Endocrine disruptor exposure during development increases incidence of uterine fibroids by altering DNA repair in myometrial stem cells

TGFβ signaling links early life endocrine-disrupting chemicals exposure to suppression of nucleotide excision repair in rat myometrial stem cells

Environmental exposure to endocrine-disrupting chemicals (EDCs) is linked to the development of uterine fibroids (UFs) in women. UFs, non-cancerous tumors, are thought to originate from abnormal myometrial stem cells (MMSCs). Defective DNA repair capacity may contribute to the emergence of mutations that promote tumor growth. The multifunctional cytokine TGFβ1 is associated with UF progression and DNA damage repair pathways. To investigate the impact of EDC exposure on TGFβ1 and nucleotide excision repair (NER) pathways, we isolated MMSCs from 5-month-old Eker rats exposed neonatally to diethylstilbestrol (DES), an EDC, or to vehicle (VEH). EDC-MMSCs exhibited overactivated TGFβ1 signaling and reduced mRNA and protein levels of NER pathway components compared to VEH-MMSCs. EDC-MMSCs also demonstrated impaired NER capacity. Exposing VEH-MMSCs to TGFβ1 decreased NER capacity while inhibiting TGFβ signaling in EDC-MMSCs restored it. RNA-seq analysis and further validation revealed decreased expression of Uvrag, a tumor suppressor gene involved in DNA damage recognition, in VEH-MMSCs treated with TGFβ1, but increased expression in EDC-MMSCs after TGFβ signaling inhibition. Overall, we demonstrated that the overactivation of the TGFβ pathway links early life exposure to EDCs with impaired NER capacity, which would lead to increased genetic instability, arise of mutations, and fibroid tumorigenesis. We demonstrated that the overactivation of the TGFβ pathway links early life exposure to EDCs with impaired NER capacity, which would lead to increased fibroid incidence.

Developmental reprogramming of myometrial stem cells by endocrine disruptor linking to risk of uterine fibroids

BACKGROUND

The stage, when tissues and organs are growing, is very vulnerable to environmental influences, but it's not clear how exposure during this time causes changes to the epigenome and increases the risk of hormone-related illnesses like uterine fibroids (UFs).

METHODS

Developmental reprogramming of myometrial stem cells (MMSCs), the putative origin from which UFs originate, was investigated in vitro and in the Eker rat model by RNA-seq, ChIP-seq, RRBS, gain/loss of function analysis, and luciferase activity assays.

RESULTS

When exposed to the endocrine-disrupting chemical (EDC) diethylstilbestrol during Eker rat development, MMSCs undergo a reprogramming of their estrogen-responsive transcriptome. The reprogrammed genes in MMSCs are known as estrogen-responsive genes (ERGs) and are activated by mixed lineage leukemia protein-1 (MLL1) and DNA hypo-methylation mechanisms. Additionally, we observed a notable elevation in the expression of ERGs in MMSCs from Eker rats exposed to natural steroids after developmental exposure to EDC, thereby augmenting estrogen activity.

CONCLUSION

Our studies identify epigenetic mechanisms of MLL1/DNA hypo-methylation-mediated MMSC reprogramming. EDC exposure epigenetically targets MMSCs and leads to persistent changes in the expression of a subset of ERGs, imparting a hormonal imprint on the ERGs, resulting in a "hyper-estrogenic" phenotype, and increasing the hormone-dependent risk of UFs.

TGFβ signaling links early-life endocrine-disrupting chemicals exposure to suppression of nucleotide excision repair in rat myometrial stem cells

Environmental exposure to endocrine-disrupting chemicals (EDCs) is linked to the development of uterine fibroids (UFs) in women. UFs, non-cancerous tumors, are thought to originate from abnormal myometrial stem cells (MMSCs). Defective DNA repair capacity may contribute to the emergence of mutations that promote tumor growth. The multifunctional cytokine TGFβ1 is associated with UF progression and DNA damage repair pathways. To investigate the impact of EDC exposure on TGFβ1 and nucleotide excision repair (NER) pathways, we isolated MMSCs from 5-months old Eker rats exposed neonatally to Diethylstilbestrol (DES), an EDC, or to vehicle (VEH). EDC-MMSCs exhibited overactivated TGFβ1 signaling and reduced mRNA and protein levels of NER pathway components compared to VEH-MMSCs. EDC-MMSCs also demonstrated impaired NER capacity. Exposing VEH-MMSCs to TGFβ1 decreased NER capacity while inhibiting TGFβ signaling in EDC-MMSCs restored it. RNA-seq analysis and further validation revealed decreased expression of Uvrag, a tumor suppressor gene involved in DNA damage recognition, in VEH-MMSCs treated with TGFβ1, but increased expression in EDC-MMSCs after TGFβ signaling inhibition. Overall, we demonstrated that the overactivation of the TGFβ pathway links early-life exposure to EDCs with impaired NER capacity, which would lead to increased genetic instability, arise of mutations, and fibroid tumorigenesis. We demonstrated that the overactivation of the TGFβ pathway links early-life exposure to EDCs with impaired NER capacity, which would lead to increased fibroid incidence.

Gut and genital tract microbiomes: Dysbiosis and link to gynecological disorders

Every year, millions of women are affected by genital tract disorders, such as bacterial vaginosis (BV), endometrial cancer, polycystic ovary syndrome (PCOS), endometriosis, and uterine fibroids (UFs). These disorders pose a significant economic burden on healthcare systems and have serious implications for health and fertility outcomes. This review explores the relationships between gut, vaginal, and uterine dysbiosis and the pathogenesis of various diseases of the female genital tract. In recent years, reproductive health clinicians and scientists have focused on the microbiome to investigate its role in the pathogenesis and prevention of such diseases. Recent studies of the gut, vaginal, and uterine microbiomes have identified patterns in bacterial composition and changes across individuals' lives associated with specific healthy and diseased states, particularly regarding the effects of the estrogen-gut microbiome axis on estrogen-driven disorders (such as endometrial cancer, endometriosis, and UFs) and disorders associated with estrogen deficiency (such as PCOS). Furthermore, this review discusses the contribution of vitamin D deficiency to gut dysbiosis and altered estrogen metabolism as well as how these changes play key roles in the pathogenesis of UFs. More research on the microbiome influences on reproductive health and fertility is vital.

Biomechanical Forces Determine Fibroid Stem Cell Transformation and the Receptivity Status of the Endometrium: A Critical Appraisal

Myometrium cells are an important reproductive niche in which cyclic mechanical forces of a pico-newton range are produced continuously at millisecond and second intervals. Overproduction and/or underproduction of micro-forces, due to point or epigenetic mutation, aberrant methylation, and abnormal response to hypoxia, may lead to the transformation of fibroid stem cells into fibroid-initiating stem cells. Fibroids are tumors with a high modulus of stiffness disturbing the critical homeostasis of the myometrium and they may cause unfavorable and strong mechanical forces. Micro-mechanical forces and soluble-chemical signals play a critical role in transcriptional and translational processes' maintenance, by regulating communication between the cell nucleus and its organelles. Signals coming from the external environment can stimulate cells in the format of both soluble biochemical signals and mechanical ones. The shape of the cell and the plasma membrane have a significant character in sensing electro-chemical signals, through specialized receptors and generating responses, accordingly. In order for mechanical signals to be perceived by the cell, they must be converted into biological stimuli, through a process called mechanotransduction. Transmission of fibroid-derived mechanical signals to the endometrium and their effects on receptivity modulators are mediated through a pathway known as solid-state signaling. It is not sufficiently clear which type of receptors and mechanical signals impair endometrial receptivity. However, it is known that biomechanical signals reaching the endometrium affect epithelial sodium channels, lysophosphatidic acid receptors or Rho GTPases, leading to conformational changes in endometrial proteins. Translational changes in receptivity modulators may disrupt the selectivity and receptivity functions of the endometrium, resulting in failed implantation or early pregnancy loss. By hypermethylation of the receptivity genes, micro-forces can also negatively affect decidualization and implantation. The purpose of this narrative review is to summarize the state of the art of the biomechanical forces which can determine fibroid stem cell transformation and, thus, affect the receptivity status of the endometrium with regard to fertilization and pregnancy.

Human Myometrial and Uterine Fibroid Stem Cell-Derived Organoids for Intervening the Pathophysiology of Uterine Fibroid

Uterine fibroids (UFs) (leiomyomas or myomas) are the most common clonal neoplasms of the uterus in women of reproductive age worldwide. UFs originate from myometrium consist of smooth muscle and fibroblast components, in addition to a substantial amount of fibrous extracellular matrix which all contribute to the pathogenetic process. Current treatments are primarily limited to surgical and interventional. Here, we have established a novel and promising organoid model from both normal and patient myometrial stem cells (MMSCs). MMSCs embedded in Matrigel in stem cell media swiftly formed organoids which successfully proliferate and self-organized into complex structures developing a sustainable organoid culture that maintain their capacity to differentiate into the different cell types recapitulating their tissue of origin and shows responsiveness to the reproductive hormones (estrogen and progesterone). Gene expression analysis and structural features indicated the early onset of uterine fibrosis led to the accumulation of extracellular matrix suggesting the potential use of this model in better understanding of the pathophysiology associated with UFs and inventing novel therapeutics for the treatment of UFs.

Uterine Fibroids: Hiding in Plain Sight

Uterine fibroids (leiomyomas) are present in >75% of women and can cause serious morbidity. They are by far the leading cause of hysterectomy. Fibroids are a complex mixture of cells that include fibroblasts and smooth muscle cells. Rich in extracellular matrix, they typically arise through somatic mutations, most commonly MED12. Their lack of growth inhibition and their ability to have facets of malignancy yet be histologically and biologically benign provide opportunities to explore basic processes. To date, the mechanisms responsible for growth and development of leiomyomas are an enigma. This review provides an overview of current understanding and future directions for clinical and basic research of fibroids.

Mice Uterine Stem Cells are Affected by Neonatal Endocrine Disruption & Initiate Uteropathies in Adult Life Independent of Circulatory Ovarian Hormones

It is generally believed that ovarian hormones regulate uterine functions and their altered levels result in various uteropathies like non-receptive uterus, endometrial hyperplasia, adenomyosis, endometriosis, leiomyomas and cancer. Uterus harbors two populations of stem cells including pluripotent, very small embryonic-like stem cells (VSELs) and tissue-specific progenitors (endometrial stem cells, EnSCs). Unlike endometrial mesenchymal stem/ stromal cells, VSELs/EnSCs express ERα, ERβ and PR which makes them directly vulnerable to perinatal endocrine insults. Present study was undertaken to evaluate whether uteropathies occur due to altered hormones and/or intrinsic changes in stem/progenitor cells. Mice pups, exposed to estradiol (20 µg/pup/day) on postnatal days 3-7 or vehicle, were subjected to bilateral ovariectomy on day 30 and later exposed sequentially to estradiol and progesterone resulting in receptive uterus in control mice. Despite similar hormonal exposure, endocrine disruption resulted in non-receptive uterus with noticeable endometrial and myometrial hyperplasia and up-regulation of stem cell markers (Oct-4A, Oct-4, Sox2, Nanog). Glands were poorly formed and 'defective' epithelial progenitors were found disseminated into myometrium and blood vessels revealing how adenomyosis and endometriosis possibly initiate. Progesterone resistance and estradiol dominance due to downregulation of Erα & Pr and upregulation of Erβ transcripts was observed in both intact uterus and stem cells enriched from uterus. Transcripts specific for DNA mismatch repair axis (Pcna, NP95 and Dnmt1), repair enzymes (Brca-1, Rad51 and Mlh1) were dysregulated whereas Ki67 was ten-folds increased suggestive of genomic instability. Study reveals role of stem cells in initiating uteropathies during adult life independent of circulatory ovarian hormones. Endocrine disruption affects tissue resident stem/progenitor cells (VSELs/EnSCs) in both endometrium and myometrium, result in epithelial cells hyperplasia, non-receptive endometrium, adenomyosis and defective stem cells and epithelial progenitors were detected in the perimetrium from where they can mobilize to ectopic sites to initiate endometriosis. Study shows stem cell basis for various uteropathies. VSEL: Very small embryonic like stem cell; EnSC: Endometrial stem cell; E + P: Estradiol + Progesterone; E: Endometrium; P: Perimetrium; M: Myometrium; ACD: Asymmetrical cell division; SCD: Symmetrical cell division; CE: Clonal expansion; G: Gland; S: Stromal cell; US: Undifferentiated stromal cell; LE: Luminal epithelium; GE: Glandular epithelium; EP: Epithelial progenitors; SMC: Spindle-shaped myometrial cell; OMC: Oval-shaped myometrial cell.

Endocrine-Disrupting Chemicals and Vitamin D Deficiency in the Pathogenesis of Uterine Fibroids

Uterine fibroids (UFs) are the most prevalent gynecologic neoplasm, affecting 70-80% of women over their lifespan. Although UFs are benign they can become life-threatening and require invasive surgeries such as myomectomy and hysterectomy. Notwithstanding the significant negative influence UFs have on female reproductive health, very little is known about early events that initiate tumor development. Several risk factors for UFs have been identified including vitamin D deficiency, inflammation, DNA repair deficiency, and environmental exposures to endocrine-disrupting chemicals (EDCs). EDCs have come under scrutiny recently due to their role in UF development. Epidemiologic studies have found an association between increased risk for early UF diagnosis and in utero EDC exposure. Environmental exposure to EDCs during uterine development increases UF incidence in a UF animal model. Notably, several studies demonstrated that abnormal myometrial stem cells (MMSCs) are the cell origin for UFs development. Our recent studies demonstrated that early-life EDC exposure reprogrammed the MMSCs toward a pro-fibroid landscape and altered the DNA repair and inflammation pathways. Notably, Vitamin D3 (VITD3) as a natural compound shrank the UF growth concomitantly with the reversion of several abnormal biological pathways and ameliorated the developmental exposure-induced DNA damage and pro-inflammation pathway in primed MMSCs. This review highlights and emphasizes the importance of multiple pathway interactions in the context of hypovitaminosis D at the MMSCs level and provides proof-of-concept information that can help develop a safe, long-term, durable, and non-surgical therapeutic option for UFs.

Understanding the Impact of Uterine Fibroids on Human Endometrium Function

Uterine fibroids (leiomyomas) are the most common benign gynecological tumors in women of reproductive age worldwide. They cause heavy menstrual bleeding, usually leading to severe anemia, pelvic pain/pressure, infertility, and other debilitating morbidities. Fibroids are believed to be monoclonal tumors arising from the myometrium, and recent studies have demonstrated that fibroids actively influence the endometrium globally. Studies suggest a direct relationship between the number of fibroids removed and fertility problems. In this review, our objective was to provide a complete overview of the origin of uterine fibroids and the molecular pathways and processes implicated in their development and growth, which can directly affect the function of a healthy endometrium. One of the most common characteristics of fibroids is the excessive production of extracellular matrix (ECM) components, which contributes to the stiffness and expansion of fibroids. ECM may serve as a reservoir of profibrotic growth factors such as the transforming growth factor β (TGF-β) and a modulator of their availability and actions. Fibroids also elicit mechanotransduction changes that result in decreased uterine wall contractility and increased myometrium rigidity, which affect normal biological uterine functions such as menstrual bleeding, receptivity, and implantation. Changes in the microRNA (miRNA) expression in fibroids and myometrial cells appear to modulate the TGF-β pathways and the expression of regulators of ECM production. Taken together, these findings demonstrate an interaction among the ECM components, TGF-β family signaling, miRNAs, and the endometrial vascular system. Targeting these components will be fundamental to developing novel pharmacotherapies that not only treat uterine fibroids but also restore normal endometrial function.

Molecular differential analysis of uterine leiomyomas and leiomyosarcomas through weighted gene network and pathway tracing approaches

Uterine smooth muscular neoplastic growths like benign leiomyomas (UL) and metastatic leiomyosarcomas (ULMS) share similar clinical symptoms, radiological and histological appearances making their clinical distinction a difficult task. Therefore, the objective of this study is to identify key genes and pathways involved in transformation of UL to ULMS through molecular differential analysis. Global gene expression profiles of 25 ULMS, 25 UL, and 29 myometrium (Myo) tissues generated on Affymetrix U133A 2.0 human genome microarrays were analyzed by deploying robust statistical, molecular interaction network, and pathway enrichment methods. The comparison of expression signals across Myo vs UL, Myo vs ULMS, and UL vs ULMS groups identified 249, 1037, and 716 significantly expressed genes, respectively (p ≤ 0.05). The analysis of 249 DEGs from Myo vs UL confirms multistage dysregulation of various key pathways in extracellular matrix, collagen, cell contact inhibition, and cytokine receptors transform normal myometrial cells to benign leiomyomas (p value ≤ 0.01). The 716 DEGs between UL vs ULMS were found to affect cell cycle, cell division related Rho GTPases and PI3K signaling pathways triggering uncontrolled growth and metastasis of tumor cells (p value ≤ 0.01). Integration of gene networking data, with additional parameters like estimation of mutation burden of tumors and cancer driver gene identification, has led to the finding of 4 hubs (JUN, VCAN, TOP2A, and COL1A1) and 8 bottleneck genes (PIK3R1, MYH11, KDR, ESR1, WT1, CCND1, EZH2, and CDKN2A), which showed a clear distinction in their distribution pattern among leiomyomas and leiomyosarcomas. This study provides vital clues for molecular distinction of UL and ULMS which could further assist in identification of specific diagnostic markers and therapeutic targets.Abbreviations UL: Uterine Leiomyomas; ULMS: Uterine Leiomyosarcoma; Myo: Myometrium; DEGs: Differential Expressed Genes; RMA: Robust Multiarray Average; DC: Degree of Centrality; BC: Betweenness of Centrality; CGC: Cancer Gene Census; FDR: False Discovery Rate; TCGA: Cancer Genome Atlas; BP: Biological Process; CC: Cellular Components; MF: Molecular Function; PPI: Protein-Protein Interaction.

The role of endocrine-disrupting chemicals in uterine fibroid pathogenesis

PURPOSE OF REVIEW

Uterine leiomyoma (fibroids) is a gynecologic disorder impacting the majority of women in the United States. When symptomatic, these noncancerous tumors can cause severe morbidity including pelvic pain, menorrhagia, and infertility. Endocrine-disrupting chemicals (EDCs) may represent a modifiable risk factor. The aim of this review is to summarize recent human and experimental evidence on EDCs exposures and fibroids.

RECENT FINDINGS

Multiple EDCs are associated with fibroid outcomes and/or processes including phthalates, parabens, environmental phenols, alternate plasticizers, Diethylstilbestrol, organophosphate esters, and tributyltin. Epidemiologic studies suggest exposure to certain EDCs, such as di-(2-ethylhxyl)-phthalate (DEHP), are associated with increased fibroid risk and severity. Both human and experimental studies indicate that epigenetic processes may play an important role in linking EDCs to fibroid pathogenesis. In-vitro and in-vivo studies show that DEHP, bisphenol A, and diethylstilbestrol can impact biological pathways critical to fibroid pathogenesis.

SUMMARY

While research on EDCs and fibroids is still evolving, recent evidence suggests EDC exposures may contribute to fibroid risk and progression. Further research is needed to examine the impacts of EDC mixtures and to identify critical biological pathways and windows of exposure. These results could open the door to new prevention strategies for fibroids.

Vitamin D3 Ameliorates DNA Damage Caused by Developmental Exposure to Endocrine Disruptors in the Uterine Myometrial Stem Cells of Eker Rats

Early-life exposure of the myometrium to endocrine-disrupting chemicals (EDCs) has been shown to increase the risk of uterine fibroid (UF) prevalence in adulthood. Vitamin D3 (VitD3) is an unique, natural compound that may reduce the risk of developing UFs. However, little is known about the role and molecular mechanism of VitD3 on exposed myometrial stem cells (MMSCs). We investigated the role and molecular mechanism underlying VitD3 action on DNA damage response (DDR) defects in rat MMSCs due to developmental exposure to diethylstilbestrol (DES), with the additional goal of understanding how VitD3 decreases the incidence of UFs later in life. Female newborn Eker rats were exposed to DES or a vehicle early in life; they were then sacrificed at 5 months of age (pro-fibroid stage) and subjected to myometrial Stro1+/CD44+ stem cell isolation. Several techniques were performed to determine the effect of VitD3 treatment on the DNA repair pathway in DES-exposed MMSCs (DES-MMSCs). Results showed that there was a significantly reduced expression of RAD50 and MRE11, key DNA repair proteins in DES-exposed myometrial tissues, compared to vehicle (VEH)-exposed tissues (p < 0.01). VitD3 treatment significantly decreased the DNA damage levels in DES-MMSCs. Concomitantly, the levels of key DNA damage repair members, including the MRN complex, increased in DES-MMSCs following treatment with VitD3 (p < 0.01). VitD3 acts on DNA repair via the MRN complex/ATM axis, restores the DNA repair signaling network, and enhances DDR. This study demonstrates, for the first time, that VitD3 treatment attenuated the DNA damage load in MMSCs exposed to DES and classic DNA damage inducers. Moreover, VitD3 targets primed MMSCs, suggesting a novel therapeutic approach for the prevention of UF development.

Expanding upon the Human Myometrial Stem Cell Hypothesis and the Role of Race, Hormones, Age, and Parity in a Profibroid Environment

Uterine fibroids (UFs) are clonal, hormonally regulated, benign smooth-muscle myometrial tumors that severely affect female reproductive health, although their unknown etiology limits effective care. UFs occur fourfold more commonly in African American women than in Caucasian women, and African American women generally have earlier disease onset and greater UF tumor burden, although the mechanism of this ethnic disparity has not been identified. Recent findings have linked cancer (ie, tumor) risk to increased tissue-specific stem cell division and self-renewal and suggest that somatic mutations in myometrial stem cells (MyoSCs) convert them into tumor-initiating cells, leading to UF. Specifically, preliminary results in paraffin-embedded myometrial tissues have shown increased STRO-1⁺/CD44⁺ MyoSCs in African American versus Caucasian women. Using specific methods of flow cytometry and automated quantitative pathology imaging, a large cohort of myometrial samples were investigated to determine how the STRO-1⁺/CD44⁺ MyoSCs change with regard to a patient's race, age, parity, fibroid and hormone statuses, and the location of UFs within the uterus. We confirmed that the STRO-1⁺/CD44⁺ MyoSC population is expanded in African American women, is correlated with parity and fibroid number, and fluctuates with cyclic menstrual cycle hormone changes and age. Our data suggest that an expanded MyoSC population increases the formation of tumor-initiating cells, ultimately contributing to increased UF prevalence and burden in African American women.

A Preliminary Study: Human Fibroid Stro-1+/CD44+ Stem Cells Isolated From Uterine Fibroids Demonstrate Decreased DNA Repair and Genomic Integrity Compared to Adjacent Myometrial Stro-1+/CD44+ Cells

CONTEXT

Although uterine fibroids (UFs) continue to place a major burden on female reproductive health, the mechanisms behind their origin remain undetermined. Normal myometrial stem cells may be transformed into tumor-initiating stem cells, causing UFs, due to unknown causes of somatic mutations in MED12, found in up to 85% of sporadically formed UFs. It is well established in other tumor types that defective DNA repair increases the risk of such tumorigenic somatic mutations, mechanisms not yet studied in UFs.

OBJECTIVE

To examine the putative cause(s) of this stem cell transformation, we analyzed DNA repair within stem cells from human UFs compared to those from adjacent myometrium to determine whether DNA repair in fibroid stem cells is compromised.

DESIGN

Human fibroid (F) and adjacent myometrial (Myo) stem cells were isolated from fresh tissues, and gene expression relating to DNA repair was analyzed. Fibroid stem cells differentially expressed DNA repair genes related to DNA double- (DSBs) and single-strand breaks. DNA damage was measured using alkaline comet assay. Additionally, DNA DSBs were induced in these stem cells and DNA DSB repair evaluated (1) by determining changes in phosphorylation of DNA DSB-related proteins and (2) by determining differences in γ-H2AX foci formation and relative DNA repair protein RAD50 expression.

RESULTS

Overall, F stem cells demonstrated increased DNA damage and altered DNA repair gene expression and signaling, suggesting that human F stem cells demonstrate impaired DNA repair.

CONCLUSIONS

Compromised F stem cell DNA repair may contribute to further mutagenesis and, consequently, further growth and propagation of UF tumors.