Progesterone receptor-DNA methylation crosstalk regulates depletion of uterine leiomyoma stem cells: A potential therapeutic target.

Uterine leiomyoma (LM) is the most common tumor in women. Via its receptor (PGR) expressed in differentiated LM cells, progesterone stimulates paracrine signaling that induces proliferation of PGR-deficient LM stem cells (LSCs). Antiprogestins shrink LM but tumors regrow after treatment cessation possibly due to persisting LSCs. Using sorted primary LM cell populations, we found that the PGR gene locus and its target cistrome are hypermethylated in LSCs, inhibiting the expression of genes critical for progesterone-induced LSC differentiation. PGR knockdown shifted the transcriptome of total LM cells toward LSCs and increased global DNA methylation by regulating TET methylcytosine dioxygenases. DNA methylation inhibitor 5'-Aza activated PGR signaling, stimulated LSC differentiation, and synergized with antiprogestin to reduce tumor size in vivo. Taken together, targeting the feedback loop between DNA methylation and progesterone signaling may accelerate the depletion of LSCs through rapid differentiation and sensitize LM to antiprogestin therapy, thus preventing tumor regrowth.

Brain Aromatase and the Regulation of Sexual Activity in Male Mice.

The biologically active estrogen estradiol has important roles in adult brain physiology and sexual behavior. A single gene, Cyp19a1, encodes aromatase, the enzyme that catalyzes the conversion of testosterone to estradiol in the testis and brain of male mice. Estradiol formation was shown to regulate sexual activity in various species, but the relative contributions to sexual behavior of estrogen that arises in the brain versus from the gonads remained unclear. To determine the role of brain aromatase in regulating male sexual activity, we generated a brain-specific aromatase knockout (bArKO) mouse. A newly generated whole-body total aromatase knockout mouse of the same genetic background served as a positive control. Here we demonstrate that local aromatase expression and estrogen production in the brain is partially required for male sexual behavior and sex hormone homeostasis. Male bArKO mice exhibited decreased sexual activity in the presence of strikingly elevated circulating testosterone. In castrated adult bArKO mice, administration of testosterone only partially restored sexual behavior; full sexual behavior, however, was achieved only when both estradiol and testosterone were administered together. Thus, aromatase in the brain is, in part, necessary for testosterone-dependent male sexual activity. We also found that brain aromatase is required for negative feedback regulation of circulating testosterone of testicular origin. Our findings suggest testosterone activates male sexual behavior in part via conversion to estradiol in the brain. These studies provide foundational evidence that sexual behavior may be modified through inhibition or enhancement of brain aromatase enzyme activity and/or utilization of selective estrogen receptor modulators.

Activation of protein kinase B by WNT4 as a regulator of uterine leiomyoma stem cell function.

OBJECTIVE: To investigate the functional interaction between the Wnt/ß-catenin and protein kinase B (Akt) pathways in leiomyoma stem cells (LSC). DESIGN: Laboratory study. SETTING: Research laboratory. PATIENT(S): Premenopausal women (n = 36; age range: 28 to 49 years) undergoing hysterectomy or myomectomy for leiomyoma. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Gene expression, protein phosphorylation, and cell proliferation. RESULT(S): Cells from human leiomyoma tissues were sorted by fluorescence-activated cell sorting (FACS) into three populations: LSC, intermediate cells (LIC), and differentiated cells (LDC) with the function of the Wnt/ß-catenin and Akt signaling pathways in leiomyoma cells evaluated using real-time quantitative polymerase chain reaction and immunoblot analyses. The Wnt/ß-catenin signaling pathway components were differentially expressed in each leiomyoma cell population. WNT4 was distinctly overexpressed in LIC, and its receptor FZD6 was primarily expressed in LSC. WNT4 stimulated Akt phosphorylation, activated ß-catenin, and increased primary leiomyoma cell proliferation. These stimulatory effects were abolished by cotreatment with the Akt inhibitor, MK-2206. WNT4 up-regulated the expression of pro-proliferative genes, c-Myc and cyclin D1, specifically in LSC; this was also abrogated by Akt inhibition. CONCLUSION(S): Our data suggest that WNT4 regulates LSC proliferation via Akt-dependent ß-catenin activation, representing a key step toward a better understanding of LSC regulation and potentially novel therapeutic targets.

Targeting DNA Methylation Depletes Uterine Leiomyoma Stem Cell-enriched Population by Stimulating Their Differentiation.

Uterine leiomyoma (LM) is the most common tumor in women and can cause severe morbidity. Leiomyoma growth requires the maintenance and proliferation of a stem cell population. Dysregulated deoxyribonucleic acid (DNA) methylation has been reported in LM, but its role in LM stem cell regulation remains unclear. Here, we fluorescence-activated cell sorting (FACS)-sorted cells from human LM tissues into 3 populations: LM stem cell-like cells (LSC, 5%), LM intermediate cells (LIC, 7%), and differentiated LM cells (LDC, 88%), and we analyzed the transcriptome and epigenetic landscape of LM cells at different differentiation stages. Leiomyoma stem cell-like cells harbored a unique methylome, with 8862 differentially methylated regions compared to LIC and 9444 compared to LDC, most of which were hypermethylated. Consistent with global hypermethylation, transcript levels of TET1 and TET3 methylcytosine dioxygenases were lower in LSC. Integrative analyses revealed an inverse relationship between methylation and gene expression changes during LSC differentiation. In LSC, hypermethylation suppressed the genes important for myometrium- and LM-associated functions, including muscle contraction and hormone action, to maintain stemness. The hypomethylating drug, 5'-Aza, stimulated LSC differentiation, depleting the stem cell population and inhibiting tumor initiation. Our data suggest that DNA methylation maintains the pool of LSC, which is critical for the regeneration of LM tumors.

GATA2 and Progesterone Receptor Interaction in Endometrial Stromal Cells Undergoing Decidualization.

The transcription factor GATA2 is important for endometrial stromal cell decidualization in early pregnancy. Progesterone receptor (PGR) is also critical during decidualization but its interaction with GATA2 in regulating genes and pathways necessary for decidualization in human endometrium are unclear. RNA-sequencing (RNA-seq) was performed to compare gene expression profiles (n = 3), and chromatin immunoprecipitation followed by sequencing (ChIP-seq) using an antibody against GATA2 (n = 2) was performed to examine binding to target genes in human endometrial stromal cells undergoing in vitro decidualization (IVD including estrogen, progestin, and 3',5'-cyclic AMP analogue) or vehicle treatment. We identified 1232 differentially expressed genes (DEGs) in IVD vs vehicle. GATA2 cistrome in IVD-treated cells was enriched with motifs for GATA, ATF, and JUN, and gene ontology analysis of GATA2 cistrome revealed pathways that regulate cholesterol storage, p38 mitogen-activated protein kinase, and the c-Jun N-terminal kinase cascades. Integration of RNA-seq and ChIP-seq data revealed that the PGR motif is highly enriched at GATA2 binding regions surrounding upregulated genes in IVD-treated cells. The integration of a mined public PGR cistrome in IVD-treated human endometrial cells with our GATA2 cistrome showed that GATA2 binding was significantly enhanced at PGR-binding regions in IVD vs vehicle. Interrogating 2 separate ChIP-seq data sets together with RNA-seq revealed integration of GATA2 and PGR action to coregulate biologic processes during decidualization of human endometrial stromal cells, specifically via WNT activation and stem cell differentiation pathways. These findings reveal the key pathways that are coactivated by GATA2 and PGR that may be therapeutic targets for supporting implantation and early pregnancy.

Generation of Progesterone-Responsive Endometrial Stromal Fibroblasts from Human Induced Pluripotent Stem Cells: Role of the WNT/CTNNB1 Pathway.

Defective endometrial stromal fibroblasts (EMSFs) contribute to uterine factor infertility, endometriosis, and endometrial cancer. Induced pluripotent stem cells (iPSCs) derived from skin or bone marrow biopsies provide a patient-specific source that can be differentiated to various cells types. Replacement of abnormal EMSFs is a potential novel therapeutic approach for endometrial disease; however, the methodology or mechanism for differentiating iPSCs to EMSFs is unknown. The uterus differentiates from the intermediate mesoderm (IM) to form coelomic epithelium (CE) followed by the Müllerian duct (MD). Here, we successfully directed the differentiation of human iPSCs (hiPSCs) through IM, CE, and MD to EMSFs under molecularly defined embryoid body culture conditions using specific hormonal treatments. Activation of CTNNB1 was essential for expression of progesterone receptor that mediated the final differentiation step of EMSFs before implantation. These hiPSC-derived tissues illustrate the potential for iPSC-based endometrial regeneration for future cell-based treatments.

Inhibition of canonical WNT signaling attenuates human leiomyoma cell growth.

OBJECTIVE: To assess the effect of three WNT/ß-catenin pathway inhibitors-inhibitor of ß-catenin and TCF4 (ICAT), niclosamide, and XAV939-on the proliferation of primary cultures of human uterine leiomyoma cells. DESIGN: Prospective study of human leiomyoma cells obtained from myomectomy or hysterectomy. SETTING: University research laboratory. PATIENT(S): Women (n = 38) aged 27-53 years undergoing surgery. INTERVENTION(S): Adenoviral ICAT overexpression or treatment with varying concentrations of niclosamide or XAV939. MAIN OUTCOME MEASURE(S): Cell proliferation, cell death, WNT/-catenin target gene expression or reporter gene regulation, ß-catenin levels, and cellular localization. RESULT(S): Inhibitor of ß-catenin and TCF4, niclosamide, or XAV939 inhibit WNT/ß-catenin pathway activation and exert antiproliferative effects in primary cultures of human leiomyoma cells. CONCLUSION(S): Three WNT/-catenin pathway inhibitors specifically block human leiomyoma growth and proliferation, suggesting that the canonical WNT pathway may be a potential therapeutic target for the treatment of uterine leiomyoma. Our findings provide rationale for further preclinical and clinical evaluation of ICAT, niclosamide, and XAV939 as candidate antitumor agents for uterine leiomyoma.

The selective progesterone receptor modulator CDB4124 inhibits proliferation and induces apoptosis in uterine leiomyoma cells.

OBJECTIVE: To evaluate the effects of selective P receptor (PR) modulator CDB4124 on cell proliferation and apoptosis in cultured human uterine leiomyoma smooth muscle (LSM) cells and control myometrial smooth muscle (MSM) cells in matched uteri. DESIGN: Laboratory research. SETTING: Academic medical center. PATIENT(S): Premenopausal women (n = 12) undergoing hysterectomy for leiomyoma-related symptoms. INTERVENTION(S): Treatment of primary LSM and MSM cells with CDB4124 (10(-8)-10(-6) M) or vehicle for 24, 48, or 72 hours. MAIN OUTCOME MEASURE(S): Western blot for protein expression of proliferating cell nuclear antigen, cleaved polyadenosine 5'-diphosphate-ribose polymerase, Bcl-2, and Krüppel-like transcription factor 11; 93-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide (MTT) assay to evaluate viable cell numbers; and real-time polymerase chain reaction (PCR) to quantify messenger RNA (mRNA) levels. RESULT(S): Treatment with CDB4124 significantly decreased levels of the proliferation marker proliferating cell nuclear antigen, the number of viable LSM cells, and the antiapoptotic protein Bcl-2. On the other hand, treatment with CDB4124 increased levels of the apoptosis marker cleaved polyadenosine 5'-diphosphate-ribose polymerase and the tumor suppressor Krüppel-like transcription factor 11 in a dose- and time-dependent manner in LSM cells. In matched MSM cells, however, CDB4124 did not affect cell proliferation or apoptosis. CONCLUSION(S): CDB4124 selectively inhibits proliferation and induces apoptosis in LSM but not in MSM cells.