The role of microRNAs in the pathogenesis of endometrial cancer: a systematic review

Are micro-RNA 21 and 143 indicative as prognostic biomarkers in dedifferentiated endometrial adenocarcinoma?

AIM

Dedifferentiated endometrial adenocarcinoma (DEAC) is a rare, aggressive subtype, accounting for 2% of all endometrial cancers. Poor survival in DEAC prompts the need for effective treatment modalities through better prognostic classification. MicroRNAs (miRNA) have essential roles in tumor angiogenesis, which might enable their use as novel biomarkers. In this study, we aimed to reveal the relationship between the expression of miRNA-21 and miRNA-143, which are associated with angiogenesis, and the prognosis of DEAC.

METHOD

The study included six cases diagnosed with DEAC. The expression levels of miRNA-21 and miRNA-143 were detected by quantitative real-time PCR. Microvascular density (MVD) was measured by CD34 staining. All data and effects on survival were compared for statistical significance.

RESULTS

Six cases diagnosed with DEAC were included in the study. The percentage of undifferentiated components ranged from 50 to 90%. The second component of differentiated carcinoma was detected as endometrioid (3/5 grade I, 1/5 grade II, 1/5 grade III) in five cases and serous in one case. The mean MVD was 27 (range 17-44, SD 9.4). In three cases, miRNA-21 expression was down-regulated in neoplastic areas compared to non-neoplastic areas. On the contrary, it was found to be up-regulated in the remaining three cases. MiRNA-143 expression decreased in four cases and increased in two cases.

CONCLUSIONS

Based on these findings, we found a significant irregular expression of miRNA-21 in DEACs. As in other cancers, angiogenesis is significantly associated with survival in DEACs. This study provides initial data for revealing possible implications of miRNAs as prognostic indicators in DEAC.

Epigallocatechin Gallate for the Treatment of Benign and Malignant Gynecological Diseases-Focus on Epigenetic Mechanisms

The most common malignant gynecologic diseases are cervical, uterine, ovarian, vaginal, and vulvar cancer. Among them, ovarian cancer causes more deaths than any other cancer of the female reproductive system. A great number of women suffer from endometriosis, uterine fibroids (UFs), adenomyosis, dysmenorrhea, and polycystic ovary syndrome (PCOS), which are widespread benign health problems causing troublesome and painful symptoms and significantly impairing the quality of life of affected women, and they are some of the main causes of infertility. In addition to the available surgical and pharmacological options, the effects of supporting standard treatment with naturally occurring compounds, mainly polyphenols, are being studied. Catechins are responsible for the majority of potential health benefits attributed to green tea consumption. Epigallocatechin gallate (EGCG) is considered a non-toxic, natural compound with potential anticancer properties. Antioxidant action is its most common function, but attention is also drawn to its participation in cell division inhibition, apoptosis stimulation and epigenetic regulation. In this narrative review, we describe the role of EGCG consumption in preventing the development of benign reproductive disorders such as UF, endometriosis, and PCOS, as well as malignant gynecologic conditions. We discuss possible epigenetic mechanisms that may be related to the action of EGCG.

MicroRNAs as Predictors of Future Uterine Malignancy in Endometrial Hyperplasia without Atypia

The histological criteria for classifying endometrial hyperplasia (EH) are based on architectural crowding and nuclear atypia; however, diagnostic agreement among pathologists is poor. We investigated molecular biomarkers of endometrial cancer (EC) risk in women with simple hyperplasia or complex hyperplasia without atypia (SH/CH-nonA). Forty-nine patients with EC preceded by SH/CH-nonA were identified, of which 23 were excluded (15 with complex atypical hyperplasia (CAH), six not consenting, one with a diagnosis < 6 months prior, and one lost to follow-up). The EH tissues of these patients were compared with those of patients with SH/CH-nonA that did not progress to EC (control) through microRNA (miRNA) array analysis, and the results were verified in an expanded cohort through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). MiRNA arrays analyses revealed 20 miRNAs that differed significantly (p < 0.05, fold change > 4) between the control (n = 12) and case (n = 6) patients. Multiplex RT-qPCR for the 20 miRNAs in the expanded cohort (94 control and 25 case patients) led to the validation of miR-30a-3p (p = 0.0009), miR-141 (p < 0.0001), miR-200a (p < 0.0001), and miR-200b (p < 0.0001) as relevant biomarkers, among which miR-141, miR-200a, and miR-200b regulate the expression of phosphatase and tensin homolog (PTEN). For the prediction of EC, the area under the curve for miR-30a-3p, miR-141, miR-200a, and miR-200b was 0.623, 0.754, 0.783, and 0.704, respectively. The percentage of complete PTEN loss was significantly higher in the case group than in the control group (24% vs. 0%, p < 0.001, Fisher’s exact test). A combination of complete PTEN loss and miR-200a provided optimal prediction performance (sensitivity = 0.760; specificity = 1.000; positive predictive value = 1.000; negative predictive value = 0.937; accuracy = 0.947). MiR-30a-3p, miR-141, miR-200a, miR-200b, and complete PTEN loss may be useful tissue biomarkers for predicting EC risk among patients with SH/CH-nonA.

Extracellular vesicle encapsulated microRNA-320a inhibits endometrial cancer by suppression of the HIF1α/VEGFA axis

Accumulating evidence indicates that cancer-associated fibroblasts (CAFs) play a crucial role in endometrial cancer (EC) pathogenesis. The present study investigated the clinical significance and biological function of extracellular vesicle (EV) encapsulated miR-320a released from CAFs in EC. EC-related microarray data was obtained from the GSE25405 database and differential analysis was performed. Expression of miR-320a in CAFs and normal endometrial fibroblasts (NFs) as well as CAF-delivered EVs was detected; also, delivery of miR-320a from CAFs to EC cells was observed. In addition we confirmed that miR-320a targets HIF1α via a dual-luciferase reporter assay. Phenotypic analysis was used to study the functional significance of EV delivered miR-320a and its downstream effects. miR-320a was found to have low expression in EC cells and tissues. CAF-secreted EVs were successfully isolated and miR-320a was found also be expressed at low levels in these EVs. Finally, we found direct transfer of CAF-secreted exosomal miR-320a to EC cells, which inhibited their proliferation. Mechanistically, we found this is due to downregulation of HIF1α by miR-320a, which led to lowered VEGFA expression in vitro. Accordingly, we overexpressed HIF1α also showed that the inhibitory effect of miR-320a overexpression in EC cells could be reversed. These results point to CAF-derived EVs carrying overexpressed miR-320a as a novel direction for therapeutic strategies for EC.

Diagnostic value of microRNA panel in endometrial cancer: A systematic review

PURPOSE

We conducted a systematic review to evaluate the overall diagnostic accuracy of miRNAs in detecting endometrial cancer.

MATERIALS AND METHODS

A systematic search of Medline, Embase, Cinahl and the Cochrane Controlled Register of Trials was performed to identify studies reporting on the diagnostic value of miRNA in EC patients. Included were diagnostic studies looking at miRNA expression in women diagnosed with endometrial cancer. Two reviewers independently selected studies and assessed quality of studies using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) score system. Data extraction was completed and the vote-counting strategy was used to rank miRNAs.

RESULTS

26 studies were included with a total number of 1,400 EC patients reporting on 106 differentially expressed miRNAs. The most frequently found up-regulated miRNA was miR-205 followed by miR-200c, -223, -182, -183 and -200a. In addition, miR-135b, miR-429, miR-141 and miR-200b were also frequently up-regulated. There was less consensus on down-regulated miRNAs.

CONCLUSIONS

miRNAs yield a promising diagnostic biomarker potential in endometrial cancer, especially miR-205, the miR-200 family and miR-135b, -182, -183 and -223. However, no sufficient high quality data are available to draw hard conclusions. More research is needed to validate the diagnostic potential of these miRNAs in larger studies. In addition, the potential of urine as a non-invasive biofluid should be investigated in more detail.

Risk factors for endometrial cancer: An umbrella review of the literature

Although many risk factors could have causal association with endometrial cancer, they are also prone to residual confounding or other biases which could lead to over- or underestimation. This umbrella review evaluates the strength and validity of evidence pertaining risk factors for endometrial cancer. Systematic reviews or meta-analyses of observational studies evaluating the association between non-genetic risk factors and risk of developing or dying from endometrial cancer were identified from inception to April 2018 using PubMed, the Cochrane database and manual reference screening. Evidence was graded strong, highly suggestive, suggestive or weak based on statistical significance of random-effects summary estimate, largest study included, number of cases, between-study heterogeneity, 95% prediction intervals, small study effects, excess significance bias and sensitivity analysis with credibility ceilings. We identified 171 meta-analyses investigating associations between 53 risk factors and endometrial cancer incidence and mortality. Risk factors were categorised: anthropometric indices, dietary intake, physical activity, medical conditions, hormonal therapy use, biochemical markers, gynaecological history and smoking. Of 127 meta-analyses including cohort studies, three associations were graded with strong evidence. Body mass index and waist-to-hip ratio were associated with increased cancer risk in premenopausal women (RR per 5 kg/m2 1.49; CI 1.39-1.61) and for total endometrial cancer (RR per 0.1unit 1.21; CI 1.13-1.29), respectively. Parity reduced risk of disease (RR 0.66, CI 0.60-0.74). Of many proposed risk factors, only three had strong association without hints of bias. Identification of genuine risk factors associated with endometrial cancer may assist in developing targeted prevention strategies for women at high risk.

A four-miRNA signature as a novel biomarker for predicting survival in endometrial cancer

BACKGROUND

The microRNAs (miRNAs) have been validated as prognostic markers in many cancers. The aim of this study was to identify new miRNA prognostic biomarkers in endometrial cancer (EC) and to develop an expression-based miRNA signature to provide survival risk prediction for EC patients.

METHODS

From TCGA database, the miRNA datasets of EC and clinical information were downloaded in April 2018. Using univariate and multivariate Cox regression analyses identify prognostic factors. Using area under the curve (AUC) of receiver operating characteristic (ROC) curve assess the sensitivity and specificity of prognostic model.

RESULTS

530 patients were randomly divided into training set and testing set. Among 561 differentially expressed miRNAs, 4 miRNAs (miR-4758, miR-876, miR-142, miR-190b) were demonstrated to be predictive biomarkers of overall survival (OS) for EC patients in training set. Based on the risk score of 4-miRNA model, patients in the training set were divided into high-risk and low-risk groups with significantly different OS. This 4-miRNA model was validated in testing and entire set. The AUC for the ROC curves in the entire set was 0.704. Meanwhile, multivariate Cox regression combined with other traditional clinical parameters indicated that the 4-miRNA model can be used as an independent OS prognostic factor. Functional enrichment analysis revealed that these miRNAs are involved in biological processes and pathways that are closely related to cancer.

CONCLUSION

A robust 4-miRNA signature as an independent prognostic factor for OS in EC patients was established.

MicroRNA-320a acts as a tumor suppressor in endometrial carcinoma by targeting IGF-1R

Dysregulation of microRNAs (miRs) is implicated in the carcinogenesis of various types of malignant tumor by manipulating cell growth and apoptosis. Abnormal expression of miR‑320a is involved in tumorigenesis of many types of cancer. The potential association of miR‑320a and the possible regulatory mechanisms in endometrial carcinoma is rarely elucidated. In the present study, it was demonstrated that miR‑320a expression was decreased in endometrial carcinoma tissues and cell lines. The present results also indicated that overexpression of miR‑320a suppressed cell proliferation through inducing G2/M phrase arrest and apoptosis. Insulin‑like growth factor receptror‑1 (IGF‑1R) was verified to be the potential target of miR‑320a by computational analysis and luciferase reporter assays. In addition, overexpression of miR‑320a reduced endogenous IGF‑1R expression in cells. Furthermore, it was demonstrated that upregulation of miR‑320a inhibited phosphorylated (p)‑protein kinase B and p‑mechanistic target of rapamycin activation and promoted B cell lymphoma‑2‑associated death promoter expression. Reintroduction of IGF‑1R into miR‑320a‑overexpressed cells antagonized the impact of miR‑320a on its downstream protein, which demonstrated that the tumor suppressive role of miR‑320a in endometrial carcinoma is exerted by the signal pathway mediated by IGF‑1R. It was therefore concluded that miR‑320a served an anti‑tumor role on endometrial carcinoma through the regulation of IGF‑1R, and miR‑320a may be used as the target for the gene therapy of endometrial carcinoma.

Comparison of protocols and RNA carriers for plasma miRNA isolation. Unraveling RNA carrier influence on miRNA isolation

microRNAs are promising biomarkers in biological fluids in several diseases. Different plasma RNA isolation protocols and carriers are available, but their efficiencies have been scarcely compared. Plasma microRNAs were isolated using a phenol and column-based procedure and a column-based procedure, in the presence or absence of two RNA carriers (yeast RNA and MS2 RNA). We evaluated the presence of PCR inhibitors and the relative abundance of certain microRNAs by qRT-PCR. Furthermore, we analyzed the association between different isolation protocols, the relative abundance of the miRNAs in the sample, the GC content and the free energy of microRNAs. In all microRNAs analyzed, the addition of yeast RNA as a carrier in the different isolation protocols used gave lower raw Cq values, indicating higher microRNA recovery. Moreover, this increase in microRNAs recovery was dependent on their own relative abundance in the sample, their GC content and the free-energy of their own most stable secondary structure. Furthermore, the normalization of microRNA levels by an endogenous microRNA is more reliable than the normalization by plasma volume, as it reduced the difference in microRNA fold abundance between the different isolation protocols evaluated. Our thorough study indicates that a standardization of pre- and analytical conditions is necessary to obtain reproducible inter-laboratory results in plasma microRNA studies.

Evaluation Analysis of miRNAs Overexpression in Liquid-Based Cytology Endometrial Samples

Background: miRNAs have an important role as their deregulation is linked to endometrial cancer.

Methods: A custom miScript® miRNA PCR Array was used to investigate for the first time the expression of eight miRNAs in forty-nine histologically confirmed Liquid Based cytology endometrial samples. The expression profile of the same miRNAs was also examined in sixty formalin-fixed tissue samples.

Results: Expression of seven miRNAs was significantly higher in malignant samples with three of them (mir-182, mir-141 and mir-205) performing optimally.

Conclusion: These results suggest the potential use of this non-invasive method of sampling for miRNA expression studies. Furthermore miRNA overexpression could serve as an ancillary or reflex test for optimal identification of malignant samples especially in morphologically inadequate samples.

Hypoxia- and acidosis-driven aberrations of secreted microRNAs in endometrial cancer in vitro

Due to their post-transcriptional regulatory impact on gene expression, microRNAs (miRNA, miRs) influence decisively cellular processes of differentiation, proliferation and apoptosis. In oncogenic pathways various miRNAs exert either oncogenic or tumor suppressor activities in a stage-specific manner. Dysregulation of miRNA expression pattern has been associated with several human cancers including endometrial cancer (EC). In the present study, expression profile alterations of EC associated secreted miRNAs were determined under the microenvironmental stress situations hypoxia and acidosis occurring in tumor progression and metastasis. The potential influence of hypoxia and acidosis vs. control conditions on the expression levels of 24 EC-relevant miRNA types was quantitatively accessed via real-time PCR in three established EC in vitro models. Expression data were analyzed statistically. In vitro application of hypoxia resulted in downregulation of miR-15a, miR-20a, miR-20b and miR-128-1 in Ishikawa cells (type I EC) and upregulation of miR-21 in EFE-184 cells (type I EC). Acidosis triggered upregulation of tumor promoting miR-125b in AN3-CA cell (type II EC), whereas in Ishikawa cells (type I EC) miRNAs with tumor suppressive function were found altered in divergent directions, both up- (let-7a) and down- (miR-22) regulated. Our current findings emphasize the functional importance of secreted miRNAs in the immediate response of EC cells to exogenic stress situations such as the typical tumor epiphenomena hypoxia and acidosis. Focusing on the specific potential of secreted, thus circulating miRNA molecules, alterations in expression levels not only influence intracellular gene expression and signaling cascades, but also transfer the induction of (tumor)biological cellular changes to adjacent cells.

Epigenetics in endometrial carcinogenesis - part 2: histone modifications, chromatin remodeling and noncoding RNAs

Carcinogenesis is a multistep multifactorial process that involves the accumulation of genetic and epigenetic alterations. In the past two decades, there has been an exponential growth of knowledge establishing the importance of epigenetic changes in cancer. Our work focused on reviewing the main role of epigenetics in the pathogenesis of endometrial carcinoma, highlighting the reported results concerning each epigenetic mechanistic layer. In a previous review, we assessed DNA methylation alterations. The present review examines the contribution of histone modifications, chromatin remodeling and noncoding RNA alterations for endometrial carcinogenesis.

The colonization with Candida species is more harmful in the second trimester of pregnancy

Purpose

Vaginal colonization with Candida species (spp.) during pregnancy has been associated with impaired pregnancy outcomes. There is a reduction in spontaneous preterm birth among women with recurrent asymptomatic colonization of Candida who were treated with clotrimazole. This study aimed to evaluate the impact of the trimester of vulvovaginal colonization with Candida species.

Methods

Data from all women, who were tested positive for the vaginal colonization with Candida spp. during the first or second trimester of pregnancy, and who registered for a planned birth at our tertiary referral center between 2005 and 2014 were retrospectively analyzed. Their preterm birth rate served as the primary outcome variable. Secondary outcome variables were neonatal birthweight and Apgar score.

Results

Overall, 1066 women were eligible for the study. In 673 women (63%), who were diagnosed with Candida spp. during the first trimester of pregnancy, the rate of preterm birth was 10% (N = 64). In 393 women (37%), who were diagnosed with candidosis during the second trimester, the preterm birth rate was 18% (N = 71; p = 0.0002). Neonates of women, who presented with vulvovaginal candidosis during the first trimester, had a mean birthweight of 3243 g, compared to 2989 g in the group with a second trimester colonization (p < 0.0001).

Conclusion

Women who are colonized with Candida spp. during the second trimester of pregnancy have higher rates of preterm birth and lower neonatal birthweight than those who are colonized during the first trimester of their pregnancy. Screening programs for asymptomatic Candida colonization should take this information into account.

Web-based tools for microRNAs involved in human cancer

MicroRNAs (miRNAs/miRs) are a family of small, endogenous and evolutionarily-conserved non-coding RNAs that are involved in the regulation of several cellular and functional processes. miRNAs can act as oncogenes or tumor suppressors in all types of cancer, and could be used as prognostic and diagnostic biomarkers. Databases and computational algorithms are behind the majority of the research performed on miRNAs. These tools assemble and curate the relevant information on miRNAs and present it in a user-friendly manner. The current review presents 14 online databases that address every aspect of miRNA cancer research. Certain databases focus on miRNAs and a particular type of cancer, while others analyze the behavior of miRNAs in different malignancies at the same time. Additional databases allow researchers to search for mutations in miRNAs or their targets, and to review the naming history of a particular miRNA. All these databases are open-access, and are a valuable tool for those researchers working with these molecules, particularly those who lack access to an advanced computational infrastructure.

Identification of microRNA expression profile related to lymph node status in women with early-stage grade 1-2 endometrial cancer

Conventional methods used for histologic classification and grading of endometrial cancer (EC) are not sufficient to predict lymph node metastases. microRNA signatures have recently been related to EC pathologic characteristics or prognosis. The aim of this study was to evaluate whether microRNA profiles of grade 1-2 endometrioid adenocarcinomas can be related to nodal status and used as a tool to adapt surgical staging in early-stage EC. microRNA expression was assessed in nine formalin-fixed paraffin-embedded (FFPE) EC primary tumors with positive lymph node and in 27 FFPE EC primary tumors with negative lymph node, matched for grade, stage, and lymphovascular space involvement status. A microarray analysis showed that there was more than a twofold significant difference in the expression of 12 microRNAs between the two groups. A quantitative reverse transcriptase-PCR assay was used to confirm these results: the expression levels of five microRNAs (microRNA-34c-5p, -375, -184, -34c-3p, and -34b-5p) were significantly lower in the EC primary tumor with positive lymph node compared with those with negative lymph node. A minimal P-value approach revealed that women with a microRNA-375-fold change <0.30 were more likely to have positive lymph node (n=8; 53.3%) compared with those with a microRNA-375-fold change >0.30 (n=1; 4.8%), P=0.001. Furthermore, women with a microRNA 184-fold change <0.30 were more likely to have positive lymph node (n=6; 60.0%) compared with those with a microRNA 184-fold change >0.30 (n=3; 11.5%), P=0.006. This is the first study investigating the relative expression of mature microRNA genes in early-stage grade 1-2 EC primary tumors according to the nodal status. This microRNA expression profile provides a potential basis for further study of the microRNA function in EC and could be used as a diagnostic tool for nodal status.

Insulinemia, heterogeneity of obesity and the risk of different types of endometrial cancer: existing evidence

Due to a number of reasons, endometrial cancer is a point of interest not only for oncologists, but also for a variety of specialists - especially endocrinologists. The endocrinology of endometrial cancer can be firmly divided into two categories - steroid and non-steroid. The steroid approach dominated during several decades due to hyperestrogenization signs observed in some patients. The balance was only regained in the last 15 years, when the role of diabetes and insulin resistance began to draw attention. This review aims to provide an update on connections between insulinemia (insulin resistance) and different obesity phenotypes as well to discuss their relation to development of endometrial cancer, its clinical-morphological features and the increasing number of its molecular-biological subtypes.

Analysis of differentially expressed genes between endometrial carcinosarcomas and endometrioid endometrial carcinoma by bioinformatics

PURPOSE

This study aimed to explore the underlying molecular mechanisms of endometrial carcinosarcomas (ECS) and endometrioid endometrial carcinoma (EEC) by bioinformatics analysis.

METHODS

Gene expression profile GSE33723 was downloaded from the Gene Expression Omnibus. A total of 15 ECS and 23 EEC samples were used to identify the differentially expressed genes (DEGs) by significance analysis of microarrays. After construction of protein-protein interaction (PPI) network, Gene Ontology (GO) functional and pathway enrichment analyses of DEGs were performed, followed by network module analysis.

RESULTS

A total of 49 DEGs were identified between EEC and ECS samples. In the PPI network, TP53 (tumor protein p53) was selected as the highest degree, hub centrality and betweenness. The top 10 enriched GO terms including regulation of cell death and top 10 significant pathways including cell cycle were selected. After network module analysis, PIK3R1 (phosphoinositide-3-kinase, regulatory subunit 1) and AKT2 (v-akt murine thymoma viral oncogene homolog 2) were selected as the co-expressed genes in the states of ECS while STAT3 (signal transducer and activator of transcription 3) and JAZF (JAZF zinc finger 1) were selected as the co-expressed genes in the states of EEC.

CONCLUSIONS

The DEGs, such as TP53, PIK3R1 and AKT2 may be used for targeted diagnosis and treatment of ECS while STAT3 and JAZF1 may be served as a target for EEC.

The role of microRNAs expression in laryngeal cancer

MicroRNAs (miRs, miRs) is a class of small non-coding RNAs, which posttranscriptionally regulate gene expression. Deregulated miRs are frequently obseved in patients with laryngeal cancer. In addition, numerous studies have showed miRs play significant roles in the pathogenesis of laryngeal cancer through regulating tumor cell proliferation, metastasis, invasion and apoptosis. miR can play either an oncogenic or tumor suppressive role in laryngeal cancer. In our review, we summarize the recent researches on laryngeal cancer-associated miRs, focusing on their role in the pathogenesis of laryngeal cancer. As changes in the levels of specific miRs in tissues or serum associate with diagnosis and prognosis of patients, we will also discuss the potential use of miRs in laryngeal cancer diagnosis and prognosis. Furthermore, supplementation of oncomiRs or inhibition of tumor suppressive miRs in vivo may be future therapeutic strategy for laryngeal cancer.