In Vivo Evidence of the Androgen Receptor in Association With Myometrial Cell Proliferation and Apoptosis

Androgen Signaling in Uterine Diseases: New Insights and New Targets

Common uterine diseases include endometriosis, uterine fibroids, endometrial polyps, endometrial hyperplasia, endometrial cancer, and endometrial dysfunction causing infertility. Patients with uterine diseases often suffer from abdominal pain, menorrhagia, infertility and other symptoms, which seriously impair their health and disturb their lives. Androgens play important roles in the normal physiological functions of the uterus and pathological progress of uterine diseases. Androgens in women are synthesized in the ovaries and adrenal glands. The action of androgens in the uterus is mainly mediated by its ligand androgen receptor (AR) that regulates transcription of the target genes. However, much less is known about the signaling pathways through which androgen functions in uterine diseases, and contradictory findings have been reported. This review summarizes and discusses the progress of research on androgens and the involvement of AR in uterine diseases. Future studies should focus on developing new therapeutic strategies that precisely target specific AR and their related signaling pathways in uterine diseases.

FKBP51 Contributes to Uterine Leiomyoma Pathogenesis by Inducing Cell Proliferation and Extracellular Matrix Deposition

The FK506-binding protein 51 (FKBP51) binds progesterone receptor (PR), glucocorticoid receptor (GR), and androgen receptor (AR) to coregulate their transcriptional activity. We evaluated FKBP51 expression and function in human leiomyoma vs. myometrial tissues and primary cultures to discover FKBP51 role(s) in the pathogenesis of leiomyomas. Quantification of in situ FKBP51 mRNA and protein levels inpaired myometrial vs. leiomyoma tissues from proliferative and secretory phases were analyzed by qPCR (n = 14), immunoblotting (n = 20), and immunohistochemistry (n = 12). Control (scramble) vs. FKBP5 siRNA-transfected leiomyoma cell cultures were assessed for proliferation, apoptosis, and mRNA levels of genes involved in cell survival and extracellular matrix (ECM) formation. Significantly higher FKBP5 mRNA levels were detected in leiomyoma vs. paired myometrium (P < 0.001). Immunoblot (P = 0.001) and immunostaining (P ≤ 0.001) confirmed increased FKBP51 levels in leiomyoma vs. paired myometrium. Compared to control siRNA transfection, FKBP5-silenced leiomyoma cell cultures displayed significantly decreased cell survival factors and reduced proliferation (P < 0.05). Moreover, qPCR analysis revealed significantly lower mRNA levels of ECM, TIPM1, and TIPM3 proteins in FKBP5-silenced leiomyoma cell cultures (P < 0.05). Increased FKBP51 expression in leiomyoma likely involves dysregulation of steroid signaling by blocking GR and PR action and promoting proliferation and ECM production. Evaluating the effect of FKBP51 inhibition in preclinical studies will clarify its significance as a potential therapeutic approach against leiomyoma.

Activation of β-Catenin Signaling and its Crosstalk With Estrogen and Histone Deacetylases in Human Uterine Fibroids

CONTEXT

Uterine fibroids (UF) are the most common benign tumor of the myometrium (MM) in women of reproductive age. However, the mechanism underlying the pathogenesis of UF is largely unknown.

OBJECTIVE

To explore the link between nuclear β-catenin and UF phenotype and β-catenin crosstalk with estrogen and histone deacetylases (HDACs).

DESIGN

Protein/RNA levels of β-catenin (CTNNB1 gene), its responsive markers cyclin D1 and c-Myc, androgen receptor (AR), p27, and class-I HDACs were measured in matched UF/MM tissues or cell populations. The effects of chemical inhibition/activation and genetic knockdown of CTNNB1 on UF phenotype were measured. The anti-UF effect of 2 HDAC inhibitors was evaluated.

MAIN OUTCOME MEASURE

β-catenin nuclear translocation in response to β-catenin inhibition/activation, estrogen, and HDAC inhibitors in UF cells.

RESULTS

UF tissues/cells showed significantly higher expression of nuclear β-catenin, cyclin D1, c-Myc, and HDACs 1, 2, 3, and 8 than MM. Estradiol induced β-catenin nuclear translocation and consequently its responsive genes in both MM and UF cells, while an estrogen receptor antagonist reversed this induction effect. Treatment with β-catenin or HDAC inhibitors led to dose-dependent growth inhibition, while Wnt3a treatment increased proliferation compared with control. Chemical inhibition of β-catenin decreased cyclin D1 and c-Myc expression levels, while β-catenin activation increased expression of the same markers. Genetic knockdown of CTNNB1 resulted in a marked decrease in β-catenin, cyclin D1, c-Myc, and AR expression. Treatment of UF cells with HDAC inhibitors decreased nuclear β-catenin, cyclin D1, and c-Myc expression. Moreover, HDAC inhibitors induced apoptosis of UF cells and cell cycle arrest.

CONCLUSION

β-catenin nuclear translocation contributes to UF phenotype, and β-catenin signaling is modulated by estradiol and HDAC activity.

The Selective Progesterone Receptor Modulator Ulipristal Acetate Inhibits the Activity of the Glucocorticoid Receptor

CONTEXT

The selective progesterone modulator ulipristal acetate (ulipristal) offers a much-needed therapeutic option for the clinical management of uterine fibroids. Although ulipristal initially passed safety evaluations in Europe, postmarketing analysis identified cases of hepatic injury and failure, leading to restrictions on the long-term use of ulipristal. One of the factors potentially contributing to significant side effects with the selective progesterone modulators is cross-reactivity with other steroid receptors.

OBJECTIVE

To determine whether ulipristal can alter the activity of the endogenous glucocorticoid receptor (GR) in relevant cell types.

DESIGN

Immortalized human uterine fibroid cells (UtLM) and hepatocytes (HepG2) were treated with the synthetic glucocorticoid dexamethasone and/or ulipristal. Primary uterine fibroid tissue was isolated from patients undergoing elective gynecological surgery and treated ex vivo with dexamethasone and/or ulipristal. In vivo ulipristal exposure was performed in C57Bl/6 mice to measure the effect on basal gene expression in target tissues throughout the body.

RESULTS

Dexamethasone induced the expression of established glucocorticoid-target genes period 1 (PER1), FK506 binding protein 51 (FKBP5), and glucocorticoid-induced leucine zipper (GILZ) in UtLM and HepG2 cells, whereas cotreatment with ulipristal blocked the transcriptional response to glucocorticoids in a dose-dependent manner. Ulipristal inhibited glucocorticoid-mediated phosphorylation, nuclear translocation, and DNA interactions of GR. Glucocorticoid stimulation of PER1, FKBP5, and GILZ was abolished by cotreatment with ulipristal in primary uterine fibroid tissue. The expression of glucocorticoid-responsive genes was decreased in the lung, liver, and uterus of mice exposed to 2 mg/kg ulipristal. Interestingly, transcript levels of Fkbp5 and Gilz were increased in the hippocampus and pituitary.

CONCLUSIONS

These studies demonstrate that ulipristal inhibits endogenous glucocorticoid signaling in human fibroid and liver cells, which is an important consideration for its use as a long-term therapeutic agent.

How do elevated levels of testosterone affect the function of the human fallopian tube and fertility?-New insights

Excess testosterone levels affect up to 20% of the female population worldwide and are a key component in the pathogenesis of polycystic ovary syndrome. However, little is known about how excess testosterone affects the function of the human fallopian tube-the site of gamete transport, fertilization, and early embryogenesis. Therefore, this study aimed to characterize alterations caused by long-term exposure to male testosterone levels. For this purpose, the Fallopian tubes of nine female-to-male transsexuals, who had been undergoing testosterone treatment for 1-3 years, were compared with the tubes of 19 cycling patients. In the ampulla, testosterone treatment resulted in extensive luminal accumulations of secretions and cell debris which caused ciliary clumping and luminal blockage. Additionally, the percentage of ciliated cells in the ampulla was significantly increased. Transsexual patients, who had had sexual intercourse before surgery, showed spermatozoa trapped in mucus. Finally, in the isthmus complete luminal collapse occurred. Our results imply that fertility in women with elevated levels of testosterone is altered by tubal luminal obstruction resulting in impaired gamete transport and survival.

A novel mechanism of SRRM4 in promoting neuroendocrine prostate cancer development via a pluripotency gene network

Background

Prostate adenocarcinoma (AdPC) cells can undergo lineage switching to neuroendocrine cells and develop into therapy-resistant neuroendocrine prostate cancer (NEPC). While genomic/epigenetic alterations are shown to induce neuroendocrine differentiation via an intermediate stem-like state, RNA splicing factor SRRM4 can transform AdPC cells into NEPC xenografts through a direct neuroendocrine transdifferentiation mechanism. Whether SRRM4 can also regulate a stem-cell gene network for NEPC development remains unclear.

Methods

Multiple AdPC cell models were transduced by lentiviral vectors encoding SRRM4. SRRM4-mediated RNA splicing and neuroendocrine differentiation of cells and xenografts were determined by qPCR, immunoblotting, and immunohistochemistry. Cell morphology, proliferation, and colony formation rates were also studied. SRRM4 transcriptome in the DU145 cell model was profiled by AmpliSeq and analyzed by gene enrichment studies.

Findings

SRRM4 induces an overall NEPC-specific RNA splicing program in multiple cell models but creates heterogeneous transcriptomes. SRRM4-transduced DU145 cells present the most dramatic neuronal morphological changes, accelerated cell proliferation, and enhanced resistance to apoptosis. The derived xenografts show classic phenotypes similar to clinical NEPC. Whole transcriptome analyses further reveal that SRRM4 induces a pluripotency gene network consisting of the stem-cell differentiation gene, SOX2. While SRRM4 overexpression enhances SOX2 expression in both time- and dose-dependent manners in DU145 cells, RNA depletion of SOX2 compromises SRRM4-mediated stimulation of pluripotency genes. More importantly, this SRRM4-SOX2 axis is present in a subset of NEPC patient cohorts, patient-derived xenografts, and clinically relevant transgenic mouse models.

Interpretation

We report a novel mechanism by which SRRM4 drives NEPC progression via a pluripotency gene network.

Fund

Canadian Institutes of Health Research, National Nature Science Foundation of China, and China Scholar Council.

Endocrine-disrupting chemicals and uterine fibroids

Uterine fibroids are the most frequent gynecologic tumor, affecting 70% to 80% of women over their lifetime. Although these tumors are benign, they can cause significant morbidity and may require invasive treatments such as myomectomy and hysterectomy. Many risk factors for these tumors have been identified, including environmental exposures to endocrine-disrupting chemicals (EDCs) such as genistein and diethylstilbestrol. Uterine development may be a particularly sensitive window to environmental exposures, as some perinatal EDC exposures have been shown to increase tumorigenesis in both rodent models and human epidemiologic studies. The mechanisms by which EDC exposures may increase tumorigenesis are still being elucidated, but epigenetic reprogramming of the developing uterus is an emerging hypothesis. Given the remarkably high incidence of uterine fibroids and their significant impact on women's health, understanding more about how prenatal exposures to EDCs (and other environmental agents) may increase fibroid risk could be key to developing prevention and treatment strategies in the future.

Uterine fibroids

Uterine fibroids (also known as leiomyomas or myomas) are common clonal neoplasms of the uterus. Fibroids have both smooth muscle and fibroblast components, in addition to a substantial amount of fibrous extracellular matrix, which all contribute to the pathogenetic process. Fibroids are extremely heterogeneous in their pathophysiology, size, location and clinical symptomatology. They are also a part of a range of disease in which some variants have facets of malignant behaviour but overall are benign. Risk for fibroids is associated with race; black women have a higher risk of developing fibroids earlier in life than their white counterparts and also develop more-severe forms of the disease. Clinically, fibroids account for one-third to half of all hysterectomies and are associated with substantial morbidity and health care costs for women of reproductive age. Indeed, current treatments are primarily surgical and interventional; approximately three-quarters of all fibroid treatments are hysterectomies. However, clinical innovations are emerging in the use of progesterone receptor modulators as a medical therapy. New information is rapidly accumulating about the genetic subgroups that lead to fibroid formation, which might aid further understanding of the clinical heterogeneity of this disease and lead to individualized treatments. This information is a crucial development given the current lack of high-quality evidence on which to base therapeutic decisions.