The expression levels of stem cell markers importin13, c-kit, CD146, and telomerase are decreased in endometrial polyps

NOTCH1- and CD117-Positive Stem Cells in Human Endometriosis and Adenomyosis Lesions

Adenomyosis and endometriosis are distinct gynecological disorders characterized by ectopic growth of endometrial tissue. Their etiology remains unclear, but stem cells have been implicated in both. The aim of this study was to investigate and compare the quantity of NOTCH1+ and CD117+ stem cells in endometriosis and adenomyosis lesions. Immunohistochemical staining of ectopic endometrium biopsies using antibodies against NOTCH1 and CD117 was performed. The quantity and spatial distribution of endometrial stromal cells positive for these markers were determined and compared between endometriosis and adenomyosis lesions. Additionally, their quantities were compared between endometriosis lesion types. Mann-Whitney U test showed that the median percentages of both NOTCH1+ and CD117+ cells in the endometriosis lesions were significantly higher than those in the adenomyosis lesions (2.26% vs. 0.13%, p = 0.002 and 0.44% vs. 0.26%, p = 0.016, respectively). Spearman's test showed a positive correlation between NOTCH1+ and CD117+ cells in endometriosis lesions (R = 0.45, p = 0.027) but no significant correlation in adenomyosis lesions (R = -0.11, p = 0.69). The quantity of both stem cell types was highest in extragenital endometriotic lesions. Unlike adenomyosis, endometriosis lesions are associated with higher quantities of NOTCH1+ and CD117+ stem cells and a coordinated increase in their number. These findings support the distinct origin of the two conditions.

Transcriptomic Analysis Reveals Intrinsic Abnormalities in Endometrial Polyps

Endometrial polyps (EPs) are benign overgrowths of the endometrial tissue lining the uterus, often causing abnormal bleeding or infertility. This study analyzed gene expression differences between EPs and adjacent endometrial tissue to elucidate intrinsic abnormalities promoting pathological overgrowth. RNA sequencing of 12 pairs of EPs and the surrounding endometrial tissue from infertile women revealed 322 differentially expressed genes. Protein-protein interaction network analysis revealed significant alterations in specific signaling pathways, notably Wnt signaling and vascular smooth muscle regulation, suggesting these pathways play critical roles in the pathophysiology of EPs. Wnt-related genes DKK1 and DKKL1 were upregulated, while GPC3, GREM1, RSPO3, SFRP5, and WNT10B were downregulated. Relevant genes for vascular smooth muscle contraction were nearly all downregulated in EPs, including ACTA2, ACTG2, KCNMB1, KCNMB2, MYL9, PPP1R12B, and TAGLN. Overall, the results indicate fundamental gene expression changes promote EP formation through unrestrained growth signaling and vascular defects. The intrinsic signaling abnormalities likely contribute to clinical symptoms of abnormal uterine bleeding and infertility common in EP patients. This analysis provides molecular insights into abnormal endometrial overgrowth to guide improved diagnostic and therapeutic approaches for this troublesome women's health condition. Confirmation of expanded cohorts and further investigations into implicated regulatory relationships are warranted.

Comparison of the regenerative effects of bone marrow/adipose-derived stem cells in the Asherman model following local or systemic administration

PURPOSE

Cell therapy is a promising strategy for the treatment of Asherman's syndrome (AS), but the origin of these cells and injection route influence the therapeutic effect and complications of cell therapy. Herein, we compared the effects of systemic or local intrauterine injection of bone marrow or adipose-derived mesenchymal stem cells (BMSCs/AMSCs) on the endometrium in a rat model of AS.

METHODS

After induction of AS in adult Wistar rats, the CM-Dil-positive BMSCs or AMSCs were injected either locally or intravenously. After 3 weeks, endometrial thickness, collagen deposition, cell migration, and VEGF expression were evaluated using histochemistry/immunofluorescence studies.

RESULTS

In all stem cell-treated groups, an ameliorative effect on the damaged endometrium was noted. Collagen deposition diminished in both groups (IV and local injection) compared to the AS model. In rats injected locally with MSC, fibrosis decreased compared to the other groups. Moreover, endometrial thickness increased in the groups that received local injection of BMSCs and AMSCs more than the IV-transplanted AMSCs group. Immunofluorescent staining demonstrated that although the systemic transplantation of BMSCs was more effective than the other groups on VEGF expression, it led to the lowest number of CM-Dil+ stem cells in the damaged endometrium.

CONCLUSION

Stem cell transplantation may reconstruct the damaged endometrium, but it is recommended to select the most effective stem cells and injection route. Because the removal of the fibrosis and the replacement of the epithelia cells is an effective therapeutic strategy for AS, in this study, we conclude that the local injection of AMSCs is more appropriate than BMSCs to treat AS.

Telomerase and Telomeres in Endometrial Cancer

Telomeres at the termini of human chromosomes are shortened with each round of cell division due to the “end replication problem” as well as oxidative stress. During carcinogenesis, cells acquire or retain mechanisms to maintain telomeres to avoid initiation of cellular senescence or apoptosis and halting cell division by critically short telomeres. The unique reverse transcriptase enzyme complex, telomerase, catalyzes the maintenance of telomeres but most human somatic cells do not have sufficient telomerase activity to prevent telomere shortening. Tissues with high and prolonged replicative potential demonstrate adequate cellular telomerase activity to prevent telomere erosion, and high telomerase activity appears to be a critical feature of most (80–90%) epithelial cancers, including endometrial cancer. Endometrial cancers regress in response to progesterone which is frequently used to treat advanced endometrial cancer. Endometrial telomerase is inhibited by progestogens and deciphering telomere and telomerase biology in endometrial cancer is therefore important, as targeting telomerase (a downstream target of progestogens) in endometrial cancer may provide novel and more effective therapeutic avenues. This review aims to examine the available evidence for the role and importance of telomere and telomerase biology in endometrial cancer.

Implications of telomeres and telomerase in endometrial pathology

BACKGROUND

Eukaryotic chromosomal ends are linear and are protected by nucleoprotein complexes known as telomeres. The complex structural anatomy and the diverse functions of telomeres as well as the unique reverse transcriptase enzyme, telomerase that maintains telomeres are under intensive scientific scrutiny. Both are involved in many human diseases including cancer, but also in ageing and chronic disease such as diabetes. Their intricate involvement in many cellular processes and pathways is being dynamically deciphered in many organs including the endometrium. This review summarizes our current knowledge on the topic of telomeres and telomerase and their potential role in providing plausible explanations for endometrial aberrations related to common gynaecological pathologies.

OBJECTIVE AND RATIONALE

This review outlines the recent major findings in telomere and telomerase functions in the context of endometrial biology. It highlights the contemporary discoveries in hormonal regulation, normal endometrial regeneration, stem cells and common gynaecological diseases such as endometriosis, infertility, recurrent reproductive failure and endometrial cancer (EC).

SEARCH METHODS

The authors carried out systematic PubMed (Medline) and Ovid searches using the key words: telomerase, telomeres, telomere length, human telomerase reverse transcriptase, telomeric RNA component, with endometrium, hormonal regulation, endometrial stem/progenitor cells, endometrial regeneration, endometriosis, recurrent miscarriage, infertility, endometrial hyperplasia, EC and uterine cancer. Publications used in this review date from 1995 until 31st June 2016.

OUTCOMES

The human endometrium is a unique somatic organ, which displays dynamic telomerase activity (TA) related to the menstrual cycle. Telomerase is implicated in almost all endometrial pathologies and appears to be crucial to endometrial stem cells. In particular, it is vital for normal endometrial regeneration, providing a distinct route to formulate possible curative, non-hormonal therapies to treat chronic endometrial conditions. Furthermore, our current understanding of telomere maintenance in EC is incomplete. Data derived from other malignancies on the role of telomerase in carcinogenesis cannot be extrapolated to EC because unlike in other cancers, TA is already present in proliferating healthy endometrial cells.

WIDER IMPLICATIONS

Since telomerase is pivotal to endometrial regeneration, further studies elucidating the role of telomeres, telomerase, their associated proteins and their regulation in normal endometrial regeneration as well as their role in endometrial pathologies are essential. This approach may allow future development of novel treatment strategies that are not only non-hormonal but also potentially curative.

The expression of marker for endometrial stem cell and fibrosis was increased in intrauterine adhesious

OBJECTIVES

The objective of the present study was to evaluate whether fibrotic markers and endometrial stem cell markers were abnormal expressed in endometrium of intrauterine adhesions and a female mouse model for intrauterine adhesions.

METHODS

We revaluated endometrial fibrosis using Masson's stain. We detected the expression of endometrium stem cell markers (CD146 and CD140b) and fibrosis markers (TGF-Beta, CTGF, collagen protein I and collagen protein III) in endometrial tissue with intrauterine adhesions using real-time PCR and S-P (Streptavidin-Peroxidase) immunohistochemistry. We create a female mouse model for intrauterine adhesions using mechanical injury, and then revalue the expression of endometrial stem cell markers and fibrosis markers in endometrial tissue of mouse model for intrauterine adhesions.

RESULTS

The ratio of the area with endometrial fibrosis to total endometrial area in intrauterine adhesious significantly increased compared with the normal endometrial tissue (P < 0.05); The expression levels of fibrotic markers and endometrial stem cell markers were higher in the endometrial tissue with intrauterine adhesious compared to normal endometrial tissue (P < 0.05). The animal experiments showed that the ratio of the area with endometrial fibrosis to total endometrial area significantly increased compared with the control group (P < 0.05); The expression levels of fibrotic markers and endometrial stem cell markers were higher in the endometrial tissue compared to the control group (P < 0.05).

CONCLUSION

Aberrant activation of fibrosis may be involved in the pathology of intrauterine adhesious.

Increased importin 13 activity is associated with the pathogenesis of pterygium

PURPOSE

We previously reported that importin 13 (IPO13), a member of the importin-β family of nuclear import proteins, regulates nuclear import of the glucocorticoid receptor in airway epithelial cells, IPO13 serves as a potential marker for corneal epithelial progenitor cells, and IPO13 is associated with corneal cell proliferation. Here we investigated the role of IPO13 in the pathogenesis of pterygium and the underlying mechanism including interaction with other cell proliferation-related factors: keratin 17 (K17), a lesional protein and a member of the type I keratins, and c-Jun, a protein of the activator protein-1 complex.

METHODS

Tissue samples were collected from primary pterygia, recurrent pterygia, and normal conjunctiva to perform the following experiments: immunohistochemical measurement of IPO13 and K17. Pterygium epithelial cells (PECs) were cultured in keratinocyte serum-free defined medium to examine the expression of IPO13 and K17. Lentivirus-mediated silencing and overexpression IPO13 testing was conducted, and K17 alternation was evaluated with western blot and immunostaining. In addition, the translocation of c-Jun (a K17 regulator) was further examined after IPO13 was silenced.

RESULTS

IPO13 activity was significantly increased in the basal layer of the epithelium of the pterygium. In cultured PECs, overexpression or knockdown of the IPO13 gene increased or decreased PEC proliferation, respectively. IPO13 was colocalized with K17 in the epithelium of the pterygium, and overexpression or knockdown of the IPO13 gene induced upregulation or downregulation of K17 expression in PECs, respectively. In addition, silencing of the IPO13 gene blocked nuclear translocation of c-Jun.

CONCLUSIONS

We provided novel evidence that IPO13 may contribute to the pathogenesis of pterygium via modulation of K17 and c-Jun.

Increased expression of importin13 in endometriosis and endometrial carcinoma

Background

Importin13 (IPO13) is a novel potential marker of corneal epithelial progenitor cells. We investigated the expression and localization of IPO13 in endometrial, endometriotic and endometrial carcinoma tissue.

Material/Methods

IPO13 expression in endometrial, endometriotic and endometrial carcinoma tissue was examined by immunohistochemistry, qPCR and Western blot.

Results

Immunohistochemistry studies showed that IPO13 protein was expressed mainly in cytoplasm of glandular epithelial cell and stromal cells. The rate of importin13-positive cells in proliferative phase endometrium was higher (by about 6-fold) than that in secretory endometrium (P<0.05) and the rate of importin13-positive cells in endometriosis and endometrial carcinoma was higher than that in normal secretory phase endometrial tissues (by about 4- and 9-fold, respectively). Immunofluorescence microscopy revealed co-localization of IPO13 with CD34, CD45, c-kit, telomerase, CD90 and CD146. QPCR revealed significantly increased IPO13 mRNA in endometriosis and endometrial carcinoma versus secretory phase endometrium (by about 2- and 10-fold, respectively). Western blot analysis showed that IPO13 protein is enhanced in endometriosis and endometrial carcinoma versus secretory phase endometrium (p<0.05).

Conclusions

These results demonstrate an increased expression of IPO13 in endometriosis and endometrial carcinoma, which could be involved in the pathogenesis of endometriosis and endometrial carcinoma; IPO13 can serve as an endometrial progenitor/stem cell marker.

E2F1: a potential negative regulator of hTERT transcription in normal cells upon activation of oncogenic c-Myc

Previous studies have revealed that the link between c-Myc and E2F1 pathway plays a pivotal role in regulating cell growth and death. Human telomerase reverse transcriptase (hTERT), activation of which is required for cell immortalization and transformation, has been confirmed to be a direct transcriptional target of c-Myc. It is of note that E2F1, which is also a direct transcriptional target of c-Myc, can bind the hTERT promoter and repress its expression. Thus, although oncogene c-Myc can be activated in normal cells, for the subsequent induction of E2F1, it may still be insufficient to trigger the expression of hTERT. This negative feedback regulation, if it exists, may be another mechanism for normal cells to control the transmission of c-Myc-mediated oncogenic signals. In this article, we reviewed current knowledge about the crosstalk among c-Myc, E2F1 and hTERT, with an emphasis on the hypothesis that E2F1 negatively regulates c-Myc-induced hTERT transcription. Additionally, we postulated that the miR-17-92 cluster-mediated regulation of c-Myc and E2F1 expression may be of particular importance for the repression of hTERT transcription.