The role of MicroRNA molecules and MicroRNA-regulating machinery in the pathogenesis and progression of epithelial ovarian cancer

The microRNA Let-7 and its exosomal form: Epigenetic regulators of gynecological cancers

Many types of gynecological cancer (GC) are often silent until they reach an advanced stage, and are therefore often diagnosed too late for effective treatment. Hence, there is a real need for more efficient diagnosis and treatment for patients with GC. During recent years, researchers have increasingly studied the impact of microRNAs cancer development, leading to a number of applications in detection and treatment. MicroRNAs are a particular group of tiny RNA molecules that regulate regular gene expression by affecting the translation process. The downregulation of numerous miRNAs has been observed in human malignancies. Let-7 is an example of a miRNA that controls cellular processes as well as signaling cascades to affect post-transcriptional gene expression. Recent research supports the hypothesis that enhancing let-7 expression in those cancers where it is downregulated may be a potential treatment option. Exosomes are tiny vesicles that move through body fluids and can include components like miRNAs (including let-7) that are important for communication between cells. Studies proved that exosomes are able to enhance tumor growth, angiogenesis, chemoresistance, metastasis, and immune evasion, thus suggesting their importance in GC management.

Transcriptomic analyses of ovarian clear-cell carcinoma with concurrent endometriosis

Introduction

Endometriosis, a benign inflammatory disease whereby endometrial-like tissue grows outside the uterus, is a risk factor for endometriosis-associated ovarian cancers. In particular, ovarian endometriomas, cystic lesions of deeply invasive endometriosis, are considered the precursor lesion for ovarian clear-cell carcinoma (OCCC).

Methods

To explore this transcriptomic landscape, OCCC from women with pathology-proven concurrent endometriosis (n = 4) were compared to benign endometriomas (n = 4) by bulk RNA and small-RNA sequencing.

Results

Analysis of protein-coding genes identified 2449 upregulated and 3131 downregulated protein-coding genes (DESeq2, P< 0.05, log2 fold-change > |1|) in OCCC with concurrent endometriosis compared to endometriomas. Gene set enrichment analysis showed upregulation of pathways involved in cell cycle regulation and DNA replication and downregulation of pathways involved in cytokine receptor signaling and matrisome. Comparison of pathway activation scores between the clinical samples and publicly-available datasets for OCCC cell lines revealed significant molecular similarities between OCCC with concurrent endometriosis and OVTOKO, OVISE, RMG1, OVMANA, TOV21G, IGROV1, and JHOC5 cell lines. Analysis of miRNAs revealed 64 upregulated and 61 downregulated mature miRNA molecules (DESeq2, P< 0.05, log2 fold-change > |1|). MiR-10a-5p represented over 21% of the miRNA molecules in OCCC with endometriosis and was significantly upregulated (NGS: log2fold change = 4.37, P = 2.43e-18; QPCR: 8.1-fold change, P< 0.05). Correlation between miR-10a expression level in OCCC cell lines and IC50 (50% inhibitory concentration) of carboplatin in vitro revealed a positive correlation (R2 = 0.93). MiR-10a overexpression in vitro resulted in a significant decrease in proliferation (n = 6; P< 0.05) compared to transfection with a non-targeting control miRNA. Similarly, the cell-cycle analysis revealed a significant shift in cells from S and G2 to G1 (n = 6; P< 0.0001). Bioinformatic analysis predicted that miR-10a-5p target genes that were downregulated in OCCC with endometriosis were involved in receptor signaling pathways, proliferation, and cell cycle progression. MiR-10a overexpression in vitro was correlated with decreased expression of predicted miR-10a target genes critical for proliferation, cell-cycle regulation, and cell survival including [SERPINE1 (3-fold downregulated; P< 0.05), CDK6 (2.4-fold downregulated; P< 0.05), and RAP2A (2-3-fold downregulated; P< 0.05)].

Discussion

These studies in OCCC suggest that miR-10a-5p is an impactful, potentially oncogenic molecule, which warrants further studies.

Network-Based Integration of Multi-Omics Data Identifies the Determinants of miR-491-5p Effects

The identification of miRNAs' targets and associated regulatory networks might allow the definition of new strategies using drugs whose association mimics a given miRNA's effects. Based on this assumption we devised a multi-omics approach to precisely characterize miRNAs' effects. We combined miR-491-5p target affinity purification, RNA microarray, and mass spectrometry to perform an integrated analysis in ovarian cancer cell lines. We thus constructed an interaction network that highlighted highly connected hubs being either direct or indirect targets of miR-491-5p effects: the already known EGFR and BCL2L1 but also EP300, CTNNB1 and several small-GTPases. By using different combinations of specific inhibitors of these hubs, we could greatly enhance their respective cytotoxicity and mimic the miR-491-5p-induced phenotype. Our methodology thus constitutes an interesting strategy to comprehensively study the effects of a given miRNA. Moreover, we identified targets for which pharmacological inhibitors are already available for a clinical use or in clinical trials. This study might thus enable innovative therapeutic options for ovarian cancer, which remains the leading cause of death from gynecological malignancies in developed countries.

SP1-induced lncRNA DANCR contributes to proliferation and invasion of ovarian cancer

Transcription factor SP1 could manipulate pathways involved in ovarian cancer progression. LncRNAs are involved in SP1-mediated tumorigenesis. LncRNA DANCR could promote metastasis of ovarian cancer. However, the regulatory function and involvement of SP1-induced lncRNA DANCR in ovarian cancer remain elusive. Data from this study showed that SP1 was up-regulated in ovarian cancer tissues and cells (CAOV3, SKOV3, A2780), and SP1 could bind to the promoter region of DANCR through chromatin immunoprecipitation and leuciferase activity assays. Therefore, DANCR was transcriptionally induced by SP1 in ovarian cancer tissues and cells (CAOV3, SKOV3, A2780). Functionally, reduced expression of DANCR suppressed cell viability, migration and invasion of CAOV3, while enhanced DANCR expression contributed to SKOV3 growth. Over-expression of SP1 reversed the suppressive effects of DANCR interference on ovarian cancer progression. In conclusion, SP1-induced DANCR contributed to oncogenic potential of ovarian cancer, suggesting a promising therapeutic target for ovarian cancer.

Argonaute 3 (AGO3) promotes malignancy potential of cervical cancer via regulation of Wnt/β-catenin signaling pathway

We aimed to investigate the biological roles of Argonaute 3 (AGO3) in cervical cancer. RNA profiles containing 306 cervical cancer tissues and 13 normal samples revealed that AGO3 was significantly up-regulated in cervical cancer, and the expression of AGO3 was negatively associated with the outcome of cervical cancer patients. Cell proliferation and transwell assays showed that the depletion of AGO3 markedly inhibited cervical cancer cell growth and mobility. Importantly, we detected that knockdown of AGO3 exerted suppressive effect on cellular behaviors via inactivating Wnt/β-catenin signaling pathway. Collectively, we conclude that AGO3 is a novel tumor promoter in cervical cancer and has a potential to be a drug target and prognostic predictor of cervical cancer patients.

The negative feedback between miR-143 and DNMT3A regulates cisplatin resistance in ovarian cancer

Emerging evidence suggests that miR-143 plays an important role in the regulation of tumor sensitivity to chemotherapeutic agents. The study explores the underlying mechanism of miR-143 in reversing cisplatin resistance in ovarian cancer. The cisplatin-resistant ovarian cancer cell line A2780/CDDP was induced and established via treating A2780 cells by gradually increasing cisplatin concentrations. The IC50 values of A2780/CDDP and A2780 to cisplatin were 218.10 ± 1.12 and 21.99 ± 1.12 μM, respectively. Quantitative real-time polymerase chain reaction (qRT-PCR) results showed that miR-143 was significantly decreased in A2780/CDDP cells compared with A2780 cells. miR-143 overexpression decreased cisplatin resistance in A2780/CDDP, and miR-143 inhibition decreased A2780 sensitivity to cisplatin. Results of qRT-PCR, Western blot analysis, and luciferase reporter assay indicated that the direct target of miR-143 was DNMT3A, which, in turn, was upregulated in A2780/CDDP. DNMT3A overexpression antagonized the sensitizing effect of miR-143 on A2780/CDDP to cisplatin. Knocking down of DNMT3A reduced cisplatin resistance in A2780/CDDP, while overexpression of DNMT3A increased cisplatin resistance in A2780. Methylation-specific polymerase chain reaction results showed that the methylation level in the promoter region of the miR-143 precursor gene was higher in A2780/CDDP cells than in A2780 cells. DNMT3A mediated the hypermethylation of the miR-143 precursor gene, resulting in miR-143 downregulation in A2780/CDDP. miR-143 inhibited cell growth of A2780/CDDP cell in nude mice. Our findings indicated the negative feedback between miR-143 and DNMT3A as a crucial epigenetic modifier of cisplatin resistance in ovarian cancer.

Pten and Dicer1 loss in the mouse uterus causes poorly differentiated endometrial adenocarcinoma

Endometrial cancer remains the most common gynecological malignancy in the United States. While the loss of the tumor suppressor, PTEN (phosphatase and tensin homolog), is well studied in endometrial cancer, recent studies suggest that DICER1, the endoribonuclease responsible for miRNA genesis, also plays a significant role in endometrial adenocarcinoma. Conditional uterine deletion of Dicer1 and Pten in mice resulted in poorly differentiated endometrial adenocarcinomas, which expressed Napsin A and HNF1B (hepatocyte nuclear factor 1 homeobox B), markers of clear-cell adenocarcinoma. Adenocarcinomas were hormone-independent. Treatment with progesterone did not mitigate poorly differentiated adenocarcinoma, nor did it affect adnexal metastasis. Transcriptomic analyses of DICER1 deleted uteri or Ishikawa cells revealed unique transcriptomic profiles and global miRNA downregulation. Computational integration of miRNA with mRNA targets revealed deregulated let-7 and miR-16 target genes, similar to published human DICER1-mutant endometrial cancers from TCGA (The Cancer Genome Atlas). Similar to human endometrial cancers, tumors exhibited dysregulation of ephrin-receptor signaling and transforming growth factor-beta signaling pathways. LIM kinase 2 (LIMK2), an essential molecule in p21 signal transduction, was significantly upregulated and represents a novel mechanism for hormone-independent pathogenesis of endometrial adenocarcinoma. This preclinical mouse model represents the first genetically engineered mouse model of poorly differentiated endometrial adenocarcinoma.

A Polyethylene Glycol-Based Method for Enrichment of Extracellular Vesicles from Culture Supernatant of Human Ovarian Cancer Cell Line A2780 and Body Fluids of High-Grade Serous Carcinoma Patients

Objective

This study tried to evaluate whether 8% polyethylene glycol (PEG) 6000 precipitation combined with differential ultracentrifugation (PPDU) was an efficient and practical method for the enrichment and purification of extracellular vesicles (EVs) derived from the culture supernatant of human ovarian cancer cell line A2780 and from body fluids of patients with high-grade serous carcinoma (HGSC).

Methods

PPDU was used to enrich and purify the EVs derived from body fluids of patients with HSGC and cell culture supernatant of subclones of human ovarian cancer cell line A2780 with high/low invasive capacity (named as A-H/A-L, respectively). Transmission electron microscope (TEM) and nanoparticle tracking analysis (NTA) were used to identificate the EVs size and distribution. Western blots (WB) were used to detect the expression of CD9, CD63, Alix and Calnexin. The high-purity EVs derived from the cell culture supernatant of A-H/A-L were detected by the protein profile. Expression of integrins (ITGs) αV, β1 and β3 in the EVs derived from body fluids of HGSC patients was also evaluated.

Results

The diameter of EVs was about 30–260 nm observed under the TEM. Under the NTA identification, the peak size of EVs was ranged from 70 to 159nm. EVs derived from different specimens did not significantly differ in mean size and peak size. Presence of CD9, CD63 and Alix and absence of Calnexin were confirmed in the EVs. The protein concentrations of EVs’ sample extracted from A-H/A-L cell culture supernatant were 0.36µg/µL and 0.20µg/µL, respectively. The total amount of protein obtained from 300ul EVs was 108.02ug and 61.44ug, respectively. Totally, 2397 peptides and 952 proteins were identified by isobaric tags for relative and absolute quantitation (ITRAQ). The expression of ITGαV, β1, and β3 in the EVs from plasma and ascites of HGSC patients was significantly higher than the control group (plasma: all P<0.0001; ascites: P=0.036, 0.001 and 0.004, respectively). The expression level of ITGαV and β1 in EVs of HGSC’s ascites was significantly higher than that in plasma (P= 0.004, 0.001, respectively). The expression of ITGβ3 was also slightly elevated in EVs-derived HGSC patients’ ascites (P=0.492).

Conclusion

PPDU was an efficient and practical method to enrich EVs from body fluids and cell culture supernatant. The characteristic expression of ITGαV, β1 and β3 in ascites and plasma EVs of patients with HGSC provided useful information on the development of EVs in HGSC.

From the Argonauts Mythological Sailors to the Argonautes RNA-Silencing Navigators: Their Emerging Roles in Human-Cell Pathologies

Regulation of gene expression has emerged as a fundamental element of transcript homeostasis. Key effectors in this process are the Argonautes (AGOs), highly specialized RNA-binding proteins (RBPs) that form complexes, such as the RNA-Induced Silencing Complex (RISC). AGOs dictate post-transcriptional gene-silencing by directly loading small RNAs and repressing their mRNA targets through small RNA-sequence complementarity. The four human highly-conserved family-members (AGO1, AGO2, AGO3, and AGO4) demonstrate multi-faceted and versatile roles in transcriptome’s stability, plasticity, and functionality. The post-translational modifications of AGOs in critical amino acid residues, the nucleotide polymorphisms and mutations, and the deregulation of expression and interactions are tightly associated with aberrant activities, which are observed in a wide spectrum of pathologies. Through constantly accumulating information, the AGOs’ fundamental engagement in multiple human diseases has recently emerged. The present review examines new insights into AGO-driven pathology and AGO-deregulation patterns in a variety of diseases such as in viral infections and propagations, autoimmune diseases, cancers, metabolic deficiencies, neuronal disorders, and human infertility. Altogether, AGO seems to be a crucial contributor to pathogenesis and its targeting may serve as a novel and powerful therapeutic tool for the successful management of diverse human diseases in the clinic.

MicroRNA-936 targets FGF2 to inhibit epithelial ovarian cancer aggressiveness by deactivating the PI3K/Akt pathway

Purpose

MicroRNA-936 (miR-936) was previously reported to be dysregulated and involved in the development of non-small cell lung cancer and glioma. However, the functional roles of miR-936 in epithelial ovarian cancer (EOC) remain unclear. In this study, we aimed to evaluate miR-936 expression in EOC and investigate its regulatory role in EOC cell behavior.

Methods

The expression of miR-936 in EOC was measured by RT-qPCR. Cell proliferation, apoptosis, migration, and invasion in vitro, as well as tumor growth in vivo, were determined by CCK-8, flow cytometry, migration and invasion assays, and xenograft models in nude mice, respectively. Bioinformatics analysis, luciferase reporter assays, RT-qPCR, and Western blot analysis were performed to investigate the relationship between miR-936 and fibroblast growth factor 2 (FGF2).

Results

miR-936 expression was significantly downregulated in EOC tissues and cell lines. Low miR-936 expression was found to be correlated with the tumor size, FIGO stage, and lymphatic metastasis in EOC patients. Functional experiments indicated that ectopic miR-936 expression suppressed EOC cell proliferation, migration, and invasion; promoted cell apoptosis; and decreased tumor growth in vivo. In addition, the FGF2 gene was verified to be a direct target of miR-936 in EOC cells. FGF2 expression levels were upregulated in EOC tissues and were inversely correlated with miR-936 expression. Furthermore, effects of FGF2 silencing were similar to those of miR-936 overexpression in EOC cells. Recovered FGF2 expression rescued the miR-936-induced inhibitory effects in EOC cells. Notably, miR-936 was able to deactivate the PI3K/Akt signaling pathway in EOC cells by regulating FGF2 both in vitro and in vivo.

Conclusion

Altogether, our findings provided initial evidence that miR-936 inhibits the aggressiveness of EOC cells in vitro and in vivo, at least partially, by targeting FGF2-mediated suppression of the PI3K/Akt pathway. Therefore, the miR-936/FGF2/PI3K/Akt pathway is a promising therapeutic target for the treatment of EOC patients.

Branched rolling circle amplification method for measuring serum circulating microRNA levels for early breast cancer detection

Serum circulating microRNAs (c‐miRNAs) are serving as useful biomarkers for cancer diagnosis. Here, we describe the development of a one‐step branched rolling circle amplification (BRCA) method to measure serum c‐miRNAs levels for early diagnosis of breast cancer. Four c‐miRNAs, c‐miRNA16 (c‐miR‐16), c‐miRNA21 (c‐miR‐21), c‐miRNA155 (c‐miR‐155), and c‐miRNA195 (c‐miR‐195) were isolated from the serum of 49 breast cancer patients (stages I‐IV) and 19 healthy controls, and analyzed using one‐step BRCA. The serum levels of c‐miR16, c‐miR21, c‐miR155, and c‐miR195 were higher (P < 0.0001) in stage I breast cancer patients than healthy controls. These levels were also higher in several breast cancer molecular subtypes (HER‐2 over‐expression, Luminal A, Luminal B, and triple negative breast cancer) than in healthy control subjects. The diagnostic accuracy of c‐miR16, c‐miR21, c‐miR155, and c‐miR195 for early diagnosis of breast cancer was confirmed by receiver operating characteristic (ROC) curve assay. These results show that the BRCA method can be used to measure serum c‐miRNAs levels, and that this method has high accuracy, sensitivity, and specificity. Moreover, both BRCA approach and quantitative real‐time PCR (qRT‐PCR) method show that the serum levels of c‐miR16, c‐miR21, c‐miR155, and c‐miR195 could be used as biomarkers to improve the early diagnosis of breast cancer, and distinguish different breast cancer molecular subtypes.

Integrated microarray meta-analysis identifies miRNA-27a as an oncogene in ovarian cancer by inhibiting FOXO1

AIMS

Survival of ovarian cancer patients is generally poor, partly because most of them are already at an advanced stage when diagnosed. The purpose of this study was to screen prognostic miRNAs for ovarian cancer, and to explore the underlying mechanisms.

MAIN METHODS

Integrated meta-analysis of miRNA microarrays retrieved from public repositories was employed to identify clinically significant miRNAs involved in ovarian cancer. Targets of candidate miRNA were predicted using four online databases, and validated with dual luciferase assay. Loss and gain of function were performed to investigate the role of miR27a in the growth of ovarian cancer cell lines.

KEY FINDINGS

Based on cross-validation results in multiple datasets, we recognized hsa-miR-27a as an oncogenic molecular and a prognostic factor for ovarian cancer patients. Dual luciferase assay indicated tumor suppressor FOXO1 was a direct target of miR-27a. In addition, hsa-miR-27a could stimulate SKOV3 and A2780 cell proliferation and migration by regulating the expression of FOXO1.

SIGNIFICANCE

In summary, our results indicate that miR-27a can promote progression of ovarian cancer by mediating FOXO1. To our knowledge, this is the first study focusing on the role of miR-27a/FOXO1 axis using the microarray meta-analysis in ovarian cancer. Furthermore, inhibiting miR-27a expression may be a new strategy for the treatment of ovarian cancer.

The Endometriotic Tumor Microenvironment in Ovarian Cancer

Women with endometriosis are at increased risk of developing ovarian cancer, specifically ovarian endometrioid, low-grade serous, and clear-cell adenocarcinoma. An important clinical caveat to the association of endometriosis with ovarian cancer is the improved prognosis for women with endometriosis at time of ovarian cancer staging. Whether endometriosis-associated ovarian cancers develop from the molecular transformation of endometriosis or develop because of the endometriotic tumor microenvironment remain unknown. Additionally, how the presence of endometriosis improves prognosis is also undefined, but likely relies on the endometriotic microenvironment. The unique tumor microenvironment of endometriosis is composed of epithelial, stromal, and immune cells, which adapt to survive in hypoxic conditions with high levels of iron, estrogen, and inflammatory cytokines and chemokines. Understanding the unique molecular features of the endometriotic tumor microenvironment may lead to impactful precision therapies and/or modalities for prevention. A challenge to this important study is the rarity of well-characterized clinical samples and the limited model systems. In this review, we will describe the unique molecular features of endometriosis-associated ovarian cancers, the endometriotic tumor microenvironment, and available model systems for endometriosis-associated ovarian cancers. Continued research on these unique ovarian cancers may lead to improved prevention and treatment options.

MicroRNA-125a-5p enhances the sensitivity of esophageal squamous cell carcinoma cells to cisplatin by suppressing the activation of the STAT3 signaling pathway

Increasing evidence has demonstrated that microRNAs (miRNAs or miRs) play a variety of roles in tumor development, progression and chemosensitivity in a wide range of tumors. In this study, we found that miR-125a-5p exhibited a low expression in esophageal squamous cell carcinoma (ESCC) tissues and cells, and that its low expression was associated with higher tumor staging and shorter a survival time of patients with ESCC. Moreover, miR-125a-5p overexpression contributed to the suppression of cell proliferation, cell cycle arrest, cell apoptosis and a decrease in cell migratory and invasive abilities, whereas the downregulation of miR-125a-5p promoted cell proliferation, accelerated cell cycle progression, suppressed apoptosis and enhanced the migratory and invasive abilities of ESCC EC1 and TE1 cells, which may be tightly associated with the epithelial-mesenchymal transition (EMT) process in ESCC. Importantly, miR-125a-5p enhanced the cytotoxic effects of cisplatin on EC1 and TE1 cells, and co-treatment with miR-125a-5p and cisplatin significantly induced cell apoptosis and reduced the cell migratory and invasive abilities of EC1 and TE1 cells, coupled with an increase in the E-cadherin level and a decrease in the N-cadherin and Vimentin levels. Most notably, signal transducer and activator of transcription-3 (STAT3) was found to be a direct target of miR-125a-5p in ESCC cells, and miR-125a-5p overexpression significantly reduced the protein levels of t-STAT3, p-STAT3 and vascular endothelial growth factor (VEGF) in EC1 and TE1 cells. Furthermore, the combination of miR-125a-5p and cisplatin markedly inactivated the STAT3 signaling pathway; however, interleukin (IL)-6, a widely reported activator of the STAT3 signaling pathway, reversed the suppressive effects of miR-125a-5p/cisplatin in ESCC cells on the activation of the STAT3 signaling pathway. Of note, we found that IL-6 markedly reversed the altered cell phenotype mediated by the combination of miR-125a-5p and cisplatin in ESCC cells. These findings suggest that miR-125a-5p may play a pivotal role in the development and progression of ESCC, which may be achieved via the manipulation of the STAT3 signaling pathway.

Identification of circulating microRNAs as diagnostic biomarkers for ovarian cancer:A pooled analysis of individual studies

BACKGROUND

Circulating microRNAs (miRNAs) are proposed as promising non-invasive diagnostic biomarkers for many cancers. However, the diagnostic value of circulating miRNAs in ovarian cancer is inconsistent in different studies. Thus we performed this meta-analysis to systematically evaluate the diagnostic value of circulating miRNAs in ovarian cancer.

METHODS

Eligible studies that were published prior to 30 June 2017 were searched from the PubMed, EMBASE, Cochrane Library, and Chinese National Knowledge Infrastructure. All analyses were performed using STATA 12.0 software. A bivariate regression was used to calculate pooled diagnostic accuracy estimates.

RESULTS

A total of 36 studies from 16 publications were included in this meta-analysis. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of circulating miRNAs for ovarian cancer diagnosis were 0.76 (95% confidence intervals (CI): 0.69, 0.81), 0.81 (95% CI 0.74, 0.87), 4.00 (95% CI 2.70, 5.30), 0.30(95% CI 0.24, 0.37) and 13.00 (95% CI 9.00, 19.00), respectively. The area under the summary receiver operating characteristic curve was 0.85 (95% CI 0.82, 0.88). Subgroup analyses showed that multiple miRNA assays yielded better diagnostic characteristics than a single miRNA assay, and plasma miRNAs were better than serum miRNAs for ovarian cancer detection.

CONCLUSION

Circulating miRNAs, especially the combination of multiple circulating miRNAs, are promising biomarkers for the diagnosis of ovarian cancer. However, further large-scale prospective studies are necessary to validate the applicability of the miRNAs in the early detection of ovarian cancer.