Molecular Background of Estrogen Receptor Gene Expression in Endometriotic Cells

Differential expression of estrogen receptor subtypes in ovarian high-grade serous carcinoma and clear cell carcinoma

PURPOSE

To investigate the role of estrogen receptors (ERs) in high-grade serous carcinoma (HGSC) and clear cell carcinoma (CCC) of the ovary and evaluate ERs as prognostic biomarkers for ovarian cancer.

METHODS

This study included 79 patients with HGSC (n = 38) or CCC (n = 41) treated at our institution between 2005 and 2014. Immunohistochemistry examined protein expression of ERα, ERβ, and G protein-coupled estrogen receptor-1 (GPER-1); relationships between ERα, ERβ, and GPER-1 with patient survival were evaluated. Additionally, cell proliferation assay and phosphokinase proteome profiling were performed.

RESULTS

In HGSC patients, expression of ERα, cytoplasmic GPER-1, or nuclear GPER-1 was associated with poor progression-free survival (PFS) (P = .041, P = .010, or P = .013, respectively). Cytoplasmic GPER-1 was an independent prognostic factor for PFS in HGSC patients (HR = 2.83, 95% CI = 1.03-9.16, P = .007). ER expressions were not associated with prognosis in CCC patients. GPER-1 knockdown by siRNA reduced the cells number to 60% of siRNA-control-treated cells (P < .05), and GPER-1 antagonist, G-15 inhibited two HGSC cell lines proliferation (KF and UWB1.289) in a dose-dependent manner. Phosphoprotein array revealed that GPER-1 silencing decreased relative phosphorylation of glycogen synthase kinase-3.

CONCLUSIONS

High GPER-1 expression is an independent prognostic factor for PFS in HGSC patients, and GPER-1 may play a role in HGSC cell proliferation.

RhoA/ROCK pathway mediates the effect of oestrogen on regulating epithelial-mesenchymal transition and proliferation in endometriosis

Endometriosis is a benign gynaecological disease appearing with pelvic pain, rising dysmenorrhoea and infertility seriously impacting on 10% of reproductive‐age females. This research attempts to demonstrate the function and molecular mechanism of RhoA/ROCK pathway on epithelial‐mesenchymal transition (EMT) and proliferation in endometriosis. The expression of Rho family was abnormally changed in endometriotic lesions; in particular, RhoA and ROCK1/2 were significantly elevated. Overexpression of RhoA in human eutopic endometrial epithelial cells (eutopic EECs) enhanced the cell mobility, epithelial‐mesenchymal transition (EMT) and proliferation, and RhoA knockdown exhibited the opposite function. Oestrogen up‐regulated the RhoA activity and expression of RhoA and ROCK1/2. RhoA overexpression reinforced the effect of oestrogen on promoting EMT and proliferation, and RhoA knockdown impaired the effect of oestrogen. oestrogen receptor α (ERα) was involved with the regulation of oestrogen on EMT and proliferation and up‐regulated RhoA activity and expression of RhoA and ROCK1/2. The function of ERα was modulated by the change in RhoA expression. Furthermore, phosphorylated ERK that was enhanced by oestrogen and ERα promoted the protein expression of RhoA/ROCK pathway. Endometriosis mouse model revealed that oestrogen enhanced the size and weight of endometriotic lesions. The expression of RhoA and phosphorylated ERK in mouse endometriotic lesions was significantly elevated by oestrogen. We conclude that abnormal activated RhoA/ROCK pathway in endometriosis is responsible for the function of oestrogen/ERα/ERK signalling, which promoted EMT and proliferation and resulted in the development of endometriosis.

Human Endometriosis Tissue Microarray Reveals Site-specific Expression of Estrogen Receptors, Progesterone Receptor, and Ki67

Most available therapies for endometriosis are hormone-based and generally broadly used without taking into consideration the ovarian hormone receptor expression status. This contrasts strikingly with the standard of care for other hormone-based conditions such as breast cancer. We therefore aimed to characterize the expression of ovarian steroid hormone receptors for estrogen alpha (ESR1), estrogen beta (ESR2), and progesterone (PGR) in different types of endometriotic lesions and eutopic endometrium from women with endometriosis and controls using a tissue microarray (TMA). Nuclear expression levels of the receptors were analyzed by tissue (ie, ectopic vs. eutopic endometrium) and cell type (ie, glands vs. stroma). Ovarian lesions showed the lowest expression of ESR1 and PGR, and the highest expression of ESR2, whereas the fallopian tube lesions showed high expression of the 3 receptors. Differences among endometria included lower expression of ESR1 and higher expression of ESR2 in stroma of proliferative endometrium from patients versus patients, and a trend towards loss of PGR nuclear positivity in proliferative endometrium from patients. The largest ESR2:ESR1 ratios were observed in ovarian lesions and secretory endometrium. The highest proportion of samples with >10% Ki67 positive nuclei was in glands of fallopian tube (54%) and extrapelvic lesions (75%); 60% of glands of secretory endometrium from patients had >10% Ki67 positivity compared with only 15% in controls. Our results provide a better understanding of endometriosis heterogeneity by revealing lesion type-specific differences and case-by-case variability in the expression of ovarian hormone receptors. This knowledge could potentially predict individual responses to hormone therapies, and set the basis for the application of personalized medicine approaches for women with endometriosis.

Estradiol promotes EMT in endometriosis via MALAT1/miR200s sponge function

Endometriosis is an estrogen-dependent benign gynecological disease that shares some common features of malignancy. Epithelial-mesenchymal transition (EMT) has been recognized as a core mechanism of endometriosis. MALAT1 is widely known as EMT promoter, while miR200 family members (miR200s) are considered as EMT inhibitors. Previous studies have reported that MALAT1 upregulation and miR200s downregulation are observed in endometriosis. MiR200c has been regarded as the strongest member of miR200s to interact with MALAT1. However, whether MALAT1/miR200c regulates EMT remains largely unclear. In this study, the roles of miR200s and MALAT1 in ectopic endometrium were investigated. Additionally, the effects of E2 on EMT and MALAT1/miR200s were examined in both EECs and Ishikawa cells. Notably, E2 could upregulate MALAT1 and downregulate miR200s expression levels and induce EMT in EECs and Ishikawa cells. PHTPP, an ERβ antagonist, could reverse the effect of E2. Overexpression of miR200c and knockdown of MALAT1 significantly inhibited E2-mediated EMT, suggesting that both miR200c and MALAT1 are involved in the E2-induced EMT process in endometriosis. In addition, a reciprocal inhibition was found between miR200s and MALAT1. Therefore, the role of MALAT1/miR200c in EMT is influenced by the presence of estrogen during endometriosis development.

GATA6 expression promoted by an active enhancer may become a molecular marker in endometriosis lesions

PROBLEM

Genome-wide profiling of DNA methylation in endometriotic cells has shown a distinct facet of epigenetic backgrounds; however, specific DNA methylation sites responsible for aberrant gene expression in endometriosis were unknown. Are there specific endometriosis-associated DNA methylations that can be used as molecular markers in endometriosis lesions?

METHOD OF STUDY

This study used endometriotic tissues from the chocolate cyst lining of the ovaries of patients with endometriosis, and endometrial tissues from disease-free patients. For analysis, stromal cells were collected from endometrial and endometriotic tissues. Using endometrial cells as control, differentially methylated cytosine-phosphate-guanine (CpG) characteristic in endometriotic cells was extracted. Among these CpGs, we focused on a stretch of hypomethylated CpGs within GATA6 gene and examined the potential role as enhancer in endometriotic cells and tissues.

RESULT(S)

We identified a stretch of hypomethylated CpGs within the GATA6 gene body in endometriotic cells. Because GATA6 mRNA was highly expressed in endometriotic cells but not in endometrial cells, we then hypothesized that the hypomethylated sequence may function as an enhancer in GATA6 gene expression. Chromatin immunoprecipitation analysis predicted the presence of active enhancer within the gene body sequence in endometriotic cells. Immunohistochemistry showed a positive staining of GATA6 in ovarian chocolate cysts, while in endometrial tissues and in some peritoneal tissues with endometriosis, GATA6 staining was at a marginal level.

CONCLUSION

This is the first implication showing a link between an aberrant DNA methylation of cis element and gene expression in endometriosis. GATA6 expression may become a molecular marker to diagnose endometriosis lesions.

Villainous role of estrogen in macrophage-nerve interaction in endometriosis

Endometriosis is a complex and heterogeneous disorder with unknown etiology. Dysregulation of macrophages and innervation are important factors influencing the pathogenesis of endometriosis-associated pain. It is known to be an estrogen-dependent disease, estrogen can promote secretion of chemokines from peripheral nerves, enhancing the recruitment and polarization of macrophages in endometriotic tissue. Macrophages have a role in the expression of multiple nerve growth factors (NGF), which mediates the imbalance of neurogenesis in an estrogen-dependent manner. Under the influence of estrogen, co-existence of macrophages and nerves induces an innovative neuro-immune communication. Persistent stimulation by inflammatory cytokines from macrophages on nociceptors of peripheral nerves aggravates neuroinflammation through the release of inflammatory neurotransmitters. This neuro-immune interaction regulated by estrogen sensitizes peripheral nerves, leading to neuropathic pain in endometriosis. The aim of this review is to highlight the significance of estrogen in the interaction between macrophages and nerve fibers, and to suggest a potentially valuable therapeutic target for endometriosis-associated pain.

microRNA Let-7b: A Novel treatment for endometriosis

Endometriosis is an oestrogen-dependent, chronic inflammatory disease that affects 10% of reproductive-aged women. Current treatment options depend on female sex steroid hormone modulation; however, all have side effects and are not useful in women who want to conceive. microRNAs treatments have provided promising results for some chronic diseases and cancers. We have previously shown the microRNA Let-7b is repressed in endometriosis and that loss of Let-7 contributes to the pathophysiology of the disease. Here, we propose using microRNA Let-7b for the treatment of endometriosis in a murine model. Endometriosis was treated using microRNA Let-7b or a scrambled control microRNA. Let-7b treatment resulted in reduced endometriosis lesion size. Decreased gene expression was noted in several genes known to promote endometriosis growth including ER-α, ER-ß, Cyp19a, KRAS 4A, KRAS 4B and IL-6. These results indicate that microRNA Let-7b has a pleiotropic role in endometriosis pathophysiology affecting oestrogen signalling, inflammation and growth factor receptors. Local treatment of endometriosis with Let-7b is a promising therapy for endometriosis that simultaneously affects multiple pathways driving endometriosis without systemic hormonal side effects.