Influence of Cancer-Associated Endometrial Stromal Cells on Hormone-Driven Endometrial Tumor Growth

Downregulation of miR-455-3p in decidual cells promotes macrophage polarization and suppresses trophoblasts invasion

Preeclampsia (PE) is a common complication of pregnancy, usually accompanied by symptoms such as hypertension and proteinuria. It can induce severe conditions that may result in maternal and fetal morbidity and fatality. In this study, we use bioinformatics analysis to compare microRNA microassay in decidual stromal cells from PE patients and healthy donors. Our result indicated that placentas from PE patients had a higher CCL1/CXCL2 expression, compared with those from healthy donors. Bioinformatics analysis confirmed that decidual stromal cells derived from PE patients expressed significantly lower miR-455-3p than those derived from healthy donors. Transfection of miR-455-3p inhibitors enhanced the CCL2/CXCL8 expression in decidual stromal cells, and luciferase activity assay confirmed that nuclear factor of activated T cells 5 (NFAT5) mRNA was the direct target of miR-455-3p; NFAT5 also promoted cytokine secretion. In the flow cytometry study, higher M1 macrophage infiltration was observed in placentas from PE patients than in those from healthy donors. We also observed that condition medium (CM) derived from decidual stromal cells could significantly promote M1 polarization of macrophages after transfection with miR-455-3p inhibitor; further, transwell invasion assay confirmed that decidual stromal cells-CM educated macrophages suppressed trophoblast invasion. Taken together, our result demonstrates that downregulation of miR-455-3p in decidual stromal cells can promote macrophage polarization and suppress trophoblasts invasion.

MIG-6 Is Critical for Progesterone Responsiveness in Human Complex Atypical Hyperplasia and Early-Stage Endometrial Cancer

Women with complex atypical hyperplasia (CAH) or early-stage endometrioid endometrial cancer (EEC) are candidates for fertility preservation. The most common approach is progesterone (P4) therapy and deferral of hysterectomy until after completion of childbearing. However, P4 therapy response rates vary, and molecular mechanisms behind P4 resistance are poorly understood. One potential molecular cause of P4 resistance is a loss or attenuation of PGR expression. Mitogen-inducible gene 6 (MIG-6) is critical for P4 responsiveness. MIG-6 protein expression in the endometrial epithelial and stromal cells from women with CAH and EEC was significantly lower compared to women without CAH or EEC. The P4-responsive women (10/15) exhibited an increase of MIG-6 expression in epithelial and stromal cells compared to P4-resistant women (5/15). In addition, immunohistochemical analysis for PGR results showed that stromal PGR levels are significantly higher in P4-responsive women compared to P4-resistant women, whereas epithelial PGR expression was not different. A reverse correlation of MIG-6 and pAKT levels was observed in early-stage EEC patients. Studies strongly suggest that loss of MIG-6 and PGR and activation of pAKT lead to P4 resistance in CAH and EEC. These results will help to elucidate the molecular mechanism leading to P4 resistance in CAH and EEC.

Aberrant upregulation of CDK1 contributes to medroxyprogesterone acetate (MPA) resistance in cancer-associated fibroblasts of the endometrium

The response to medroxyprogesterone acetate (MPA) decreases as endometrial disease progresses from the benign to malignancy. In a mouse model, progesterone receptor (PR) expression in normal fibroblasts is accountable for the MPA's inhibitory effects in cancer cells. However, it is still unclear, if and how, fibroblasts from human tumors respond to MPA. In this study, three benign-associated fibroblasts (BAFs) and four cancer-associated fibroblasts (CAFs) were isolated from human benign and cancerous endometrial tissues, respectively, to examine MPA activation on PR signaling. PR-B protein expression were heterogeneously expressed in both CAFs and BAFs, despite a lower mRNA expression in the former. In a luciferase reporter assay, MPA treatment stimulated some PR DNA-binding activity in BAFs but not in CAFs. Yet, activation of PR target gene was generally more pronounced in MPA-treated CAFs compared to BAFs. Cyclin-dependent kinase 1 (CDK1) was exclusively upregulated by 10 nM MPA in CAFs (5.1-fold vs. 1.1-fold in BAFs, P < 0.05), leading to a higher CDK1 protein expression. Subsequently in a dose-response study, CAFs showed an average of ∼20% higher cell viability when compared to BAFs, indicative of drug resistance to MPA. MPA resistance was also observed in EC-CAFs co-culture, when MPA-treated cells showed greater tumor spheroid formation than in EC-BAFs co-culture (2-fold, P < 0.01). The increased cell viability observed in CAFs was reversed with mifepristone (RU486), a PR antagonist which suppressed MPA-induced CDK1 expression. This indicates that MPA-induced abnormal upregulation of CDK1 may contribute to the enhanced CAFs cell proliferation, suggesting a new mechanism of MPA resistance within endometrial cancer microenvironment.

MPA alters metabolic phenotype of endometrial cancer-associated fibroblasts from obese women via IRS2 signaling

Obese women have a higher risk of developing endometrial cancer (EC) than lean women. Besides affecting EC progression, obesity also affects sensitivity of patients to treatment including medroxprogesterone acetate (MPA). Obese women have a lower response to MPA with an increased risk for tumor recurrence. While MPA inhibits the growth of normal fibroblasts, human endometrial cancer-associated fibroblasts (CAFs) were reported to be less responsive to MPA. However, it is still unknown how CAFs from obese women respond to progesterone. CAFs from the EC tissues of obese (CO) and non-obese (CN) women were established as primary cell models. MPA increased cell proliferation and downregulated stromal differentiation genes, including BMP2 in CO than in CN. Induction of IRS2 (a BMP2 regulator) mRNA expression by MPA led to activation of glucose metabolism in CO, with evidence of greater mRNA levels of GLUT6, GAPDH, PKM2, LDHA, and increased in GAPDH enzymatic activity. Concomitantly, MPA increased the mRNA expression of a fatty acid transporter, CD36 and lipid droplet formation in CO. MPA-mediated increase in glucose metabolism genes in CO was reversed with a progesterone receptor inhibitor, mifepristone (RU486), leading to a decreased proliferation. Our data suggests that PR signaling is aberrantly activated by MPA in CAFs isolated from endometrial tissues of obese women, leading to activation of IRS2 and glucose metabolism, which may lead to lower response and sensitivity to progesterone in obese women.

Cancer-associated fibroblasts as cellular vehicles in endometrial cancer cell migration

Cell motility is a critical step in the metastasis cascade. However, the role of cancer-associated fibroblasts (CAFs) in facilitating endometrial cancer (EC) cell motility remains unclear. The present study aimed to investigate the role of CAFs in EC motility in a 3D environment. A co-culture model was established using an EC cell line (ECC-1) and CAFs on a Matrigel^® matrix and compared to the respective individual monocultures. It was demonstrated that endometrial CAFs increased the motility of the EC cell line, compared with the monoculture. Using live cell imaging, CAFs were observed to form cell projections that served as contact guidance for ECC-1 cell locomotion in the spheroid formation process. These effects were specific to CAFs, as fibroblasts isolated from benign endometrial tissue samples did not form cell projections. Molecular analysis revealed that RhoA/Rho-associated, coiled-coil containing protein kinase 1 (ROCK1) signaling activation partly contributed to CAF-mediated ECC-1 cell migration. The presence of Matrigel^® increased the mRNA expression of RhoA, and the mRNA and protein expression levels of its downstream effectors, ROCK1 and p-MLC, respectively, in the ECC-1 and CAF co-culture, as well as the ECC-1 and CAF monocultures. Interestingly, high phosphorylation levels of myosin light chain mediated the activation of RhoA/ROCK1 signaling in the ECC-1 and CAF co-culture. The ROCK1 inhibitor Y-27632 attenuated the motility of tumor cells in ECC-1 and CAF co-cultures. However, similar treatment led to a significant inhibition in the motility of the CAF monoculture, but not the ECC-1 monoculture. Moreover, tumor spheroid formation was inhibited due to a reduction in stress fiber formation in ECC-1 and CAF co-cultures. Altogether, these findings suggest that the regulation of the RhoA/ROCK1 signaling pathway is required for CAFs to serve as cellular vehicles in order for EC cells to migrate and form spheroids in a 3D environment.

Cancer-Associated Fibroblasts in Conversation with Tumor Cells in Endometrial Cancers: A Partner in Crime

A tumor cell carrying characteristic genomic alteration(s) exists within its host’s microenvironment. The tumor microenvironment (TME) renders holistic support to the tumor via cross-talk between tumor cells and three components of TME, immune components, vascular components, and fibroblast components. The tempero-spatial interaction of tumor cells with its microenvironment is the deterministic factor for tumor growth, progression, resistance to therapy, and its outcome in clinics. TME (1) facilitates proliferation, and the ensuing metastasis-associated phenotypes, (2) perturbs immune surveillance and supports tumor cells in their effort to evade immune recognition, and (3) actively participates in developing drug-induced resistance in cancer cells. Cancer-Associated Fibroblast (CAF) is a unique component of TME. CAF is the host mesenchyme immediately surrounding the tumor cells in solid tumors. It facilitates tumor growth and progression and participates in developing drug resistance in tumor cells by playing a critical role in all the ways mentioned above. The clinical outcome of a disease is thus critically contributed to by the CAF component of TME. Although CAFs have been identified historically, the functional relevance of CAF-tumor cell cross-talk and their influence on angiogenic and immune-components of TME are yet to be characterized in solid tumors, especially in endometrial cancers. Currently, the standard of care for the treatment of endometrial cancers is primarily guided by therapies directed towards the disease’s tumor compartment and immune compartments. Unfortunately, in the current state of therapies, a complete response (CR) to the therapy is still limited despite a more commonly achieved partial response (PR) and stable disease (SD) in patients. Acknowledging the limitations of the current sets of therapies based on only the tumor and immune compartments of the disease, we sought to put forward this review based on the importance of the cross-talk between CAF of the tumor microenvironment and tumor cells. The premise of the review is to recognize the critical role of CAF in disease progression. This manuscript presents a systemic review of the role of CAF in endometrial cancers. We critically interrogated the active involvement of CAF in the tumor compartment of endometrial cancers. Here we present the functional characteristics of CAF in the context of endometrial cancers. We review (1) the characteristics of CAF, (2) their evolution from being anti-tumor to pro-tumor, (3) their involvement in regulating growth and several metastasis-associated phenotypes of tumor cells, (4) their participation in perturbing immune defense and evading immune surveillance, and (5) their role in mediating drug resistance via tumor-CAF cross-talk with particular reference to endometrial cancers. We interrogate the functional characteristics of CAF in the light of its dialogue with tumor cells and other components of TME towards developing a CAF-based strategy for precision therapy to supplement tumor-based therapy. The purpose of the review is to present a new vision and initiate a thought process which recognizes the importance of CAF in a tumor, thereby resulting in a novel approach to the design and management of the disease in endometrial cancers.

ALDH1 expression predicts progression of premalignant lesions to cancer in Type I endometrial carcinomas

In type 1 endometrial cancer, unopposed estrogen stimulation is thought to lead to endometrial hyperplasia which precedes malignant progression. Recent data from our group and others suggest that ALDH activity mediates stemness in endometrial cancer, but while aldehyde dehydrogenase 1 (ALDH1) has been suggested as a putative cancer stem cell marker in several cancer types, its clinical and prognostic value in endometrial cancer remains debated. The aim of this study was to investigate the clinical value of ALDH1 expression in endometrial hyperplasia and to determine its ability to predict progression to endometrial cancer. Interrogation of the TCGA database revealed upregulation of several isoforms in endometrial cancer, of which the ALDH1 isoforms collectively constituted the largest group. To translate its expression, a tissue microarray was previously constructed which contained a wide sampling of benign and malignant endometrial samples. The array contained a metachronous cohort of samples from individuals who either developed or did not develop endometrial cancer. Immunohistochemical staining was used to determine the intensity and frequency of ALDH1 expression. While benign proliferative and secretory endometrium showed very low levels of ALDH1, slightly higher expression was observed within the stratum basalis. In disease progression, cytoplasmic ALDH1 expression showed a step-wise increase between endometrial hyperplasia, atypical hyperplasia, and endometrial cancer. ALDH1 was also shown to be an early predictor of EC development, suggesting that it can serve as an independent prognostic indicator of patients with endometrial hyperplasia with or without atypia who would progress to cancer (p = 0.012).

Organoid technology in female reproductive biomedicine

Recent developments in organoid technology are revolutionizing our knowledge about the biology, physiology, and function of various organs. Female reproductive biology and medicine also benefit from this technology. Organoids recapitulate features of different reproductive organs including the uterus, fallopian tubes, and ovaries, as well as trophoblasts. The genetic stability of organoids and long-lasting commitment to their tissue of origin during long-term culture makes them attractive substitutes for animal and in vitro models. Despite current limitations, organoids offer a promising platform to address fundamental questions regarding the reproductive system's physiology and pathology. They provide a human source to harness stem cells for regenerative medicine, heal damaged epithelia in specific diseases, and study biological processes in healthy and pathological conditions. The combination of male and female reproductive organoids with other technologies, such as microfluidics technology, would enable scientists to create a multi-organoid-on-a-chip platform for the next step to human-on-a-chip platforms for clinical applications, drug discovery, and toxicology studies. The present review discusses recent advances in producing organoid models of reproductive organs and highlights their applications, as well as technical challenges and future directions.

Association of body mass index with ER, PR and 14-3-3σ expression in tumor and stroma of type I and type II endometrial carcinoma

Obesity is a prominent risk factor for endometrial cancer (EC) and can impede on surgical and hormonal treatments. Markers of EC, estrogen receptor (ER), progesterone receptor (PR), phospho(Ser473)-AKT (pAKT) and 14-3-3 sigma (14-3-3σ) were measured in EC tissues in both the tumor and stroma and grouped by body mass index (BMI). Immunohistochemical scoring of 82 cases of Type 1 and Type II EC tissues revealed a significantly increased tumor expression of ER, PR and 14-3-3σ in women with Type I (BMI < 40) as compared to Type II (BMI < 30) EC. With higher BMI, only PR and 14-3-3σ in the tumor epithelium was significantly higher in Type I than Type II. In particular, Type I EC exhibited significantly increased levels of only PR from patients with BMI > 40 compared to BMI < 40. Type II EC showed increased expression of ER in the stroma only between high and low BMI. Analysis of the TCGA RNA-Seq mRNA expression of ER, PR, PIK3CA, PTEN and SFN (gene for 14-3-3σ) confirmed increased PR expression in EC of obese women. In conclusion, ER, PR and 14-3-3σ are differentially regulated in Type I compared to Type II EC while PR is dysregulated in obese women with Type I EC. These findings have potential implications for efficacy of progestin treatment in obese women.

Ulipristal Acetate Interferes With Actin Remodeling Induced by 17β-Estradiol and Progesterone in Human Endometrial Stromal Cells

Ulipristal acetate (UPA) is a selective progesterone receptor modulator (SPRM) used for emergency contraception and for the medical management of symptomatic uterine fibroids (UF). Treatment with UPA turns in amenorrhea and UF volume reduction. Treatment with UPA is associated with the frequent development of benign, transitory endometrial changes known as SPRM-associated endometrial changes (PAECs). Why PAECs develop and their biological or cellular basis is unknown. Sex steroids, including estrogen and progesterone, are established modulators of the actin cytoskeleton in various cells, including endometrial cells. This explains several morphological and functional changes in endometrial cells. We thus hypothesized that UPA may alter the appearance of the endometrium by interfering with the actions of 17β-estradiol (E2) or progesterone (P4) on actin dynamics. We isolated and cultured human endometrial stromal cells (ESC) from endometrial biopsies from healthy fertile women. Treatment with E2 or P4 stimulated visible actin rearrangements with actin remodeling toward the membrane. Activation through phosphorylation of the actin regulatory proteins, Moesin, and focal adhesion kinase (FAK), hacked actin remodeling induced by E2 and P4. Membrane re-localization of Paxillin and Vinculin were also induced by E2 and P4, showing the formation of focal adhesion complexes. All these E2 and P4 actions were inhibited by co-treatment with UPA, which was otherwise inactive if given alone. The cytoskeletal changes induced by E2 and P4 turned into increased motility of ESC, and UPA again blocked the actions E2 and P4. In conclusion, we find that UPA interferes with the cytoskeletal actions of E2 and P4 in ESC. This finding helps understanding the mode of actions of SPRMs in the endometrium and may be relevant for other potential clinical applications of UPA.

Hormonal and Growth Regulation of Epithelial and Stromal Cells From the Normal and Malignant Endometrium by Pigment Epithelium-Derived Factor

We discovered that pigment epithelium-derived factor (PEDF)-null mice have endometrial hyperplasia, the precursor to human type I endometrial cancer (ECA), which is etiologically linked to unopposed estrogen (E2), suggesting that this potent antiangiogenic factor might contribute to dysregulated growth and the development of type I ECA. Treatment of both ECA cell lines and primary ECA cells with recombinant PEDF dose dependently decreased cellular proliferation via an autocrine mechanism by blocking cells in G1 and G2 phases of the cell cycle. Consistent with the known opposing effects of E2 and progesterone (Pg) on endometrial proliferation, Pg increases PEDF protein synthesis and release, whereas E2 has the converse effect. Using PEDF luciferase promoter constructs containing two Pg and one E2 response elements, E2 reduced and Pg increased promoter activity due to distal response elements. Furthermore, E2 decreases and Pg increases PEDF secretion into conditioned media (CM) by both normal endometrial stromal fibroblasts (ESFs) and cancer-associated fibroblasts (CAFs), but only CM from ESFs mediated growth-inhibitory activity of primary endometrial epithelial cells (EECs). In addition, in cocultures with primary EECs, Pg-induced growth inhibition is mediated by ESFs, but not CAFs. This is consistent with reduced levels of Pg receptors on CAFs surrounding human malignant glands in vivo. Taken together, the data suggest that PEDF is a hormone-regulated negative autocrine mediator of endometrial proliferation, and that paracrine growth inhibition by soluble factors, possibly PEDF, released by ESFs in response to Pg, but not CAFs, exemplifies a tumor microenvironment that contributes to the pathogenesis of ECA.

Cholesterol Synthetase DHCR24 Induced by Insulin Aggravates Cancer Invasion and Progesterone Resistance in Endometrial Carcinoma

3β-Hydroxysteroid-Δ24 reductase (DHCR24), the final enzyme of the cholesterol biosynthetic pathway, has been associated with urogenital neoplasms. However, the function of DHCR24 in endometrial cancer (EC) remains largely elusive. Here, we analyzed the expression profile of DHCR24 and the progesterone receptor (PGR) in our tissue microarray of EC (n = 258), the existing EC database in GEO (Gene Expression Omnibus), and TCGA (The Cancer Genome Atlas). We found that DHCR24 was significantly elevated in patients with EC, and that the up-regulation of DHCR24 was associated with advanced clinical stage, histological grading, vascular invasion, lymphatic metastasis, and reduced overall survival. In addition, DHCR24 expression could be induced by insulin though STAT3, which directly binds to the promoter elements of DHCR24, as demonstrated by ChIP-PCR and luciferase assays. Furthermore, genetically silencing DHCR24 inhibited the metastatic ability of endometrial cancer cells and up-regulated PGR expression, which made cells more sensitive to progestin. Taken together, we have demonstrated for the first time the crucial role of the insulin/STAT3/DHCR24/PGR axis in the progression of EC by modulating the metastasis and progesterone response, which could serve as potential therapeutic targets for the treatment of EC with progesterone receptor loss.

Exosomal transfer of functional small RNAs mediates cancer-stroma communication in human endometrium

Exosomes are small membrane vesicles secreted from a variety of cell types. Recent evidence indicates that human cells communicate with each other by exchanging exosomes. Cancer cells closely interact with neighboring stromal cells, and together they cooperatively promote disease via bidirectional communication. Here, we investigated whether exosomes can play roles in intercellular communication between cancer cells and neighboring fibroblasts. Endometrial fibroblasts were isolated from normal endometrial tissues and from endometrial cancer tissues, and cell-to-cell transfer of endometrial cancer cell line Ishikawa-derived exosomes was examined. The isolated fibroblasts were cultured in conditioned media from CD63-GFP-expressing Ishikawa cells, and we found that GFP-positive exosomes were transferred from Ishikawa cells to the fibroblasts. Next, we introduced a shRNA for a luciferase gene into Ishikawa cells. This shRNA was encapsulated into exosomes, was transferred to the fibroblasts, and then downregulated luciferase expression in the fibroblasts. The mature microRNAs naturally expressed in Ishikawa-derived exosomes were also transported into the endometrial fibroblasts, and they altered the microRNA expression profiles of the fibroblasts. These results indicated that endometrial cancer cells could transmit small regulatory RNAs to endometrial fibroblasts via exosomes. Our findings document a previously unknown mode of intercellular communication between cancer cells and related fibroblasts in human endometrium.