Updates and current challenges in microRNA research for personalized medicine in ovarian cancer

Synergy of the microRNA Ratio as a Promising Diagnosis Biomarker for Mucinous Borderline and Malignant Ovarian Tumors

Epithelial ovarian cancers (EOCs) are a heterogeneous collection of malignancies, each with their own developmental origin, clinical behavior and molecular profile. With less than 5% of EOC cases, mucinous ovarian carcinoma is a rare form with a poor prognosis and a 5-year survival of 11% for advanced stages (III/IV). At the early stages, these malignant forms are clinically difficult to distinguish from borderline (15%) and benign (80%) forms with a better prognosis due to the large size and heterogeneity of mucinous tumors. Improving their diagnosis is therefore a challenge with regard to the risk of under-treating a malignant form or of unnecessarily undertaking radical surgical excision. The involvement of microRNAs (miRNAs) in tumor progression and their potential as biomarkers of diagnosis are becoming increasingly recognized. In this study, the comparison of miRNA microarray expression profiles between malignant and borderline tumor FFPE samples identified 10 down-regulated and 5 up-regulated malignant miRNAs, which were validated by individual RT-qPCR. To overcome normalization issues and to improve the accuracy of the results, a ratio analysis combining paired up-regulated and down-regulated miRNAs was performed. Although 21/50 miRNA expression ratios were significantly different between malignant and borderline tumor samples, any ratio could perfectly discriminate the two groups. However, a combination of 14 pairs of miRNA ratios (double ratio) showed high discriminatory potential, with 100% of accuracy in distinguishing malignant and borderline ovarian tumors, which suggests that miRNAs may hold significant clinical potential as a diagnostic tool. In summary, these ratio miRNA-based signatures may help to improve the precision of histological diagnosis, likely to provide a preoperative diagnosis in order to adapt surgical procedures.

MicroRNA-409-5p inhibits cell proliferation, and induces G2/M phase arrest and apoptosis by targeting DLGAP5 in ovarian cancer cells

MicroRNA (miRNA/miR)-409-5p has been reported to be implicated in prostate and breast cancers; however, its functional role in ovarian cancer (OC) remains unclear. Therefore the aim of the present study was to investigate the clinical significance and biological function of miR-409-5p in OC. Here, reverse transcription-quantitative PCR analysis was performed to detect miR-409-5p expression in OC tissues and cell lines. The association between miR-409-5p expression and the clinicopathological characteristics of patients with OC was assessed using the Fisher's exact test. Furthermore, the Cell Counting Kit-8 assay was performed to assess cell proliferation. Cell cycle distribution and apoptosis were evaluated via flow cytometric analysis, and the target gene of miR-409-5p was validated via the dual-luciferase reporter assay. The results demonstrated that miR-409-5p expression was significantly downregulated in OC tissues and cell lines compared with adjacent normal tissues and epithelial cells, respectively. In addition, low miR-409-5p expression was significantly associated with tumor size (P=0.044) and the International Federation of Gynecology and Obstetrics staging system (P=0.005). Notably, overexpression of miR-409-5p suppressed cell proliferation, and induced G₂/M phase arrest and apoptosis of OC cells. Mechanistically, discs large-associated protein 5 (DLGAP5) was identified as a novel target of miR-409-5p, which was negatively regulated by miR-409-5p. DLGAP5 expression was significantly upregulated in OC tissues and cell lines compared with adjacent normal tissues and epithelial cells, respectively. Furthermore, overexpression of DLGAP5 reversed the effects of miR-409-5p on SKOV-3 cell proliferation, and G₂/M phase and apoptosis. Taken together, these results suggest that miR-409-5p acts as a tumor suppressor in OC by modulating DLGAP5 expression.

The Profile of MicroRNA Expression and Potential Role in the Regulation of Drug-Resistant Genes in Doxorubicin and Topotecan Resistant Ovarian Cancer Cell Lines

Epithelial ovarian cancer has the highest mortality among all gynecological malignancies. The main reasons for high mortality are late diagnosis and development of resistance to chemotherapy. Resistance to chemotherapeutic drugs can result from altered expression of drug-resistance genes regulated by miRNA. The main goal of our study was to detect differences in miRNA expression levels in two doxorubicin (DOX)- and two topotecan (TOP)-resistant variants of the A2780 drug-sensitive ovarian cancer cell line by miRNA microarray. The next aim was to recognize miRNAs as factors responsible for the regulation of drug-resistance genes. We observed altered expression of 28 miRNA that may be related to drug resistance. The upregulation of miR-125b-5p and miR-935 and downregulation of miR-218-5p was observed in both DOX-resistant cell lines. In both TOP-resistant cell lines, we noted the overexpression of miR-99a-5p, miR-100-5p, miR-125b-5p, and miR-125b-2-3p and decreased expression of miR-551b-3p, miR-551b-5p, and miR-383-5p. Analysis of the targets suggested that expression of important drug-resistant genes such as the collagen type I alpha 2 chain (COL1A2), protein Tyrosine Phosphatase Receptor Type K (PTPRK), receptor tyrosine kinase—EPHA7, Roundabout Guidance Receptor 2 (ROBO2), myristoylated alanine-rich C-kinase substrate (MARCK), and the ATP-binding cassette subfamily G member 2 (ABCG2) can be regulated by miRNA.

The Profile of MicroRNA Expression and Potential Role in the Regulation of Drug-Resistant Genes in Cisplatin- and Paclitaxel-Resistant Ovarian Cancer Cell Lines

Ovarian cancer is the most lethal gynecological malignancy. The high mortality results from late diagnosis and the development of drug resistance. Drug resistance results from changes in the expression of different drug-resistance genes that may be regulated miRNA. The main aim of our study was to detect changes in miRNA expression levels in two cisplatin (CIS) and two paclitaxel (PAC)—resistant variants of the A2780 drug-sensitive ovarian cancer cell line—by miRNA microarray. The next goal was to identify miRNAs responsible for the regulation of drug-resistance genes. We observed changes in the expression of 46 miRNA that may be related to drug resistance. The overexpression of miR-125b-5p, miR-99a-5p, miR-296-3p, and miR-887-3p and downregulation of miR-218-5p, miR-221-3p, and miR-222-3p was observed in both CIS-resistant cell lines. In both PAC-resistant cell lines, we observed the upregulation of miR-221-3p, miR-222-3p, and miR-4485, and decreased expression of miR-551b-3p, miR-551b-5p, and miR-218-5p. Analysis of targets suggest that expression of important drug-resistant genes like protein Tyrosine Phosphatase Receptor Type K (PTPRK), receptor tyrosine kinase—EPHA7, Semaphorin 3A (SEMA3A), or the ATP-binding cassette subfamily B member 1 gene (ABCB1) can be regulated by miRNA.

Ovarian cancer: epigenetics, drug resistance, and progression

Ovarian cancer (OC) is one of the most common malignant tumors in women. OC is associated with the activation of oncogenes, the inactivation of tumor suppressor genes, and the activation of abnormal cell signaling pathways. Moreover, epigenetic processes have been found to play an important role in OC tumorigenesis. Epigenetic processes do not change DNA sequences but regulate gene expression through DNA methylation, histone modification, and non-coding RNA. This review comprehensively considers the importance of epigenetics in OC, with a focus on microRNA and long non-coding RNA. These types of RNA are promising molecular markers and therapeutic targets that may support precision medicine in OC. DNA methylation inhibitors and histone deacetylase inhibitors may be useful for such targeting, with a possible novel approach combining these two therapies. Currently, the clinical application of such epigenetic approaches is limited by multiple obstacles, including the heterogeneity of OC, insufficient sample sizes in reported studies, and non-optimized methods for detecting potential tumor markers. Nonetheless, the application of epigenetic approaches to OC patient diagnosis, treatment, and prognosis is a promising area for future clinical investigation.

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.

Predictive Relevance of Circulating miR-622 in Patients with Newly Diagnosed and Recurrent High-Grade Serous Ovarian Carcinoma

BACKGROUND

Identifying patients with high-grade serous ovarian cancer (HGSOC) who will respond to treatment remains a clinical challenge. We focused on miR-622, a miRNA involved in the homologous recombination repair (HRR) pathway, and we assessed its predictive value in serum prior to first-line chemotherapy and at relapse.

METHODS

Serum miR-622 expression was assessed in serum prior to first-line platinum-based chemotherapy in a prospective multicenter study (miRNA Serum Analysis, miRSA, NCT01391351) and a retrospective cohort (Biological Resource Center, BRC), and was also studied at relapse. Progression-free survival (PFS) and overall survival (OS) were used as primary and secondary endpoints prior to first-line chemotherapy and OS as a primary endpoint at relapse.

RESULTS

The group with high serum miR-622 expression was associated with a significantly lower PFS (15.4 versus 24.4 months; adjusted HR 2.11, 95% CI 1.2 3.8, P = 0.015) and OS (29.7 versus 40.6 months; adjusted HR 7.68, 95% CI 2.2-26.2, P = 0.0011) in the miRSA cohort. In the BRC cohort, a high expression of miR-622 was also associated with a significantly lower OS (22.8 versus 35.9 months; adjusted HR 1.98, 95% CI 1.1-3.6, P = 0.026). At relapse, high serum miR-622 was associated with a significantly lower OS (7.9 versus 20.6 months; adjusted HR 3.15, 95% CI 1.4-7.2, P = 0.0062). Serum miR-622 expression is a predictive independent biomarker of response to platinum-based chemotherapy for newly diagnosed and recurrent HGSOC.

CONCLUSIONS

These results may open new perspectives for HGSOC patient stratification and monitoring of resistance to platinum-based and poly(ADP-ribose)-polymerase-inhibitor-maintenance therapies, facilitating better and personalized treatment decisions.

MicroRNAs in endometriosis: biological function and emerging biomarker candidates†

MicroRNAs (miRNAs), a class of small noncoding RNA molecules, have been recognized as key post-transcriptional regulators associated with a multitude of human diseases. Global expression profiling studies have uncovered hundreds of miRNAs that are dysregulated in several diseases, and yielded many candidate biomarkers. This review will focus on miRNAs in endometriosis, a common chronic disease affecting nearly 10% of reproductive-aged women, which can cause pelvic pain, infertility, and a myriad of other symptoms. Endometriosis has delayed time to diagnosis when compared to other chronic diseases, as there is no current accurate, easily accessible, and noninvasive tool for diagnosis. Specific miRNAs have been identified as potential biomarkers for this disease in multiple studies. These and other miRNAs have been linked to target genes and functional pathways in disease-specific pathophysiology. Highlighting investigations into the roles of tissue and circulating miRNAs in endometriosis, published through June 2018, this review summarizes new connections between miRNA expression and the pathophysiology of endometriosis, including impacts on fertility. Future applications of miRNA biomarkers for precision medicine in diagnosing and managing endometriosis treatment are also discussed.

Functional miRNA Screening Identifies Wide-ranging Antitumor Properties of miR-3622b-5p and Reveals a New Therapeutic Combination Strategy in Ovarian Tumor Organoids

Novel therapeutic strategies are urgently required for the clinical management of chemoresistant ovarian carcinoma, which is the most lethal of the gynecologic malignancies. miRNAs hold promise because they play a critical role in determining the cell phenotype by regulating several hundreds of targets, which could constitute vulnerabilities of cancer cells. A combination of gain-of-function miRNA screening and real-time continuous cell monitoring allows the identification of miRNAs with robust cytotoxic effects in chemoresistant ovarian cancer cells. Focusing on miR-3622b-5p, we show that it induces apoptosis in several ovarian cancer cell lines by both directly targeting Bcl-xL and EGFR-mediating BIM upregulation. miR-3622b-5p also sensitizes cells to cisplatin by inhibiting Bcl-xL in ovarian cancer cell lines escaping BIM induction. miR-3622b-5p also exerts antimigratory capacities by targeting both LIMK1 and NOTCH1. These wide-ranging antitumor properties of miR-3622b-5p in ovarian cancer cells are mimicked by the associations of pharmacologic inhibitors targeting these proteins. The combination of an EGFR inhibitor together with a BH3-mimetic molecule induced a large decrease in cell viability in a panel of ovarian cancer cell lines and several ovarian patient-derived tumor organoids, suggesting the value of pursuing such a combination therapy in ovarian carcinoma. Altogether, our work highlights the potential of phenotype-based miRNA screening approaches to identify lethal interactions which might lead to new drug combinations and clinically applicable strategies.

MiR-200a-3p promoted the malignant behaviors of ovarian cancer cells through regulating PCDH9

Background

Increasing evidence has revealed that the aberrant expression of microRNAs (miRNAs) plays vital roles in the development and progression of ovarian cancer. MiR-200a-3p was found to act as an oncogene in a variety of cancers, however, the expression and function of miR-200a-3p in ovarian cancer has not been characterized.

Materials and methods

The expression of miR-200a-3p in ovarian cancer tissues and cell lines was detected by the RT-qPCR. The influence of miR-200a-3p on the growth of ovarian cancer cells was determined with the Cell Counting Kit-8 assay, colony formation and cell invasion assay. The binding of miR-200a-3p with the 3ʹ-untranslated region (UTR) of PDCH9 was detected by luciferase reporter assay. The expression of PCDH9 was investigated by RT-qPCR and Western blot analysis.

Results

miR-200a-3p was up-regulated in ovarian cancer tissues and cell lines. Highly expressed miR-200a-3p was significantly associated with the tumor size, tumor metastasis and TNM stage. Overexpression of miR-200a-3p markedly promoted the proliferation, colony formation and invasion of ovarian cancer cells. Functional study uncovered that miR-200a-3p bound the 3ʹ-untranslated region (UTR) of PCDH9 and decreased the expression of PCDH9 in ovarian cancer cells. The expression of miR-200a-3p in ovarian cancer tissues was significantly negatively correlated with that of PCDH9. Restored PCDH9 inhibited the promoting effect of miR-200a-3p on the proliferation of ovarian cancer cells.

Conclusion

Our results suggested the potential oncogenic function of miR-200a-3p via modulating PCDH9 in ovarian cancer.

Ovarian Cancer: Differentially Expressed microRNAs in Tumor Tissue and Cell-Free Ascitic Fluid as Potential Novel Biomarkers

Ovarian cancer is the deadliest gynecologic cancer. The large-scale microRNA (miRNA) expression profiling and individual miRNA validation was performed to find potential novel biomarkers for ovarian cancer. The most consistent overexpression of miRs-200b-3p, 135 b-5p and 182-5p was found in both ascitic fluid and tumors and suggests their potential as oncogenes. miR-451a was consistently underexpressed so may be a tumor suppressor. Results were inconsistent for miR-204-5p, which was overexpressed in ascitic fluid but underexpressed in tumor tissue. miR-203a-3p was generally overexpressed but this failed to be proved in independent sample set in tissue validation.

miR-96-5p promotes the proliferation and migration of ovarian cancer cells by suppressing Caveolae1

BACKGROUND

Ovarian cancer (OC) is the second most common gynaecological malignancy. MicroRNAs (miRNAs) have been found to be aberrantly expressed in OC tissue and have been proposed as biomarkers and therapeutic targets for OC.

RESULTS

In this study, we found that miR-96-5p was up-regulated in OC tissues and OC cells compared to normal ovarian tissues and epithelial cell line. And, miR-96-5p was also up-regulated in the serum samples from OC patients compared to health participants. In addition, there was a positive correlation of miR-96-5p levels between OC tissues and serum samples. At the cellular level, overexpression of miR-96-5p promoted cell proliferation and migration in OC cells. Moreover, we further validated Caveolae1 (CAV1) as the direct target of miR-96-5p in OC cells through luciferase activity assays and western blot. CAV1 was obvious low expression in OC tissues. The overexpression of CAV1 abrogated the promotion of miR-96-5p on the OC cells proliferation and migration. Finally, we found that AKT signaling pathway was involved in this process. MiR-96-5p inhibited the phosphorylation of AKT and expression of down-stream proteins Cyclin D1 and P70 by targeting CAV1.

CONCLUSIONS

The above findings suggested that targeting miR-96-5p may be a promising strategy for OC treatment.

Pattern of cell-to-cell transfer of microRNA by gap junction and its effect on the proliferation of glioma cells

MicroRNA is expected to be a novel therapeutic tool for tumors. Gap junctions facilitate the transfer of microRNA, which exerts biological effects on tumor cells. However, the length of microRNA that can pass through certain gap junctions composed of specific connexin remains unknown. To address this question, the present study investigated the permeability of gap junctions composed of various connexins, including connexin 43, connexin 32 or connexin 37, to microRNAs consisting of 18-27 nucleotides in glioma cells and cervical cancer cells. Results indicated that all of the microRNAs were able to be transferred from donor glioma cells to neighboring cells through the connexin 43 composed gap junction, but not the gap junctions composed of connexin 32 or connexin 37, in cervical cancer cells. Downregulation of the function of gap junctions comprising connexin 43 by pharmacological inhibition and shRNA significantly decreased the transfer of these microRNAs. In contrast, gap junction enhancers and overexpression of connexin 43 effectively increased these transfers. In glioma cells, cell proliferation was inhibited by microRNA-34a. Additionally, these effects of microRNA-34a were significantly enhanced by overexpression of connexin 43 in U251 cells, indicating that gap junctions play an important role in the antitumor effect of microRNA by transfer of microRNA to neighboring cells. Our data are the first to clarify the pattern of microRNA transmission through gap junctions and provide novel insights to show that antitumor microRNAs should be combined with connexin 43 or a connexin 43 enhancer, not connexin 32 or connexin 37, in order to improve the therapeutic effect.

Clinical Implication of MicroRNAs in Molecular Pathology: An Update for 2018

MicroRNAs (miRNAs) are poised to provide diagnostic, prognostic, and therapeutic targets for several diseases including malignancies for precision medicine applications. The miRNAs have immense potential in the clinical arena because they can be detected in the blood, serum, tissues (fresh and formalin-fixed paraffin-embedded), and fine-needle aspirate specimens. The most attractive feature of miRNA-based therapy is that a single miRNA could be useful for targeting multiple genes that are deregulated in cancers, which can be further investigated through systems biology and network analysis that may provide cancer-specific personalized therapy.

Prognostic value of HE4 in patients with ovarian cancer

Background

There is no consensus in the medical community about the prognostic role of preoperative serum levels of human epididymis protein 4 (HE4) in ovarian cancer (OC). The purpose of this meta-analysis was to establish whether preoperative serum levels of HE4 are associated with OC prognosis.

Content

Eligible studies were searched for in PubMed, ClinicalTrials.gov, CNKI and Wanfang Med Online. We performed a meta-analysis of 1315 OC cases from 14 published articles.

Summary

Our meta-analysis demonstrated that high HE4 was associated with poor overall survival (OS) (random effects model, hazard ratio [HR]=1.91, 95% confidence interval [CI]=1.40–2.614, p<0.0001; I2=52%, p=0.04) and; progression-free survival (PFS) (random effects model, HR=1.38, 95% CI=1.13–1.69, p=0.002; I2=85%, p<0.00001). However, subgroup analysis showed that high HE4 was not associated with poor OS (fixed effects model, HR=1.86, 95% CI=0.89–3.89, p=0.1; I2=34%, p=0.22) or PFS (random effects model, HR=1.34, 95% CI=0.95–1.88, p=0.1; I2=69%, p=0.007) for studies including only Asian populations.

Outlook

In conclusion, this meta-analysis shows that high HE4 was associated with poor OC OS and PFS overall. However, the association of high HE4 with poor OS and PFS was not observed for Asians. Large-scale, multi-center investigations should be performed.