment of breast cancer and more recently pharmaceutical companies have produced agonists which are very selective for ERα or ERβ. ERβ agonists are being considered for preventing progression of cancer, treatment of anxiety and depression, as anti-inflammatory agents and as agents, which prevent or reduce the severity of neurodegenerative diseases.