CircASPH promotes KGN cells proliferation through miR-375/MAP2K6 axis in Polycystic Ovary Syndrome

Biomarker potential of competing endogenous RNA networks in Polycystic Ovary Syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is the most common condition affecting women of reproductive age globally. PCOS continues to be the largest contributing factor to female infertility despite significant progress in our knowledge of the molecular underpinnings and treatment of the condition. The fact that PCOS is a very diverse condition makes it one of the key reasons why we haven't been able to overcome it. Non-coding RNAs (ncRNAs) are implicated in the development of PCOS, according to growing evidence. However, it is unclear how the complex regulatory relationships between the many ncRNA types contribute to the growth of this malignancy. Competing endogenous RNA (ceRNA), a recently identified mechanism in the RNA world, suggests regulatory interactions between various RNAs, including long non-coding RNAs (lncRNAs), microRNAs (miRNAs), transcribed pseudogenes, and circular RNAs (circRNAs). Recent studies on PCOS have shown that dysregulation of multiple ceRNA networks (ceRNETs) between these ncRNAs plays crucial roles in developing the defining characteristics of PCOS development. And it is believed that such a finding may open a new door for a deeper comprehension of PCOS's unexplored facets. In addition, it may be able to provide fresh biomarkers and effective therapy targets for PCOS. This review will go over the body of information that exists about the primary roles of ceRNETs before highlighting the developing involvement of several newly found ceRNETs in a number of PCOS characteristics.

CircRAB11A act as miR-24-5p sponge promotes proliferation and resists apoptosis of chicken granulosa cell via EGFR/ERK1/2 and RAB11A/ PI3K/AKT pathways

Circular RNAs (circRNAs) are a class of endogenous non-coding RNAs that have been implicated in mediating granulosa cell (GC) proliferation and apoptosis. CircRAB11A was found to have a significantly higher expression in normal follicles compared to atrophic follicles. In this study, we determined that the knockdown of circRAB11A resulted in the inhibition of proliferation and promotion of apoptosis in GCs of chicken. Moreover, circRAB11A was found to act as a sponge for miR-24-5p, both member RAS oncogene family (RAB11A) and epidermal growth factor receptor (EGFR) were revealed to be targets of miR-24-5p through a dual-luciferase reporter assay. RAB11A or EGFR promoted proliferation and suppressed apoptosis in GCs through the phosphatidylinositol-kinase (PI3K)/AKT or extracellular signal-regulated kinase (ERK)1/2 pathway. These findings suggest that circRAB11A may function as a competing endogenous RNA (ceRNA) by targeting the miR-24-5p/RAB11A and miR-24-5p/EGFR axes and activating the ERK1/2 and PI3K/AKT pathways, offering a potential avenue for exploring the mechanism of follicle development.

Role of circular RNA/miRNA axes in the pathophysiology of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a disorder resulted from interactions between genetic and environmental factors. Based on the importance of epigenetic factors in the pathoetiology of PCOS, the current review focused on identification of circular RNAs (circRNAs) that are involved in PCOS through acting as molecular sponges for microRNAs (miRNAs). The literature search led to identification of circ_0043533/miR-1179, circ_0030018/miR-136, circ_FURIN/miR-423-5p, circ-FURIN/miR-195-5p, circ_0043532/miR-182, circ_RANBP9/miR-136-5p, circRHBG/miR-515-5p, circMTO1/miR-320b, circASPH/miR-375, circPSMC3/miR-296-3p, circLDLR/miR-1294, circPUM1/miR-760, and hsa_circ_0118530/miR-136 as molecular axes contributing to the pathogenesis of PCOS. To set the stage for future research on the role of the ceRNA network in PCOS, in-silico analyses were performed using miRWalk, miRNet, and miRDIP databases. miRWalk identified 80 genes regulated by 5 miRNAs, miRNet revealed 6449 circRNAs potentially controlling 11 miRNAs, and miRDIP identified 11 miRNAs associated with 35 human pathways. These targets can be used in the treatment options, design of personalized medicine and prediction of prognosis of PCOS.

The Role of MicroRNA, Long Non-Coding RNA and Circular RNA in the Pathogenesis of Polycystic Ovary Syndrome: A Literature Review

Polycystic ovary syndrome (PCOS) is the most common endocrine-metabolic disease in females of reproductive age, affecting 4-20% of pre-menopausal women worldwide. MicroRNAs (miRNAs) are endogenous, single-stranded, non-coding, regulatory ribonucleic acid molecules found in eukaryotic cells. Abnormal miRNA expression has been associated with several diseases and could possibly explain their underlying pathophysiology. MiRNAs have been extensively studied for their potential diagnostic, prognostic, and therapeutic uses in many diseases, such as type 2 diabetes, obesity, cardiovascular disease, PCOS, and endometriosis. In women with PCOS, miRNAs were found to be abnormally expressed in theca cells, follicular fluid, granulosa cells, peripheral blood leukocytes, serum, and adipose tissue when compared to those without PCOS, making miRNAs a useful potential biomarker for the disease. Key pathways involved in PCOS, such as folliculogenesis, steroidogenesis, and cellular adhesion, are regulated by miRNA. This also highlights their importance as potential prognostic markers. In addition, recent evidence suggests a role for miRNAs in regulating the circadian rhythm (CR). CR is crucial for regulating reproduction through the various functions of the hypothalamic-pituitary-gonadal (HPG) axis and the ovaries. A disordered CR affects reproductive outcomes by inducing insulin resistance, oxidative stress, and systemic inflammation. Moreover, miRNAs were demonstrated to interact with lncRNA and circRNAs, which are thought to play a role in the pathogenesis of PCOS. This review discusses what is currently understood about miRNAs in PCOS, the cellular pathways involved, and their potential role as biomarkers and therapeutic targets.

Circular RNAs: Emerging Modulators in the Pathophysiology of Polycystic Ovary Syndrome and their Clinical Implications

Polycystic ovary syndrome (PCOS) is a prevalent endocrine/metabolic disorder in women of reproductive age. PCOS is characterized by hyperandrogenism, polycystic ovary morphology, and ovulatory dysfunction/anovulation. It involves multiple effects in patients, including granulosa/theca cell hyperplasia, menstrual disturbances, infertility, acne, obesity, insulin resistance, and cardiovascular disorders. Biochemical analyses and the results of RNA sequencing studies in recent years have shown a type of non-coding RNAs as a splicing product known as circular RNAs (circRNAs). Several biological functions have been identified in relation to circRNAs, including a role in miRNA sponge, protein sequestration, increased parental gene expression, and translation leading to polypeptides. These circular molecules are more plentiful and specialized than other types of RNAs. For this reason, they are referred to as potential biomarkers in different diseases. Evidence suggests that circRNAs may have regulatory potentials through different signaling pathways, such as the miRNA network. Probably most experts in the field of obstetricians are not aware of circRNAs as a useful biomarker. Therefore, this review focused on the researches that have been done on the involvement of circRNAs in PCOS and summarized recent supportive evidence, and evaluated the circRNA association and mechanisms involved in PCOS.

CircASPH Enhances Exosomal STING to Facilitate M2 Macrophage Polarization in Colorectal Cancer

Exosomes are considered a mediator of communication within the tumor microenvironment (TME), which modulates cancer progression through transmitting cargos between cancer cells and other cancer-related cells in TME. Circular RNAs (circRNAs) have emerged to be regulators in colorectal cancer (CRC) progression, but most of them have not been discussed in CRC. This study aims to investigate the role of circRNA aspartate beta-hydroxylase (circASPH) in CRC progression and its correlation with exosome-mediated TME. At first, we determined that circASPH was upregulated in CRC samples and cell lines. Functionally, the circASPH deficiency suppressed the malignant processes of CRC cells and also inhibited in vivo tumor growth via enhancing antitumor immunity. Mechanically, circASPH facilitated macrophage M2 polarization by upregulating exosomal stimulator of interferon genes (STING). CircASPH interacted with insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2) to stabilize IGF2BP2 protein, therefore enhancing the stability of m6A-modified STING mRNA. In turn, coculture of STING-overexpressed macrophages recovered the suppression of silenced circASPH on the malignancy of CRC cells both in vitro and in vivo. Our study demonstrated that circASPH enhances exosomal STING to facilitate M2 macrophage polarization, which further accelerates CRC progression. The findings support circASPH as a promising therapeutic target for CRC treatment.

hsa_circRNA_BECN1 acts as a ceRNA to promote polycystic ovary syndrome progression by sponging the miR-619-5p/Rab5b axis

Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disease that affects women of reproductive age. It is also a significant cause of infertility. Circular RNAs have been found to have a crucial role in the development and progression of reproductive system diseases. In this study, we focused on circ_BECN1 and aimed to investigate its role and mechanism in PCOS, providing a foundation for early diagnosis and treatment of this condition. Our findings revealed an upregulation of circ_BECN1 expression in the ovarian granulosa cells (GCs) of PCOS patients. Additionally, the silencing of circ_BECN1 resulted in inhibited proliferation and enhanced apoptosis of the human ovarian granulosa-like tumor cell line (KGN), therefore implicating circ_BECN1 in the cell cycle process. Through a dual-luciferase reporting assay, we determined that circ_BECN1 acts as a sponge for miR-619-5p and that Rab5b is the target gene of miR-619-5p. Moreover, the expression of Rab5b was found to be upregulated in the ovarian tissue of PCOS patients. Knocking down circ_BECN1 resulted in decreased Rab5b expression, which was then restored by using a miR-619-5p inhibitor. Additionally, rescue experiments demonstrated that overexpressing Rab5b reversed the effects of circ_BECN1 knockdown on cell proliferation and apoptosis in KGN cells. In summary, our findings indicate that circ_BECN1 is upregulated in PCOS GCs and promotes cell growth and cell cycle progression, and reduces cell apoptosis by modulating the miR-619-5p/Rab5b axis. Therefore, circ_BECN1 may serve as a potential therapeutic target for PCOS treatment.

Circ_0115118 regulates endometrial functions through the miR-138-1-3p/WDFY2 axis in patients with PCOS†

To investigate the expression profiles of circular RNAs (circRNAs) in the endometria of women with polycystic ovary syndrome (PCOS) and to explore the role of aberrant circ_0115118 expression in endometrial dysfunction in patients with PCOS. CircRNA microarray hybridization and bioinformatic analyses were performed to determine the expression patterns of circRNAs in the endometria of patients with or without PCOS, the expression of target circRNA was evaluated by real-time polymerase chain reaction (PCR). Cell counting kit-8 and Transwell assays were used to detect cellular proliferative, invasive, and migratory capacities. The influence of the circRNA on decidualization was explored by real-time PCR. Animal models were established to investigate the regulatory effect of the circRNA on embryo implantation. Downstream microRNAs and genes were predicted using bioinformatic websites and verified by dual-luciferase reporter assays, real-time PCR, and western blotting. In the endometria of patients with PCOS, there were 113 differentially expressed circRNAs in the secretory phase and 1119 differentially expressed circRNAs in the proliferative phase. The expression of circ_0115118 was significantly higher in endometrial stromal cells during the proliferative phase in patients with PCOS, leading to inhibition of cellular mobilization and embryo implantation. In addition, circ_0115118 exerted effects by sponging miR-138-1-3p, subsequently increasing the expression of WD repeat and FYVE domain-containing protein 2 (WDFY2). Circ_0115118 expression is dysregulated in the endometria of patients with PCOS and adversely affects endometrial function. Our findings reveal that circ_0115118 may be a potential therapeutic target to improve pregnancy outcomes in women with PCOS.

Multi-omics insights and therapeutic implications in polycystic ovary syndrome: a review

Polycystic ovary syndrome (PCOS) is a common gynecological disease that causes adverse effects in women in their reproductive phase. Nonetheless, the molecular mechanisms remain unclear. Over the last decade, sequencing and omics approaches have advanced at an increased pace. Omics initiatives have come to the forefront of biomedical research by presenting the significance of biological functions and processes. Thus, multi-omics profiling has yielded important insights into understanding the biology of PCOS by identifying potential biomarkers and therapeutic targets. Multi-omics platforms provide high-throughput data to leverage the molecular mechanisms and pathways involving genetic alteration, epigenetic regulation, transcriptional regulation, protein interaction, and metabolic alterations in PCOS. The purpose of this review is to outline the prospects of multi-omics technologies in PCOS research by revealing novel biomarkers and therapeutic targets. Finally, we address the knowledge gaps and emerging treatment strategies for the management of PCOS. Future PCOS research in multi-omics at the single-cell level may enhance diagnostic and treatment options.

Circ_0005925 Promotes Granulosa Cell Growth by Targeting MiR-324-3p to Upregulate MAP2K6 in Polycystic Ovary Syndrome

Circular RNA has been reported to be involved in the development of polycystic ovary syndrome (PCOS), but the role of circ_0005925 in the progression of PCOS is unclear. The expression levels of circ_0005925, microRNA (miR)-324-3p, and MAPK kinase 6 (MAP2K6) were examined by quantitative real-time PCR. Cell proliferation and apoptosis were determined using cell counting kit 8 assay, EdU assay, colony formation assay, and flow cytometry. Western blot analysis was used to detect the protein expression of apoptosis markers and MAP2K6. RNA interaction was verified by dual-luciferase reporter assay and RNA pull-down assay. Circ_0005925 was upregulated in GCs from PCOS patients, as well as in KGN and SVOG cells. Circ_0005925 knockdown repressed GCs proliferation and promoted apoptosis. MiR-324-3p was downregulated in PCOS patients, and it was sponged by circ_0005925. The regulation of circ_0005925 knockdown on GCs growth was abolished by miR-324-3p inhibitor. MAP2K6 was targeted by miR-324-3p, and its expression was positively regulated by circ_0005925. MiR-324-3p inhibited GCs proliferation and increased apoptosis by targeting MAP2K6. Collectively, our findings suggested that circ_0005925 promoted GCs growth through miR-324-3p/MAP2K6, which provided a promising therapeutic target for PCOS.

The Role of Circular RNAs in the Physiology and Pathology of the Mammalian Ovary

Circular RNAs (circRNAs) are an abundant class of endogenous non-coding RNAs (ncRNAs) generated from exonic, intronic, or untranslated regions of protein-coding genes or intergenic regions. The diverse, stable, and specific expression patterns of circRNAs and their possible functions through cis/trans regulation and protein-coding mechanisms make circRNA a research hotspot in various biological and pathological processes. It also shows practical value as biomarkers, diagnostic indicators, and therapeutic targets. This review summarized the characteristics, classification, biogenesis and elimination, detection and confirmation, and functions of circRNAs. We focused on research advances circRNAs in the mammalian ovary under conditions including ovarian cancer, polycystic ovarian syndrome (PCOS), and maternal aging, as well as during reproductive status, including ovarian follicle development and atresia. The roles of circRNAs in high reproductive traits in domestic animals were also summarized. Finally, we outlined some obstructive factors and prospects to work with circRNA, aiming to provide insights into the functional research interests of circRNAs in the reproduction and gynecology areas.

CircASPH Promotes Hepatocellular Carcinoma Progression Through Methylation and Expression of HAO2

CircRNAs have been reported to be related to hepatocellular carcinoma (HCC) development. Limited studies have revealed the expression profile of circRNAs in tumor and para-tumor normal samples in HCC patients. We found that circASPH was significantly increased in HCC tumor samples and that the level of circASPH was closely related to the overall survival of HCC patients. Mechanistically, circASPH could regulate the methylation of the promoter and expression of hydrocyanic oxidase 2 (HAO2) to promote HCC progression by acting as a sponge for miR-370-3p, and miR-370-3p could target DNMT3b and increase the 5mC level. In summary, our study determined that circASPH could regulate the methylation and expression of HAO2 and it could be considered an important epigenetic regulator in HCC progression.

Ferroptosis inhibitor ferrostatin‑1 alleviates homocysteine‑induced ovarian granulosa cell injury by regulating TET activity and DNA methylation

Polycystic ovary syndrome is one of the most common endocrine and metabolic gynecological disorders, of which dysfunction of ovarian granulosa cells is a key contributing factor. The aim of the present study was to explore the role of ferrostatin-1 (Fer-1), a ferroptosis inhibitor, in a cell injury model established by homocysteine (Hcy)-induced ovarian granulosa KGN cell line and the potential underlying mechanism. Cell viability was measured using Cell Counting Kit-8 assay in the presence or absence of Hcy and Fer-1. Cell apoptosis was assessed using TUNEL staining and the expression levels of apoptosis-related proteins were measured using western blotting. To explore the effects of Fer-1 on oxidative stress in Hcy-treated ovarian granulosa cells, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), lactate dehydrogenase (LDH) and glutathione (GSH) were measured using their corresponding kits. Furthermore, Fe²⁺ levels were assessed using Phen Green^™ SK labeling and western blotting was performed to measure the protein expression levels of ferroptosis-associated proteins GPX4, SLC7A11, ASCL4 and DMT1. Subsequently, DNA methylation and ten-eleven translocation (TET) 1/2 demethylase levels were also detected to evaluate the extent of overall DNA methylation in ovarian granulosa cells after Hcy treatment. The TET1/2 inhibitor Bobcat339 hydrochloride was applied to treat ovarian granulosa cells before evaluating the possible effects of Fer-1 on TET1/2 and DNA methylation. Fer-1 was found to markedly elevate ovarian granulosa cell viability following Hcy treatment. The apoptosis rate in Fer-1-treated groups was also markedly decreased, which was accompanied by downregulated Bax and cleaved caspase-3 expression and upregulated Bcl-2 protein expression. In addition, Fer-1 treatment reduced the levels of ROS, MDA and LDH whilst enhancing the levels of GSH. Fe²⁺ levels were significantly decreased following Fer-1 treatment, which also elevated glutathione peroxidase 4 expression whilst reducing solute carrier family 7 member 11, achaete-scute family BHLH transcription factor 4 and divalent metal transporter 1 protein expression. Fer-1 significantly inhibited DNA methylation and enhanced TET1/2 levels, which were reversed by treatment with Bobcat339 hydrochloride. Subsequent experiments on cell viability, oxidative stress, Fe²⁺ content, ferroptosis- and apoptosis-related proteins levels revealed that Bobcat339 hydrochloride reversed the effects of Fer-1 on ovarian granulosa Hcy-induced cell injury. These results suggest that Fer-1 may potentially protect ovarian granulosa cells against Hcy-induced injury by increasing TET levels and reducing DNA methylation.

Comprehensive analysis of N6-methyladenosine regulators with the tumor immune landscape and correlation between the insulin-like growth factor 2 mRNA-binding protein 3 and programmed death ligand 1 in bladder cancer

Background

N⁶-methyladenosine (m⁶A) is one of the most abundant post-transcriptional modifications of RNA. However, there is limited information about the potential roles of m⁶A regulators in tumor immunity. Therefore, in this study, we aimed to testify the functions of m⁶A regulators in bladder cancer as well as their association with the tumor immune landscape.

Methods

We reported the variation and expression levels of m6A regulators in the TCGA database and GTEx database of bladder cancer. Clusters, risk score patterns, and nomograms were constructed to evaluate the function and prognostic value of m⁶A regulators. Furthermore, we constructed nomogram to evaluate the prognosis of the individual patients. The correlation between insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) and programmed cell death ligand 1 (PD-L1) was evaluated both in vitro and in vivo.

Results

We found that the tumor grade and DNA damage pathways were strongly correlated with distinct clusters. Furthermore, two risk score groups with six m⁶A regulators were identified using the least absolute shrinkage and selection operator (LASSO) and multivariable Cox regression analysis, which could be regarded as independent prognostic markers in patients with bladder cancer. The risk score pattern was linked to the tumor immune landscape, indicating a correlation between immune checkpoints and m⁶A regulators. Moreover, an m⁶A regulator, IGF2BP3, was found to be highly expressed in the tumor samples, regulating both the total and membrane-bound PD-L1 expression levels.

Conclusions

The results of this study revealed that the m⁶A clusters and patterns play crucial roles in the regulation of tumor immunity, which may be used to develop comprehensive treatment strategies for the management of bladder cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02456-7.

WGCNA Analysis Identifies Polycystic Ovary Syndrome-Associated Circular RNAs That Interact with RNA-Binding Proteins and Sponge miRNAs

Objective

Dysfunction of cumulus granulosa cells has been suggested as a contributor to abnormal folliculogenesis and the development of polycystic ovary syndrome (PCOS), but the underlying molecular mechanisms remain unclear. Recent studies indicate that circular RNAs (circRNAs) exert important roles for diseases. We aimed to screen crucial circRNAs of PCOS patients and predict their functions.

Methods

The high-throughput datasets of circRNAs (GSE145296), microRNAs (miRNAs; GSE72274) and messenger RNAs (mRNAs; GSE155489) in cumulus cells of PCOS patients and controls were collected from the Gene Expression Omnibus database. Differentially expressed circRNAs (DECs), miRNAs (DEMs) and protein-coding genes (DEGs) were identified by the limma method. The weighted correlation network analysis (WGCNA) was conducted using the DECs to mine PCOS-associated modules. Hub DECs in modules were defined as both of |gene significance| and |module membership| >0.8. The downstream effectors of hub DECs were predicted by constructing DEC-DEM-DEG ceRNA and DEC-RNA binding protein (RBP) networks. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed to explore the functions of circRNAs.

Results

A total of 3614 DECs, 3544 DEGs and 1469 DEMs were identified between PCOS and controls. WGCNA analysis yielded five PCOS-related modules, of which 190 DECs were hub circRNAs. Seventeen hub DECs, nine DEMs, and 315 DEGs were identified to construct the ceRNA network, while 56 hub DECs and two DEGs (MBNL2, RBPMS) constituted the circRNA-RBP network. Five hub DECs (hsa_circ_0063309, hsa_circ_0054275, hsa_circ_0056196, hsa_circ_0018108 and hsa_circ_0070987) were overlapped between ceRNA and DEC-MBNL2 regulatory networks and thus they may be pivotal for PCOS. Furthermore, hsa_circ_0099109 could interact with the RBP gene RBPMS. Function analyses showed these circRNAs were inflammation-, apoptosis- or steroidogenesis-related.

Conclusion

Aberrant expression of six circRNAs that function as RBP regulators or miRNA sponges may be possible mechanisms underlying the pathogenesis of PCOS by affecting apoptosis and steroidogenesis in cumulus cells.

Identification of Three Potential circRNA Biomarkers of Polycystic Ovary Syndrome by Bioinformatics Analysis and Validation

Objective

It is well known that circRNAs are closely involved in the progression of various diseases. However, their functions and potential regulatory mechanisms in polycystic ovary syndrome (PCOS) remain largely unknown. In the present study, our aim was to investigate the potential diagnostic value of circRNAs in PCOS.

Methods

The circRNA dataset GSE145296, mRNA dataset GSE155489 and miRNA GSE138572 were downloaded from Gene Expression Omnibus (GEO) database. Then, differentially expressed genes (DEGs) were identified. Based on the potential interactions, a network of cirRNA-related competing endogenous RNAs (ceRNAs) was constructed. Biological functions were predicted by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. For further validation, qRT-PCR method was used to detect the expression level of the candidate circRNAs. Then, receiver operating characteristics (ROC) were constructed to evaluate the diagnostic value of the three differentially expressed circRNA (DE-circRNA).

Results

We constructed a network of cirRNA-related ceRNA network. Hsa_circ_0075691, hsa_circ_0075692 and hsa_circ_0085997 were validate to be dysregulated in PCOS.

Conclusion

Hsa_circ_0075691, hsa_circ_0075692 and hsa_circ_0085997 may be potential diagnostic biomarkers of PCOS, but their specific regulatory mechanisms still need to be further studied.

Circular RNA circ_RANBP9 exacerbates polycystic ovary syndrome via microRNA-136-5p/XIAP axis

Polycystic ovary syndrome (PCOS) is an endocrine disease that affects the health of many women. Circular RNAs (circRNAs) are associated with the occurrence and progression of PCOS. This study aimed to explore the function of circ_RANBP9 in PCOS. First, the circ_RANBP9 level was found to be increased in the plasma of patients with PCOS and ovarian granulosa cells (GCs) using Reverse Transcription-Quantitative Polymerase Chain Reaction (RT-qPCR). In GCs, loss of circ_RANBP9 decelerated proliferation and accelerated apoptosis of KGN and COV434 cells, as determined by MTT assay, colony formation assay, and flow cytometry. Furthermore, bioinformatics analysis showed that circ_RANBP9 and XIAP can be targeted by the microRNA, miR-136-5p. Luciferase reporter assay and RNA pull-down assay further verified the interaction between miR-136-5p and circ_RANBP9 or XIAP. Importantly, knockdown of circ_RANBP9 suppressed proliferation and promoted apoptosis of KGN and COV434 cells, whereas inhibition of miR-136-5p reversed these effects. Additionally, XIAP abolished the repression of proliferation and acceleration of apoptosis induced by miR-136-5p. The promotion of apoptosis was accompanied by upregulation of caspase-3 and Bax, and downregulation of Bcl-2, as estimated by western blotting. In conclusion, silencing of circ_RANBP9 inhibited GC proliferation and facilitated apoptosis by mediating the miR-136-5p/XIAP pathway. These findings provide a new theoretical basis for screening and treatment of PCOS.

Involvement of ferroptosis in the granulosa cells proliferation of PCOS through the circRHBG/miR-515/SLC7A11 axis

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common endocrine disease among women, but its etiology remains unknown. In recent years, many circular RNAs (circRNAs) have been confirmed to be related to the development of PCOS. The role and mechanism of circRNA in the development of PCOS need to be further explored.

METHODS

In the present study, we used the circRNA chip to detect the difference in the expression of circRNA in the granulosa cells of PCOS patients and controls. Five upregulated circRNAs were then selected for quantitative reverse transcription polymerase chain reaction (qRT-PCR) verification, and circRHBG was found to be upregulated in PCOS. Subsequently, Cell Counting Kit-8 assay and EdU assay were used to observe the effect of circRHBG on the proliferation of KGN and SVOG cells. Furthermore, the pairwise binding relationship between circRHBG/miR515-5 and miR515-5p/SLC7A11 was verified by luciferase reporter assay. The interaction between circRHBG and SLC7A11 was detected with qRT-PCR and Western blot.

RESULTS

CircRNA high-throughput chips and qRT-PCR verified that circRHBG was significantly upregulated in granular cells of PCOS patients. Knockdown of circRHBG inhibits KGN and SVOG cell proliferation. Luciferase reporter assays and Ago2-RIP detection showed that circRHBG competes with SLC7A11 to bind to miR-515-5p. Subsequent experiments verified knockdown of circRHBG promotes ferroptosis in PCOS.

CONCLUSIONS

circRHBG inhibits ferroptosis in PCOS cells through the circRHBG/miR-515-5p/SLC7A11 axis in PCOS, which may provide new diagnostic molecular markers and therapeutic targets for PCOS.