Stem cells in human endometrium and endometrial carcinoma

Single-cell transcriptomic analysis highlights origin and pathological process of human endometrioid endometrial carcinoma

Endometrial cancers are complex ecosystems composed of cells with distinct phenotypes, genotypes, and epigenetic states. Current models do not adequately reflect oncogenic origin and pathological progression in patients. Here we use single-cell RNA sequencing to profile cells from normal endometrium, atypical endometrial hyperplasia, and endometrioid endometrial cancer (EEC), which altogether represent the step-by-step development of endometrial cancer. We find that EEC originates from endometrial epithelial cells but not stromal cells, and unciliated glandular epithelium is the source of EEC. We also identify LCN2 + /SAA1/2 + cells as a featured subpopulation of endometrial tumorigenesis. Finally, the stromal niche and immune environment changes during EEC progression are described. This study elucidates the evolution of cell populations in EEC development at single-cell resolution, which would provide a direction to facilitate EEC research and diagnosis.

Expression of glucocorticoid and androgen receptors in bone marrow-derived hematopoietic and nonhematopoietic murine endometrial cells

OBJECTIVE

To determine whether bone marrow (BM)-derived cells engrafting the murine endometrium express the glucocorticoid receptor (GR) and androgen receptor (AR). Recent data demonstrate that BM is a long-term source of multiple hematopoietic and nonhematopoietic endometrial cell types. Important roles for glucocorticoids and androgens in regulating endometrial functions, including decidualization and early embryo attachment/invasion, have very recently emerged. Whether endometrial cells of BM origin express glucocorticoid or ARs has not been previously studied.

DESIGN

Animal study.

SETTING

Basic science laboratory.

ANIMAL(S)

Wild-type C57BL/6J male mice expressing enhanced green fluorescent protein (GFP) and syngeneic wild-type C57BL/6J female mice aged 6-9 weeks.

INTERVENTION(S)

Murine bone marrow transplant.

MAIN OUTCOME MEASURE(S)

Bone marrow cells were harvested from adult wild-type C57BL/6 mice and subjected to flow cytometry to identify the percentage of hematopoietic and nonhematopoietic cells expressing GR or AR. Uterine tissue sections from lethally irradiated syngeneic adult female C57BL/6 mice that had been recipients of BM transplants from adult male transgenic donor mice ubiquitously expressing GFP were studied. Immunohistochemistry was performed in the uterine tissue sections of the recipient mice at 5, 9, and 12 months after transplant using specific anti-GR, anti-AR, anti-GFP, anti-CD45 (pan leukocyte marker), and anti-F4/80 (murine macrophage marker) primary antibodies. Confocal laser microscopy was used to localize and quantitate BM-derived (GFP⁺) cell types in the endometrial stromal and epithelial compartments and determine whether BM-derived cell types in the murine endometrium express GR or AR.

RESULT(S)

Hematopoietic cells comprised 93.6%-96.6% of all cells in the BM, of which 98.1% ± 0.2% expressed GR and 92.2% ± 4.4% expressed AR. Nonhematopoietic cells comprised 0.4%-1.3% of BM, of which 52.8% ± 5.9% expressed GR and 48.9% ± 3.4% expressed AR. After BM transplant, the proportion of cells originating from BM in the endometrial stromal compartment increased over time, reaching 13.5% ± 2.3% at 12 months after transplant. In the epithelial compartments, <1% of the cells were of BM origin at 12 months after transplant. Most (60%-72%) GR⁺ and/or AR⁺ BM-derived cells in the stroma were hematopoietic (CD45⁺) cells, of which 37%-51% were macrophages. Nonetheless, 28%-33% of GR⁺ cells, and 28%-40% of AR⁺ BM-derived cells, were nonhematopoietic (CD45^-) stromal cells of BM origin.

CONCLUSION(S)

A substantial number of BM-derived cells express GR and AR, suggesting a role for these cells in both glucocorticoid-regulated and androgen-regulated endometrial functions, such as proliferation and/or decidualization.

Single-cell chromatin accessibility landscape of human umbilical cord blood in trisomy 18 syndrome

BACKGROUND

Trisomy 18 syndrome (Edwards syndrome, ES) is a type of aneuploidy caused by the presence of an extra chromosome 18. Aneuploidy is the leading cause of early pregnancy loss, intellectual disability, and multiple congenital anomalies. The research of trisomy 18 is progressing slowly, and the molecular characteristics of the disease mechanism and phenotype are still largely unclear.

RESULTS

In this study, we used the commercial Chromium platform (10× Genomics) to perform sc-ATAC-seq to measure chromatin accessibility in 11,611 single umbilical cord blood cells derived from one trisomy 18 syndrome patient and one healthy donor. We obtained 13 distinct major clusters of cells and identified them as 6 human umbilical cord blood mononuclear cell types using analysis tool. Compared with the NC group, the ES group had a lower ratio of T cells to NK cells, the ratio of monocytes/DC cell population did not change significantly, and the ratio of B cell nuclear progenitor and megakaryocyte erythroid cells was higher. The differential genes of ME-0 are enriched in Human T cell leukemia virus 1 infection pathway, and the differential peak genes of ME-1 are enriched in apopotosis pathway. We found that CCNB2 and MCM3 may be vital to the development of trisomy 18. CCNB2 and MCM3, which have been reported to be essential components of the cell cycle and chromatin.

CONCLUSIONS

We have identified 6 cell populations in cord blood. Disorder in megakaryocyte erythroid cells implicates trisomy 18 in perturbing fetal hematopoiesis. We identified a pathway in which the master differential regulatory pathway in the ME-0 cell population involves human T cell leukemia virus 1 infection, a pathway that is dysregulated in patients with trisomy 18 and which may increase the risk of leukemia in patients with trisomy 18. CCNB2 and MCM3 in progenitor may be vital to the development of trisomy 18. CCNB2 and MCM3, which have been reported to be essential components of the cell cycle and chromatin, may be related to chromosomal abnormalities in trisomy 18.

The ectonucleoside triphosphate diphosphohydrolase-2 (NTPDase2) in human endometrium: a novel marker of basal stroma and mesenchymal stem cells

The human endometrium undergoes repetitive regeneration cycles in order to recover the functional layer, shed during menses. The basal layer, which remains in charge of endometrial regeneration in every cycle, contains adult stem or progenitor cells of epithelial and mesenchymal lineage. Some pathologies such as adenomyosis, in which endometrial tissue develops within the myometrium, originate from this layer. It is well known that the balance between adenosine triphosphate (ATP) and adenosine plays a crucial role in stem/progenitor cell physiology, influencing proliferation, differentiation, and migration. The extracellular levels of nucleotides and nucleosides are regulated by the ectonucleotidases, such as the nucleoside triphosphate diphosphohydrolase 2 (NTPDase2). NTPDase2 is a membrane-expressed enzyme found in cells of mesenchymal origin such as perivascular cells of different tissues and the stem cells of adult neurogenic regions. The aim of this study was to characterize the expression of NTPDase2 in human nonpathological cyclic and postmenopausic endometria and in adenomyosis. We examined proliferative, secretory, and atrophic endometria from women without endometrial pathology and also adenomyotic lesions. Importantly, we identified NTPDase2 as the first marker of basal endometrium since other stromal cell markers such as CD10 label the entire stroma. As expected, NTPDase2 was also found in adenomyotic stroma, thus becoming a convenient tracer of these lesions. We did not record any changes in the expression levels or the localization of NTPDase2 along the cycle, thus suggesting that the enzyme is not influenced by the female sex hormones like other previously studied ectoenzymes. Remarkably, NTPDase2 was expressed by the Sushi Domain containing 2 (SUSD2)⁺ endometrial mesenchymal stem cells (eMSCs) found perivascularly, rendering it useful as a cell marker to improve the isolation of eMSCs needed for regenerative medicine therapies.

MicroRNA-34a inhibits cells proliferation and invasion by downregulating Notch1 in endometrial cancer

MicroRNAs (miRNAs) are small non-coding RNAs composed of 18-25 nucleotides that regulate the expression of approximately 30% of human protein coding genes. Dysregulation of miRNAs plays a pivotal role in the initiation and progression of malignancies. Our study has shown that microRNA-34a (miR-34a) was upregulated in human endometrial cancer stem cells (ECSCs). However, it is unknown how miR-34a regulates endometrial cancer itself. Here, we report that miR-34a directly and functionally targeted Notch1. MiR-34a inhibited the proliferation, migration, invasion, EMT-associated phenotypes by downregulating Notch1 in endometrial cancer cells. Overexpression of miR-34a also suppressed tumor growth in nude mice. Importantly, further results suggested miR-34a was significantly downregulated in endometrial cancer tissues and negatively correlated with Notch1 expression. There was a significant association between decreased miR-34a expression and worse patient prognosis. Taken together, our results suggest that miR-34a plays tumor-suppressive roles in endometrial cancer through downregulating Notch1. Thus miR-34a could be a potential therapeutic target for prevention and treatment of endometrial cancer.

In-vitro construction of endometrial-like epithelium using CD146+ mesenchymal cells derived from human endometrium

Endometrial CD146⁺ cells were purified, using magnetic activated cell sorting, and then embedded and cultured in a collagen-matrigel scaffold on top of myometrial smooth muscle cells for 10 days. At the end of culture period, the differentiation and formation of the epithelial-like cells were confirmed by morphological and ultrastructural evaluations, and analysis by reverse transcription polymerase chain reaction of the specific expression of genes: osteopontin (SPP1), matrix metalloproteinase 2, zonula occludens 1, laminin alpha 2 and collagen type IV; and by western blotting of CD9 protein. The results showed that the human endometrial mesenchymal CD146⁺ cells were able to produce endometrial glandular tube-like structures in vitro. Ultrastructural observation revealed some projections on the apical surfaces, appearance of basal lamina-like structures on the basal surface, and tight junctions and desmosomes on the lateral surfaces of the epithelial-like cells. The expression of studied genes at RNA level and CD9 at protein level confirmed the formation of endometrial epithelial-like cells. This culture system may have potential applications in cell therapy and in studies on human embryo implantation.

Clinical translation for endometrial cancer stem cells hypothesis

Endometrial cancer is the most frequent gynecological malignancy in developed world. Cancer stem cells (CSC) are recognized as a small proportion of cells among the tumor cell population that are capable of self-renewal, aberrant differentiation, and escape homeostasis. This review aims to systematize the existing evidence of CSC of endometrial cancer and its clinical translation. In endometrial cancer, the cancer stem cell hypothesis has been studied in vitro using the isolation of colony forming units, side population with dye efflux capacity, and tumorospheres. The stem cell markers for endometrial cancer do not have uniform characteristics, albeit CD133 and aldehyde dehydrogenase (ALDH) were being associated with CSC phenotype. The application of endometrial CSC on xenograft models proves the tumorigenic capacity of this small group of cells. The metastatic process has been explained due to epithelial-mesenchymal transition (EMT) in which CSC seems to have a critical role. The chemoresistance is characteristic of CSC that in endometrial cancer has been shown in CSC phenotype and associated with CSC markers. The most ambitious potential for CSC is the development of targeted therapies. Its application on endometrial cancer is still poor, being a future perspective for research.

Endometriosis: a role for stem cells

Endometriosis is a complex gynecologic condition affecting 6-10% of reproductive aged women and is a major cause of chronic pain and infertility. Mechanisms of disease pathogenesis are poorly understood. Considerable evidence supports the existence of a stem cell population in the endometrium which provides a physiologic source of regenerative endometrial cells, and multiple lines of evidence now support a key role for stem cells in the pathogenesis of endometriosis. In addition, new blood vessel formation is critical for the establishment and maintenance of endometriotic implants, a process in which endothelial progenitor cells may play an integral role. These new insights into disease pathogenesis present exciting opportunities to develop targeted and more effective therapeutic options in the management of this common and challenging disease.

Differentiation of human CD146-positive endometrial stem cells to adipogenic-, osteogenic-, neural progenitor-, and glial-like cells

The aim of this study was to investigate the potential differentiation of CD146(+) endometrial stem cells to several lineages. Endometrial stromal cells were cultured using Dulbecco's modified Eagle's medium/Hams F-12 (DMEM/F-12) and were passaged every 7-10 d when cultures reached 80-100% of confluency. The immunophenotypes of single endometrial cells were analyzed using flow cytometry at fourth passage. Then the CD146(+) cells were sorted using magnetic-activated cell sorting, and they were cultured and analyzed for in vitro differentiation to several lineages. Detection of adipocyte- and osteocyte-like cells were assessed by oil red O and alizarin red staining, respectively. For detection of neural progenitor and oligodendrocyte-like cells, the cells were immunostained by neurofilament 68 and oligo2, respectively. The rates of CD90, CD105, CD146, CD31, CD34, and CD9 of cultured endometrial cells were 94.98 ± 3%, 95.77 ± 2.5%, 27.61 ± 2%, 0.79 ± 0.05%, 1.43 ± 0.1%, and 1.01 ± 0.06%, respectively. CD146(+) cells were isolated to high purity. CD146(+)-differentiated cells to adipogenic cell with typical lipid-rich vacuoles and osteogenic cells were observed and confirmed their mesenchymal origin. They also differentiated into neural progenitor and glial differentiation by retinoic acid, basic fibroblast growth factor, and epidermal growth factor signaling molecules, respectively, and confirmed by neurofilament 68 and oligo2 immunocytochemistry. The efficiency of differentiation to neural progenitor and oligodendrocyte-like cells was 90 ± 3.4% and 79 ± 2.8%, respectively. This study showed that CD146(+) cells from human endometrium after in vitro cultivation can differentiate into adipogenic-, osteogenic-, neural progenitor-, and glial-like cells. They may provide available alternative source of stem cells for future cell-based therapies and tissue engineering applications.

Isolation and identification of epithelial and stromal stem cells from eutopic endometrium of women with endometriosis

OBJECTIVE

The recent characterization of possible stem/progenitor cells in the endometrium has shed new light on the origins of ectopic endometrial tissue and the mechanism for the pathogenesis of endometriosis, but has raised new questions. Is it possible that abnormal endometrial stem/progenitor cells increase their capacity to implant and establish themselves as ectopic tissue, or that normal stem cells implant in abnormal peritoneum? This study investigated key stem cell properties in cologenic epithelial and stromal cells obtained from eutopic endometrium of women with endometriosis.

STUDY DESIGN

Single cell suspensions of endometrial epithelial and stromal cells were cultured at densities of 20, 50, 100 and 200cells/cm(2). Cloning efficiency (CE) was determined, and stem cell phenotypic surface markers were detected using Western blotting and quantitative real-time polymerase chain reaction.

RESULTS

CE was significantly higher in cells cultured at a density of 50cells/cm(2) compared with the other groups. After 15 days of culture, small and large colonies were observed. Large-colony-derived epithelial and stromal cells had high proliferative potentials, producing millions of cells in vitro, with strong expression of epithelial and stromal stem cell phenotypic surface markers EMA, CK, CD49f, THY-1(CD90), collagen type I, 5B5 and vimentin.

CONCLUSION

Adult stem cells were found in eutopic endometrium of women with endometriosis, and this may play an important role in disease development.

Specificity factors in cytoplasmic polyadenylation

Poly(A) tail elongation after export of an messenger RNA (mRNA) to the cytoplasm is called cytoplasmic polyadenylation. It was first discovered in oocytes and embryos, where it has roles in meiosis and development. In recent years, however, has been implicated in many other processes, including synaptic plasticity and mitosis. This review aims to introduce cytoplasmic polyadenylation with an emphasis on the factors and elements mediating this process for different mRNAs and in different animal species. We will discuss the RNA sequence elements mediating cytoplasmic polyadenylation in the 3' untranslated regions of mRNAs, including the CPE, MBE, TCS, eCPE, and C-CPE. In addition to describing the role of general polyadenylation factors, we discuss the specific RNA binding protein families associated with cytoplasmic polyadenylation elements, including CPEB (CPEB1, CPEB2, CPEB3, and CPEB4), Pumilio (PUM2), Musashi (MSI1, MSI2), zygote arrest (ZAR2), ELAV like proteins (ELAVL1, HuR), poly(C) binding proteins (PCBP2, αCP2, hnRNP-E2), and Bicaudal C (BICC1). Some emerging themes in cytoplasmic polyadenylation will be highlighted. To facilitate understanding for those working in different organisms and fields, particularly those who are analyzing high throughput data, HUGO gene nomenclature for the human orthologs is used throughout. Where human orthologs have not been clearly identified, reference is made to protein families identified in man.

Increased expression of the adult stem cell marker Musashi-1 in the ectopic endometrium of adenomyosis does not correlate with serum estradiol and progesterone levels

OBJECTIVE

To investigate whether abnormal expression of Musashi-1 occurs in eutopic and ectopic endometria from patients with adenomyosis and whether it is correlated with serum estradiol or progesterone levels.

STUDY DESIGN

Musashi-1 expression in ectopic and paired eutopic endometrium of patients with adenomyosis (adenomyosis group, 30 cases) and in normal endometrium (control group, 29 cases) was studied with immunohistochemistry, and serum estradiol and progesterone levels in these cases were measured with electrochemiluminescence immunoassay.

RESULTS

In all the normal endometrial tissues from control group and paired eutopic and ectopic endometrium of adenomyosis, epithelial and stromal Musashi-1 expression was observed throughout the menstrual cycle. Musashi-1 immunostaining was localized both in the nucleus and cytoplasm. The epithelial cells in normal endometrium showed a significantly higher staining index of Musashi-1 in the proliferative phase than in the secretory phase. The staining index of epithelial Musashi-1 in the ectopic endometrium was significantly higher than in the paired eutopic endometrium and normal endometrium throughout the menstrual cycle. In the secretory phase, the epithelial Musashi-1 immunoreactivity in eutopic endometrium and the stromal Musashi-1 immunoreactivity in ectopic endometrium were significantly higher than those in the normal endometrium. The Musashi-1 expression in the ectopic endometrium of adenomyosis was not correlated with the serum estradiol or progesterone levels.

CONCLUSION

Aberrant Musashi-1 expression in adenomyosis may be involved in the pathogenesis and pathophysiology of adenomyosis, but it does not correlate with changes in serum estradiol or progesterone levels.

Prospective biomarkers of stem cells of human endometrium and fallopian tube compared with bone marrow

The applicability of stem cells from the human endometrium and fallopian tube for regeneration is a fascinating area of research because of the role of these cells in dynamic tissue remodelling and their cyclical regenerative property during the menstrual cycle and pregnancy. Nevertheless, studies on the identity of biomarkers of these stem cells are limited and need to be extended. The present study has aimed at exploring the tissue-specific biomarkers of stem cells derived from the human endometrium and fallopian tube compared with those from bone marrow. Cells were isolated from human endometrium and fallopian tubes and characterized for biomarkers, including CD34, CD133, CD117, CD90, CD105, CD73, nestin, CD29, CD44, CD31, CD54, CD166, CD106, CD49d, CD45, ABCG2, SSEA4, OCT4, SOX2, CD140b and CD146, by flowcytometry. Both endometrium and fallopian tube sources exhibited positivity over a wide range of markers, as did bone marrow. In particular, they exhibited pluripotency, perivascular and mesenchymal stem cell markers and cell adhesion molecules, thereby suggesting their relevance in tissue repair and regeneration. Overall, the results of this study provide evidence for the presence of stem cells in the human endometrium and fallopian tube, which could thus represent additional stem cell sources for regenerative medicine.

The RNA-Binding Protein Musashi1: A Major Player in Intestinal Epithelium Renewal and Colon Cancer Development

Aberrant gene expression is the cause and the consequence of tumorigenesis. A major component of gene expression is translation regulation; a process whose main players are RNA-binding-proteins (RBPs). More than 800 RBPs have been identified in the human genome and several of them have been shown to control gene networks associated with relevant cancer processes. A more systematic characterization of RBPs starts to reveal that similar to transcription factors, they can function as tumor suppressors or oncogenes. A relevant example is Musashi1 (Msi1), which is emerging as a critical regulator of tumorigenesis in multiple cancer types, including colon cancer. Msi1 is a stem marker in several tissues and is critical in maintaining the balance between self-renewal and differentiation. However, a boost in Msi1 expression can most likely lead cells towards an oncogenic pathway. In this article, we discuss the parallels between Msi1 function in normal renewal of intestinal epithelium and in colon cancer.

Endometrial stem cells and reproduction

Abnormal endometrial function remains a significant cause of implantation failure, recurrent pregnancy loss, and other pathologies responsible for female infertility. The development of novel therapies to treat infertility due to endometrial dysfunction requires an understanding of the latest advancements in endometrial cell biology, such as the role of endometrial stem cells. The remarkable regenerative capacity of the human endometrium is absolutely essential for successful reproduction and likely requires a population of stem cells in the endometrium. The purpose of this review is to provide an introduction to some of the newest concepts in endometrial stem cell biology.