Down-regulated circPAPPA suppresses the proliferation and invasion of trophoblast cells via the miR-384/STAT3 pathway

Hsa_circ_0109320 Serves as a Novel Circular RNA Biomarker in Non-small Cell Lung Cancer by Promoting Metastasis

Non-small cell lung cancer (NSCLC), including squamous cell carcinoma and adenocarcinoma, ranks among the top 10 cancers worldwide in terms of prevalence and mortality. NSCLC, a highly malignant tumor, exhibits distant invasion and migration as well as an unfavorable prognosis. As an innovative circular RNA, hsa _circ_0109320 (circ_0109320) has been recognized as a promising cancer modulator. However, our understanding of the influence of circ_0109320 in NSCLC remains insufficient. Our research explored the clinical significance and effects of circ_0109320 on oncogenic non-small cell lung cancer (NSCLC) phenotypes. Microarray analysis and qPCR indicated that circ_0109320 expression in NSCLC specimens increased relative to that in adjacent normal tissues and was further elevated in metastatic lymph nodes. The specimens acquired from 25 patients confirmed these findings. Additionally, circ_0109320 indicated a good score (AUC = 0.688, P = 0.013) on the ROC curves, which suggests its suitability as a promising biomarker for lung cancer. Meanwhile, circ_0109320 was noticeably upregulated in lung cancer (LC) cell lines compared to human bronchial epithelial cells. Next, we performed loss- and gain-of-function experiments to examine the role of circ_0109320 in the tumor phenotypes of the cell lines. We observed that depletion or overexpression of circ_0109320 did not alter cell viability. However, the ectopic removal of circ_0109320 repressed the migration and invasion of A549 and SK-MES-1 cells, whereas circ_0109320 overexpression promoted cell migration and invasion. Furthermore, the examination of epithelial-mesenchymal transition (EMT) markers indicated that circ_0109320 elevates cell EMT activity. In conclusion, circ_0109320 level was highly associated with increased tumor cell proliferation and metastasis. circ_0109320 could be a promising predictor of clinical outcomes and a reliable target to treat NSCLC by inhibiting metastasis.

Circ_0007445 inhibits trophoblast cell proliferation, migration and invasion by mediating the miR-4432/HTRA1 axis in preeclampsia

BACKGROUND

: Circular RNAs (circRNAs) have been shown to be extensively involved in preeclampsia progression. At present, the role of circ_0007445 in preeclampsia progression is not clear.

METHODS

A total of 30 preeclampsia patients and 30 normal pregnant women were recruited in our study. The function of trophoblast cells was explored to clarify the role and mechanism of circ_0007445 on the preeclampsia progression. The expression of circ_0007445, microRNA (miR)-4432 and high temperature requirement A1 (HTRA1) was analyzed by quantitative real-time PCR. The proliferation, migration and invasion of trophoblast cells were determined by cell counting kit 8 assay, EdU assay, colony formation assay, flow cytometry, and transwell assay. Protein expression was examined by western blot analysis. Dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull-down assay were used to assess RNA interaction relationships.

RESULTS

Our data suggested that circ_0007445 had increased expression in preeclampsia patients. Knockdown of circ_0007445 enhanced trophoblast cell proliferation, migration and invasion. MiR-4432 was lowly expressed in preeclampsia patients, and it could be sponged by circ_0007445. MiR-4432 inhibitor overturned the promotion effects of circ_0007445 knockdown on trophoblast cell functions. HTRA1 was highly expressed in preeclampsia patients, and it could be targeted by miR-4432. HTRA1 overexpression could also reverse the proliferation, migration and invasion of trophoblast cells promoted by miR-4432 mimic. In addition, circ_0007445 positively regulated HTRA1 through targeting miR-4432.

CONCLUSION

:Our results suggested that circ_0007445 facilitated the development of preeclampsia by suppressing trophoblast cell function through miR-4432/HTRA1 axis.

Current understanding of circular RNAs in preeclampsia

Preeclampsia (PE) is a multiple organ and system disease that seriously threatens the safety of the mother and infant during pregnancy, and has a profound impact on the morbidity and mortality of the mother and new babies. Presently, there are no remedies for cure of PE as to the mechanisms of PE are still unclear, and the only way to eliminate the symptoms is to deliver the placenta. Thus, new therapeutic targets for PE are urgently needed. Approximately 95% of human transcripts are thought to be non-coding RNAs, and the roles of them are to be increasingly recognized of great importance in various biological processes. Circular RNAs (circRNAs) are a class of non-coding RNAs, with no 5' caps and 3' polyadenylated tails, commonly produced by back-splicing of exons. The structure of circRNAs makes them more stable than their counterparts. Increasing evidence shows that circRNAs are involved in the pathogenesis of PE, but the biogenesis, functions, and mechanisms of circRNAs in PE are poorly understood. In the present review, we mainly summarize the biogenesis, functions, and possible mechanisms of circRNAs in the development and progression of PE, as well as opportunities and challenges in the treatment and prevention of PE.

Circ_0001861 facilitates trophoblast cell proliferation, migration, invasion and epithelial-mesenchymal transition via the miR-296-5p/forkhead box protein 1 pathway in preeclampsia

BACKGROUND

Preeclampsia (PE) is one of the leading causes of maternal mortality and placental trophoblastic disorders. Recent studies reported that circular RNAs (circRNAs) were involved in PE pathogenesis. However, the role of circ_0001861 in PE progression is largely unknown.

METHODS

The RNA expression of circ_0001861, forkhead box protein 1 (FOXP1) and microRNA-296-5p (miR-296-5p) was detected by quantitative real-time polymerase chain reaction (qRT-PCR) assay. Western blot assay was performed to examine the protein levels of FOXP1 and epithelial-mesenchymal transition (EMT) markers. Cell viability, proliferation, migration and invasion were detected by cell counting kit-8, 5-ethynyl-2'-deoxyuridine, and transwell assays. Luciferase reporter assay, RNA pull-down assay, and RNA immunoprecipitation (RIP) assay were conducted to explore the interaction between miR-296-5p and circ_0001861 or FOXP1.

RESULTS

Circ_0001861 and FOXP1 were downregulated but miR-296-5p was upregulated in PE placenta. Upregulation of circ_0001861 facilitated trophoblast cell proliferation, migration, invasion and EMT. Mechanistically, circ_0001861 sponged miR-296-5p to elevate FOXP1 expression, thus promoting trophoblast cell progression.

CONCLUSION

The circ_0001861/miR-296-5p/FOXP1 axis plays a critical role in trophoblast cell proliferation, migration, invasion and EMT, which may provide a novel insight into developing potential therapeutic targets for PE.

The role of circular RNA in preeclampsia: From pathophysiological mechanism to clinical application

Preeclampsia (PE) is a common pregnancy-induced hypertension disorder that poses a significant threat to the health of pregnant women and fetuses, and has become a leading cause of maternal, fetal, and neonatal mortality. Currently, the therapy strategy for PE is mainly prevention management and symptomatic treatment, and only delivery can completely terminate PE. Therefore, a deeper understanding of the pathogenesis of PE is needed to make treatment and prevention more effective and targeted. With the deepening of molecular etiology research, circular RNAs (circRNAs) have been found to be widely involved in various processes of PE pathogenesis. As a kind of RNA with a special "head to tail" loop structure, the characteristics of circRNAs enable them to play diverse roles in the pathophysiology of PE, and can also serve as ideal biomarkers for early prediction and monitoring progression of PE. In this review, we summarized the latest research on PE-related circRNAs, trying to elucidate the unique or shared roles of circRNAs in various pathophysiological mechanisms of PE, aiming to provide a whole picture of current research on PE-related circRNAs, and extend a new perspective for the precise screening and targeted therapy of PE.

Hsa_circ_0015382 is involved in the pathogenesis of preeclampsia by mediating THBS2 expression

BACKGROUND

Preeclampsia (PE) is a hypertensive disorder of pregnancy that causes significant maternal and perinatal morbidity and mortality. Circular RNA (circRNA) hsa_circ_0015382 is associated with the pathogenesis of PE, but its underlying regulatory mechanism remains to be explored.

METHODS

Relative RNA levels of hsa_circ_0015382, microRNA-616-3p and thrombospondin-2 (THBS2) were detected by quantitative reverse transcription-polymerase chain reaction. In vitro regulatory effects of hsa_circ_0015382 on the proliferation, migration, invasion and angiogenesis of trophoblasts were evaluated by CCK-8, flow cytometry for cell cycle, EdU, transwell, wound healing and HUVEC tube formation assays, respectively. Targeting interaction was verified by dual-luciferase reporter and RNA immunoprecipitation assays.

RESULTS

Hsa_circ_0015382 was highly expressed in placental tissues from PE patients. Upregulation of hsa_circ_0015382 repressed trophoblast proliferation, migration, invasion and lowered trophoblast-induced HUVEC tube formation. Hsa_circ_0015382 was validated as a miR-616-3p sponge and miR-616-3p targeted THBS2. Hsa_circ_0015382 could mediate trophoblast proliferation, migration, invasion and regulate trophoblast-induced HUVEC tube formation by sponging miR-616-3p and regulating THBS2 expression.

CONCLUSION

Hsa_circ_0015382 is associated with the pathogenesis of PPE by regulating the miR-616-3p/THBS2 axis.

HIGHLIGHTS

Hsa_circ_0015382 is overexpressed in preeclampsia patients. Hsa_circ_0015382 inhibits trophoblast proliferation, migration, invasion and decreases trophoblast-induced HUVEC tube formation. Hsa_circ_0015382 interacts with miR-616-3p to regulate THBS2 expression.

Emerging role of miRNAs, lncRNAs, and circRNAs in pregnancy-associated diseases

ABSTRACT

Accumulating studies have demonstrated that non-coding RNAs (ncRNAs), functioning as important regulators of transcription and translation, are involved in the establishment and maintenance of pregnancy, especially the maternal immune adaptation process. The endometrial stromal cells (ESCs), trophoblast cells, and decidua immune cells that reside at the maternal-fetal interface are thought to play significant roles in normal pregnancy and pregnancy-associated diseases. Here, we reviewed the up-to-date evidence on how microRNA, long non-coding RNA, and circular RNA regulate ESCs, trophoblast cells, and immune cells and discussed the potential applications of these ncRNAs as diagnostic and therapeutic markers in pregnancy complications.

The Role of Placental Non-Coding RNAs in Adverse Pregnancy Outcomes

Non-coding RNAs (ncRNAs) are transcribed from the genome and do not encode proteins. In recent years, ncRNAs have attracted increasing attention as critical participants in gene regulation and disease pathogenesis. Different categories of ncRNAs, which mainly include microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are involved in the progression of pregnancy, while abnormal expression of placental ncRNAs impacts the onset and development of adverse pregnancy outcomes (APOs). Therefore, we reviewed the current status of research on placental ncRNAs and APOs to further understand the regulatory mechanisms of placental ncRNAs, which provides a new perspective for treating and preventing related diseases.

The expression profiles of circular RNAs and competing endogenous RNA networks in intrahepatic cholangiocarcinoma

Introduction: Intrahepatic cholangiocarcinoma (iCCA) is a heterogeneous entity with diverse etiologies, morphologies, and clinical outcomes, but our knowledge of its epidemiology and carcinogenesis is very limited. Materials and methods: The expression patterns of circRNAs were explored in iCCA tissues and corresponding adjacent normal ones, denoted by (iCCA) and (iCCAP), respectively, using high-throughput sequencing. Results: A total of 117 differential expressed (DE) circRNAs were identified. Based on the parental transcripts of circRNAs, these DE circRNAs were related to several important GO terms and were enriched in important pathways. Two circRNA-mediated ceRNA networks were constructed and many important metabolic pathways related to mRNAs were regulated by DE circRNAs via miRNAs. Conclusion: Our study revealed the DE circRNAs in the iCCA tissues compared with iCCAP ones, suggesting that circRNAs may play crucial roles in the pathogenesis of iCCA.

Reduced cell invasion may be a characteristic of placental defects in pregnant women of advanced maternal age at single-cell level

The mechanisms underlying pregnancy complications caused by advanced maternal age (AMA) remain unclear. We analyzed the cellular signature and transcriptomes of human placentas in AMA women to elucidate these mechanisms. Placental tissues from two AMA women and two controls were used for single-cell RNA-sequencing (scRNA-seq). Controls consisted of AMA women who did not experience any pregnancy complications and pregnant women below the age of 35 years without pregnancy complications. Trophoblast cells were obtained from the placentas of another six pregnant women (three AMA women and three controls), and in-vitro transwell assays were conducted to observe the cell invasion ability. Thirty additional samples (from 15 AMA women and 15 controls) were analyzed to verify the specific expression of serine protease inhibitor clade E member 1 (SERPINE1). Preliminary study of the role of SERPINE1 in cell invasion was carried out with HTR8-S/Vneo cells. High-quality transcriptomes of 27 ‍607 cells were detected. Three types of trophoblast cells were detected, which were further classified into eight subtypes according to differences in gene expression and Gene Ontology (GO) function. We identified 110 differentially expressed genes (DEGs) in trophoblast cells between the AMA and control groups, and the DEGs were enriched in multiple pathways related to cell invasion. In-vitro transwell assays suggested that the invading trophoblast cells in AMA women were reduced. SERPINE1 was specifically expressed in the trophoblast, and its expression was higher in AMA women (P<0.05). Transfection of human SERPINE1 (hSERPINE1) into HTR8-S/Vneo trophoblast cells showed fewer invading cells in the hSERPINE1 group. Impaired cell invasion may underlie the increased risk of adverse pregnancy outcomes in AMA women. Abnormal expression of SERPINE1 in extravillous trophoblast (EVT) cells appears to play an important role.

Regulatory roles of non-coding RNAs and m6A modification in trophoblast functions and the occurrence of its related adverse pregnancy outcomes

Adverse pregnancy outcomes, such as preeclampsia, gestational diabetes mellitus, fetal growth restriction, and recurrent miscarriage, occur frequently in pregnant women and might further induce morbidity and mortality for both mother and fetus. Increasing studies have shown that dysfunctions of human trophoblast are related to these adverse pregnancy outcomes. Recent studies also showed that environmental toxicants could induce trophoblast dysfunctions. Moreover, non-coding RNAs (ncRNAs) have been reported to play important regulatory roles in various cellular processes. However, the roles of ncRNAs in the regulation of trophoblast dysfunctions and the occurrence of adverse pregnancy outcomes still need to be further investigated, especially with exposure to environmental toxicants. In this review, we analyzed the regulatory mechanisms of ncRNAs and m6A methylation modification in the dysfunctions of trophoblast cells and the occurrence of adverse pregnancy outcomes and also summarized the harmful effects of environmental toxicants. In addition to DNA replication, mRNA transcription, and protein translation, ncRNAs and m6A modification might be considered as the fourth and fifth elements that regulate the genetic central dogma, respectively. Environmental toxicants might also affect these processes. In this review, we expect to provide a deeper scientific understanding of the occurrence of adverse pregnancy outcomes and to discover potential biomarkers for the diagnosis and treatment of these outcomes.

Circ_0005714/miR-223-3p/ADAM9 regulatory axis affects proliferation, migration, invasion, and angiopoiesis in trophoblast cells

BACKGROUND

Circular RNAs (circRNAs) have critical roles in various types of diseases, including preeclampsia (PE). Circ_0005714 function in PE was explored in this study.

METHODS

Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed for level analysis of circ_0005714, micoRNA-223-3p (miR-223-3p), and a disintegrin and metalloproteinase 9 (ADAM9). Cell Counting Kit-8 (CCK-8) and colony formation assays were used for cell viability and colony formation detection. Cell proliferation was determined by EdU assay. The determination of migration and invasion was conducted by wound healing assay and transwell assay. Tube formation assay was applied to assess angiopoiesis. Target binding analysis was performed by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Western blot was used for protein examination.

RESULTS

Circ_0005714 was highly expressed in PE placenta tissues. The expression promotion of circ_0005714 reduced proliferation, migration, invasion, and angiopoiesis in trophoblast cells. Furthermore, circ_0005714 acted as a molecular sponge for miR-223-3p and the effects of circ_0005714 on trophoblast cells were achieved by sponging miR-223-3p. Moreover, miR-223-3p could target ADAM9 and knockdown of ADAM9 reversed cell progression inhibition induced by miR-223-3p inhibitor. In addition, circ_0005714 upregulated the ADAM9 expression and inactivated the Wnt/β-catenin pathway through targeting miR-223-3p.

CONCLUSIONS

All results manifested that circ_0005714 retarded the progression of PE by mediating the miR-223-3p/ADAM9 signal network.

Circ_FURIN promotes trophoblast cell proliferation, migration and invasion in preeclampsia by regulating miR-34a-5p and TFAP2A

Emerging evidence has shown that circular RNAs (circRNAs) play vital roles in the progression of diverse human diseases. However, the functions of circRNAs in preeclampsia (PE) are largely unknown. In this study, we aimed to explore the functions of the circRNA furin, paired basic amino acid cleaving enzyme (circ_FURIN) in PE development. qRT-PCR and western blot analyses were conducted to determine the levels of circ_FURIN, miR-34a-5p and transcription factor AP-2 alpha (TFAP2A). A Cell Counting Kit-8 (CCK-8) assay and a 5'-ethynyl-2'-deoxyuridine (EdU) incorporation assay were utilized to evaluate the cell proliferation ability. Transwell assays were adopted to estimate cell migration and invasion. A dual-luciferase reporter assay and an RNA pulldown assay were utilized to analyze the relationships among circ_FURIN, miR-34a-5p and TFAP2A. It was found that circ_FURIN was downregulated in PE placental tissues and hypoxia-treated placental trophoblast cells. Overexpression of circ_FURIN promoted trophoblast cell proliferation, migration and invasion under hypoxic conditions. Circ_FURIN functioned as the sponge for miR-34a-5p. MiR-34a-5p overexpression abrogated the effects of circ_FURIN on the proliferation, migration and invasion of trophoblast cells under hypoxic conditions. In addition, TFAP2A was demonstrated to be the target gene of miR-34a-5p. TFAP2A silencing ameliorated the promotive effects of miR-34a-5p inhibition on trophoblast cell proliferation, migration and invasion under hypoxic conditions. In conclusion, circ_FURIN enhanced trophoblast cell proliferation, migration and invasion under hypoxic conditions by elevating TFAP2A expression through sponging miR-34a-5p.

The Role of Non-Coding RNAs in the Human Placenta

Non-coding RNAs (ncRNAs) play a central and regulatory role in almost all cells, organs, and species, which has been broadly recognized since the human ENCODE project and several other genome projects. Nevertheless, a small fraction of ncRNAs have been identified, and in the placenta they have been investigated very marginally. To date, most examples of ncRNAs which have been identified to be specific for fetal tissues, including placenta, are members of the group of microRNAs (miRNAs). Due to their quantity, it can be expected that the fairly larger group of other ncRNAs exerts far stronger effects than miRNAs. The syncytiotrophoblast of fetal origin forms the interface between fetus and mother, and releases permanently extracellular vesicles (EVs) into the maternal circulation which contain fetal proteins and RNA, including ncRNA, for communication with neighboring and distant maternal cells. Disorders of ncRNA in placental tissue, especially in trophoblast cells, and in EVs seem to be involved in pregnancy disorders, potentially as a cause or consequence. This review summarizes the current knowledge on placental ncRNA, their transport in EVs, and their involvement and pregnancy pathologies, as well as their potential for novel diagnostic tools.

Epigenetic regulation of epithelial to mesenchymal transition: a trophoblast perspective

Epigenetic changes alter expression of genes at both pre- and post-transcriptional levels without changing their DNA sequence. Accumulating evidence suggests that such changes can modify cellular behaviour and characteristics required during development and in response to various extracellular stimuli. Trophoblast cells develop from the outermost trophectoderm layer of the blastocyst and undergo many phenotypic changes as the placenta develops. One such phenotypic change is differentiation of the epithelial natured cytotrophoblasts into the mesenchymal natured extravillous trophoblasts. The extravillous trophoblasts are primarily responsible for invading into the maternal decidua and thus establishing connection with the maternal spiral arteries. Any dysregulation of this process can have adverse effects on the pregnancy outcome. Hence, tight regulation of this epithelial-mesenchymal transition is critical for successful pregnancy. This review summarizes the recent research on the epigenetic regulation of the epithelial-mesenchymal transition occurring in the trophoblast cells during placental development. The functional significance of chemical modifications of DNA and histone, which regulate transcription, as well as non-coding RNAs, which control gene expression post-transcriptionally, is discussed in relation to trophoblast biology.

circ_0085296 inhibits the biological functions of trophoblast cells to promote the progression of preeclampsia via the miR-942-5p/THBS2 network

Insufficient invasion of trophoblast cells is one of the important causes of preeclampsia (PE). Circular RNA (circRNA) has been proven to regulate the biological functions of trophoblast cells and mediate the progression of PE. The expression of circ_0085296, microRNA (miR)-942-5p, and thrombospondin 2 (THBS2) was detected by quantitative real-time PCR. In addition, the interaction between miR-942-5p and circ_0085296 or THBS2 was confirmed by dual-luciferase reporter assay and RIP assay. Our data showed that circ_0085296 was upregulated in the placental tissues of PE patients. Silenced circ_0085296 could enhance the proliferation, migration, invasion, and angiogenesis of HTR-8/SVneo cells. Besides, circ_0085296 was found to act as miR-942-5p sponge. Function analysis results suggested that miR-942-5p inhibitor reversed the positive regulation of circ_0085296 knockdown on the biological functions of HTR-8/SVneo cells. Moreover, THBS2 was a target of miR-942-5p, and its overexpression also reversed the promotion effect of miR-942-5p on the proliferation, migration, invasion, and angiogenesis of HTR-8/SVneo cells. Also, circ_0085296 was discovered to positively regulate THBS2 by sponging miR-942-5p. To sum up, our results revealed that circ_0085296 could inhibit trophoblast cells proliferation, migration, invasion, and angiogenesis by regulating miR-942-5p/THBS2, confirming that circ_0085296 might be a potential therapeutic target for PE.

CircPAPPA Regulates the Proliferation, Migration, Invasion, Apoptosis, and Cell Cycle of Trophoblast Cells Through the miR-3127-5p/HOXA7 Axis

Abnormal function of trophoblast cells is one of the important causes of preeclampsia (PE). Circular RNA (circRNA) is thought to be involved in the regulation of various diseases progression, including PE. However, the role of circRNA pregnancy-associated plasma protein A (circPAPPA) in PE is less studied. The expression levels of circPAPPA, miR-3127-5p, and homeobox A7 (HOXA7) were determined by quantitative real-time PCR. Cell proliferation was evaluated using MTT assay and colony formation assay. Besides, flow cytometry was used to detect cell apoptosis and cell cycle distribution. In addition, the interaction between miR-3127-5p and circPAPPA or HOXA7 was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay. CircPAPPA was lowly expressed in the placental tissues of PE patients. Knockdown of circPAPPA inhibited proliferation, migration, and invasion, while induced apoptosis and cell cycle arrest in trophoblast cells. MiR-3127-5p could be targeted by circPAPPA, and its inhibitor reversed the effect of circPAPPA silencing on the biological function of trophoblast cells. Moreover, HOXA7 was a target of miR-3127-5p. HOXA7 overexpression reversed the effect of miR-3127-5p on the biological function of trophoblast cells. Our research indicated that circPAPPA positively regulated the biological function of trophoblast cells to mediate the progression of PE by miR-3127-5p/HOXA7 axis, which suggested that circPAPPA might be a potential biomarker for PE.

Identification of Circular RNA circ_0017068 as a Regulator of Proliferation and Apoptosis in Trophoblast Cells by miR-330-5p/XIAP Axis

Preeclampsia (PE) is a major and serious complication of pregnancy. Circular RNAs (circRNAs) have been implicated in the initiation and progression of PE. In this paper, we explored the precise actions of circ_0017068 in trophoblast cell functional properties. Ribonuclease (RNase) R, and Actinomycin D treatments were used to characterize circ_0017068. The levels of circ_0017068, microRNA (miR)-330-5p and X-linked inhibitor of apoptosis protein (XIAP) were measured by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot analysis. Cell proliferation, cell cycle progression, and apoptosis were gauged by the Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), and flow cytometry assays, respectively. Direct relationship between miR-330-5p and circ_0017068 or XIAP was validated by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Our data showed that circ_0017068 was downregulated in PE placental samples. Enforced expression of circ_0017068 promoted HTR-8/SVneo cell proliferation, cycle progression, and suppressed apoptosis, while silencing of circ_0017068 exhibited opposite effects. Mechanistically, circ_0017068 targeted miR-330-5p, and circ_0017068 regulated proliferation, cycle progression, and apoptosis of HTR-8/SVneo cells through miR-330-5p. Moreover, XIAP was identified as a direct and functional target of miR-330-5p. Furthermore, circ_0017068 operated as a post-transcriptional regulator of XIAP expression through miR-330-5p. Our study identifies circ_0017068 as an important regulator of the proliferation and apoptosis of HTR-8/SVneo trophoblast cells at least in part by miR-330-5p-dependent regulation of XIAP, highlighting circ_0017068 as a potential therapeutic agent for PE treatment.

CircHIPK3 contributes to human villous trophoblast growth, migration and invasion via modulating the pathway of miR-346/KCMF1

INTRODUCTION

Preeclampsia (PE) is one of the leading causes of maternal and perinatal morbidity and mortality worldwide. The regular growth, migration and invasion of villous trophoblast cells contribute to placental development. The objective of this study was to investigate the role and mechanism of circular RNA homeodomain interacting protein kinase 3 (circHIPK3) in the biological functions of trophoblast cells.

METHODS

The expression of circHIPK3, microRNA-346 (miR-346) and potassium channel modulatory factor 1 (KCMF1) mRNA was measured by quantitative real-time PCR (qPCR). Trophoblast cell proliferation, migration/invasion and cell cycle progression/apoptosis were determined by CCK-8 assay, transwell assay and flow cytometry assay, respectively. The predicted relationship between miR-346 and circHIPK3 or KCMF1 by bioinformatics was confirmed dual-luciferase reporter assay and RIP assay.

RESULTS

CircHIPK3 and KCMF1 were downregulated, while miR-346 was upregulated in placenta tissues from PE patients. The forced expression of circHIPK3 promoted trophoblast cell proliferation and migration/invasion but alleviated cell cycle arrest and cell apoptosis. MiR-346 was a target of circHIPK3, and miR-346 restoration reversed the effects of circHIPK3 upregulation. In addition, circHIPK3 acted as miR-346 sponge to modulate KCMF1 expression. KCMF1 downregulation partially repressed trophoblast cell proliferation, migration and invasion that were facilitated by miR-346 inhibition or circHIPK3 upregulation.

DISCUSSION

CircHIPK3 contributes to trophoblast cell proliferation, migration and invasion by upregulating KCMF1 via acting as miR-346 sponge.

Upregulation of circRNA hsa_circ_0008726 in Pre-eclampsia Inhibits Trophoblast Migration, Invasion, and EMT by Regulating miR-345-3p/RYBP Axis

Accumulating evidence shows that impaired spiral artery remodeling, placental dysfunction, and insufficient trophoblast infiltration contribute to the etiology and pathogenesis of pre-eclampsia (PE). circRNAs are a class of endogenous non-coding RNAs implicated in the pathogenesis of many diseases, including PE. This study aims to investigate the role of circRNA hsa_circ_0008726 in regulating the migration and invasion of extravillous trophoblast cells. RNase R assay was performed to confirm that circ_0008726 was a circular transcript. The expression of circ_0008726, RYBP, and miR-345-3p was examined by qRT-PCR. The functional interaction between miR-345-3p and circ_0008726 or RYBP was confirmed using dual-luciferase reporter assay and RNA immunoprecipitation (RIP). Cell migration and invasion ability was analyzed by Transwell assays. Western blot was used for the quantification of RYBP protein level. Circ_0008726 expression was significantly increased in PE placenta tissues as compared with normal placenta tissues. Circ_0008726 was resistant to RNase R digestion and was predominately located in the cytoplasm of HTR-8/SVneo cells. Silencing circ_0008726 promoted cell migration and EMT (epithelial-mesenchymal transition), while circ_0008726 overexpression suppressed these processes. Mechanistically, circ_0008726 sponged miR-345-3p to negatively regulate its expression, and miR-345-3p negatively modulated the expression of RYBP. In PE samples, the expression level of circ_0008726 was negatively correlated with miR-345-3p level, but was positively correlated with RYBP expression. Transfection of miR-345-3p mimic or RYBP knockdown counteracted the effects of circ_0008726 overexpression on cell migration and EMT. Our data demonstrate the upregulation of circ_0008726 in PE placenta, which inhibits the migration, invasion, and EMT of HTR-8/SVneo cells by targeting miR-345-3p/RYBP axis. These data suggest that circ_0008726 could be a potential biomarker and therapeutic target for PE.

LINC02532 Contributes to Radiosensitivity in Clear Cell Renal Cell Carcinoma through the miR-654-5p/YY1 Axis

Background: Studies have shown that long non-coding RNAs (lncRNAs) play essential roles in tumor progression and can affect the response to radiotherapy, including in clear cell renal cell carcinoma (ccRCC). LINC02532 has been found to be upregulated in ccRCC. However, not much is known about this lncRNA. Hence, this study aimed to investigate the role of LINC02532 in ccRCC, especially in terms of radioresistance. Methods: Quantitative real-time PCR was used to detect the expression of LINC02532, miR-654-5p, and YY1 in ccRCC cells. Protein levels of YY1, cleaved PARP, and cleaved-Caspase-3 were detected by Western blotting. Cell survival fractions, viability, and apoptosis were determined by clonogenic survival assays, CCK-8 assays, and flow cytometry, respectively. The interplay among LINC02532, miR-654-5p, and YY1 was detected by chromatin immunoprecipitation and dual-luciferase reporter assays. In addition, in vivo xenograft models were established to investigate the effect of LINC02532 on ccRCC radioresistance in 10 nude mice. Results: LINC02532 was highly expressed in ccRCC cells and was upregulated in the cells after irradiation. Moreover, LINC02532 knockdown enhanced cell radiosensitivity both in vitro and in vivo. Furthermore, YY1 activated LINC02532 in ccRCC cells, and LINC02532 acted as a competing endogenous RNA that sponged miR-654-5p to regulate YY1 expression. Rescue experiments indicated that miR-654-5p overexpression or YY1 inhibition recovered ccRCC cell functions that had been previously impaired by LINC02532 overexpression. Conclusions: Our results revealed a positive feedback loop of LINC02532/miR-654-5p/YY1 in regulating the radiosensitivity of ccRCC, suggesting that LINC02532 might be a potential target for ccRCC radiotherapy. This study could serve as a foundation for further research on the role of LINC02532 in ccRCC and other cancers.

Circ_0011460 upregulates HTRA1 expression by sponging miR-762 to suppress HTR8/SVneo cell growth, migration, and invasion

BACKGROUND

Aberrant expression of circular RNAs (circRNAs) during placental development could affect fetal growth and contribute to preeclampsia (PE). Circ_0011460 was found to be differentially expressed in placental samples of PE. However, the exact function and mechanism of circ_0011460 in PE process remain largely undefined.

METHODS

Levels of circ_0011460, microRNA (miR)-762, and high-temperature requirement-A serine peptidase 1 (HTRA1) were detected using quantitative real-time polymerase chain reaction and Western blot. In vitro experiments in HTR8/SVneo cells were conducted using cell counting kit-8, wound healing, transwell, flow cytometry and Western blot assays. The direct interactions between miR-762 and circ_0011460 or HTRA1 were verified using dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays.

RESULTS

Circ_0011460 possessed a loop structure and was highly expressed in placental tissues of PE patients. Overexpression of circ_0011460 greatly suppressed HTR8/SVneo cell proliferation, migration, and invasion, and accelerated cell apoptosis. While circ_0011460 knockdown yielded the opposite trends on above biological behaviors. Mechanistically, we confirmed that circ_0011460 could up-regulate HTRA1 expression via serving as a sponge of miR-762. Further rescue studies demonstrated that circ_0011460 exerted its roles via targeting miR-762, and miR-762 promoted HTR8/SVneo cell growth, migration and invasion via regulating HTRA1.

CONCLUSION

In all, circ_0011460 suppressed HTR8/SVneo cell growth, migration, and invasion via miR-762/HTRA1 axis, suggesting a new insight into the pathogenesis of PE.

Circular RNA hsa_circ_0026552 inhibits the proliferation, migration and invasion of trophoblast cells via the miR‑331‑3p/TGF‑βR1 axis in pre‑eclampsia

Globally, pre-eclampsia (PE) is a gestational disorder that causes increased morbidity of the fetus and mortality induced by pregnancy. Despite various studies, the understanding of the causes or mechanism of the development of PE remains elusive. Thus, the present study aimed to investigate the role of circular (circ)RNA hsa_circ_0026552 (hsa_circ_0026552) in the development of PE and its mechanism of regulation. hsa_circ_0026552 differential expression in PE tissue data and clinical samples were analyzed and it was observed that hsa_circ_0026552 is highly upregulated in PE samples. Furthermore, miR-331-3p was detected as an hsa_circ_0026552 target miRNA and TGF-βR1 gene as a target of miR-331-3p. These results were confirmed using various assays, including dual-luciferase reporter, reverse transcription-quantitative PCR and RNA pull-down assay. It was observed that miR-331-3p expression was negatively correlated to hsa_circ_0026552 relative expression, while TGF-βR1 expression was positively correlated to hsa_circ_0026552 expression evaluated by Pearson's correlation test. The functional experiments, including Cell Counting Kit-8, colony formation and Transwell assay, showed that silencing hsa_circ_0026552 could significantly strengthen the proliferation, migration and invasion of the trophoblastic HTR-8/SVneo cells, but the subsequent overexpression of hsa_circ_0026552 reversed this. Mechanistically, it was concluded that hsa_circ_0026552 acts as a miR-331-3p sponge to upregulate TGF-βR1 expression in trophoblasts and is involved significantly in PE development and progression in pregnant women. The circRNA hsa_circ_0026552 could be a novel therapeutic target and prognostic biomarker for PE.

Roles of noncoding RNAs in preeclampsia

Preeclampsia (PE) is an idiopathic disease that occurs during pregnancy. It comprises multiple organ and system damage, and can seriously threaten the safety of the mother and infant throughout the perinatal period. As the pathogenesis of PE is unclear, there are few specific remedies. Currently, the only way to eliminate the clinical symptoms is to terminate the pregnancy. Although noncoding RNA (ncRNA) was once thought to be the "junk" of gene transcription, it is now known to be widely involved in pathological and physiological processes, including pregnancy-related disorders. Moreover, there is growing evidence that the unbalanced expression of specific ncRNA is involved in the pathogenesis of PE. In the present review, we summarize the expression patterns of ncRNAs, i.e., microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), and the functional mechanisms by which they affect the development of PE, and examine the clinical significance of ncRNAs as biomarkers for the diagnosis of PE. We also discuss the contributions made by genetic polymorphisms and epigenetic ncRNA regulation to PE. In the present review, we wish to explore and reinforce the clinical value of ncRNAs as noninvasive biomarkers of PE.

Non-Coding RNAs Regulate Placental Trophoblast Function and Participate in Recurrent Abortion

Recurrent spontaneous abortion (RSA) is a serious pregnancy complication with an increasing clinical incidence. The various causes of recurrent abortion are complicated. Developments in genetics, immunology, and cell biology have identified important roles of non-coding RNAs (ncRNAs) in the occurrence and progress of recurrent abortion. NcRNAs can affect the growth, migration, and invasion of placental trophoblasts by regulating cell processes such as the cell cycle, apoptosis, and epithelial-mesenchymal transformation. Therefore, their abnormal expression might lead to the occurrence and development of RSA. NcRNAs include small nuclear RNA (snRNA), small nucleolar RNA (snoRNA), ribosomal RNA (rRNA), transfer, RNA (tRNA), circular RNA (cRNA), and Piwi-interacting RNA (piRNA). In this review, we discuss recent research that focused on the function and mechanism of microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNA (circRNA) in regulating placental trophoblasts. The use of ncRNAs as potential diagnostic and predictive biomarkers in RSA is also discussed to provide future research insights.

Identification and comparison of circular RNAs in preeclampsia

Background

Preeclampsia (PE) is a pregnancy-specific syndrome, belongs to the gestational hypertension diseases category and is considered among the causes of maternal and perinatal mortality and morbidity. However, the pathogenesis of PE is still vague.

Methods

In the present study, the circular RNA (circRNA) expression patterns of normal pregnant women and PE patients were investigated using whole RNA sequencing.

Results

A total of 151 differential expressed circRNAs were identified including 121 upregulated and 30 downregulated ones. Functional and pathway enrichment analysis was conducted on the differentially expressed circRNAs using Gene Ontology and KEGG databases. The results of this analysis indicated that several crucial biological processes and pathways were enriched in PE patients. circRNA–microRNA (miRNA) interaction analysis indicated that the reported differentially expresse circRNAs may be associated with some regulatory functions through miRNAs in PE patients. Two ceRNAs networks were constructed according to the targeting relationship between circRNAs/miRNAs and miRNAs/mRNAs. One sub-network contained one upregulated circRNA, four downregulated miRNAs and five upregulated mRNAs, and another sub-network contained 10 downregulated circRNAs, 21 upregulated miRNAs and 15 downregulated mRNAs.

Conclusion

CircRNA expression patterns have been investigated and this analysis revealed their potential regulatory mechanisms in PE patients. We constructed the ceRNAs (competing endogenous RNA) to reveal the potential molecular roles of dysregulated circRNAs in the PE patients using RNA sequencing data. circRNA_13301 was the only one upregulated circRNA in ceRNA being targeted by four miRNAs.

Circ_0015382 is associated with preeclampsia and regulates biological behaviors of trophoblast cells through miR-149-5p/TFPI2 axis

INTRODUCTION

Circ_0015382 expression was found to be up-regulated in preeclampsia (PE) placenta tissues, while the role and molecular mechanisms of circ_0015382 in PE remain unclear.

METHODS

The expression of circ_0015382, microRNA (miR)-149-5p, and tissue factor pathway inhibitor 2 (TFPI2) was measured using quantitative real-time polymerase chain reaction and Western blot. Cell proliferation, migration, invasion, apoptosis, and cell cycle, were detected using cell counting kit-8, transwell, and flow cytometry assays, respectively. The direct interaction between miR-149-5p and circ_0015382 or TFPI2 was analyzed using the dual-luciferase reporter assay.

RESULTS

Circ_0015382 was highly expressed in placental tissues of PE. Overexpression of circ_0015382 suppressed trophoblast cell proliferation, migration, invasion and epithelial-mesenchymal transition (EMT), but induced apoptosis and cell cycle progression, while circ_0015382 knockdown showed inverse effects. MiR-149-5p was confirmed to be a target of circ_0015382, and silencing miR-149-5p reversed the regulatory effects of circ_0015382 knockdown on trophoblast cell biological behaviors. MiR-149-5P was expressed at lower levels in placental tissues of PE, while the expression of its target TFPI2 was higher. Importantly, circ_0015382 could regulate TFPI2 expression via miR-149-5p. Additionally, miR-149-5p was shown to promote trophoblast cell growth, migration, invasion and EMT through TFPI2.

DISCUSSION

Circ_0015382 was associated with the onset and development of PE through suppressing trophoblast cell growth, migration, invasion and EMT via miR-149-5p/TFPI2 axis, revealing a new insight into the pathogenesis of PE and a potential therapeutic target for PE treatment.

Circular RNA VRK1 facilitates pre-eclampsia progression via sponging miR-221-3P to regulate PTEN/Akt

Pre‐eclampsia (PE) is a worldwide pregnancy‐related disorder. It is mainly characterized by defect migration and invasion of trophoblast cells. Recently, circular RNAs (circRNAs) have been believed to play a vital role in PE. The expression patterns and the biological functions of circRNAs in PE remain elusive. Here, we performed a circRNA microarray to identify putative PE‐related circRNAs. Bioinformatics analyses were used to screen the circRNAs which have potential relationships with pre‐eclampsia, and we identified a novel circRNA (circVRK1) that was up‐regulated in PE placenta tissues. By using HTR‐8/SVneo cells, circVRK1 knockdown significantly enhanced cell migration and invasion abilities, as well as epithelial‐mesenchymal transition (EMT). Mechanistically, we found that circVRK1 and PTEN could function as the ceRNAs to miR‐221‐3p. Overexpression of miR‐221‐3p promoted cell migration, invasion and EMT via regulating PTEN. The cotransfection of miR‐221‐3p inhibitor or PTEN reversed the effect from circVRK1 knockdown. Moreover, the circVRK1/miR‐221‐3p/PTEN axis greatly regulated Akt phosphorylation. In general, circVRK1 suppresses trophoblast cell migration, invasion and EMT, by acting as a ceRNA to miR‐221‐3p to regulate PTEN, and further inhibit PI3K/Akt activation. The purpose of this paper is to open wide insights to investigate the onset of PE and provide new potential therapeutic targets in PE.

Decreased circUBAP2 Expression Is Associated with Preeclampsia by Limiting Trophoblast Cell Proliferation and Migration

Preeclampsia (PE) is a common obstetric disease and a major cause of maternal, newborn, and fetal death. This condition is a multisystem disorder characterized by hypertension, proteinuria, and involvement of the kidney, liver, and nervous system. It is generally believed that the placenta is the main cause of PE. circRNAs are a special class of noncoding RNAs that can form covalently closed continuous ring structures with tissue-specific conservation, and they have been reported to play a wide range of regulatory functions in various diseases, including PE. In this study, we reported a novel circUBAP2 (hsa_circ_0003496) and found that it was downregulated in placental tissues from patients with PE compared to healthy controls. After knocking down circUBAP2 in trophoblast cells, we found that cell proliferation and migration were significantly suppressed. In addition, preliminary mechanistic studies showed that circUBAP2 can sponge miR-1244, and FOXM1 was identified as a target gene for miR-1244. Cotransfection of si-circUBAP2 and a miR-1244 inhibitor partially reversed the suppressive effect induced by circUBAP2 depletion on proliferation and migration. In conclusion, the circUBAP2/miR-1244/FOXM1 axis might be a promising molecular marker for the diagnosis and treatment of PE.

Circular RNA circ_0020123 Promotes Non-Small Cell Lung Cancer Progression Through miR-384/TRIM44 Axis

Background

It was reported that circular RNAs (circRNAs) and microRNAs (miRNAs) were related to non-small cell lung cancer (NSCLC) development. However, the detailed mechanisms of circ_0020123 and miR-384 in NSCLC are elusive.

Methods

QRT-PCR and Western blot assay were performed to detect the transcription and protein levels of genes, respectively. Then, the functional experiments, including MTT assay, flow cytometry, and transwell assay, were employed. Besides, the interaction between miR-384 and circ_0020123 or tripartite motif‑containing protein 44 (TRIM44) was predicted by starbase or targetscan, and then verified by the dual-luciferase reporter, RNA pull-down assays and RNA immunoprecipitation assay (RIP). Mouse xenograft assay was performed to evaluate the effect of circ_0020123 on tumor growth in vivo.

Results

Levels of circ_0020123 and TRIM44 were enhanced, and the miR-384 level was attenuated in NSCLC tissues and cells. Circ_0020123 depletion attenuated the abilities of NSCLC cell viability, migration, invasion, and epithelial–mesenchymal transition (EMT), and induced apoptosis. Besides, circ_0020123 interacted with miR-384, and miR-384 targeted TRIM44. Circ_0020123 regulated cell progression by regulating miR-384 and subsequently mediated TRIM44 expression. Besides, circ_0020123 depletion repressed tumor growth in vivo.

Conclusion

We demonstrated that circ_0020123 knockdown suppressed NSCLC cell progression by regulating the miR-384/TRIM44 axis, providing the theoretical basis for the therapy of NSCLC.

CircLRRK1 targets miR-223-3p to inhibit the proliferation, migration and invasion of trophoblast cells by regulating the PI3K/AKT signaling pathway

INTRODUCTION

Many studies have shown that circular RNAs (circRNAs) are related to the occurrence of preeclampsia (PE). However, the role of circLRRK1 in the progression of PE is unclear.

METHODS

The identification and localization of circLRRK1 were verified by Actinomycin D (ActD) assay, Ribonuclease R (RNase R) digestion assay and subcellular localization assay. Moreover, the proliferation of trophoblast cells was detected by 3-(45)-dimethylthiahiazo (-z-y1)-35-di-phenytetrazoliumromide (MTT) assay and colony formation assay. Furthermore, the migration and invasion of trophoblast cells were determined by wound healing assay and transwell assay. Meanwhile, Western blot (WB) analysis was used to examine the protein levels of migration markers and PI3K/AKT signaling pathway markers. In addition, the interaction between circLRRK1 and miR-223-3p was confirmed by dual-luciferase reporter assay and biotin-labeled RNA pull-down assay.

RESULTS

Our results showed that circLRRK1 was significantly highly expressed in PE patients. Silenced circLRRK1 could markedly enhance the proliferation, migration and invasion of trophoblast cells. Additionally, we found that circLRRK1 could target miR-223-3p. MiR-223-3p overexpression also promoted the proliferation, migration and invasion of trophoblast cells. The rescue experiments revealed that miR-223-3p inhibitor could reverse the promoting effect of circLRRK1 silencing on the proliferation, migration and invasion of trophoblast cells. Furthermore, circLRRK1 silencing could activate the PI3K/AKT signaling pathway by targeting miR-223-3p.

DISCUSSION

CircLRRK1 could suppress the proliferation, migration and invasion of trophoblast cells by regulating the PI3K/AKT signaling pathway via targeting miR-223-3p, suggesting that circLRRK1 might be a potential biomarker for the treatment of PE.

Circ-AK2 is associated with preeclampsia and regulates biological behaviors of trophoblast cells through miR-454-3p/THBS2

INTRODUCTION

Circ-AK2 has been found to be differentially expressed in PE placenta tissues, however, the role and the underlying molecular mechanisms of circ-AK2 in PE remain poorly known.

METHODS

The expression of circ-AK2, miR-454-3p, and THBS2 mRNA was detected using quantitative real-time polymerase chain reaction. Protein levels of CyclinD1, MMP-9 and THBS2 were measured using Western blot. Cell proliferation, migration, and invasion were analyzed by 3-(4, 5)-dimethylthiahiazo (-z-y1)-3, 5-di-phenytetrazoliumromide (MTT) assay and transwell assay. The interaction between miR-454-3p and circ-AK2 or THBS2 was analyzed by the dual-luciferase reporter assay.

RESULTS

Circ-AK2 was highly expressed in placental tissues of PE, and overexpression of circ-AK2 inhibited trophoblast cell proliferation, migration and invasion. Circ-AK2 directly bound to miR-454-3p, and miR-454-3p overexpression reversed the inhibitory action of circ-AK2 in biological functions of trophoblast cells. MiR-454-3p was lowly expressed in placental tissues of PE, and directly regulated THBS2 expression in a targeted manner. Silencing miR-454-3p suppressed the proliferating, migratory, and invasive abilities of trophoblast cells, while this condition was abolished by THBS2 knockdown. Besides, we also proved circ-AK2 could regulate THBS2 expression via miR-454-3p.

DISCUSSION

Circ-AK2 inhibited the proliferation, migration and invasion of trophoblast cells via targeting miR-454-3p/THBS2 axis, suggesting a novel insight into the etiology of PE and a potential therapeutic target for PE treatment.

Circular RNA hsa_circ_0007121 regulates proliferation, migration, invasion, and epithelial-mesenchymal transition of trophoblast cells by miR-182-5p/PGF axis in preeclampsia

Background

Mounting evidence has revealed that abnormal expression of circular RNAs play pivotal roles in many human diseases including preeclampsia (PE). While human sapiens circular RNA 0007121 (hsa_circ_0007121) has been verified to be downregulated in human placental tissues, the underlying mechanisms were still unclear. This research aims to investigate the effect and underlying mechanisms of hsa_circ_0007121 in preeclampsia.

Methods

The expression of hsa_circ_0007121, microRNA (miR)-182-5p, and placental growth factor (PGF) was assessed by quantitative reverse transcription polymerase chain reaction in PE placentas relative to the expression in normal pregnancy placentas. After transfection, cell counting kit-8 assay was employed to detect cell proliferation. Cell migration and invasion were tested by the transwell assay. The relative level of epithelial–mesenchymal transition (EMT)-related proteins in HTR-8/SVneo cells and PGF in placentas samples were measured by western blot. The relationship between miR-182-5p and hsa_circ_0007121 or PGF was predicated by circular RNA interactome or ENCORI and verified by dual-luciferase reporter assay and RNA immunoprecipitation assay.

Results

The levels of hsa_circ_0007121 and PGF were significantly declined in PE placental tissues and HTR-8/SVneo cells, whereas miR-182-5p had an opposite result. Downregulation of hsa_circ_0007121 obviously inhibited HTR-8/SVneo cell proliferation, migration, invasion, and EMT, while upregulation of hsa_circ_0007121 promoted this process. Besides, miR-182-5p was a target gene of hsa_circ_0007121 and could target PGF. Further analysis indicated that hsa_circ_0007121 regulated the proliferation, migration, invasion, and EMT of HTR-8/SVneo cells via altering PGF expression by interacting with miR-182-5p.

Conclusion

Hsa_circ_0007121 mediated the progression of PE via miR-182-5p/PGF axis.

Differentially expressed circular RNAs and the competing endogenous RNA network associated with preeclampsia

INTRODUCTION

Circular RNAs (circRNAs) are non-coding RNAs that are implicated in preeclampsia (PE) pathogenesis; however, their expression and functions in PE remain unclear. In this study, we aimed to investigate the expression of circRNAs in PE and construct a competing endogenous RNA (ceRNA) network, and analyze the associated pathways in PE pathogenesis.

METHODS

We performed circRNA sequencing to identify the differential expression profile of circRNAs in PE as compared to normal pregnancy. The circRNA candidates were validated using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Subsequently, we used datasets from the GEO database to generate the interaction network between circRNAs, microRNAs (miRNAs), and mRNAs. GO and KEGG enrichment analyses were performed to understand the functional significance of the differentially expressed circRNAs in PE.

RESULTS

We identified 361 differentially expressed circRNAs (252 upregulated and 109 downregulated) in preeclamptic placentas. Within the selected 31 circRNAs, 6 of them were verified by qRT-PCR. GO and KEGG analyses revealed the potential pathways affected by these circRNAs, e.g., T cell receptor signaling and MAP kinase pathways. A total of 134 miRNAs and 199 mRNAs were revealed to be differentially expressed in PE by analyzing datasets from the GEO database. The circRNA-miRNA-mRNA network comprised 206 circRNAs, 50 miRNAs, and 38 mRNAs. KEGG analysis of the 38 mRNAs included pathways involved in AMPK and PI3K-Akt signaling.

DISCUSSION

Our results reported the differential expression profile of circRNAs and the circRNA-miRNA-mRNA network in PE, which provides potential therapeutic targets for this disease.

Exosomes released from decidual macrophages deliver miR-153-3p, which inhibits trophoblastic biological behavior in unexplained recurrent spontaneous abortion

BACKGROUND

Spontaneous abortion is a common disease in human pregnancy. Increasing evidence suggests that proper function of trophoblasts and immune balance of the maternal-fetal interface are crucial for successful pregnancy. Macrophages are involved in the maternal-fetal immune microenvironment. However, mechanisms associated with how macrophages impair trophoblasts' function in spontaneous abortion remain to be explored.

METHODS

Firstly, the characteristics of the isolated macrophage-derived exosomes were verified by TEM and Western blot. Then, we established the co-culture of macrophage-derived exosomes with trophoblasts, and explored the role of the exosomes in trophoblasts. Moreover, expression of miR-153-3p in the macrophage-derived exosomes was detected. A miR-153-3p mimic was transfected into trophoblasts to investigate its function in the biological functions of trophoblast cells. MRNA and protein expressions were detected by qRT-PCR and Western blot. CCK8 assay was performed to measure cell proliferation and Transwell assay was utilized to examine migration of trophoblasts.

RESULTS

Compared with those in normal pregnant women, decidual macrophage-derived exosomes from unexplained recurrent spontaneous abortion (URSA) patients suppressed the proliferation and migration of trophoblast cells through the IDO/STAT3 pathway. MiR-153-3p was highly expressed in exosomes released from decidual macrophages of URSA patients. Transfecting miR-153-3p mimics into trophoblast cells directly inhibited IDO genes, which suppressed STAT3 pathway activation, regulating the biological behavior of trophoblast cells.

CONCLUSIONS

This study outlines the role of decidual macrophage-derived exosomal miR-153-3p in successful pregnancy maintenance, paving a new approach for the development of novel treatments for URSA.

Circular RNA-hsa-circ-0000670 promotes gastric cancer progression through the microRNA-384/SIX4 axis

Circular RNAs (circRNAs), a special type of non-coding RNA molecules, have been addressed to be implicated in gastric cancer progression. The GSE93541 and GSE83521 microarrays found hsa-circRNA-000670 (hsa-circ-0000670) as an up-regulated circRNAin gastric cancer. We mainly investigated the function and molecular mechanisms of hsa-circ-0000670 involved in gastric cancer. The expression of hsa-circ-0000670 was determined by RT-qPCR to be highly expressed in gastric cancer tissues relative to corresponding adjacent normal tissues, as well as in gastric cancer cell lines relative to normal gastric mucosal epithelial cell line. By conducting EdU, scratch test and Transwell assays, hsa-circ-000670 was found to be a tumor promoter by potentiating the proliferative, invasive and migrating capabilities of gastric cancer cells. Consistently, a tumor-promotive role of hsa-circ-000670 was validated in vivo. Dual-luciferase reporter gene and RIP assays identified the binding of hsa-circ-0000670 to microRNA-384 (miR-384) and the binding of miR-384 to sine oculis-related homeobox 4 (SIX4). The oncogenic potential of hsa-circ-0000670 in gastric cancer cells were inhibited by overexpressed miR-384. Mechanistically, SIX4 was targeted by miR-384 and was upregulated in gastric cancer. High SIX4 expression was suggested to correlate with the poor prognosis of gastric cancer patients. Additionally, silencing of SIX4 delayed tumor growth and progression, which were reversed by overexpression of hsa-circ-0000670. Taken together, hsa-circ-0000670 acts as a tumor promotor in gastric cancer progression and might be a potential target for gastric cancer treatment.

Suppression of Circular RNA Hsa_circ_0109320 Attenuates Non-Small Cell Lung Cancer Progression via MiR-595/E2F7 Axis

Background

Circular RNAs (circRNAs) are frequently aberrantly expressed in non-small cell lung cancer (NSCLC) and are considered to exert a pivotal role in the occurrence and development of NSCLC via targeting and negatively regulating microRNAs (miRNAs). We aimed to investigate the role of hsa_circ_0109320 in the proliferation, invasion and apoptosis of NSCLC, and explore its underlying molecular mechanism.

Material/Methods

Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis was performed to determine the circ_0109320 and miR-595 expression in tissues or cells. Western blot analysis was conducted to examine the cleaved caspase-3, Bax, Bcl-2, and E2F7 protein expression. Transwell detection was used to evaluate the invasion level of NSCLC cell lines.

Results

The results of present study indicated that circ_0109320 expression in NSCLC patients was upregulated significantly in tumor tissues compared with tissues adjacent to carcinoma. Upregulated circ_0109320 level was significantly associated with TNM stages as well as lymph node metastasis of NSCLC. Moreover, downregulation of circ_0109320 attenuated proliferation and invasion while promoting apoptosis in NSCLC cells. We further confirmed that circ_0109320 could sponge miR-595 to upregulate E2F7 expression. Silencing of miR-595 or overexpression of E2F2 could partially reversed the inhibitory role of circ_0109320 knockdown in NSCLC cells. These data provided evidence that the suppression of circ_0109320 attenuates NSCLC cell proliferation and invasion and enhances apoptosis through the miR-595/E2F7 pathway.

Conclusions

Circ_0109320/miR-595/E2F2 axis may exert a pivotal role in the pathological mechanism of NSCLC progression, and it has potential application in the future treatment of NSCLC.

MiR-384 inhibits proliferation and migration of trophoblast cells via targeting PTBP3

Preeclampsia (PE) is one type of hypertension during pregnancy that seriously threatens maternal and infant health. Trophoblast dysfunction, such as decreased proliferation and migration, is closely related to the occurrence and development of PE. MicroRNAs (miRNAs) have been proven to play an important role in many diseases, including PE. miR-384 was reported to play a regulatory role in promoting cell apoptosis and inhibiting proliferation, migration and invasion in a variety of tumors. Previously, we found that miR-384 is upregulated in the placenta and plasma in the context of PE. In this study, we elucidated the function of miR-384 in the trophoblast cell line HTR-8/SVneo and the trophoblastic tumor cell line JEG-3. Cell proliferation and migration were inhibited by miR-384 overexpression but promoted by miR-384 downregulation. Subsequently, polypyrimidine tract-binding protein 3(PTBP3) was found to be a direct target gene of miR-384. PTBP3 was downregulated in placental tissues from PE patients, and a negative correlation was found between PTBP3 and miR-384. Our results suggest that the miR-384/PTBP3 axis plays an important role in regulating trophoblast function during the progression of PE, and these data provide novel insight into the molecular pathogenesis of this disorder.

The Role of LIN28-let-7-ARID3B Pathway in Placental Development

Placental disorders are a major cause of pregnancy loss in humans, and 40–60% of embryos are lost between fertilization and birth. Successful embryo implantation and placental development requires rapid proliferation, invasion, and migration of trophoblast cells. In recent years, microRNAs (miRNAs) have emerged as key regulators of molecular pathways involved in trophoblast function. A miRNA binds its target mRNA in the 3ʹ-untranslated region (3ʹ-UTR), causing its degradation or translational repression. Lethal-7 (let-7) miRNAs induce cell differentiation and reduce cell proliferation by targeting proliferation-associated genes. The oncoprotein LIN28 represses the biogenesis of mature let-7 miRNAs. Proliferating cells have high LIN28 and low let-7 miRNAs, whereas differentiating cells have low LIN28 and high let-7 miRNAs. In placenta, low LIN28 and high let-7 miRNAs can lead to reduced proliferation of trophoblast cells, resulting in abnormal placental development. In trophoblast cells, let-7 miRNAs reduce the expression of proliferation factors either directly by binding their mRNA in 3ʹ-UTR or indirectly by targeting the AT-rich interaction domain (ARID)3B complex, a transcription-activating complex comprised of ARID3A, ARID3B, and histone demethylase 4C (KDM4C). In this review, we discuss regulation of trophoblast function by miRNAs, focusing on the role of LIN28-let-7-ARID3B pathway in placental development.

Circular RNA hsa_circ_0000848 Promotes Trophoblast Cell Migration and Invasion and Inhibits Cell Apoptosis by Sponging hsa-miR-6768-5p

Background

Fetal growth restriction (FGR) is a worldwide problem, and a major cause of perinatal morbidity. The precise molecular mechanisms involved in placental development and function during FGR remain poorly understood. Circular RNAs (circRNAs) are important biological molecules associated with disease pathogenesis. However, the role of circRNAs in FGR has not been well studied.

Methods

circRNA expression profiles in placental tissues with and without FGR were identified by circRNA microarray. circRNA expression was verified by quantitative reverse-transcription PCR (RT-qPCR) assay. The effect of hsa_circ_0000848 and hsa-miR-6768-5p on HTR-8 cell apoptosis, migration, and invasion was evaluated. The association between hsa_circ_0000848 and hsa-miR-6768-5p was confirmed by dual luciferase activity and anti-AGO2 RNA immunoprecipitation (RIP) assays. Protein levels were examined via western blotting.

Results

RT-qPCR results showed that hsa_circ_0000848 expression was significantly down-regulated in FGR placenta. Hsa_circ_0000848 overexpression and hsa-miR-6768-5p inhibitor suppressed apoptosis, and promoted cell migration and invasion. In addition, hsa_circ_0000848 overexpression and hsa-miR-6768-5p inhibitor increased the protein abundance of BCL2, MMP2 and MMP9, and decreased the protein abundance of cleaved caspase-3, cleaved caspase-9, and BAX, whereas hsa_circ_0000848 knockdown caused the opposite effect. Moreover, a significant increase in hsa-miR-6768-5p expression and a negative correlation between hsa_circ_0000848 and hsa-miR-6768-5p were identified in the FGR tissues. Luciferase reporter and RIP assay results revealed binding of hsa-miR-6768-5p to hsa_circ_0000848. Furthermore, hsa-miR-6768-5p overexpression eliminated the effect of hsa_circ_0000848 overexpression in HTR-8 cells.

Conclusions

hsa_circ_0000848 expression is significantly down-regulated in the FGR placenta. hsa_circ_0000848 promotes trophoblast cell migration and invasion, and inhibits cell apoptosis via the sponging of hsa-miR-6768-5p. Our study provided a novel insight into mechanisms underlying the pathogenesis of FGR, as well as into new strategies for the treatment of FGR.

CircZDHHC20 represses the proliferation, migration and invasion in trophoblast cells by miR-144/GRHL2 axis

Background

Preeclampsia (PE) is a prevalent pregnancy disorder that has been one of the leading causes of maternal and perinatal mortality worldwide. Circular RNAs (circRNAs) have recently considered as important regulators in PE pathogenesis. In the current study, we aimed to explore the impact and mechanisms of circRNA zinc finger DHHC-type palmitoyltransferase 20 (circZDHHC20) in PE pathogenesis.

Methods

RNase R assay and reverse transcription with Oligo(dT)₁₈ primers were performed to confirm that circZDHHC20 was indeed circular transcript. The expression of circZDHHC20, grainyhead-like 2 (GRHL2) and miR-144 were assessed by quantitative real-time polymerase chain reaction (qRT-PCR). Subcellular localization assay was used to determine whether circZDHHC20 was predominantly present in the cytoplasm. The target correlations between miR-144 and circZDHHC20 or GRHL2 were confirmed using dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Cell proliferation, migration, and invasion were detected by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetr-azolium (MTS), wound healing and transwell assays, respectively. Western blot was used for the quantification of GRHL2 protein level.

Results

Our data indicated that circZDHHC20 was up-regulated and miR-144 was down-regulated in PE placenta. CircZDHHC20 sequestered miR-144 by acting as a miR-144 sponge. CircZDHHC20 overexpression repressed trophoblast cell proliferation, migration, and invasion, while its knockdown exerted opposite effects. Moreover, miR-144 mediated the regulation of circZDHHC20 on trophoblast cell behaviors. GRHL2 was directly targeted and inhibited by miR-144. MiR-144 exerted regulatory effects on trophoblast cell proliferation, migration and invasion by GRHL2. Furthermore, circZDHHC20 modulated GRHL2 expression through sponging miR-144.

Conclusion

Our study suggested that a high level of circZDHHC20 inhibited the proliferation, migration, and invasion in trophoblast cells at least partially through sponging miR-144 and up-regulating GRHL2, providing a novel mechanism of PE pathogenesis.