hsa_circ_0000745 promotes cervical cancer by increasing cell proliferation, migration, and invasion

Research progress of circular RNAs in myocardial ischemia

Circular RNAs (circRNAs) are a type of single-stranded RNA that forms a covalently closed continuous loop. Its structure, stability, properties, and cell- and tissue-specificity have gained considerable recognition in the research and clinical sectors, as its role has been observed in different diseases, such as cardiovascular diseases, cancers, and central nervous system diseases, etc. Cardiovascular disease is still named as the number one cause of death globally, with myocardial ischemia (MI) accounting for 15 % of mortality annually. A number of circRNAs have been identified and are being studied for their ability to reduce MI by inhibiting the molecular mechanisms associated with myocardial ischemia reperfusion injury, such as inflammation, oxidative stress, autophagy, apoptosis, and so on. CircRNAs play a significant role as crucial regulatory elements at transcriptional levels, regulating different proteins, and at posttranscriptional levels, having interactions with RNA-binding proteins, ribosomal proteins, micro-RNAS, and long non-coding RNAS, making it possible to exert their effects through the circRNA-miRNA-mRNA axis. CircRNAs are a potential novel biomarker and therapeutic target for myocardial ischemia and cardiovascular diseases in general. The purpose of this review is to summarize the relationship, function, and mechanism observed between circRNAs and MI injury, as well as to provide directions for future research and clinical trials.

Bibliometric Analysis of Global Research on Circular RNA: Current Status and Future Directions

Circular RNAs (circRNAs) have gained significant attention in recent years. This bibliometric analysis aimed to provide insights into the current state and future trends of global circRNA research. The scientific output on circRNAs from 2010 to 2022 was retrieved from the Web of Science Core Collection with circRNA-related terms as the subjects. Key bibliometric indicators were calculated and evaluated using CiteSpace. A total of 7385 studies on circRNAs were identified. The output and citation number have increased rapidly after 2015. China, the USA, and Germany were top three publishing countries. Currently, circCDR1as, circHIPK3, circPVT1, circSHPRH, and circZNF609 are the most studied circRNAs; and all are related to cancer. The theme of research have shifted from transcript, exon circularization and miRNA sponge topics to the transcriptome, tumor suppressor, and biomarkers, indicating that research interests have evolved from basic to applied research. CircRNAs will continue to be a highly active research area in the near future. From the current understanding of circRNA characterization and regulatory mechanisms as miRNA sponges in cancer, future directions may examine potential diagnostic and therapeutic roles of circRNAs in cancers or the function and mechanism of circRNAs in other diseases.

circZNF532 promotes endothelial-to-mesenchymal transition in diabetic retinopathy by recruiting TAF15 to stabilize PIK3CD

Endothelial-to-mesenchymal transition (EndMT) is a pivotal event in diabetic retinopathy (DR). This study explored the role of circRNA zinc finger protein 532 (circZNF532) in regulating EndMT in DR progression. Human retinal microvascular endothelial cells (HRMECs) were exposed to high glucose (HG) to induce the DR cell model. Actinomycin D-treated HRMECs were used to confirm the mRNA stability of phosphoinositide-3 kinase catalytic subunit δ (PIK3CD). The interaction between TATA-box-binding protein-associated factor 15 (TAF15) and circZNF532/PIK3CD was subsequently analyzed using RNA immunoprecipitation (RIP), RNA pull-down. It was found that HG treatment accelerated EndMT process, facilitated cell migration and angiogenesis, and enhanced PIK3CD and p-AKT levels in HRMECs, whereas si-circZNF532 transfection neutralized these effects. Further data showed that circZNF532 recruited TAF15 to stabilize PIK3CD, thus elevating PIK3CD expression. Following rescue experiments suggested that PIK3CD overexpression partially negated the inhibitory effect of circZNF532 silencing on EndMT, migration, and angiogenesis of HG-treated HRMECs. In conclusion, our results suggest that circZNF532 recruits TAF15 to stabilize PIK3CD, thereby facilitating EndMT in DR.

CircVIRMA enhances cell malignant behavior by governing the miR-452-5p/CREBRF pathway in cervical cancer

Our current study aimed to investigate the role and mechanism of circVIRMA in cervical cancer (CC) progression. CircVIRMA, microRNA-452-5p (miR-452-5p) and CREB3 regulatory factor (CREBRF) mRNA levels were examined in CC via quantitative real-time PCR (qRT-PCR). The protein level of CREBRF in CC was checked by Western blot. Cell Counting Kit-8 (CCK-8), colony formation, 5-Ethynyl-2'-deoxyuridine (EdU) staining, cell cycle, flow cytometry and transwell assays were conducted to estimate the effects of circVIRMA on malignant phenotypes of CC tumors. Western blot was used to measure related marker protein levels. The interaction between miR-452-5p and circVIRMA or CREBRF was predicted by bioinformatics analysis and verified by dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays. Xenograft assay was used to assess the effect of circVIRMA on tumor growth in vivo. Immunohistochemistry (IHC) assay was performed to detect Ki-67 expression in tissues of mice. CircVIRMA and CREBRF levels were upregulated, while miR-452-5p was downregulated in CC tissues and cells. CircVIRMA silencing restrained CC cell proliferation, migration and invasion whereas induced apoptosis in vitro. In addition circVIRMA knockdown markedly attenuated xenograft tumor growth in vivo. circVIRMA was an efficient molecular sponge for miR-452-5p, and negatively regulated miR-452-5p expression. circVIRMA regulated CREBRF expression to modulate CC progression via miR-452-5p. MiR-452-5p downregulation reversed the effects of circVIRMA knockdown on CC progression. MiR-452-5p directly targeted CREBRF, and CREBRF overexpression partly restored the impact of miR-452-5p mimics on CC progression. circVIRMA mediated CC progression via regulating miR-452-5p/CREBRF axis, providing a novel therapeutic target for CC treatment.

Hsa_circ_0000069 Accelerates Cervical Cancer Progression by Sponging miR-1270 to Facilitate CPEB4 Expression

The critical importance of circular RNAs (circRNAs) in human cancers, including cervical cancer (CC), has been discovered in recent years. However, the function and mechanism of hsa_circ_0000069 (circ_0000069) in CC have been fully understood. The expression levels of circ_0000069, microRNAs (miR-1270, miR-1276 and miR-620) and cytoplasmic polyadenylation element binding protein 4 (CPEB4) mRNA were detected by quantitative real time polymerase chain reaction (qRT-PCR). Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, wound healing, transwell and tube formation assays were used to clarify the effects of circ_0000069 on the functional behaviors of CC cells. The binding relationships among miR-1270, circ_0000069 and CPEB4 were detected by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. A xenograft tumor model was established to explore the effect of circ_0000069 on tumor growth in vivo. Circ_0000069 was upregulated in CC clinical samples and cell lines, and its expression was associated with the clinical stage of CC patients. Circ_0000069 knockdown significantly decreased cell proliferation, invasion, migration, and tube formation and increased cell apoptosis in vitro. Moreover, miR-1270 was a direct target of circ_0000069, and CPEB4 was the downstream target of miR-1270. Knockdown of miR-1270 reversed the inhibitory effect of circ_0000069 knockdown on CC progression, and CPEB4 overexpression overturned the effect of miR-1270 on CC progression. In xenograft experiments, the oncogenic effect of circ_0000069 on tumor growth was verified. Altogether, circ_0000069 adsorbed miR-1270 to upregulate CPEB4 expression, thereby promoting the malignant phenotypes of CC cells. Circ_0000069 might be a potential target for treatment of CC.

Circular RNAs in EMT-driven metastasis regulation: modulation of cancer cell plasticity, tumorigenesis and therapy resistance

The non-coding RNAs comprise a large part of human genome lack of capacity in encoding functional proteins. Among various members of non-coding RNAs, the circular RNAs (circRNAs) have been of importance in the pathogenesis of human diseases, especially cancer. The circRNAs have a unique closed loop structure and due to their stability, they are potential diagnostic and prognostic factors in cancer. The increasing evidences have highlighted the role of circRNAs in the modulation of proliferation and metastasis of cancer cells. On the other hand, metastasis has been responsible for up to 90% of cancer-related deaths in patients, requiring more investigation regarding the underlying mechanisms modulating this mechanism. EMT enhances metastasis and invasion of tumor cells, and can trigger resistance to therapy. The cells demonstrate dynamic changes during EMT including transformation from epithelial phenotype into mesenchymal phenotype and increase in N-cadherin and vimentin levels. The process of EMT is reversible and its reprogramming can disrupt the progression of tumor cells. The aim of current review is to understanding the interaction of circRNAs and EMT in human cancers and such interaction is beyond the regulation of cancer metastasis and can affect the response of tumor cells to chemotherapy and radiotherapy. The onco-suppressor circRNAs inhibit EMT, while the tumor-promoting circRNAs mediate EMT for acceleration of carcinogenesis. Moreover, the EMT-inducing transcription factors can be controlled by circRNAs in different human tumors.

Riddle of the Sphinx: Emerging role of circular RNAs in cervical cancer

Cervical cancer is a prominent cause of cancer-related mortality among women, with recent attention directed toward exploring the involvement of circular RNAs (circRNAs) in this particular cancer. CircRNAs, characterized by a covalently closed loop structure, belong to a class of single-stranded non-coding RNA (ncRNA) molecules that play crucial roles in cancer development and progression through diverse mechanisms. The abnormal expression of circRNAs in vivo is significantly associated with the development of cervical cancer. Notably, circRNAs actively interact with miRNAs in cervical cancer, leading to the regulation of diverse signaling pathways, and they can contribute to cancer hallmarks such as self-sufficiency in growth signals, insensitivity to antigrowth signals, limitless proliferation, evading apoptosis, tissue invasion and metastasis, and sustained angiogenesis. Moreover, the distinctive biomedical attributes exhibited by circRNAs, including their abundance, conservation, and stability in body fluids, position them as promising biomarkers for various cancers. In this review, we elucidate the tremendous potential of circRNAs as diagnostic markers or therapeutic targets in cervical cancer by expounding upon their biogenesis, characteristics, functions, and databases, highlighting the novel advances in the signaling pathways associated with circRNAs in cervical cancer.

Interference of the Circular RNA Sperm Antigen With Calponin Homology and Coiled-Coil Domains 1 Suppresses Growth and Promotes Apoptosis of Breast Cancer Cells Partially Through Targeting miR-1236-3p/Chromobox 8 Pathway

Noncoding RNAs and RNA modifiers are implicated in cancer radiotherapy. Here, we aimed to investigate the role of sperm antigen with calponin homology and coiled-coil domains 1 (SPECC1)-derived circular RNA (circSPECC1; hsa_circ_0000745) in breast cancer (BC) cells under radiation treatment. Based on quantitative real-time PCR, circSPECC1 was highly upregulated in BC patients' tumors and cells, and circSPECC1 expression was further increased with the dosage of radiation in BC cells. Moreover, circSPECC1 upregulation was found to be concomitant with higher chromobox 8 (CBX8) and lower microRNA (miR)-1236-3p expression. Functionally, 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide (MTT), 5-ethynyl-2'-deoxyuridine (EdU) and colony formation assays showed that circSPECC1 interference suppressed cell proliferation and long-term survival in BC cells and irradiated BC cells. Xenograft tumor model experiments showed that circSPECC1 knockdown restrained BC tumor growth in vivo. Meanwhile, flow cytometry assay and western blotting revealed an enhanced apoptosis by silencing circSPECC1. Moreover, miR-1236-3p overexpression, similar to circSPECC1 silencing, displayed anti-growth and proapoptosis roles in irradiated BC cells. Mechanistically, dual-luciferase reporter assay and RNA immunoprecipitation assay identified a target relationship between miR-1236-3p and circSPECC1 or CBX8. Also, CBX8 expression could be modulated by circSPECC1 via miR-1236-3p regulation. Collectively, we indicated that inhibiting circSPECC1 could suppress growth and promote apoptosis of BC cells in both irradiated and nonirradiated conditions at least partially via miR-1236-3p/CBX8 axis, confirming that circSPECC1 might be target to develop anticancer drug in BC.

Circ_0051428 targeting miR-885-3p/MMP2 axis enhances the malignancy of cervical cancer

Circular RNAs (circRNAs) are key regulators of cervical cancer (CC) progression. This study aimed to elucidate the role and mechanism of circ_0051428, a novel circRNA, in CC tumorigenesis. Quantitative real-time polymerase chain reaction and western blotting analyses confirmed that circ_0051428 and matrix metalloprotein-2 (MMP2) were overexpressed in CC, whereas the microRNA miR-885-3p was poorly expressed. After performing a series of in vitro and in vivo experiments, circ_0051428 knockdown was shown to repress CC cell invasion and proliferation in vitro, and hamper tumor formation in vivo. Dual-luciferase reporter and RNA-binding protein immunoprecipitation experiments verified that circ_0051428 interacts with miR-885-3p to regulate the target gene MMP2 of miR-885-3p in CC. In addition, miR-885-3p knockdown offset the anticancer effects of circ_0051428 or MMP2 knockdown on CC cell malignancy. Overall, this study revealed that circ_0051428 executes a tumor-promoting function in CC pathogenesis by modulating the miR-885-3p/MMP2 axis. Our findings provide a novel approach for CC treatment.

Circular RNA in cervical cancer: Fundamental mechanism and clinical potential

CC (CC) remains a significant global health concern, imposing a substantial health burden on women worldwide due to its high incidence and mortality rates. To address this issue, there is a need for ongoing research to uncover the underlying molecular mechanisms of CC and to discover novel diagnostic and therapeutic strategies. Recent progress in non-coding RNAs (ncRNAs) has opened new avenues for investigation, and circular RNAs (circRNAs) have emerged as molecules with diverse roles in various cellular processes. These circRNAs are distinct in structure, forming a closed loop, setting them apart from their linear counterparts. They are intricately involved in regulating different aspects of cellular functions, particularly in cell growth and development. Remarkably, circRNAs can have varying functions, either promoting or inhibiting oncogenic processes, depending on the specific cellular context. Recent studies have identified abnormal circRNAs expression patterns associated with CC, indicating their significant involvement in disease development. The differing circRNAs profiles linked to CC present promising opportunities for early detection, precise prognosis evaluation, and personalized treatment strategies. In this comprehensive review, we embark on a detailed exploration of CC-related circRNAs, elucidating their distinct roles and providing insights into the intricate molecular mechanisms governing CC's onset and progression. A growing body of evidence strongly suggests that circRNAs can serve as valuable biomarkers for early CC detection and hold potential as therapeutic targets for intervention. By delving into the complex interplay between circRNAs and CC, we are paving the way for innovative, individualized approaches to combat this serious disease, with the goal of reducing its impact on women's health globally and improving patient outcomes. As our understanding of circRNAs in the context of CC continues to deepen, the outlook for breakthroughs in diagnosis and treatment becomes increasingly promising.

Circ_BLNK is a Unique Molecular Marker in Non-small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) patients are characterized by distant metastasis and poor prognosis. Growing evidence has implied that circular RNAs (circRNAs) are involved in multiple tumor progression, including NSCLC. The objective of the present study was to functionally dissect the role and mechanism of circ_BLNK in NSCLC development and progression. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect the expression of circ_BLNK, miR-942-5p, and forkhead box protein O1 (FOXO1) in NSCLC tissues and cells. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay and colony formation assay detected cell proliferation; the protein expression levels were tested by western blot assay; cell apoptosis was measured by flow cytometry, and transwell assay detected cell migration and invasion. The molecular targeting relationship was determined by dual-luciferase reporter assay. The effect of circ_BLNK overexpression on tumor growth was detected by in vivo experiments and immunohistochemistry. Circ_BLNK was dramatically decreased in NSCLC, and overexpression of circ_BLNK inhibited proliferation, migration, and invasion of NSCLC cells and promoted cell apoptosis. Circ_BLNK level was negatively correlated with miR-942-5p expression and positively correlated with FOXO1 expression. Moreover, circ_BLNK acted as a sponge for miR-942-5p, which targeted FOXO1. Rescue assays presented that miR-942-5p reversed the anticancer action of circ_BLNK in NSCLC. Besides that, miR-942-5p inhibition suppressed the oncogenic behaviors, which were attenuated by FOXO1 knockdown. Animal experiments exhibited that circ_BLNK upregulation repressed tumor growth in vivo. Our study demonstrated a novel regulatory mechanism that circ_BLNK/miR-942-5p/FOXO1 axis adjusted non-small cell lung cancer development.

Circular RNAs and cervical cancer: friends or foes? A landscape on circRNA-mediated regulation of key signaling pathways involved in the onset and progression of HPV-related cervical neoplasms

Cervical cancer (CC) is a common gynecologic malignancy, accounting for a significant proportion of women death worldwide. Human papillomavirus (HPV) infection is one of the major etiological causes leading to CC onset; however, genetic, and epigenetic factors are also responsible for disease expansion. Circular RNAs (circRNAs), which are known as a particular subset of non-coding RNA (ncRNA) superfamily, with covalently closed loop structures, have been reported to be involved in the progression of diverse diseases, especially neoplasms. In this framework, abnormally expressed circRNAs are in strong correlation with CC pathogenesis through regulating substantial signaling pathways. Also, these RNA molecules can be considered as promising biomarkers and therapeutic targets for CC diagnosis/prognosis and treatment, respectively. Herein, we first review key molecular mechanisms, including Wnt/β-catenin, MAPK, and PI3K/Akt/mTOR signaling pathways, as well as angiogenesis and metastasis, by which circRNAs interfere with CC development. Then, diagnostic, prognostic, and therapeutic potentials of these ncRNA molecules will be highlighted in depth.

Y-box protein-1 modulates circSPECC1 to promote glioma tumorigenesis via miR-615-5p/HIP1/AKT axis

Y-box binding protein-1 (YB-1) is upregulated in glioma and plays an important role in its occurrence and drug resistance. However, the involved regulatory processes and downstream pathways are still unclear. Since various circular RNAs (circRNAs) and microRNAs (miRNAs) also play roles in the pathogenesis of glioma, we hypothesize that YB-1 may exert its function through a circRNA-miRNA-protein interaction network. In this study, we use the RNA binding protein immunoprecipitation assay and quantitative reverse transcription polymerase chain reaction to determine the circRNAs involved in the regulation of YB-1 and further elucidate their biological functions. The level of circSPECC1 (hsa_circ_0000745) modulated by YB-1 is significantly upregulated in the U251 and U87 glioma cell lines. Downregulation of circSPECC1 markedly inhibits the proliferation and invasiveness of U251 and U87 cells by inducing apoptosis. Bioinformatics analysis reveals that miR-615-5p could interact with circSPECC1 and huntingtin-interacting protein-1 (HIP-1). Then we determine the interactions between miR-615-5p, circSPECC1, and HIP1 using dual luciferase reporter system and pull-down assays. Mechanistic analysis indicates that the downregulation of circSPECC1 results in a decreased HIP1 expression. This study demonstrates that circSPECC1 modulated by YB-1 is increased in glioma cell lines. In addition, circSPECC1 promotes glioma growth through the upregulation of HIP1 by sponging miR-615-5p and targeting the HIP1/AKT pathway. This indicates that YB-1 and circSPECC1 may both be promising targets for glioma treatment.

Hsa_circ_0000078 Regulates miR-205-5p/EREG Pathway to Inhibit Cervical Cancer Progression

It is well established that circular RNAs (circRNAs) play a role in tumor initiation and tumorigenesis. The goal of this study was to reveal the detailed functions and regulatory mechanisms of circ_0000078 in cervical cancer (CC). Circ_0000078, miR-205-5p, and epiregulin (EREG) mRNA expression levels were examined using RT-qPCR. Western blotting was performed to quantify EREG protein. Cell proliferation, apoptosis, migration, and invasion were examined by performing CCK-8, caspase 3 activity, wound healing, and transwell assays, respectively. The effect of circ_0000078 on tumor growth in vivo was confirmed in a xenograft model. The putative relationship between miR-205-5p and circ_0000078 or EREG, as predicted by bioinformatics analysis, was evaluated by dual-luciferase and RNA immunoprecipitation assays. Aberrant downregulation of circ_0000078 and EREG as well as upregulation of miR-205-5p were observed in cervical tumor samples and cancer cells. Ectopic expression of circ _0000078 not only restrained cancer cell growth, survival, migration, and invasiveness, but also decelerated tumor formation and development in a mouse model. miR-205-5p, acts as a target of circ_0000078 and directly binds to EREG to repress its expression. Overexpression of miR-205-5p reversed the inhibitory effects of circ_0000078 upregulation on cancer cell behavior and also partially abolished the anti-cancer effects of EREG upregulation in vitro. Circ_0000078 inhibits the growth of cancer by interfering with the miR-205-5p/EREG network, acting as a tumor suppressor in CC. These results provide a better understanding of the pathogenesis of this disease.

Circular RNA circ_0000119 promotes cervical cancer cell growth and migration via miR-433-3p/PAK2 axis

The purpose of this study was to investigate the role of circ_0000119 on CC progression and its molecular mechanism. The expression levels of circ_0000119, miR-433-3p, and p21-activated kinase 2 (PAK2) in CC tissues and cell lines were measured by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was assessed using 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay, 5-Ethynyl-2'-deoxyuridine (EdU) assay and colony formation assay. Cell cycle and apoptosis were assessed by flow cytometry. Cell migration and invasive ability were examined by Transwell assays. Downstream binding targets of circ_0000119 were predicted by online bioinformatics tools and confirmed by dual luciferase reporter gene assay, RNA immunoprecipitation (RIP) assay, and RNA pull-down assay. The role of circ_0000119/miR-433-3p/PAK2 axis in regulating the CC process was explored by rescue experiments. A xenograft model was constructed to further determine the effect of circ_0000119 on CC tumor growth in vivo. Immunohistochemistry (IHC) assay was conducted for Ki67 expression. Circ_0000119 was aberrantly upregulated in CC tissues and cell lines. Knockdown of circ_0000119 inhibited CC cell proliferation, cell cycle progress, migration, invasion, and promoted apoptosis of CC cells. MiR-433-3p was a binding target of circ_0000119, and PAK2 was a downstream gene of miR-433-3p. MiR-433-3p inhibition reversed the inhibitory effect of silencing circ_0000119 on CC progression. In addition, PAK2 overexpression reversed the effect of miR-433-3p on CC progression. PAK2 expression was regulated by circ_0000119 and miR-433-3p. Moreover, circ_0000119 knockdown reduced tumor growth of CC in vivo. Circ_0000119 was upregulated in CC, and circ_0000119 knockdown suppressed CC malignant development through the miR-433-3p/PAK2 axis.

CircRNA hsa_circ_0001627 aggravates cervical cancer progression through upregulation of FNDC3B and activating PI3K/mTOR signaling pathway

Circular RNAs (CircRNAs) are key regulators in the development and progression of human cancers. However, the biological roles and mechanisms of circRNAs in gastric cancer (GC) remain largely unknown. Analyzing circRNA microarray dataset (GSE102686) and clinical specimens, a novel circRNA termed hsa_circ_0001627, was identified and it was highly expressed in CC cancerous tissues and cells, and was associated with poor clinical outcomes. Functionally, hsa_circ_0001627 silencing impaired the malignant progression of CC cells and the growth of CC xenografts in nude mice. Mechanistically, hsa_circ_0001627 acted as a miR-1225-5p sponge, thus indirectly regulating FNDC3B and leading to the activation of PI3K/mTOR signaling pathway. Collectively, the present study indicates that hsa_circ_0001627 regulates miR-1225-5p/FNDC3B/PI3K/mTOR axis and functions as an oncogene in CC progression, suggesting the potential therapeutic use of hsa_circ_0001627 in CC treatment.

CircRNA hsa_circ_0075048 promotes the malignant progression of non-small cell lung cancer by up-regulating HMGB2 expression via targeting miR-1225-5p

BACKGROUND

Non-small cell lung cancer (NSCLC) is one of the most common forms of lung cancer. Circular RNAs (circRNAs) have been recognized that can be used as novel molecular markers for cancer therapy. Here, we attempted to identify the role of hsa_circRNA_0075048 (circ_0075048) in NSCLC.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to analyze the levels of hsa_circ_0075048, miR-1225-5p and high mobility group box-2 (HMGB2). Cell proliferation was detected by Cell Counting Kit 8 (CCK8) and 5-Ethynyl-2'-deoxyuridine (EdU) assays. Flow cytometry was used to detect apoptosis. Transwell assay was used to assess cell migration and invasion. Sphere formation ability was tested by cell pellet test. The protein expression levels were detected by western blot and immunohistochemistry. Dual-luciferase reporter assay, RNA-pull down and RNA immunoprecipitation (RIP) assays were used to verify the targeting relationships between miR-1225-5p and circ_0075048 or HMGB2. Mice tumor models were constructed to ascertain the effects of circ_0075048 on tumor growth in vivo.

RESULTS

Circ_0075048 was increased in NSCLC tissues and cells. NSCLC cell proliferation, migration, invasion and sphere formation ability were decreased by circ_0075048 knockdown, and cell apoptosis was induced. Downregulation of miR-1225-5p recuperated the effects of circ_0075048 knockdown on NSCLC progression. The effects of miR-1225-5p on cell proliferation, apoptosis, migration, invasion and sphere formation were attenuated by HMGB2 overexpression.

CONCLUSION

This study indicated that circ_0075048 played an oncogenic role in the development of NSCLC by regulating miR-1225-5p and HMGB2. The data provide more possibilities for the treatment of NSCLC.

Circ_0042986 Presence Restrains Cervical Cancer Development via Upregulating PEG3 by Directly Targeting miR-582-3p

The participation of circular RNAs (circRNAs) in carcinogenesis is widely established. Numerous circRNAs with aberrant expression in cervical cancer (CC) are identified by RNA sequencing, whereas the function of these circRNAs remains unclear. We thus aimed to unveil the effects and mechanisms of circ_0042986 in CC. Circ_0042986 with aberrant downregulation in CC was obtained from GSE10286 dataset. qPCR and western blotting were employed for the detection of circ_0042986, miR-582-3p, and paternally expressed 3 (PEG3) expressions. EdU assay, colony formation assay, wound healing assay, transwell assay, tube formation assay, and flow cytometry assay were applied for functional analyses. The potential binding site was ensured by dual-luciferase reporter analysis, and their binding relationship was verified by pull-down assay. The transplanted tumor models were constructed for in vivo function verification of circ_0042986. Our findings exposed that the downregulation of circ_0042986 was verified in clinical CC samples. Circ_0042986 overexpression largely attenuated CC cell growth, invasiveness, angiogenesis, and survival. MiR-582-3p was targeted by circ_0042986, and the inhibitory roles of circ_0042986 presence were partly abolished by miR-582-3p enrichment. MiR-582-3p combined with PEG3, and circ_0042986 increased PEG3 expression via decoying miR-582-3p. The interaction between miR-582-3p and PEG3 on CC cell functions was confirmed, evidenced by the reversal effects of PEG3 knockdown on miR-582-3p deficiency-inhibited cancer cell malignant behaviors. Circ_0042986 overexpression also limited tumorigenesis of CC in animal models. In summary, circ_0042986 overexpression decoyed miR-582-3p to increase PEG3 expression, thereby blocking the malignant progression of CC.

Serum hsa_circ_0000615 is a prognostic biomarker of sorafenib resistance in hepatocellular carcinoma

BACKGROUND

Circular RNAs (circRNAs) can shape tumor progression and chemoresistance. How specific circRNAs shape hepatocellular carcinoma (HCC) chemoresistance, however, remains to be fully elucidated.

METHODS

In total, serum samples were collected from 202 HCC patients that had completed four sorafenib chemotherapy cycles. Serum hsa_circ_0000615 levels in these patients were quantified via quantitative real-time polymerase chain reaction (qRT-PCR), with demographic details and survival outcomes being recorded for subsequent analyses.

RESULTS

We found hsa_circ_0000615 to be significantly upregulated in chemoresistant HCC patients relative to chemosensitive patients, with such upregulation being positively correlated with disease stage. Moreover, the area under the curve (AUC) value for hsa_circ_0000615 was moderately good, and high levels of hsa_circ_0000615 expression were associated with shorter overall survival among chemoresistant HCC patients.

CONCLUSION

Our results highlight hsa_circ_0000615 as a promising driver of sorafenib resistance in HCC patients, highlighting it as a promising target for the treatment of this deadly cancer type.

Identification of a dysregulated CircRNA-associated gene signature for predicting prognosis, immune landscape, and drug candidates in bladder cancer

Increasing evidences have demonstrated that circular RNA (circRNAs) plays a an essential regulatory role in initiation, progression and immunotherapy resistance of various cancers. However, circRNAs have rarely been studied in bladder cancer (BCa). The purpose of this research is to explore new circRNAs and their potential mechanisms in BCa. A novel ceRNA-regulated network, including 87 differentially expressed circRNAs (DE-circRNAs), 126 DE-miRNAs, and 217 DE-mRNAs was constructed to better understanding the biological processes using Cytoscape 3.7.1 based on our previously high-throughput circRNA sequencing and five GEO datasets. Subsequently, five randomly selected circRNAs (upregulated circ_0001681; downregulated circ_0000643, circ_0001798, circ_0006117 and circ_0067900) in 20 pairs of BCa and paracancerous tissues were confirmed using qRT-PCR. Functional analysis results determined that 772 GO functions and 32 KEGG pathways were enriched in the ceRNA network. Ten genes (PFKFB4, EDNRA, GSN, GAS1, PAPPA, DTL, TGFBI, PRSS8, RGS1 and TCF4) were selected for signature construction among the ceRNA network. The Human Protein Atlas (HPA) expression of these genes were consistent with the above sequencing data. Notably, the model was validated in multiple external datasets (GSE13507, GSE31684, GSE48075, IMvigor210 and GSE32894). The immune-infiltration was evaluated by 7 published algorithms (i.e., TIMER, CIBERSORT, CIBERSORT-ABS, QUANTISEQ, MCPCOUNTER, XCELL and EPIC). Next, Correlations between riskscore or risk groups and clinicopathological data, overall survival, recognized immunoregulatory cells or common chemotherapeutic agents of BCa patients were performed using wilcox rank test, chi-square test, cox regression and spearman’s correlation analysis; and, these results are significant. According to R package “GSVA” and “clusterProfiler”, the most significantly enriched HALLMARK and KEGG pathway was separately the ‘Epithelial Mesenchymal Transition’ and ‘Ecm Receptor Interaction’ in the high- vs. low-risk group. Additionally, the functional experiments in vitro also revealed that the overexpression of has_circ_0067900 significantly impaired the proliferation, migration, and invasion capacities of BCa cells. Collectively, the results of the current study provide a novel landscape of circRNA-associated ceRNA-regulated network in BCa. The ceRNA-associated gene model which was constructed presented a high predictive performance for the prognosis, immunotherapeutic responsiveness, and chemotherapeutic sensitivity of BCa. And, has_circ_0067900 was originally proposed as tumor suppressor for patients with BCa.

Circ_0072995 drives cervical cancer development by regulating the miR-29a/WDR5 axis

Circular RNA_0072995 (Circ_0072995) is involved in the pathogenesis of cancers; however, no study has investigated its role in cervical cancer. Therefore, we aimed to investigate the function of circ_0072995 in cervical cancer. Normal human cervical epithelial cells (hCECs), HeLa cells, and forty female nude BALB/c mice were used. Immunohistochemistry, invasion assays, flow cytometric analysis, luciferase assays, and tumour volume measurements were performed to explore the potential mechanism. Circ_0072995 was significantly up-regulated in cancer tissues, and its level was markedly correlated with the International Federation of Gynecology and Obstetrics system (FIGO) staging. In vitro studies revealed that circ_0072995 interacts with miR-29a to induce WD repeat domain 5 (WDR5) expression and promotes the proliferation and invasion of cells, but inhibits apoptosis of cells. Knockdown of circ_0072995 or WDR5, or overexpression of miR-29a significantly inhibited tumour growth in vivo. In conclusion, circ_0072995 promoted cervical cancer development by inducing miR-29a-mediated WDR5 expression.Impact statementWhat is already known on this subject? Global Cancer Statistics 2020 estimated that there were 1 021,494 new cases of cervical cancer and 439 201 deaths from cervical cancer. Circ_0072995 was first shown to promote breast cancer development in 2018. Subsequent studies have revealed that circ_0072995 is also involved in the development of other cancers, including epithelial ovarian cancer and hepatocellular carcinoma. However, no studies have explored the association between circ_0072995 and cervical cancer.What do the results of this study add? We hypothesized that circ_0072995 drives cervical cancer development by sponging miRNAs and inducing the expression of key factors involved in tumorigenesis. Based on this hypothesis, we investigated the role of circ_0072995 in cervical cancer and paracancerous tissues and explored the underlying mechanism in both in vitro and in vivo studies.What are the implications of these findings for clinical practice and/or further research? For the first time, our study revealed the key role of WDR5 in cervical cancer progression regulated by circ_0072995. We first reported the promoting effects of circ_0072995 in cervical cancer development by inducing miR-29a mediated WDR5 expression and also revealed the therapeutic potential of circ_0072995, miR-29a, and WDR5 in cervical cancer.

The Down-Regulation of Circ_0059707 in Acute Myeloid Leukemia Promotes Cell Growth and Inhibits Apoptosis by Regulating miR-1287-5p

Acute myeloid leukemia (AML) is the most common type of hematological malignancy. Recently, an increasing number of reports have shown that many circular RNAs can act as effective targets for AML. However, the roles of circ_0059707 in AML remain largely unclear. In this study, we found that the expression levels of circ_0059707 were significantly decreased in AML patients with respect to normal controls (p < 0.001). Low expression levels of circ_0059707 were also associated with a poor prognosis. Furthermore, circ_0059707 overexpression inhibited cell growth and promoted apoptosis in leukemia cells, compared with control cells. Circ_0059707- and empty plasmid-transfected cells were injected subcutaneously into BALB/c nude mice. We found that the tumor volume was significantly lower in mice in the circ_0059707 group than in control mice (p < 0.01). Nuclear pyknosis, nuclear fragmentation, nuclear dissolution, and cell necrosis were observed in the circ_0059707 group by HE staining. CircInteractome analysis showed that 25 microRNAs (miRNAs), including miR-1287-5p, ©-miR-1825, a©hsa-miR-326, may be potential targets for circ_0059707. The expression of these miRNAs was analyzed in both the GEO GSE51908 and the GSE142700 databases. miR-1287-5p expression was lower in AML patients compared with controls in both the GSE51908 and the GSE142700 datasets. Moreover, we demonstrated that miR-1287-5p expression was down-regulated in AML patients and up-regulated in circ_0059707-overexpressing cells. Collectively, our research demonstrated that the down-regulation of circ_0059707 was highly evident in de novo AML patients. Our analysis also demonstrated that circ_0059707 inhibited cell growth and promoted apoptosis by up-regulating miR-1287-5p.

CircRNA 0009043 suppresses non-small-cell lung cancer development via targeting the miR-148a-3p/DNAJB4 axis

Background

Circular RNAs (circRNAs) are important regulators of the development and progression of non-small-cell lung cancer (NSCLC) and many other malignancies. The functional importance of circ_0009043 in NSCLC, however, has yet to be established.

Methods

The expression of circ_0009043, miR-148a-3p, and DnaJ heat shock protein family (Hsp40) member B4 (DNAJB4) in NSCLC cells was assessed via qPCR. The proliferative activity of these cells was examined through EdU uptake and CCK-8 assays, while flow cytometry approaches were used to examine apoptotic cell death rates. Protein expression was measured through Western immunoblotting. Interactions between miR-148a-3p and circ_0009043 or DNAJB4 were detected through RNA immunoprecipitation (RIP) and dual-luciferase reporter assays. The in vivo importance of circ_0009043 as a regulator of oncogenic activity was assessed using murine xenograft models.

Results

Both NSCLC cells and tissue samples were found to exhibit circ_0009043 upregulation, and lower circ_0009043 expression levels were found to be related to poorer NSCLC patient overall survival. Knocking down circ_0009043 resulted in the enhancement of NSCLC cell proliferative activity and the suppression of apoptotic tumor cell death in vitro, while also driving more rapid in vivo tumorigenesis. Mechanistically, circ_0009043 was found to function as a molecular sponge that sequestered miR-148a-3p, which was in turn able to directly suppress DNAJB4 expression. When miR-148a-3p was overexpressed, this reversed the impact of knocking down circ_0009043 on the apoptotic death and proliferation of NSCLC cells. Conversely, miR-148a-3p inhibition resulted in the suppression of NSCLC cell apoptosis and the enhancement of tumor cell growth, while the downregulation of DNAJB4 reversed these changes.

Conclusion

Circ_0009043 acts as a tumor suppressor in NSCLC cells, promoting DNAJB4 upregulation via the sequestration of miR-148a-3p.

Hsa_circ_0007312 Promotes Third-Generation Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor Resistance through Pyroptosis and Apoptosis via the MiR-764/MAPK1 Axis in Lung Adenocarcinoma Cells

Purposes: Osimertinib is a third-generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) used for patients with gefitinib (first-generation EGFR-TKI) resistance, but osimertinib resistance inevitably occurs. Therefore, it is necessary to explore the mechanisms of osimertinib resistance. Materials and Methods: We performed quantitative real-time polymerase chain reaction to detect hsa_circ_0007312 (circ7312), miR-764, and MAPK1 expressions in tissues and cells. Western blotting was used to detect protein levels in cells. Cell Counting Kit-8, apoptotic, and Transwell assays were used to explore biological functions. Luciferase assays were used to identify the interactions between circ7312 and miR-764, MAPK1 and miR-764. A xenograft experiment was performed to clarify the role of circ7312 in vivo. Public datasets were used to identify the relation between circ7312 expression and the cell half maximal inhibitory concentration value of osimertinib in 41 lung adenocarcinoma cell lines. The Student t-test, Kaplan-Meier analysis, and Pearson correlation analysis were used in data analysis. Results: We found that circ7312 knockdown increased miR-764 expression and decreased MAPK1 expression, and circ7312 regulated MAPK1 by sponging miR-764. In addition, high circ7312 expression has significant positive correlation with osimertinib IC50 values, circ7312 knockdown decreased the cell half maximal inhibitory concentration value of osimertinib and increased pyroptosis and apoptosis by sponging the miR-764/MAPK1 axis. We also found that circ7312 and MAPK1 were highly expressed in tumor tissues and related to poor prognosis. Xenograft experiments revealed that circ7312 knockdown decreased osimertinib resistance in vivo. Conclusion: We demonstrated that the inhibition of circ7312 decreased osimertinib resistance by promoting pyroptosis and apoptosis via the miR-764/MAPK1 axis, providing a novel target for osimertinib resistance therapy.

Circ_0009035 regulates the progression of cervical cancer by targeting miR-1305/CREBRF axis

Circular RNAs (circRNAs) have a crucial role in the occurrence of many diseases, such as tumors. Yet the roles of circ_0009035 (circRACGAP1) in cervical cancer are not fully characterized. The expression levels of circRACGAP1, miR-1305 and cAMP-responsive element-binding protein 3 regulatory factor (CREBRF) were detected by using real-time quantitative PCR or western blot. Cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine, colony formation assay, transwell assay and tube formation assay were used to detect cell proliferation, migration and invasion and angiogenesis, respectively. Flow cytometry assay was used to analyze the cell apoptosis. Dual-luciferase reporter assay and RNA immunoprecipitation assay were performed to analyze the targeting about miR-1305 and circ_0009035 or CREBRF. Xenograft model was built to study the role of circ_0009035 in vivo. Immunohistochemistry was used to detect the expression of Ki67, epithelial cadherin and vimentin. First, we found that circ_0009035 expression was significantly upregulated in tumor cells and tissues; second, knockdown of circ_0009035 could inhibit cell proliferation, migration and invasion and promote cell apoptosis. Subsequently, circ_0009035 was found to be able to target miR-1305, and the expression of miR-1305 in tumor tissues and cells was significantly lower. MiR-1305 inhibitor could restore cell-related progression of cervical cancer inhibited by si-circ_0009035. Finally, miR-1305 could target CREBRF, and circ_0009035 could regulate CREBRF expression by targeting miR-1305, thereby affecting cervical cancer tumorigenesis. In summary, our study confirmed that circ_0009035 could influence the development of cervical cancer through the targeted regulation of miR-1305/CREBRF.

Circular RNAs as novel biomarkers in triple-negative breast cancer: a systematic review

More effective prognostic and diagnostic tools are urgently required for early detecting and treating triple-negative breast cancer, which is the most acute type of breast cancer because of its lower survival rate, aggressiveness, and non-response to various common treatments. So, it remains the most harmful malignancy for women worldwide. Recently, circular RNAs, as a group of non-coding RNAs, with covalently closed loop and high stability have been discovered, which can modulate gene expression through competing with endogenous microRNA sponges. This finding provided further insight into novel approaches for controlling genes affected in many disorders and malignancies. This review concentrates on the dysregulated expression of circRNAs like their diagnostic and prognostic values in TNBC. This review aims to focus on the abnormal expression of circRNAs and their diagnostic and prognostic values in TNBC. We used PubMed, Embase, and Web of Science databases and ClinicalTrials.gov to systematically search for all relevant clinical studies. This review is based on articles published in databases up to April 2022 with the following keywords: "Circular RNA", "CircRNA", "Triple-Negative Breast Cancer" and "TNBC". We conducted a review of published CircRNA profiled-research articles to identify candidate CircRNA biomarkers for TNBC. The review is registered on JBI at https://jbi.global/systematic-review-register . Accumulating evidence has shown that several circRNAs are downregulated and some are upregulated in TNBC. The results of these studies confirm that circRNAs might be potential biomarkers with the diagnostic, prognostic, and therapeutic target value for TNBC. We also consider the connection between circRNAs and TNBC cell proliferation, apoptosis, metastasis, and chemotherapy resistance and sensitivity.

Circular RNAs as emerging players in cervical cancer tumorigenesis; A review to roles and biomarker potentials

Cervical cancer is the most lethal gynecological cancer among women worldwide. Most of the patients are diagnosed at the advanced stages due to late diagnosis and lack of accessible and valuable approaches for early detection of the disease. Circular RNAs (circRNAs) are a distinguishable class of non-coding RNAs with characteristic loop structures. Although their function has not been completely elucidated; however, recent evidence has suggested regulatory functions for circRNAs on gene expression controlling various biological functions like cell growth and apoptosis, development, embryogenesis, and pathogenesis of human diseases particularly cancers. Studies show the role of dysregulated circRNAs in biological processes including cell proliferation, migration, invasion, apoptosis, angiogenesis, and chemoresistance contributing to affect tumorigenesis in ovarian cancer cells, animal, and clinical studies. These effects can be defined as consistent with several tumorigenesis characteristics, which are defined as "hallmarks of cancer". Additionally, dysregulated circRNAs exhibit prognostic, and diagnostic potentials both in the prediction of prognosis in ovarian cancer patients, and also their discrimination from healthy individuals. Furthermore, targeting circRNAs has shown positive results in the suppression of malignant features of cancer cells, and also in overcoming chemoresistance. In this review, I have gathered the majority of studies evaluating the role of circRNAs in the development, and progression of cervical cancer, and also have discussed prognostic, diagnostic, and therapeutic potentials of circRNAs for clinical applications in cervical cancer patients.

Circular RNA 0001823 aggravates the growth and metastasis of the cervical cancer cells through modulating the microRNA-613/RAB8A axis

Cervical cancer (CC) is a gynecological cancer, which has become the second malignant tumor with mortality in developing countries. The purpose of current study was to explore the influence of Circular RNA 0001823 (circ_0001823) in the CC development. Thirty CC tissues and paracancerous tissues were obtained, and Hela and CaSki CC cells were purchased for this study. The cell growth was analyzed by CCK-8 and colony formation assays. The cell metastasis was determined with Transwell assay. The circ_0001823, miR-613, and RAB8A expression were analyzed with qRT-PCR analysis. The specific mechanisms of circRNA_0001823 were analyzed by Dual luciferase reporter and RNA pull-down assays. The circ_0001823 and RAB8A expressions were increased, and miR-613 were decreased in the CC cells and tissues. Knockdown of circ_0001823 inhibited the malignant behavior of the CC cells, which was antagonized by miR-613 inhibitor. Over-expressed RAB8A reversed the miR-613 effects in the CC cells. Knockdown of circ_0001823 inhibited the malignant behaviors of the CC cells via regulating the miR-613/RAB8A axis.

Circular RNA circ_0004277 Inhibits Acute Myeloid Leukemia Progression Through MicroRNA-134-5p / Single stranded DNA binding protein 2

Circular RNAs (circRNAs) are crucial non-coding RNAs in the process of tumorigenesis. Nevertheless, the biological function of circ_0004277 in acute myeloid leukemia (AML) is blurred. Microarray data of circRNAs were utilized to evaluate circRNAs’ differential expression in AML. Quantitative real-time polymerase chain reaction (qRT-PCR) was executed to determine circ_0004277 and microRNA-134-5p (miR-134-5p) expression levels. The growth, migration and invasion of AML cells were tested by the cell counting kit-8 and Transwell experiment. Dual-luciferase reporter gene experiment, RNA immunoprecipitation (RIP) experiment and RNA pull-down experiment were executed to determine the targeting relationship between circ_0004277 and miR-134-5p. Western blot assay was used to detect single stranded DNA binding protein 2 (SSBP2) expression. We observed that circ_0004277 was down-regulated in AML, while miR-134-5p was up-regulated. Functionally, circ_0004277 overexpression or inhibition of miR-134-5p remarkably suppressed AML cell viability, migration and invasion. Furthermore, miR-134-5p served as a direct downstream target of circ_0004277 and SSBP2 was identified as a target of miR-134-5p. Compensation experiments showed that miR-134-5p mimics abolished the biological function of circ_0004277 on malignant phenotypes of AML cells. Collectively, circ_0004277 impedes AML development by adsorbing miR-134-5p and up-regulating SSBP2.

hsa_circ_0119412 overexpression promotes cervical cancer progression by targeting miR-217 to upregulate anterior gradient 2

BACKGROUND

Mounting evidence summarizes that circRNA is closely implicated in the development of numerous cancers. Our study aimed to investigate the role of circ_0119412 whose function was not explored in cervical cancer.

METHODS

RT-qPCR analysis was utilized for the expression analysis of circ_0119412, miR-217, and anterior gradient 2 (AGR2). CCK-8 assay, transwell assay, and MTT assay were employed to assess cell proliferation, migration, and adhesion, respectively. Animal study was performed to check the role of circ_0119412 in vivo. Bioinformatics analysis was applied to predict the downstream targets of circ_0119412. RIP assay was utilized to examine miRNAs potentially bound by circ_0119412. The interplays between miR-217 and circ_0119412 or AGR2 were validated by dual-luciferase reporter assay.

RESULTS

circ_0119412 expression was highly enhanced in cervical tumor tissues and cancer cells. circ_0119412 overexpression aggravated cervical cancer cell proliferation, migration, and adhesion, and its overexpression was also conducive to tumor formation and growth in animal models. AGR2 was upregulated in cervical cancer by the public bioinformatics data. circ_0119412 bound to miR-217, and miR-217 bound to AGR 3'UTR. The promoting effects of circ_0119412 overexpression on cancer cell malignant phenotypes were reversed by miR-217 enrichment. In addition, increased expression of miR-217 suppressed AGR2 expression, thus weakening the functional effects of AGR2.

CONCLUSION

circ_0119412 functioned as an oncogenic driver to promote the malignant development of cervical cancer by targeting the miR-217/AGR2 pathway.

Circular RNA hsa_circ_0011385 contributes to cervical cancer progression through sequestering miR-149-5p and increasing PRDX6 expression

Cervical cancer (CC) is a common tumor in the female reproductive tract. Circular RNA hsa_circ_0011385 has been reported to be up-regulated in CC tissues. Nevertheless, the role and regulatory mechanism of hsa_circ_0011385 in CC are still being further verified. The levels of hsa_circ_0011385, microRNA (miR)- 149-5p, and peroxiredoxin 6 (PRDX6) mRNA in CC samples and cell lines were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Loss-of-function experiments were performed to survey the impacts of hsa_circ_0011385 inhibition on CC cell proliferation, colony formation, cycle progression, apoptosis, metastasis, invasion, and angiogenesis. Protein levels were detected by western blotting. The relationship between hsa_circ_0011385 or PRDX6 and miR-149-5p was verified by dual-luciferase reporter, RNA immunoprecipitation (RIP), and/or RNA pull-down assays. The tumorigenesis role of hsa_circ_0011385 in CC was confirmed by xenograft assay. We observed that hsa_circ_0011385 and PRDX6 were up-regulated while miR-149-5p was down-regulated in CC samples and cell lines. CC patients with high hsa_circ_0011385 expression possessed a shorter overall survival. Hsa_circ_0011385 knockdown reduced tumor growth in vivo and facilitated apoptosis, cell cycle arrest, impeded proliferation, metastasis, invasion, and angiogenesis of CC cells in vitro. Hsa_circ_0011385 could mediate PRDX6 expression through binding to miR-149-5p. MiR-149-5p silencing reversed hsa_circ_0011385 knockdown-mediated effects on CC cell angiogenesis and malignancy. PRDX6 overexpression overturned the inhibitory effects of miR-149-5p overexpression on angiogenesis and malignant behaviors of CC cells. In conclusion, hsa_circ_0011385 accelerated angiogenesis and malignant behaviors of CC cells by regulating the miR-149-5p/PRDX6 axis, manifesting that hsa_circ_0011385 might be a therapeutic target for CC.

CircCDK17 knockdown inhibits tumor progression and cell glycolysis by downregulaing YWHAZ expression through sponging miR-1294 in cervical cancer

BACKGROUND

Cervical cancer (CC) is the fourth aggressive tumor affecting women worldwide. Circular RNA (circRNA) is enrolled in CC process. This study aims to unveil the profiles of circ_101119 (circCDK17) in cell proliferation, migration, invasion, apoptosis and glycolysis in CC.

METHODS

The expression levels of circCDK17, microRNA-1294 (miR-1294) and tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta (YWHAZ) mRNA were detected by quantitative real time polymerase chain reaction (qRT-PCR). The protein expression levels of YWHAZ, recombinant glucose transporter 1 (GLUT1) and hexokinase 2 (HK2) were determined by western blot. Cell proliferation, migratory and invasive abilities and apoptosis were illustrated by cell counting kit-8 (CCK-8) assay, transwell assay and flow cytometry analysis, respectively. Cell lactate production, glucose uptake and adenosine 5'-triphosphate (ATP) level were severally elucidated by lactate assay kit, glucose assay kit and ATP detection kit.

RESULTS

CircCDK17 expression and the mRNA and protein expression levels of YWHAZ were dramatically upregulated, while miR-1294 expression was obviously downregulated in CC tissues or cells compared with control groups. CircCDK17 silencing suppressed cell proliferation, migration, invasion and glycolysis, and induced cell apoptosis in CC; however, miR-1294 inhibitor restrained these effects. Additionally, circCDK17 was a sponge of miR-1294 and miR-1294 bound to YWHAZ. Furthermore, circCDK17 knockdown inhibited tumor formation in vivo.

CONCLUSION

CircCDK17 knockdown repressed cell proliferation, migration, invasion and glycolysis, and promoted cell apoptosis via miR-1294/YWHAZ axis in CC. This finding provides a theoretical basis in studying circRNA-mediated therapy in CC.

Circular RNA Rbms1 inhibited the development of myocardial ischemia reperfusion injury by regulating miR-92a/BCL2L11 signaling pathway

Acute myocardial infarction (AMI) is characterized by high morbidity and mortality rates. Circular RNAs collectively participate in the initiation and development of AMI. The purpose of this study was to investigate the role of circRbms1 in AMI. Ischemia-reperfusion (I/R) was performed to establish an AMI model. RT-qPCR and Western blotting were performed to detect mRNA and analyze protein expression, respectively. The interaction between miR-92a and circRbms1/BCL2L11 was confirmed by luciferase and RNA pull-down assays. circRbms1 is overexpressed in AMI. However, circRbms1 knockdown alleviated H9c2 cell apoptosis and reduced the release of reactive oxygen species. circRbms1 targeted miR-92a, the downregulation of which alleviated the effects of circRbms1 knockdown and increased oxidative stress and H9c2 cell apoptosis. Moreover, circRbms1 sponged miR-92a to upregulate BCL2L11, which modulated the expression of apoptosis-related genes. circRbms1 participated in myocardial I/R injury by regulating the miR-92a/BCL2L11 signaling pathway, which may provide a new strategy for the treatment of AMI.

Circ_0003221 Downregulation Restrains Cervical Cancer Cell Growth, Metastasis and Angiogenesis by Governing the miR-139-3p/S100A14 Pathway

Circular RNA (circRNA) has considerable potency in carcinogenesis, which has aroused much attention. The objective of our study was to disclose the role of circ_0003221 in cervical cancer. Circ_0003221, miR-139-3p, and S100 calcium-binding protein A14 (S100A14) mRNA were quantified by quantitative real-time PCR (qPCR). The proliferation of cancer cells was checked by CCK-8 assay and EdU assay. The migration and invasion of cancer cells were checked by transwell assay. Angiogenesis was determined by tube formation assay. The protein levels of epithelial-mesenchymal transition (EMT)-related markers, angiogenesis-related markers, and S100A14 protein were measured by western blot. The interplays between miR-139-3p and circ_0003221 or S100A14 were ensured by RIP assay and dual-luciferase reporter assay. Further animal study was conducted to verify the role of circ_0003221 in vivo. Circ_0003221 was highly expressed in cancer tissues and cells, and its downregulation suppressed cancer cell proliferation, migration, invasion, and angiogenesis and also delayed tumor growth in vivo. Circ_0003221 bound to miR-139-3p and sequestered miR-139-3p expression. The inhibitory cancer cell biological behaviors by circ_0003221 downregulation were recovered by miR-139-3p suppression. S100A14 was a target gene of miR-139-3p. MiR-139-3p upregulation repressed cancer cell malignant phenotypes by depleting S100A14. Importantly, circ_0003221 positively regulated S100A14 expression by targeting miR-139-3p. Circ_0003221 downregulation restrains cervical cancer cell growth, metastasis, and angiogenesis by governing the miR-139-3p/S100A14 pathway.

eIF4A3-induced circWAC promotes breast cancer progression through mediating miR-599/E2F3 axis

Circular RNAs (circRNAs) are implicated in the regulation of tumor progression via the "competitive endogenous RNAs (ceRNAs)" mechanism. We intended to explore the molecular mechanism of circRNA WW domain containing adaptor with coiled-coil (circWAC) in breast cancer (BC) progression. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot assay were applied to analyze RNA and protein expression. Cell proliferation, migration, invasion, apoptosis, glycolysis, and tumorigenesis in nude mice were assessed to analyze the role of circWAC/microRNA-599 (miR-599)/E2F transcription factor 3 (E2F3) axis in BC. Dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA-pull down assay were performed to verify intermolecular interactions. CircWAC was up-regulated in BC tissues and cell lines. CircWAC knockdown restrained the proliferation, migration, invasion, and glycolysis and promoted the apoptosis of BC cells. CircWAC acted as miR-599 sponge, and miR-599 interference largely reversed circWAC silencing-induced effects in BC cells. MiR-599 interacted with the 3' untranslated region (3'UTR) of E2F3, and miR-599 overexpression-induced suppressive effect on cellular malignant potential was overturned by the accumulation of E2F3 in BC cells. Eukaryotic initiation factor 4A3 (eIF4A3) induced the expression of circWAC in BC cells. CircWAC knockdown suppressed xenograft tumor growth in vivo. Our results demonstrated that eIF4A3-induced circWAC promoted the proliferation, migration, invasion, and glycolysis and suppressed the apoptosis of BC cells through mediating miR-599/E2F3 axis, which provided novel potential targets for BC therapy.

TTK (threonine tyrosine kinase) regulates the malignant behaviors of cancer cells and is regulated by microRNA-582-5p in ovarian cancer

There is growing evidence that threonine tyrosine kinase (TTK) dysregulation is linked to the progression of multiple malignancies. Nonetheless, the role of TTK in ovarian cancer (OC) remains unclear. The GEO2R method was employed to screen out the mRNAs that were abnormally expressed between OC tissues and normal ovarian tissues using three datasets from the Gene Expression Omnibus (GEO) database: GSE14407, GSE18520, and GSE36668. Moreover, the Kaplan-Meier plotter was utilized to investigate the association between TTK expression and OC patients' prognosis. Furthermore, quantitative real-time PCR (qRT-PCR) was applied to examine miR-582-5p expression and TTK mRNA expression in OC tissues and cells. Additionally, immunohistochemistry (IHC) experiment and Western blot were executed to examine TTK protein expression in OC tissues and cells, respectively. In addition, Cell Counting Kit-8 (CCK-8), transwell, and flow-cytometry experiments were performed to examine the multiplication, migration, and apoptosis of OC cells, respectively. In addition, dual-luciferase reporter gene tests were executed to validate the targeting relationship between miR-582-5p and TTK. We demonstrated that TTK expression was up-regulated in OC tissues and cells, and its overexpression was found to be associated with an adverse prognosis in OC patients. TTK overexpression enhanced OC cell multiplication and migration, and repressed apoptosis. Mechanistically, TTK was a downstream target of miR-582-5p. Furthermore, miR-582-5p overexpression impeded OC cell multiplication and migration, while TTK overexpression reversed this phenomenon. These data suggest that miR-582-5p and TTK are promising targets for OC diagnosis and therapy.

RNA-binding protein IGF2BP2 enhances circ_0000745 abundancy and promotes aggressiveness and stemness of ovarian cancer cells via the microRNA-3187-3p/ERBB4/PI3K/AKT axis

BACKGROUND

Circular RNAs (circRNAs) are increasingly recognized as important regulators in cancer including ovarian cancer (OC). This work focuses on the effects of circ_0000745 on the OC development of and molecules involved.

METHODS

Expression of circ_0000745 in collected OC tissues and the acquired OC cell lines was examined by RT-qPCR. The stability of circ_0000745 in cells was examined by RNase R treatment. The target transcripts interacted with circ_0000745 were predicted using bioinformatic systems. Gain- and loss-of-function studies of circ_0000745, microRNA (miR)-3187-3p and erb-b2 receptor tyrosine kinase 4 (ERBB4) were conducted to determine their functions on proliferation, migration, invasion and stem cell property of OC cells.

RESULTS

Circ_0000745 and ERBB4 were abundantly expressed while miR-3187-3p was poorly expressed in OC tissues and cells. Circ_0000745 sequestered miR-3187-3p and blocked its repressive effect on ERBB4. Downregulation of circ_0000745 reduced proliferation, aggressiveness, epithelial-mesenchymal transition, and stemness of SK-OV-3 cells, but this reduction was blocked upon miR-3187-3p inhibition or ERBB4 upregulation. By contrast, artificial induction of circ_0000745 upregulation, miR-3187-3p upregulation and ERBB4 downregulation led to inverse trends in ES-2 cells. ERBB4 promoted the phosphorylation of the PI3K/AKT signaling pathway. An RNA binding protein IGF2BP2 was found to circ_0000745 bind to and promote its expression and stability.

CONCLUSION

This study demonstrated that circ_0000745 upregulated by IGF2BP2 promotes aggressiveness and stemness of OC cells through a miR-3187-3p/ERBB4/PI3K/AKT axis. Circ_0000745 may serve as a promising target for OC treatment.

Identification of Circular RNAs Associated With Chemoresistance in Colorectal Cancer

Chemoresistance is a major clinical obstacle for the treatment of colorectal cancer (CRC). Circular RNAs (circRNAs) are a new type of non-coding RNA that participated in the development of chemoresistance. However, the profiles and effects of circRNAs in 5-fluorouracil (5-Fu) and cisplatin resistance of CRC are still unclear and need to be elucidated. In the present study, the profiles of circRNAs in CRC chemoresistant (HCT8/5-Fu and HCT8/DDP) and chemosensitive (HCT8) cell lines were identified via RNA-sequencing. In total, 48 and 90 differentially expressed (DE)-circRNAs were detected in HCT8/5-Fu and HCT8/DDP cell lines, respectively. Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analysis were conducted on the host genes of DE-circRNAs; the results showed that the most significant enrichment pathways in HCT8/5-Fu and HCT8/DDP cell lines were base excision repair and Hippo signaling pathway, respectively. In addition, 11 common DE-circRNAs in the two drug-resistant cell lines (two are upregulated and nine are downregulated) were screened and verified by quantitative real-time PCR; hsacirc_023607 and hsacirc_007420 were found to be the circRNAs with the highest upregulation and downregulation fold changes. However, functional studies showed hsacirc_023607 has no effect on CRC chemoresistance. Therefore, the regulatory networks of targeted miRNAs related to 5-Fu or cisplatin resistance were predicted and constructed, in which hsacirc_002482 was identified as a hub gene, and its overexpression could suppress HCT8/5-Fu and HCT8/DDP cell proliferation and promote cell apoptosis, and enhance cell chemosensitivity. Taken together, these results of the study suggested that hsacirc_002482 may play important roles in chemoresistance of CRC.

circRNA_PTPRA functions as a sponge of miR-582-3p to regulate hepatocellular carcinoma cell proliferation, migration, invasion and apoptosis

Hepatocellular carcinoma (HCC) is a lethal disease and one of the most common types of cancer. HCC is associated with exponentially increasing morbidity and mortality rates. Accumulating evidence has identified circular RNAs (circRNAs) to be regulators of cancer progression. However, to the best of our knowledge, the potential effect of circRNA protein tyrosine phosphatase receptor type A (circRNA_PTPRA) in HCC and its mechanism remain unknown. The present study aimed to assess the effects and underlying mechanism of circRNA_PTPRA in a HCC Huh-7 cells model. The sites of interaction between circRNA_PTPRA and microRNA (miR)-582-3p were predicted using the StarBase software and verified using dual luciferase reporter and RNA immunoprecipitation (RIP) assays in Huh-7 cells. HCC cell viability, apoptosis, migration and invasion were measured using MTT, flow cytometry and Transwell assays, respectively. The expression levels of circRNA_PTPRA, miR-582-3p, cyclin D1, MMP-9, Bcl-2 and Bax were analyzed using reverse transcription-quantitative PCR and western blotting. The results of the dual luciferase reporter and RIP assays demonstrated that miR-582-3p directly targeted circRNA_PTPRA. Compared with the human normal hepatocyte cell line, THLE-2, the expression levels of circRNA_PTPRA were upregulated, which were found to be inversely correlated with those of miR-582-3p expression in Huh-7 and HCCLM3 cells. miR-582-3p overexpression using mimics suppressed cell proliferation, migration and invasion, whilst downregulating cyclin D1 and MMP-9 expression in Huh-7 cells. In addition, transfection of HCC cells with the miR-582-3p mimic promoted apoptosis by downregulating Bcl-2 expression and upregulating Bax expression in Huh-7 cells. Knocking down circRNA_PTPRA expression using small interfering RNA (siRNA) markedly downregulated circRNA_PTPRA expression levels and upregulated miR-582-3p expression, but was reversed by co-transfection with the miR-582-3p inhibitor. Furthermore, reduced HCC cell proliferation, migration and invasion, increased levels of cell apoptosis, upregulated Bax expression and downregulated cyclin D1, MMP-9 and Bcl-2 expression were all observed after knocking down circRNA_PTPRA. All these effects aforementioned were reversed by co-transfection with the miR-582-3p inhibitor. In conclusion, findings from the present study suggested that circRNA_PTPRA may regulate HCC cell proliferation, invasion, apoptosis and migration by sponging miR-582-3p. This indicates that the circRNA_PTPRA/miR-582-3p axis may represent a potential target for HCC diagnosis and treatment.

The profile analysis of circular RNAs in cervical cancer

Cervical cancer (CC) is the third most common cancer among women and has a high mortality rate at the advanced stage. The mechanisms underlying the development and progression of CC are still elusive. Circular RNAs (circRNAs) play an important role in various physiological and pathological processes. The aim of this study was to identify the circRNAs significantly associated with cervical squamous cell carcinoma (CSCC), in order to discover novel diagnostic markers and elucidate their mechanistic basis.The circRNA expression profiles of CSCC and paired para-cancerous cervical tissues was downloaded from the Gene Expression Omnibus. Bioinformatics analysis were used to screen for the differentially expressed circRNAs (DECRs). The expression levels of hsa_circ_0000745, hsa_circ_0084927, hsa_circ_0002762, hsa_circ_0075341, hsa_circ_0007905, hsa_circ_0031027, hsa_circ_0065898, hsa_circ_0070190, and hsa_circ_0078383 were verified in CC and normal cervical tissues by quantitative real-time PCR.A total of 197 DECRs were identified between the CSCC and normal tissues, including 87 upregulated and 110 downregulated circRNAs. In addition, 37 miRNAs were predicted for the upregulated circRNAs and 39 for the downregulated circRNAs. Functional analysis showed that the DECRs were associated with positive regulation of substrate adhesion-dependent cell spreading, metabolism, positive regulation of GTPase activity, protein regulation, and intercellular adhesion. The MAPK signaling pathway that plays a significant role in the progression of CC, was also enriched. Consistent with the in-silico analysis, hsa_circ_0000745, hsa_circ_0084927, hsa_circ_0002762, hsa_circ_0007905 were upregulated and hsa_circ_0078383 was downregulated in CC tissues (P < .001), whereas hsa_circ_0075341 (P < .001) and hsa_circ_0031027 (P = .001) showed opposite trends.We identified novel diagnostic and therapeutic biomarkers of CSCC along with the mechanistic basis.

Screening for differentially expressed circRNAs in ischemic stroke by RNA sequencing

BACKGROUND

Ischemic stroke is a disease with high rate of death and disability worldwide. CircRNAs, as a novel type of non-coding RNAs, lacking 5' caps and 3' poly-A tails, has been associated with ischemic stroke. This study aimed to investigate key circRNAs related to ischemic stroke.

METHODS

RNA sequencing was performed obtain the circRNA expression profiles from peripheral whole blood of three ischemic stroke patients and three healthy individuals. Through bioinformatic analysis, differentially expressed circRNAs (DEcircRNAs) were identified, and GO and pathway analyses for the host genes of DEcircRNAs were conducted. The expression levels of selected circRNAs were analyzed with qRT-PCR. To further explore the functions of key circRNAs, a DEcircRNA-miRNA interaction network was constructed.

RESULTS

A total of 736 DEcircRNAs were detected in ischemic stroke. Functional annotation of host genes of DEcircRNAs revealed several significantly enriched pathways, including Fc epsilon RI signaling pathway, B cell receptor signaling pathway, and T cell receptor signaling pathway. The qRT-PCR results were largely in keeping with our RNA-seq data. The ROC curve analyses indicated that hsa_circ_0000745, hsa_circ_0001459, hsa_circ_0003694 and hsa_circ_0007706 with relatively high diagnostic value. A circRNA-miRNA network, including 1544 circRNA-miRNA pairs, 456 circRNAs and 4 miRNAs, was obtained.

CONCLUSIONS

The results of our study may help to elucidate the specific mechanism underlying ischemic stroke.

CircPTCH1 Promotes Migration in Lung Cancer by Regulating MYCN Expression Through miR-34c-5p

BACKGROUND

The incidence rate and mortality rate of lung cancer are the highest in the world. Therefore, further studies are needed to reveal the molecular mechanism of lung cancer progression and development. Previous study demonstrated that the deregulation of circRNAs can regulate cell biological functions in tumorigenesis and development. However, the roles of circPTCH1 in lung cancer have not yet been revealed.

MATERIALS AND METHODS

The expression levels of circPTCH1, miR-34c-5p, and MYCN were measured by RT-PCR in lung cancer tissues and cells; dual-luciferase reporter and RIP assay showed that circRNA served as a sponge for miRNA, and miRNA could target mRNA. In vitro, effects of si-circPTCH1 can regulate lung cancer cells' migration, invasion were detected by CCK-8 assay, wound healing assay, and transwell assay.

RESULTS

Our research demonstrated that the expression of circPTCH1 was upregulated in lung cancer tissues and cell lines and increased in metastatic tissues compared to that of non-metastatic tissues. circPTCH1 sponging miR-34c-5p to target MYCN was revealed by dual-luciferase reporter and a RIP assay. In addition, the expression level of miR-34c-5p was reduced in lung cancer tumor tissues, and MYCN was significantly increased in lung cancer tumor tissues. Pearson correlation analysis showed that miR-34c-5p with circPTCH1 and MYCN had a moderately negative correlation, and there was a moderately positive correlation between circPTCH1 and MYCN. Further, cytological studies found that circPTCH1 reduced lung cancer cells' migration and invasion by targeting MYCN via miR-34c-5p.

CONCLUSION

circPTCH1 plays a tumor enhancement role in lung cancer and that can effectively promote migration, invasion and EMT by targeting the miR-34c-5p/MYCN axis. circPTCH1 may be a novel potential treatment and diagnosis biomarker for lung cancer.

Circ-E2F3 promotes cervical cancer progression by inhibiting microRNA-296-5p and increasing STAT3 nuclear translocation

Circular RNA E2F transcription factor 3 (circ-E2F3) has been demonstrated to be differentially expressed in some diseases and cancers. However, the role of circ-E2F3 in cervical cancer (CC) progression remains unclear. Therefore, we aimed to elucidate the mechanism of circ-E2F3 regulation of CC progression. Circ-E2F3 expression was determined in CC samples, and its correlation with the clinicopathological characteristics of CC patients and cell biological processes was examined. The interaction among circ-E2F3, microRNA-296-5p (miR-296-5p), and signal transducer and activator of transcription 3 (STAT3) was analyzed by dual luciferase reporter gene and fluorescence in situ hybridization assays. Circ-E2F3-depleted CaSki cells were implanted into nude mice to verify the function of circ-E2F3 in vivo. Circ-E2F3 was upregulated in both CC tissues and cell lines, and this correlated with the clinicopathological features and poor prognosis of CC patients. Moreover, circ-E2F3 promoted the proliferation, invasion, and migration of CC cells and tumor growth in vivo. It was also observed that circ-E2F3 promoted the nuclear translocation of STAT3 through inhibition of miR-296-5p, thus affecting the expression of cyclin D1. Taken together, the key findings of our study demonstrate that circ-E2F3 induces inhibition of miR-296-5p, which triggers activation and nuclear translocation of STAT3 that then upregulates cyclin D1 expression.

Circ_0062166 aggravates cerebral ischemia-reperfusion injury through targeting miR-526b-5p/BCL2L13 axis

BACKGROUND

Cerebral ischemia-reperfusion (CIR) injury is a severe disease, which may cause serious dysfunction of the brain. Most circular RNAs (circRNAs) have been demonstrated to play a significant role in CIR injury. However, a novel circRNA, circ_0062166 (circ_BCL2L13) has not been investigated for CIR injury. Hence, we aim to disclose the role of circ_0062166 in CIR injury in this study.

METHODS

Firstly, RT-qPCR was applied to examine the expression of circ_0062166 in oxygen-glucose deprivation and reoxygenation (OGD/R) cell model. Functional assays were conducted to detect the role of circ_0062166 in CIR injury. RNA pull down, RIP and luciferase reporter assays were implemented to probe into the regulatory mechanism of circ_0062166.

RESULTS

Circ_0062166 was significantly up-regulated in neuro-2A (N2A) neuroblastoma cells following OGD/R. Functionally, the silencing of circ_0062166 inhibited cell proliferation and promoted cell apoptosis under OGD/R condition. From the perspective of mechanism, circ_0062166 functioned as a competing endogenous RNA (ceRNA) for microRNA-526b-5p (miR-526b-5p) and regulated BCL2 like 13 (BCL2L13). Eventually, the promoting role of the circ_0062166/miR-526b-5p/BCL2L13 axis in the CIR injury was verified.

CONCLUSION

To sum up, the present study has demonstrated that circ_0062166/miR-526b-5p/BCL2L13 axis accelerated the progression of CIR injury, which might provide effective strategies for CIR injury therapy.

Circular RNA circ_0011385 promotes cervical cancer progression through competitively binding to miR-149-5p and up-regulating SOX4 expression

Circular RNAs (circRNAs), emerging as a new type of non-coding RNAs, play important roles in cancers. Instead, the functions and mechanisms of circ_0011385 in cervical cancer (CC) are still inconclusive. Microarray data GSE102686 was downloaded from Gene Expression Omnibus (GEO) database, and were utilized to screen out circRNAs differently expressed in CC tissues. Circ_0011385, miR-149-5p, SRY-box transcription factor 4 (SOX4) mRNA expressions in CC tissues and cells were probed by quantitative real-time PCR (qRT-PCR). CC cell lines with circ_0011385 knockdown were constructed, and he multiplication, migration, invasion, and apoptosis of CC cells were evaluated by cell counting kit-8 (CCK-8) method, transwell assay, and flow cytometry. In addition, the targeting relationships between miR-149-5p and circ_0011385 or SOX4 mRNA 3'UTR were probed by dual-luciferase reporter gene assay and RNA pull-down assay. The regulatory function of circ_0011385 and miR-149-5p on SOX4 expression was studied with western blot. Expressions of circ_0011385 and SOX4 mRNA were raised in CC tissues and cells, while miR-149-5p expression was decreased. Knocking down circ_0011385 restrained the multiplication, migration, and invasion of CC cells and induced the apoptosis. Circ_0011385 directly targeted miR-149-5p, and SOX4 was the target of miR-149-5p, which could be positively regulated by circ_0011385. Circ_0011385 elevates SOX4 expression by targeting miR-149-5p, thus participating in promoting the malignant biological behaviors of CC cells.

A Comprehensive Overview of circRNAs: Emerging Biomarkers and Potential Therapeutics in Gynecological Cancers

Circular RNA (circRNA) is a highly conserved, stable and abundant non-coding RNA (ncRNA). Also, some circRNAs play an essential part in the progression of human cancers. CircRNA is different from traditional linear RNA. CircRNA has a closed circular structure, so it is resistant to exonuclease-mediated degradation and is more stable than linear RNA. Numerous studies have found that many circRNAs can act as a microRNA (miRNA) sponge, interact with RNA-binding proteins, regulate gene transcription, affect alternative splicing and be translated into proteins. Recently, some studies have also indicated that circRNA participates in the progression of gynecological cancers. In addition, circRNA can act as a promising biomarker for the diagnosis of gynecological tumors. Additionally, they can also play a key role in the prognosis of gynecological tumors. Furthermore, to our delight, circRNA may be a potential therapeutic target in gynecological cancers and widely used in clinical practice. This article reviews the functions and related molecular mechanisms of circRNAs in gynecological tumors, and discusses their potential as biomarkers for diagnostic and prognostic and therapeutic targets for gynecological cancers.

hsa_circ_0101119 facilitates the progression of cervical cancer via an interaction with EIF4A3 to inhibit TCEAL6 expression

Recently, circular RNAs (circRNAs/circs) have attracted increased attention due to their regulatory role in a variety of cancer types. However, the role and molecular mechanisms of circRNAs in cervical cancer (CC) remain unknown. The present study aimed to investigate the function of hsa_ circ_0101119 on CC and its potential mechanisms. The differentially expressed circRNAs associated with CC were screened out using R software, according to the database of Gene Expression Omnibus (GEO). The expression levels of hsa_circ_0101119, eukaryotic initiation factor 4A‑3 (EIF4A3) and transcription elongation factor A‑like 6 (TCEAL6) in CC cells were detected via reverse transcription‑quantitative (RT‑q)PCR, and their expression levels in CC tissues were analyzed based on the database of GEO and the Cancer Genome Atlas. Moreover, the accurate functions of hsa_circ_0101119 and TCEAL6 on the proliferation, apoptosis, migration and invasion of SiHa and HeLa cells was examined using colony formation assay, 5‑ethynyl‑20‑deoxyuridine incorporation assay, flow cytometry and Transwell assay. Next, the underlying mechanisms of hsa_circ_0101119 on CC progression were determined via bioinformatics analysis, RNA immunoprecipitation assay, RNA pull down assay, RT‑qPCR and western blotting. It was found that hsa_circ_0101119 was highly expressed in CC tissues and cells, while TCEAL6 was lowly expressed. Knockdown of hsa_circ_0101119 or TCEAL6 overexpression significantly inhibited the proliferation, migration and invasion of SiHa and HeLa cells, but facilitated apoptosis. It was also demonstrated that hsa_circ_0101119 could recruit EIF4A3 to inhibit TCEAL6 expression in CC. Furthermore, knockdown of TCEAL6 could reverse the effects of silencing hsa_circ_0101119 on the proliferation, apoptosis, migration and invasion of HeLa cells. In conclusion, the present study revealed that hsa_circ_0101119 could facilitate cell proliferation, migration and invasion, and suppress apoptosis in CC via an interaction with EIF4A3 to inhibit TCEAL6 expression, which may provide a potential therapeutic target for CC treatment.

Expression patterns and biological function of Specc1 during mouse preimplantation development

Two unique features occur during preimplantation embryo development: 1) initiation of calcium-dependent adhesion and establishment of apicobasal polarity in the morula, and 2) formation of the blastocoel by establishment of tight junctions (TJs), ion channels, and water channels in the outer blastomeres. Although several key genes involved in morula and blastocyst formation have been identified, most remain unknown. Sperm antigen with calponin homology and coiled-coil domains 1(SPECC1) is highly expressed in testis and tumor cells, and is involved in diverse cellular processes such as ribosome biogenesis, rRNA transcription, mitosis, cell growth, and apoptosis in tumor cells. However, spatiotemporal expressions of Specc1 during mouse preimplantation development have not yet been investigated. Here, we examined the expression patterns of Specc1 using qRT-PCR and immunocytochemistry, and its biological function using siRNA injection into 1-cell zygotes. Specc1 was detectable throughout preimplantation development and markedly increased from the morula stage onwards. It was particularly observed in trophectoderm cells, rather than the inner cell mass of blastocyst. Maternal and zygotic Specc1 transcripts were abolished using RNA interference. There were no significant differences in development between Specc1 knock down (KD) and control embryos until the morula stage, but was significantly reduced blastocyst development and increased tight junction permeability in KD embryos, as assessed by FITC uptake. In summary, elevated expression of Specc1 in the morula and blastocyst may affect blastocyst formation, including tight junction complex during the morula to blastocyst transition.

CircZNF124 regulates cell proliferation, leucine uptake, migration and invasion by miR-199b-5p/SLC7A5 pathway in endometrial cancer

BACKGROUND

Recent studies have revealed that circular RNA participates in endometrial carcinoma (EC) progression. Here we investigated the role of circRNA zinc finger protein 124 (circZNF124) in EC genesis and underlying mechanism.

METHODS

The expression levels of circZNF124, microRNA-199b-5p (miR-199b-5p) and solute carrier family 7 member 5 (SLC7A5) were detected by quantitative real-time polymerase chain reaction. The expression of SLC7A5 and other indicated marker proteins was determined by western blot analysis. For functional assay, cell proliferation, leucine uptake and metastasis were investigated by total cell number, cell counting kit-8, cell colony formation, leucine uptake or transwell assay. The interaction between miR-199b-5p and circZNF124 or SLC7A5 was predicted by starbase online database, and identified by mechanism assays. The impact of circZNF124 absence on tumor growth in vivo was revealed by xenograft mouse model assay. Immunohistochemistry assay was implemented to detect the positive expression rate of nuclear proliferation marker (Ki67).

RESULTS

CircZNF124 and SLC7A5 expression were significantly increased, while miR-199b-5p was decreased in EC tissues and cells compared with normal endometrial tissues or cells. CircZNF124 expression was closely associated with EC severity and lymph node metastasis. Additionally, circZNF124 depletion repressed cell proliferation, leucine uptake, migration and invasion in both HEC1A and Ishikawa cells. CircZNF124 regulated SLC7A5 expression by binding to miR-199b-5p. MiR-199b-5p inhibitors or SLC7A5 overexpression attenuated circZNF124 silencing-mediated EC malignant progression. Furthermore, SLC7A5 absence inhibited tumor growth in vivo.

CONCLUSION

CircZNF124 depletion inhibited EC cell malignancy by miR-199b-5p/SLC7A5 pathway, which demonstrated that circZNF124 had the potential as a therapeutic target for EC.