miR-15a-5p levels correlate with poor ovarian response in human follicular fluid

Evaluation of changes in exhausted T lymphocytes and miRNAs expression in the different trimesters of pregnancy in pregnant women

BACKGROUND

Throughout the three trimesters of a typical pregnancy, we looked at changes in the expression of miRNAs and exhausted T lymphocytes for this study.

METHODS AND RESULTS

Fifty healthy subjects were included in this study. The frequency of exhausted T lymphocytes was measured in isolated PBMCs using flow cytometry. PD-1, TIM-3, and related miRNAs gene expression were assessed using qRT-PCR. The analyses revealed a significant decline in PD-1 and Tim-3 expression in PBMCs from RPL women (p = 0.0003 and p = 0.001, respectively). In addition, PD-1 and TIM-3 expression increased significantly in the 2nd trimester compared with the 1st trimester of healthy pregnant women (p < 0.0001 and p = 0.0002, respectively). PD-1 and TIM-3 expression was down-regulated in the 3rd trimester compared with the 1st and 2nd trimesters. In the present study, we demonstrated that TIM-3+/CD4+, TIM-3+/CD8+, PD-1+/CD4+, and PD-1+/CD8 + exhausted T lymphocytes increased in the circulation of women in the 2nd trimester compared to the 1st and 3rd trimester. In the 3rd trimester, the expression of miR-16-5p increased significantly (p < 0.0001). miR-125a-3p expression was down and upregulated in 2nd (p < 0.0001) and 3rd (p = 0.0007) trimesters compared to 1st trimester, respectively. This study showed a significant elevation of miR-15a-5p in 3rd trimester compared to 1st trimester of pregnant women (p = 0.0002).

CONCLUSIONS

Expression pattern of PD-1 and TIM3 in exhausted T lymphocytes is different not only between normal pregnant and RPL women but also in different trimesters of pregnancy. So, our results showed the role of these markers in the modulation lymphocytes activity in different stages of pregnancy.

MicroRNAs in POI, DOR and POR

PURPOSE

Premature ovarian insufficiency (POI) is a clinical syndrome defined by loss of ovarian activity before the age of 40 years. However, the etiology of approximately 90% patients remains unknown. Diminished ovarian reserve (DOR) and poor ovarian response (POR) are related to POI in clinic. The main purpose of this review was to evaluate the roles of microRNAs (miRNAs) in the pathogenesis and therapeutic potential for POI, DOR and POR.

METHODS

A literature search was conducted using six databases (PubMed, EMBASE, Web of Science, Cochrane Library, CNKI and Wangfang Data) to obtain relevant studies.

RESULTS

This review enlightens expression profiles and functional studies of miRNAs in ovarian insufficiency in animal models and humans. Functional studies emphasized the role of miRNAs in steroidogenesis, granulosa cell proliferation/apoptosis, autophagy and follicular development by regulating target genes in specific pathways, such as the PI3K/AKT/mTOR, TGFβ, MAPK and Hippo pathways. Differentially expressed circulating miRNAs provided novel biomarkers for diagnosis and prediction, such as miR-22-3p and miR-21. Moreover, exosomes derived from stem cells restored ovarian function through miRNAs in chemotherapy-induced POI models.

CONCLUSION

Differential miRNA expression profiles in patients and animal models uncovered the underlying mechanisms and biomarkers of ovarian insufficiency. Exosomal miRNAs can restore ovarian function against chemotherapy-induced POI, which needs further investigation to develop novel preventive and therapeutic strategies in clinical practice.

Mechanisms of ovarian aging in women: a review

Ovarian aging is a natural and physiological aging process characterized by loss of quantity and quality of oocyte or follicular pool. As it is generally accepted that women are born with a finite follicle pool that will go through constant decline without renewing, which, together with decreased oocyte quality, makes a severe situation for women who is of advanced age but desperate for a healthy baby. The aim of our review was to investigate mechanisms leading to ovarian aging by discussing both extra- and intra- ovarian factors and to identify genetic characteristics of ovarian aging. The mechanisms were identified as both extra-ovarian alternation of hypothalamic-pituitary-ovarian axis and intra-ovarian alternation of ovary itself, including telomere, mitochondria, oxidative stress, DNA damage, protein homeostasis, aneuploidy, apoptosis and autophagy. Moreover, here we reviewed related Genome-wide association studies (GWAS studies) from 2009 to 2021 and next generation sequencing (NGS) studies of primary ovarian insufficiency (POI) in order to describe genetic characteristics of ovarian aging. It is reasonable to wish more reliable anti-aging interventions for ovarian aging as the exploration of mechanisms and genetics being progressing.

Melatonin suppresses serum starvation-induced autophagy of ovarian granulosa cells in premature ovarian insufficiency

OBJECTIVES

Premature ovarian insufficiency (POI) refers to the decline and cessation of ovarian functions in women under 40 years of age. Melatonin (MT) acts as a protective for the ovary. This study elucidated the role of MT in autophagy of granulosa cells (GCs) in POI via modulating the phosphatidylinositol-3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) pathway.

METHODS

The expression levels of microRNA (miR)-15a-5p, signal transducer and activator of transcription 3 (Stat3), and relevant hormones in the clinically collected serum samples of POI patients and healthy controls were examined. Human ovarian granulosa-like tumor cells (KGN) underwent serum starvation (SS) treatment to induce POI cell models and then received MT treatment. The expression levels of miR-15a-5p, Stat3, p-PI3K/PI3K, p-Akt/Akt, and p-mTOR/mTOR in KGN cells were tested via quantitative real-time polymerase chain reaction and Western blotting. KGN cell viability was assessed by MTT assay and the protein levels of autophagy-related markers Beclin-1, microtubule-associated protein light chain 3 II/I, and p62 were detected by Western blotting. The binding relation between miR-15a-5p and Stat3 was verified via the dual-luciferase reporter gene assay. Functional rescue experiments were performed to probe the underlying role of miR-15a-5p/Stat3/the PI3K-Akt-mTOR pathway in KGN cell autophagy.

RESULTS

miR-15a-5p was increased whilst Stat3 was decreased in the serum of POI patients and SS-induced KGN cells. MT inhibited miR-15a-5p and Stat3, activated the PI3K-Akt-mTOR pathway, and repressed cell autophagy in SS-induced KGN cells. miR-15a-5p targeted and repressed Stat3 expression. Upregulation of miR-15a-5p or downregulation of Stat3 or the PI3K-Akt-mTOR pathway promoted KGN cell autophagy.

CONCLUSION

MT suppressed miR-15a-5p and activated Stat3 and the PI3K-Akt-mTOR pathway, finally impeding SS-induced autophagy of GCs.

Characterization of circular RNA profiles of oviduct reveal the potential mechanism in prolificacy trait of goat in the estrus cycle

The mammalian oviduct is functionally highly diverse during the estrus cycle. It provides a suitable milieu for oocyte maturation, sperm capacitation, fertilization, early embryo development and transportation. While there have been many studies of molecular mechanisms on the kidding number of goats, a systematic analysis by which the underlying circular RNAs (circRNAs) changes in the oviduct related to prolificacy traits is lacking. Herein, we present a comprehensive circRNA atlas of the oviduct among high- and low-fecundity goats in the follicular phase (FH vs. FL), luteal phase (LH vs. LL), and estrus cycle (FH vs. LH; FL vs. LL) to unravel their potential regulatory mechanisms in improving kidding number. We generated RNA sequencing data, and identified 4,078 circRNAs from twenty sampled Yunshang black goats. Many of these circRNAs are exon-derived and differentially expressed between each comparison group. Subsequently, eight differentially expressed (DE) circRNAs were validated by RT‒qPCR, which was consistent with the RNA-seq data. GO and KEGG enrichment analyses suggested that numerous host genes of DE circRNAs were involved in the hormone secretion, gamete production, fertilization, and embryo development processes. The competing endogenous RNA (ceRNA) interaction network analysis revealed that 2,673 circRNA–miRNA–mRNA axes (including 15 DE circRNAs, 14 miRNAs, and 1,699 mRNAs) were formed, and several target genes derived from the ceRNA network were associated with oviduct functions and reproduction, including SMAD1, BMPR1B, IGF1, REV1, and BMP2K. Furthermore, miR-15a-5p, miR-181b-5p, miR-23b-5p, miR-204-3p, and miR-145-5p might play important roles in reproduction. Finally, a novel circRNA, circIQCG, was identified as potentially involved in embryo development. Overall, our study provides a resource of circRNAs to understand the oviductal function and its connection to prolificacy trait of goats in the differentiation estrus cycle.

Poor ovarian response is associated with air pollutants: A multicentre study in China

Background

Human evidence on the association between air pollution and ovarian response is scarce. Poor ovarian response (POR) with an incidence of 5–35% is a tricky problem in IVF treatment.

Methods

In this large-scale multicentre study, we included 2186 women with POR (< 4 oocytes retrieved) and 7033 women with a normal ovarian response (10–15 oocytes retrieved), who underwent their first in vitro fertilization treatment in five cities in northern China during 2015–2020. Average concentrations of six air pollutants (PM_2.5, PM₁₀, O₃, NO₂, CO, and SO₂) during different exposure windows (5 days, 1, 3, 6, and 12 months) before oocyte pick up (OPU) were calculated using data from the air monitoring station nearest to the residential site as approximate individual exposure. Logistic regression models were employed to assess the association between exposure to air pollutants and the risk of POR. Stratification analyses were conducted based on female age. Sensitivity analyses were performed in poor responders identified by Bologna criteria and women with unexpected POR.

Findings

We detected that increased SO₂ exposure during all exposure windows before OPU was associated with a higher risk of POR, especially for women ≤ 30 years old. In the stratified analysis, the effect sizes were larger for the unexpected poor ovarian response.

Interpretation

The findings provide human evidence for adverse effects of exposure to ambient air pollutants on ovarian response and underscore the need to reduce ambient air pollution exposure in women of reproductive age to protect human fertility.

Funding

This study was granted from the National Key Research and Development Program (2018YFC1004203), the Major Special Construction Plan for Discipline Construction Project of China Medical University (3110118033), the Shengjing Freelance Researcher Plan of Shengjing Hospital of China Medical University, and the National Natural Science Foundation of China (82071601), the Central Government Special Fund for Local Science and Technology Development (2020JH6/10500006).

Age-related miRNome landscape of cumulus oophorus cells during controlled ovarian stimulation protocols in IVF cycles

STUDY QUESTION

Is the microRNA (miRNA) expression pattern of cumulus oophorus cells (COCs) in women undergoing medically assisted reproduction (MAR) procedures differentially modulated according to patient age and gonadotropin treatment strategy?

SUMMARY ANSWER

Maternal age is an independent factor impacting miRNA expression in COCs while gonadotropin treatment may affect follicular miRNA expression and IVF efficacy.

WHAT IS KNOWN ALREADY

Epigenetic mechanisms in female infertility are complex and poorly studied. DNA methylation, histone modifications, miRNAs and nucleosome positioning influence cellular machinery through positive and negative feedback mechanisms either alone or interactively. miRNAs are important regulators during oogenesis, spermatogenesis and early embryogenesis, and are reported to play a role in regulating crosstalk between the oocyte and COCs. Although miRNome analysis has been performed in female human reproductive tissues (endometrium, myometrium, cervix and ovaries), epigenetic modifications in women with infertility have not been explored in detail. In addition, the impact of gonadotropin treatments during MAR on miRNA expression in COCs has not been fully investigated.

STUDY DESIGN, SIZE, DURATION

This study was carried out in 53 COC samples obtained from mature metaphase II (MII) oocytes in 53 women undergoing MAR treatment. A total of 38 samples for assay development were pooled by maternal age and gonadotropin treatment into four predetermined subgroups: ≥36 years and recombinant human FSH (r-hFSH), n = 10; ≥36 years and r-hFSH+ recombinant human-luteinizing hormone (r-hLH), n = 10; ≤35 years and r-hFSH, n = 9; ≤35 years and r-hFSH+r-hLH, n = 9. miRNome profiles were determined and compared between subgroups. Expression of defined miRNAs was validated in the remaining fifteen samples, representative of each subgroup, by quantitative polymerase chain reaction (PCR).

PARTICIPANTS/MATERIALS, SETTING, METHODS

COCs were processed for miRNA-enriched total RNA extraction and pooled in homogeneous subgroups to obtain a sufficient amount and quality of starting material to perform the analysis. Each pooled sample underwent miRNA profiling using PCR assay system to examine expression of 752 human miRNAs without pre-amplification. Data were analyzed using the delta-delta Ct method for relative quantitation and prediction of target genes (with at least four algorithms predicting the same miRNA-gene interaction pair (HIT)>4). The miRSystem database provided functional annotation enrichment (raw P-value <0.05) of co-expressed miRNAs.

MAIN RESULTS AND THE ROLE OF CHANCE

We found distinctive miRNA expression profiles in each subgroup correlating with age and MAR stimulation. In addition, a number of selective and co-expressed miRNAs were revealed by comparative analysis. A cluster of 37 miRNAs were commonly but differentially expressed in all four pools. Significant differences were observed in expression regulation of 37 miRNAs between age groups (≤35 or ≥36) in women receiving r-hFSH+r-hLH compared to those receiving r-hFSH alone. Higher concentrations and increased numbers of miRNAs were recorded in younger than in older patients, regardless of treatment. Functional and expression studies performed to retrieve common miRNome profiles revealed an enrichment of biological functions in oocyte growth and maturation, embryo development, steroidogenesis, ovarian hyperstimulation, apoptosis and cell survival, glucagon and lipid metabolism, and cell trafficking. The highest scored pathways of target genes of the 37 common miRNAs were associated with mitogen-activated protein kinase (MAPK) signaling pathways, G alpha signaling, transcription regulation, tight junctions, RNA polymerase I and III, and mitochondrial transcription. We identified a potential age- and MAR stimulation-dependent signature in the miRNA landscape of COCs.

LIMITATIONS, REASONS FOR CAUTION

We cannot rule out the possibility that other unknown individual genetic or clinical factors may have interfered with the reported results. Since miRNA profiling was conducted with a predefined array of target probes, other miRNA molecules, potentially modulated by age and hormonal stimulation, may have been missed in this study.

WIDER IMPLICATIONS OF THE FINDINGS

miRNA expression in COCs is modulated by gonadotropin treatment and correlates strongly with age. A better understanding of the expression patterns and functions of miRNAs may lead to the development of novel therapeutics to treat ovarian dysfunction and improve fertility in older women.

STUDY FUNDING/COMPETING INTEREST

This study was funded by Merck KGaA, Darmstadt, Germany. All authors declared no competing interest, except SL and TD who are fully employed by Merck KGaA.

TRIAL REGISTRATION NUMBER

N/A

Transcriptional changes of mouse ovary during follicle initial or cyclic recruitment mediated by extra hormone treatment

AIMS

Folliculogenesis contains gonadotropin-independent and -dependent stage. Disruption in any of this process would induce failure in retrieving capable oocytes during clinical treatment. However, there is still limited understanding of the molecular components specifically regulating this process.

MATERIAL AND METHODS

Ovaries of P3, P20 and exogenous gonadotropin-treated P22 mice were sampled and underwent RNA-seq to investigate the transcriptome variance during mouse folliculogenesis.

KEY FINDINGS

In our dataset, 1883 and 626 DEGs were captured for each stage respectively, which were further clustered into eight expression patterns. Pathway enrichment analysis identified distinct biological processes enriched in two stages, with the most prominent being the pathways related to metabolism, gene expression, cell cycle, immune system and DNA methylation. Transcriptional regulator inference yielded eight master transcription factors (i.e. Runx1, Stat3, Sox3, Pou5f1, Gata4, Foxl2, Cebpb, and Esr1) driving folliculogenesis.

SIGNIFICANCE

Our study revealed the temporal transcriptional reprogramming and gene expression dynamics during folliculogenesis mediated by extra hormone treatment, which could provide novel insights to controlled ovarian stimulation in future infertility treatment.

MicroRNA-15a-5p promotes the proliferation and invasion of T98G glioblastoma cells via targeting cell adhesion molecule 1

Glioblastoma (GBM) is a type of malignant tumor occurring in the brain that severely influences the life of affected individuals. GBM cells are highly infiltrative, which is one of the main obstacles in the treatment of the disease. Numerous microRNAs (miRNAs/miRs) are associated with the development of GBM. However, the effects of miR-15a-5p on GBM remain elusive. In the present study, reverse transcription-quantitative PCR and western blot analysis were applied for the detection of RNA and protein levels, respectively. Cell Counting Kit-8 and Transwell assays were performed to examine cell proliferation and invasion, respectively. TargetScan 7.1 and dual-luciferase reporter assay were utilized for the prediction and verification of the association between miRNAs and mRNAs. The present study revealed that miR-15a-5p expression was upregulated in the GBM T98G cell line. The results further demonstrated that, through the inhibition of cell adhesion molecule 1 expression and the promotion of Akt phosphorylation, miR-15a-5p was able to promote GBM cell proliferation and invasion. Overall, the present findings revealed a novel mechanism responsible for the development of GBM and provided an experimental basis for the diagnosis and treatment of GBM.

Transfer of miR-15a-5p by placental exosomes promotes pre-eclampsia progression by regulating PI3K/AKT signaling pathway via CDK1

Preeclampsia (PE) is a systemic complication that occurs after the 20th week of gestation and is characterized by the onset of hypertension and proteinuria. Dysregulated circulating microRNA (miRNA) has usually been noted in PE. Understanding the release profile and bioactivity of placental exosomes is a promising mode of identifying dysregulated miRNA, which may be useful biomarkers of PE. Herein, we aimed to investigate the role of placental exosomes and their miRNA cargo miR-15a-5p in PE. miR-15a-5p was found upregulated in exosomes isolated from maternal plasma of PE pregnant women as compared to those from normal pregnant women. Placental exosomes derived from PE pregnant women suppressed the proliferation and invasion of HTR-8/SVneo cells but promoted cell apoptosis, which was dictated by their cargo miR-15a-5p. Further investigation showed that exosomal miR-15a-5p inhibited the activation of the PI3K/AKT pathway by down-regulating CDK1, thus suppressing HTR-8/SVneo cell proliferation, invasion, and apoptosis. In vivo analysis demonstrated that placental exosomes treated with miR-15a-5p inhibitor attenuated histopathologic changes and apoptosis in the placenta of PE mice. In conclusion, these results provided evidence that transfer of miR-15a-5p by placental exosomes could be a promising therapeutic target to combat PE.

Extracellular microRNA profiling in human follicular fluid: new biomarkers in female reproductive potential

MicroRNAs (miRNAs) are small, about 22 nucleotides, non-coding RNAs which regulate a wide range of gene expression during post-transcriptional stage. They are released into intra- and extracellular microenvironments and play vital roles in different physiological and pathological pathways. Due to easy accessibility, detection of extracellular miRNAs in body fluids, e.g. serum, plasma, cerebrospinal fluid, and follicular fluid, has been explored in recent years. Since miRNAs are stable at unsuitable conditions, scientists have been investigating to use them as biomarkers in different fields of medicines. It goes without saying that experienced biomarkers would be required in reproductive medicine as well. Biomarkers can help clinicians and embryologists to diagnose disorders and assess the embryo quality via molecular pattern which is more reliable than nowadays routine methods. Follicular fluid as a noninvasive fluid in assisted reproductive techniques (ART) has attracted researchers as a rich pool for biomarkers, and miRNAs are not exception. Although miRNA biomarkers in reproduction field are located on their initial stage and there is a long path to move forward, several meticulous studies have been performed and discovered their associations with various conditions. In this regard, we summarize the reported miRNAs in follicular fluid and their correlations with female infertility and ART success rate, while subsequent investigations are required.

Serum microRNA profiling for the identification of predictive molecular markers of the response to controlled ovarian stimulation

Objective

To identify potential microRNA (miRNA) biomarkers of poor, normal and hyperresponse to controlled ovarian stimulation (COS).

Methods

In the present study, we assessed 40 serum samples from patients undergoing COS. We used ten samples to standardize miRNAs detection in the serum. The remaining 30 samples were split into three groups depending on the patient's response to COS: poor response (PR group, n=10), normal response (NR group, n=10), and hyperresponse (HR group, n=10). Aberrantly expressed miRNAs were identified using a large-scale expression analysis platform. Gene set enrichment analysis was performed to assess the biological processes potentially modulated by the identified miRNAs.

Results

Twenty-two miRNAs were detected only in the PR or HR groups when compared with the NR group. From those, 11 presented poor dissociation curves and were excluded from further analysis. A bioinformatics analysis revealed that the selected 11 miRNAs target several genes involved in GnRH, estrogen and prolactin signaling, oocyte maturation, female pregnancy, and meiosis.

Conclusion

The large-scale analysis of miRNA expression identified distinct miRNA profiles for poor and hyperresponse to COS, which potentially modulate key processes for human assisted reproduction. All evidence suggests that the serum microRNA profiling may discriminate patients who will respond in an exacerbated manner from those who will respond insufficiently to COS. Further studies may validate these miRNAs, enabling the individualization of treatment and more successful outcomes.

MicroRNAs in combined spent culture media and sperm are associated with embryo quality and pregnancy outcome

OBJECTIVE

To identify differentially abundant miRNAs in sperm samples and spent culture media (SCM) of embryos of different grade toward a prediction of pregnancy outcome.

DESIGN

Array-based reverse-transcription quantitative polymerase chain reaction profiling and validation.

SETTING

University research institute and in vitro fertilization center.

PATIENT(S)

Couples (n = 61) undergoing infertility treatment with the use of intracytoplasmic sperm injection.

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

Abundance levels of miRNAs in combined SCM of embryos of different quality and in sperm samples associated with pregnancy outcome.

RESULT(S)

Out of 372 screened miRNAs, miR-19b-3p and let-7a-5p were detected consistently in all SCM and sperm samples. The abundance levels of miRNAs were significantly altered between SCM of embryos with different quality (G1, G2, and G3 grades). Specifically, miR-320a and miR-15a-5p were differentially abundant in G1 vs. G2, miR-21-5p in G1 vs. G3, and miR-20a-5p in G2 vs. G3. The abundance levels of combined SCM and sperm derived miRNAs were also significantly altered between different pregnancy outcomes. MiR-19b-3p showed the highest area under the receiver operating characteristic curve values between positive and negative outcomes, with lower abundance levels in both combined SCM and sperm samples associated with a positive pregnancy outcome. MiR-320a, miR-15a-5p, miR-21-5p, and miR-20a-5p showed similar results in combined SCM samples.

CONCLUSION(S)

miRNA abundance levels in combined SCM and sperm differed significantly depending on embryo quality and pregnancy outcome. MiR-19b-3p may serve as a potential biomarker to predict pregnancy outcome.

Reporting on the Role of miRNAs and Affected Pathways on the Molecular Backbone of Ovarian Insufficiency: A Systematic Review and Critical Analysis Mapping of Future Research

Ovarian insufficiency is identified as a perplexing entity in the long list of pathologies impairing fertility dynamics. The three distinct classifications of ovarian insufficiency are poor ovarian response, premature ovarian insufficiency/failure, and advanced maternal age, sharing the common denominator of deteriorated ovarian reserve. Despite efforts to define clear lines among the three, the vast heterogeneity and overlap of clinical characteristics renders their diagnosis and management challenging. Lack of a consensus has prompted an empirically based management coupled by uncertainty from the clinicians' perspective. Profiling of patients in the era of precision medicine seems to be the way forward, while the necessity for a novel approach is underlined. Implicating miRNAs in the quest for patient profiling is promising in light of their fundamental role in cellular and gene expression regulation. To this end, the current study sets out to explore and compare the three pathophysiologies-from a molecular point of view-in order to enable profiling of patients in the context of in vitro fertilization treatment and enrich the data required to practice individualized medicine. Following a systematic investigation of literature, data referring to miRNAs were collected for each patient category based on five included studies. miRNA-target pairs were retrieved from the DIANA-TarBase repository and microT-CDS. Gene and miRNA annotations were derived from Ensembl and miRbase. A subsequent gene-set enrichment analysis of miRNA targets was performed for each category separately. A literature review on the most crucial of the detected pathways was performed to reveal their relevance to fertility deterioration. Results supported that all three pathophysiologies share a common ground regarding the affected pathways, naturally attributed to the common denominator of ovarian insufficiency. As evidenced, miRNAs could be employed to explore the fine lines and diverse nature of pathophysiology since they constitute invaluable biomarkers. Interestingly, it is the differentiation through miRNAs and not through the molecular affected pathways that corresponds to the three distinctive categories. Alarming discrepancies among publications were revealed, pertaining to employment of empirical and arbitrary criteria in categorizing the patients. Following bioinformatic analysis, the final step of the current study consisted of a critical analysis of the molecular data sourced, providing a clear and unique insight into the physiological mechanisms involved. It is our intention to contribute to mapping future research dedicated to ovarian insufficiency and to help researchers navigate the overwhelming information published in molecular studies.

Identification of the lncRNA-miRNA-mRNA network associated with gastric cancer via integrated bioinformatics analysis

The aim of the present study was to investigate the long non-coding RNA (lncRNA)-microRNA (miRNA)-mRNA regulatory network in gastric cancer (GC) using bioinformatics analysis. Two mRNA gene expression profiles, GSE79973 and GSE54129, and two miRNA expression profiles, GSE93415 and GSE78091, were downloaded from the Gene Expression Omnibus database. The differentially expressed mRNAs (DEMs) and the differentially expressed miRNAs (DEMis) were merged separately. Gene ontology and pathway enrichment analysis were conducted using the Database for Annotation, Visualization and Integrated Discovery. A protein-protein interaction (PPI) network was then constructed and the 10 top hub genes in the network were analyzed using the Search Tool for the Retrieval of Interacting Genes. The lncRNA-miRNA-mRNA networks were visualized using Cytoscape software. As a result, 158 shared DEMs (40 upregulated and 118 downregulated) were identified from two mRNA datasets. A total of 30 upregulated miRNAs and 1 downregulated miRNA functioned as DEMis. The PPI network consisted of 129 nodes and 572 interactions. The 10 top hub genes were selected by degree using Cytohubba, including Jun proto-oncogene, mitogen-activated protein kinase (MAPK)3, transforming growth factor-β1, Fos proto-oncogene, AP-1 transcription factor subunit, interleukin (IL)-8, MAPK1, RELA proto-oncogene nuclear factor-κB subunit, interferon regulatory factor 7, ubiquitin like modifier and vascular endothelial growth factor A. In the lncRNA-miRNA-mRNA network, a total of 1,215 regulatory associations were constructed using Cytoscape. In conclusion, the present study provides a novel perspective of the molecular mechanisms underlying GC by identifying the lncRNA-miRNA-mRNA regulatory network via bioinformatics analysis.