circRNA-UBAP2 promotes the proliferation and inhibits apoptosis of ovarian cancer though miR-382-5p/PRPF8 axis

MicroRNA-382 as a tumor suppressor during tumor progression

Despite the recent progresses in therapeutic and diagnostic methods, there is still a significantly high rate of mortality among cancer patients. One of the main reasons for the high mortality rate in cancer patients is late diagnosis, which leads to the failure of therapeutic strategies. Therefore, investigation of cancer biology can lead to the introduction of early diagnostic markers in these patients. MicroRNAs (miRNAs) play an important role in regulation of cellular processes associated with tumor progression. Due to the high stability of miRNAs in body fluids, these factors can be considered as the non-invasive tumor markers. Deregulation of miR-382 has been widely reported in different cancers. Therefore, in this review, we investigated the role of miR-382 during tumor development. It has shown that miR-382 has mainly a tumor suppressive, which inhibits the growth of tumor cells through the regulation of signaling pathways, RNA-binding proteins, and transcription factors. Therefore, miR-382 can be suggested as a diagnostic and therapeutic marker in cancer patients.

Epithelial splicing regulatory protein 1 promotes peritoneal dissemination of ovarian cancer by inducing the formation of circular RNAs modulating epithelial plasticity

Peritoneal metastases prevalently occur in ovarian cancer, deteriorating patient prognosis. During the metastatic cascade, tumor plasticity enables cells to adapt to environmental changes, thereby facilitating dissemination. We previously found that epithelial splicing regulatory protein 1 (ESRP1) is linked to peritoneal metastasis and epithelial-mesenchymal plasticity in ovarian cancer. This study delves into the underlying mechanism. We found that ESRP1 preserves epithelial plasticity in ovarian cancer cells in vitro and in vivo. Functionally, ESRP1 enhances ovarian cancer cell growth and peritoneal dissemination. High-throughput sequencing revealed several ESRP1-related epithelial RNAs, encompassing both linear and circular forms. Specifically, ESRP1 triggers the cyclization of circPAFAH1B2 and circUBAP2 through binding to the GGU sequences in adjacent introns. The two ESRP1-induced circular RNAs stabilize DKK3 and AHR mRNAs, which are critical for epithelial plasticity, through interaction with IGF2BP2. Collectively, ESRP1 triggers the formation of circPAFAH1B2 and circUBAP2, which in turn stabilizes DKK3 and AHR through IGF2BP2 binding, thereby modulating the epithelial plasticity and aiding the peritoneal spread of ovarian cancer cells. The findings unveiled a biological network, orchestrated by ESRP1, that governs the epithelial-mesenchymal plasticity of ovarian cancer cells, emphasizing the therapeutic potential of ESRP1 and its induced circular RNAs for ovarian cancer treatment.

Interplay of microRNAs and circRNAs in Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) with its high death incidence rate is generally detected at advanced stages. During its progression, EOC often develops peritoneal metastasis aggravating the outcomes of EOC patients. Studies on non-coding RNAs (ncRNAs), such as microRNAs (miRNAs) and circular RNAs (circRNAs), have analyzed the impact of miRNAs and circRNAs, along with their interaction among each other, on cancer cells. MiRNAs can act as oncogenes or tumor suppressors modulating post-transcriptional gene expression. There is accumulating evidence that circRNAs apply their stable, covalently closed, continuous circular structures to competitively inhibit miRNA function, and so act as competing endogenous RNAs (ceRNAs). This interplay between both ncRNAs participates in the malignity of a variety of cancer types, including EOC. In the current review, I describe the characteristics of miRNAs and circRNAs, and discuss their interplay with each other in the development, progression, and drug resistance of EOC. Sponging of miRNAs by circRNAs may be used as a biomarker and therapeutic target in EOC.

CircRNA Regulation of T Cells in Cancer: Unraveling Potential Targets

T lymphocytes play a critical role in antitumor immunity, but their exhaustion poses a significant challenge for immune evasion by malignant cells. Circular RNAs (circRNAs), characterized by their covalently closed looped structure, have emerged as pivotal regulators within the neoplastic landscape. Recent studies have highlighted their multifaceted roles in cellular processes, including gene expression modulation and protein function regulation, which are often disrupted in cancer. In this review, we systematically explore the intricate interplay between circRNAs and T cell modulation within the tumor microenvironment. By dissecting the regulatory mechanisms through which circRNAs impact T cell exhaustion, we aim to uncover pathways crucial for immune evasion and T cell dysfunction. These insights can inform innovative immunotherapeutic strategies targeting circRNA-mediated molecular pathways. Additionally, we discuss the translational potential of circRNAs as biomarkers for therapeutic response prediction and as intervention targets. Our comprehensive analysis aims to enhance the understanding of immune evasion dynamics in the tumor microenvironment by facilitating the development of precision immunotherapy.

Hsa_circ_0001741 Suppresses Ovarian Cancer Cell Proliferations Through Adsorption of miR-188-5p and Promotion of FOXN2 Expression

Ovarian cancer (OC) is among several general malignant gynecological cancers associated with high mortality rates on a global scale. Earlier investigations have revealed a critical role of circular RNAs (circRNAs) in OC development, which is a new class of endogenous non-coding RNA (ncRNA) that reported to mediate progression of diverse tumor types. At present, the precise involvement of circRNAs and associated regulatory mechanisms in OC remain unknown. In this study, hsa_circ_0001741 expression patterns in OC cells and tissues were tested. The underlying regulatory pathways and targets were further explored with the aid of bioinformatics, luciferase reporter, 5-ethynyl-2'-deoxyuridine (EdU) and cell counting kit-8 (CCK-8) analyses. Further investigation of the hsa_circ_0001741 effects on tumor growth in vivo revealed abnormal circRNA expression in OC. hsa_circ_0001741 expression reduced in OC cells and tissues, indicative of activity in OC progression. hsa_circ_0001741 upregulation resulted in OC proliferation inhibitions. The luciferase reporter outputs verified miR-188-5p and FOXN2 as hsa_circ_0001741 downstream targets. FOXN2 silencing or miR-188-5p upregulations reversed inhibitory effects regarding hsa_circ_0001741 on OC cell proliferation. Therefore our data suggested that hsa_circ_0001741 upregulation inhibited proliferation of OC through modulatory effects on miR-188-5p/FOXN2 signaling.

Role of circular RNA as competing endogenous RNA in ovarian cancer (Review)

Circular RNA (circRNA), a type of non‑coding RNA, plays a regulatory role in biological processes. The special loop structure of circRNA makes it highly stable and specific in diseased tissues and cells, especially in tumors. Competing endogenous RNAs (ceRNAs) compete for the binding of microRNA (miRNA) at specific binding sites and thus regulate gene expression. ceRNAs play an important role in various diseases and are currently recognized as the most prominent mechanism of action of circRNAs. circRNAs can modulate the proliferation, migration, invasion and apoptosis of tumor cells through the ceRNA mechanism. With further research, circRNAs may serve as novel markers and therapeutic targets for ovarian cancer (OC). In the present review, the research progress of circRNAs as ceRNAs in OC was summarized, focusing on the effects of the circRNA/miRNA/mRNA axis on the biological functions of OC cells through mediating pivotal signaling pathways. The role of circRNAs in the diagnosis, prognostic assessment and treatment of OC was also discussed in the present review.

Circ_0003945: an emerging biomarker and therapeutic target for human diseases

Due to the rapid development of RNA sequencing techniques, a circular non-coding RNA (ncRNA) known as circular RNAs (circRNAs) has gradually come into focus. As a distinguished member of the circRNA family, circ_0003945 has garnered attention for its aberrant expression and biochemical functions in human diseases. Subsequent studies have revealed that circ_0003945 could regulate tumor cells proliferation, migration, invasion, apoptosis, autophagy, angiogenesis, drug resistance, and radio resistance through the molecular mechanism of competitive endogenous RNA (ceRNA) during tumorigenesis. The expression of circ_0003945 is frequently associated with some clinical parameters and implies a poorer prognosis in the majority of cancers. In non-malignant conditions, circ_0003945 also holds considerable importance in diseases pathogenesis. This review aims to recapitulate molecular mechanism of circ_0003945 and elucidates its potential as a diagnostic and therapeutic target in neoplasms and other diseases.

Circ-RNF111 Promotes Proliferation of Ovarian Cancer Cell SKOV-3 by Targeting the MiR-556-5p/CCND1 Axis

The aim of this study was to investigate the role and mechanism of circ-RNF111 in the human ovarian cancer cell line SKOV-3. First, qRT-PCR was used to detect circ-RNF111 and miR-556-5p expression levels in human normal ovarian epithelial cells IOSE80 and human ovarian cancer cells SKOV-3. CCK-8 and colony formation assays were adopted to determine the proliferation rate and cell viability of SKOV-3 cells, respectively. Additionally, in an attempt to reveal the mechanism of circ-RNF111, we predicted the targeting relationship between miR-556-5p and circ-RNF111 as well as miR-556-5p and CCND1 using the circinteractome and TargetScan databases, respectively, and validated their relationship by dual-luciferase reporter assay. The protein expression levels of CCND1 in SKOV-3 cells were detected by Western blot. Based on the above experiments, the expression of circ-RNF111 was found to be up-regulated in SKOV-3, and the knockdown of circ-RNF111 significantly inhibited the proliferation and viability of SKOV-3 cells. Then we confirmed that circ-RNF111 sponged miR-556-5p in SKOV-3 cells to up-regulate CCND1 expression. In addition, simultaneous inhibition of miR-556-5p or overexpression of CCND1 in SKOV-3 cells with knockdown of circ-RNF111 reversed the inhibitory effect of knockdown of circ-RNF111 on the protein expression level of CCND1, cell proliferation rate, and cell viability. In summary, circ-RNF111 promotes the proliferation of SKOV-3 cells by targeting the miR-556-5p/CCND1 axis. Circ-RNF111 may serve as a potential target for ovarian cancer therapy.

CircCDK17 promotes the proliferation and metastasis of ovarian cancer cells by sponging miR-22-3p to regulate CD147 expression

Ovarian cancer (OC) is a common malignancy in women of reproductive age. Circular RNAs (circRNAs) are emerging players in OC progression. We investigated the function and mechanism of circular RNA hsa_circ_0027803 (circCDK17) in OC pathogenesis. Real‑time PCR (RT-qPCR) and western blot were utilized for gene and protein expression analysis, respectively. Cell counting kit‑8 (CCK-8), EdU and Transwell assays investigated OC cell proliferation, migration and invasion. The associations between circCDK17, miR-22-3p and CD147 were examined by dual-luciferase reporter and RNA-protein immunoprecipitation (RIP) assays. The in vivo model of OC nude mice was constructed to explore the role of circCDK17. CircCDK17 was increased in OC tissue and cells, and patients with higher expression of circCDK17 had a shorter survival. CircCDK17 downregulation inhibited OC cell proliferation, migration and invasion, and reduced epithelial-mesenchymal transition (EMT)-related markers. In vivo experiments showed that circCDK17 silencing inhibited OC tumor growth and metastasis. CircCDK17 depletion reduced CD147 level via sponging miR-22-3p. MiR-22-3p knockdown overturned effect of circCDK17 depletion on OC cell proliferation, migration and invasion. Meanwhile, overexpressed CD147 restored functions of circCDK17 downregulation on OC development. CircCDK17 is an important molecule that regulates OC pathogenic process through miR-22-3p/CD147.

The role of circRNAs in regulation of drug resistance in ovarian cancer

Ovarian cancer is one of the female reproductive system tumors. Chemotherapy is used for advanced ovarian cancer patients; however, drug resistance is a pivotal cause of chemotherapeutic failure. Hence, it is critical to explore the molecular mechanisms of drug resistance of ovarian cancer cells and to ameliorate chemoresistance. Noncoding RNAs (ncRNAs) have been identified to critically participate in drug sensitivity in a variety of human cancers, including ovarian cancer. Among ncRNAs, circRNAs sponge miRNAs and prevent miRNAs from regulation of their target mRNAs. CircRNAs can interact with DNA or proteins to modulate gene expression. In this review, we briefly describe the biological functions of circRNAs in the development and progression of ovarian cancer. Moreover, we discuss the underneath regulatory molecular mechanisms of circRNAs on governing drug resistance in ovarian cancer. Furthermore, we mention the novel strategies to overcome drug resistance via targeting circRNAs in ovarian cancer. Due to that circRNAs play a key role in modulation of drug resistance in ovarian cancer, targeting circRNAs could be a novel approach for attenuation of chemoresistance in ovarian cancer.

Discovery and Comprehensive Characterization of Novel Circular RNAs of the Apoptosis-Related BOK Gene in Human Ovarian and Prostate Cancer Cells, Using Nanopore Sequencing

CircRNAs have become a novel scientific research hotspot, and an increasing number of studies have shed light on their involvement in malignant progression. Prompted by the apparent scientific gap in circRNAs from apoptosis-related genes, such as BOK, we focused on the identification of novel BOK circRNAs in human ovarian and prostate cancer cells. Total RNA was extracted from ovarian and prostate cancer cell lines and reversely transcribed using random hexamer primers. A series of PCR assays utilizing gene-specific divergent primers were carried out. Next, third-generation sequencing based on nanopore technology followed by extensive bioinformatics analysis led to the discovery of 23 novel circRNAs. These novel circRNAs consist of both exonic and intronic regions of the BOK gene. Interestingly, the exons that form the back-splice junction were truncated in most circRNAs, and multiple back-splice sites were found for each BOK exon. Moreover, several BOK circRNAs are predicted to sponge microRNAs with a key role in reproductive cancers, while the presence of putative open reading frames indicates their translational potential. Overall, this study suggests that distinct alternative splicing events lead to the production of novel BOK circRNAs, which could come into play in the molecular landscape and clinical investigation of ovarian and prostate cancer.

Comparison of Oncogenes, Tumor Suppressors, and MicroRNAs Between Schizophrenia and Glioma: The Balance of Power

The risk of cancer in schizophrenia has been controversial. Confounders of the issue are cigarette smoking in schizophrenia, and antiproliferative effects of antipsychotic medications. The author has previously suggested comparison of a specific cancer like glioma to schizophrenia might help determine a more accurate relationship between cancer and schizophrenia. To accomplish this goal, the author performed three comparisons of data; the first a comparison of conventional tumor suppressors and oncogenes between schizophrenia and cancer including glioma. This comparison determined schizophrenia has both tumor-suppressive and tumor-promoting characteristics. A second, larger comparison between brain-expressed microRNAs in schizophrenia with their expression in glioma was then performed. This identified a core carcinogenic group of miRNAs in schizophrenia offset by a larger group of tumor-suppressive miRNAs. This proposed "balance of power" between oncogenes and tumor suppressors could cause neuroinflammation. This was assessed by a third comparison between schizophrenia, glioma and inflammation in asbestos-related lung cancer and mesothelioma (ALRCM). This revealed that schizophrenia shares more oncogenic similarity to ALRCM than glioma.

ncRNAs mediated RPS6KA2 inhibits ovarian cancer proliferation via p38/MAPK signaling pathway

Background

Ovarian cancer is the most lethal gynecology malignancy in the world, therefore, research on the molecular biological mechanism of ovarian cancer tumorigenesis and progression has received widespread attention.

Methods

We identified RPS6KA2 as the prognosis-related gene of ovarian cancer from TCGA, GSE26712 and GSE26193 database via bioinformatic analysis. qRT-PCR and western blot detected the differential expression of RPS6KA2 in normal ovaries and ovarian cancer tissues. The biological functions of RPS6KA2 were verified by in vitro and in vivo. GSEA analysis was used to select candidate signaling pathway of RPS6KA2 which was further verified by western blot. The possible binding sites of RPS6KA2 with miRNAs and circRNAs were predicted by bioinformatics analysis, and then a circRNA-miRNA-mRNA interaction network was constructed.

Results

We found the expression of RPS6KA2 was down-regulated in ovarian cancer tissues. Overexpression of RPS6KA2 could suppress cell proliferation, whereas knockdown of RPS6KA2 had the opposite effects on proliferation. GSEA analysis showed that the MARK signaling pathway was closely associated with RPS6KA2. Bioinformatics analysis and dual-luciferase reporter assay showed that RPS6KA2 was regulated with miR-19a-3p, miR-106a-5p and miR-519d-3p. Further analysis showed that circFAM169A was the common ceRNA of miR-19a-3p, miR-106a-5p and miR-519d-3p. Dual-luciferase reporter assay showed the relationship of circFAM169A and miR-106a-5p and miR-519d-3p. After network analysis, one circRNA-miRNA-mRNA axis (circFAM169A/miR-106a-5p, miR-519d-3p/RPS6KA2) was identified.

Conclusions

We demonstrated that circFAM169A/miR-106a-5p, miR-519d-3p mediated low expression of RPS6KA2 could affect the proliferation of ovarian cancer cells via p38/MAPK signaling pathway.

CircEML1 facilitates the steroid synthesis in follicular granulosa cells of chicken through sponging gga-miR-449a to release IGF2BP3 expression

Non-coding RNAs (ncRNAs) induced competing endogenous RNAs (ceRNA) play crucial roles in various biological process by regulating target gene expression. However, the studies of ceRNA networks in the regulation of ovarian ovulation processing of chicken remains deficient compared to that in mammals. Our present study revealed that circEML1 was differential expressed in hen's ovarian tissues at different ages (15 W/20 W/30 W/68 W) and identified as a loop structure from EML1 pre-mRNA, which promoted the expressions of CYP19A1/StAR and E2/P4 secretion in follicular granulosa cells (GCs). Furthermore, circEML1 could serve as a sponge of gga-miR-449a and also found that IGF2BP3 was targeted by gga-miR-449a to co-participate in the steroidogenesis, which possibly act the regulatory role via mTOR/p38MAPK pathways. Meanwhile, in the rescue experiment, gga-miR-449a could reverse the promoting role of circEML1 to IGF2BP3 and steroidogenesis. Eventually, this study suggested that circEML1/gga-miR-449a/IGF2BP3 axis exerted an important role in the steroidogenesis in GCs of chicken.

U5 snRNP Core Proteins Are Key Components of the Defense Response against Viral Infection through Their Roles in Programmed Cell Death and Interferon Induction

The spliceosome is a massive ribonucleoprotein structure composed of five small nuclear ribonucleoprotein (snRNP) complexes that catalyze the removal of introns from pre-mature RNA during constitutive and alternative splicing. EFTUD2, PRPF8, and SNRNP200 are core components of the U5 snRNP, which is crucial for spliceosome function as it coordinates and performs the last steps of the splicing reaction. Several studies have demonstrated U5 snRNP proteins as targeted during viral infection, with a limited understanding of their involvement in virus-host interactions. In the present study, we deciphered the respective impact of EFTUD2, PRPF8, and SNRNP200 on viral replication using mammalian reovirus as a model. Using a combination of RNA silencing, real-time cell analysis, cell death and viral replication assays, we discovered distinct and partially overlapping novel roles for EFTUD2, PRPF8, and SNRNP200 in cell survival, apoptosis, necroptosis, and the induction of the interferon response pathway. For instance, we demonstrated that EFTUD2 and SNRNP200 are required for both apoptosis and necroptosis, whereas EFTUD2 and PRPF8 are required for optimal interferon response against viral infection. Moreover, we demonstrated that EFTUD2 restricts viral replication, both in a single cycle and multiple cycles of viral replication. Altogether, these results establish U5 snRNP core components as key elements of the cellular antiviral response.

Circ_0015756 promotes ovarian cancer progression via the miR-145-5p/PSAT1 axis

Circular RNA (circRNA) have been shown to exert vital functions in the pathological progressions of ovarian cancer (OC). Herein, this study aimed to investigate the role and mechanisms of circ_0015756 in OC progression. Levels of circ_0015756, microRNA (miR)- 145-5p and phosphoserine aminotransferase 1 (PSAT1) were detected using quantitative real-time polymerase chain reaction, Western blot or immunohistochemistry assays. Cell proliferation, apoptosis, migration and invasion were determined using cell counting kit-8, 5-Ethynyl-2'-Deoxyuridine (Edu) incorporation, flow cytometry, transwell and Western blot assays. The binding interaction between miR-145-5p and circ_0015756 or PSAT1 was confirmed by bioinformatics prediction and dual-luciferase reporter assay. Tumor formation assay in nude mice was performed to determine the tumor growth in vivo. Circ_0015756 was highly expressed in OC tissues and cells. Knockdown of circ_0015756 suppressed cancer cell growth, migration and invasion in vitro, as well as impeded tumor growth in vivo. In a mechanical study, circ_0015756 directly bound to miR-145-5p, and inhibition of miR-145-5p reversed the effects of circ_0015756 knockdown on OC cells. Moreover, miR-145-5p directly targeted PSAT1, and miR-145-5p weakened OC cell growth, migration and invasion via targeting PSAT1. Importantly, further studies confirmed that circ_0015756 could indirectly regulate PSAT1 expression via sponging miR-145-5p. In all, circ_0015756 accelerated OC tumorigenesis through regulating miR-145-5p/PSAT1 axis, providing a new therapeutic target for OC.

MicroRNA-382-5p Promotes Oral Squamous Cell Carcinoma Development and Progression by Negatively Regulating PTEN Expression

PURPOSE

Oral squamous cell carcinoma (OSCC) local recurrence and distant metastasis remain a poorly understood clinical challenge. The objective of this study was to investigate how dysregulation of miR-382-5p impacts invasion and dissemination of OSCC.

METHODS

Tissue samples were collected from 20 subjects with OSCC. Expression levels of miR-382-5p were determined by quantitative real-time polymerase chain reaction (qRT-PCR), and correlations with clinical characteristics were investigated. qRT-PCR was used to determine the miR-382-5p and peptidyl-prolyl cis/trans isomerase (PTEN) expression in tumor tissues, adjacent normal tissues, normal human oral keratinocyte line, and OSCC line (SCC-9). Cell proliferation, invasion, and migration of knock-in and knock-down miR-382-5p transfectants were assessed using cell counting kit-8 and Transwell assays. PTEN was confirmed to be a downstream target using a TargetScan prediction, dual-luciferase reporter assays, and western blot analysis. Statistical analysis of experimental data was performed with SPSS 22.0 software.

RESULTS

We found high expression of miR-382-5p and significant downregulation of PTEN in tumor tissues and SCC-9 cells from OSCC patients (P < .05). miR-382-5p expression was lower in early stage (I + II) than in late stage (III + IV), while PTEN exhibited higher expression in early stage (I + II) instead of in late stage (III + IV) (P < .05). In addition, overexpression of miR-382-5p promoted the proliferation, invasion, and migration of OSCC cells. However, the proliferation, invasion, and migration of OSCC cells were inhibited after suppression of miR-382-5p. Finally, PTEN is downregulated by miR-382-5p.

CONCLUSION

MiR-382-5p supports proliferation, invasion, and migration of OSCC cells through the PTEN pathway. Further investigation may improve our understanding of OSCC local recurrence and distant metastasis.

Diagnostic value of circN4BP2L2 in type I and type II epithelial ovarian cancer

BACKGROUND

CircN4BP2L2 was previously identified to be significantly decreased in epithelial ovarian cancer (EOC) and was associated with disease progression. The aim of this study was to evaluate the diagnostic value of plasma circN4BP2L2 using the unifying model of type I and type II EOC.

METHODS

A total of 540 plasma samples were obtained from 180 EOC patients, 180 benign ovarian cyst patients, and 180 healthy volunteers. CircN4BP2L2 was assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Cancer antigen 125 (CA125) and human epididymis protein 4 (HE4) were assessed using enzyme-linked immunosorbent assay (ELISA). Receiver operating curve (ROC), the area under the curve (AUC), sensitivity and specificity were estimated.

RESULTS

Low level of circN4BP2L2 was associated with advanced tumor stage (p < 0.01) in type I EOC. Decreased circN4BP2L2 was associated with lymph node metastasis (LNM) (p = 0.04) in type II EOC. The expression level of circN4BP2L2 in type I was similar to that in type II. CircN4BP2L2 could significantly separate type I or type II from benign or normal cohort (p < 0.01). Early-stage type I or type II EOC vs. benign or normal cohort could also be distinguished by circN4BP2L2 (p < 0.01).

CONCLUSION

CircN4BP2L2 might serve as a promising diagnostic biomarker for both type I and type II EOC. The diagnostic safety for circN4BP2L2 in early-stage type I or type II EOC is also acceptable. Further large-scale well-designed studies are warranted to investigate whether circN4BP2L2 is specific for all histologic subgroups.

Roles and mechanisms of CircRNAs in ovarian cancer

Ovarian cancer (OC) is one of the female malignancies with nearly 45% 5-year survival rate. Circular RNAs (circRNAs), a kind of single-stranded non-coding RNAs, are generated from the back-splicing of cellular housekeeping noncoding RNAs and precursor messenger RNAs. Recent studies revealed that circRNAs have different biological function, including sponging miRNAs, encoding micropeptides, regulating stability of cytoplasmic mRNAs, affecting transcription and splicing, via interacting with DNA, RNA and proteins. Due to their stability, circRNAs have the potential of acting as biomarkers and treatment targets. In this review, we briefly illustrate the biogenesis mechanism and biological function of circRNAs in OC, and make a perspective of circRNAs drug targeting immune responses and signaling pathways in OC. This article can provide a systematic view into the current situation and future of circRNAs in OC.

Circular RNAs in Epithelial Ovarian Cancer: From Biomarkers to Therapeutic Targets

Epithelial ovarian cancer (EOC) is the most lethal gynecological cancer, and more than 70% of patients are diagnosed at advanced stages. Despite the application of surgery and chemotherapy, the prognosis remains poor due to the high relapse rate. It is urgent to identify novel biomarkers and develop novel therapeutic strategies for EOC. Circular RNAs (circRNAs) are a class of noncoding RNAs generated from the "back-splicing" of precursor mRNA. CircRNAs exert their functions via several mechanisms, including acting as miRNA sponges, interacting with proteins, regulating transcription, and encoding functional proteins. Recent studies have identified many circRNAs that are dysregulated in EOC and may be used as diagnostic and prognostic markers. Increasing evidence has revealed that circRNAs play a critical role in ovarian cancer progression by regulating various cellular processes, including proliferation, apoptosis, metastasis, and chemosensitivity. The circRNA-based therapy may be a novel strategy that is worth exploring in the future. Here, we provide an overview of EOC and circRNA biogenesis and functions. We then discuss the dysregulations of circRNAs in EOC and the possibility of using them as diagnostic/prognostic markers. We also summarize the role of circRNAs in regulating ovarian cancer development and speculate their potential as therapeutic targets.

circANKRD17(has_circ_0007883) confers paclitaxel resistance of ovarian cancer via interacting with FUS to stabilize FOXR2

Emerging numbers of endogenous circular RNAs (circRNAs) have gained much attention to serve as essential regulators in the carcinogenesis of human cancers. Unfortunately, the occurrence of paclitaxel (PTX) resistance to ovarian cancer remains to be responsible for the poor prognosis. Herein, the aim of our study is to reveal a dysregulation of a particular circRNA, circANKRD17 (has_circ_0007883), and its exact role involving in chemoresistance of ovarian cancer. Expression patterns of circANKRD17 in PTX-resistant ovarian cancer tissues and cell lines was examined using quantitative real-time PCR analysis. Role of circANKRD17 on drug resistance and cell viability was evaluated by CCK-8 assay. Colony formation was subjected to measure cell proliferation. Flow cytometry was employed to evaluate cell cycle either or cell apoptosis. Xenograft models were constructed for further in vivo confirmation. The cicrANKRD17/FUS/FOXR2 axis was demonstrated using bioinformatics analysis, RNA pull-down, as well as RNA immunoprecipitation assays. Dramatically high expressed circANKRD17 observed in ovarian cancer tissues and cells was correlated with PTX resistance, which indicated the poor prognosis. Functionally, knockdown of circANKRD17 decreased PTX resistance via inhibiting cell viability and inducing cell apoptosis. Mechanistically, circANKRD17 interacted with the RNA-binding protein, fused in sarcoma (FUS) to stabilize FOXR2. In summary, our study uncovered a novel machinery of circANKRD17/FUS/FOXR2 referring to ovarian cancer drug sensitivity and tumorigenesis, highlighting a potential strategy for circRNAs in chemoresistance.

The emerging roles and potential applications of circular RNAs in ovarian cancer: a comprehensive review

Ovarian cancer (OC) is among the most common human malignancies and the first cause of deaths among gynecologic cancers. Early diagnosis can help improving prognosis in those patients, and accordingly exploring novel molecular mechanisms may lead to find therapeutic targets. Circular RNAs (circRNAs) comprise a group of non-coding RNAs in multicellular organisms, which are identified with characteristic circular structure. CircRNAs have been found with substantial functions in regulating gene expression through interacting with RNA-binding proteins, targeting microRNAs, and transcriptional regulation. They have been found to be involved in regulating several critical processes such as cell growth, and death, organ development, signal transduction, and tumorigenesis. Accordingly, circRNAs have been implicated in a number of human diseases including malignancies. They are particularly reported to contribute to several hallmarks of cancer leading to cancer development and progression, although a number also are described with tumor-suppressor function. In OC, circRNAs are linked to regulation of cell growth, invasiveness, metastasis, angiogenesis, and chemoresistance. Notably, clinical studies also have shown potentials in diagnosis, prediction of prognosis, and therapeutic targets for OC. In this review, I have an overview to the putative mechanisms, and functions of circRNAs in regulating OC pathogenesis in addition to their clinical potentials.

Circular RNA circ-BNC2 (hsa_circ_0008732) inhibits the progression of ovarian cancer through microRNA-223-3p/ FBXW7 axis

Background

Circular RNAs (circRNAs) are reported to be key regulators in the progression of human cancers. This work focuses on the function and molecular mechanism of circRNA-BNC2 (circ-BNC2) (also known as hsa_circ_0008732) in ovarian cancer (OC).

Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to detect circ-BNC2, microRNA-223-3p (miR-223-3p) and F-box and WD repeat domain containing 7 (FBXW7) mRNA expressions in OC tissues and cells. Besides, cell counting kit 8 (CCK-8), transwell assay and cell cycle assays were executed to assess the proliferative, migrative, invasive abilities, and cell cycle progression of OC cells, respectively. Dual-luciferase reporter gene assay and RNA pull-down assay were used to validate the targeting relationships between miR-223-3p and circ-BNC2 or FBXW7. Western blot was adopted to determine FBXW7 protein levels in OC cells.

Results

Circ-BNC2 expression was downregulated in OC tissues and cell lines, which was associated with higher FIGO stage and lymph node metastasis of OC patients. Circ-BNC2 overexpression repressed the proliferation, migration, invasion of OC cells and induced cell cycle arrest, while silencing circ-BNC2 worked oppositely. Mechanistically, circ-BNC2 could upregulate FBXW7 expression in OC cells via sponging miR-223-3p.

Conclusion

Circ-BNC2 suppresses the progression of OC via regulating miR-223-3p / FBXW7 axis. Our findings provided potential biomarker for OC therapy.

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.

Hsa_circ_0006427 Suppresses Multiplication, Migration and Invasion of Non-Small Cell Lung Cancer Cells through miR-346/VGLL4 Pathway

Objective

Circular RNAs (circRNAs) are identified as key modulators in cancer biology. Nonetheless, the role of circ_0006427 in non-small cell lung cancer (NSCLC) and its modulatory mechanism are undefined. This study aimed to investigate the potential function and mechanism of circ_0006427 in NSCLC.

Materials and Methods

In this experimental study, circ_0006427, miR-346 and vestigial like family member 4 (VGLL4) mRNA expressions were analyzed in NSCLC tissues and cells, using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Multiplication, migration and invasion of NSCLC cells were examined using the CCK-8 method and Transwell experiment, respectively. Dual-luciferase reporter gene experiments were conducted to identify the paring relationship between circ_0006427 and miR-346. Western blot was employed to determine expressions of VGLL4 and epithelial-mesenchymal transition (EMT) markers on protein levels. Immuno-histochemistry (IHC) method was adopted to assess VGLL4 protein expression in NSCLC tissues.

Results

Circ_0006427 expression was down-regulated in NSCLC tissues and cells, and circ_0006427 suppressed multiplication, migration, invasion and EMT of NSCLC cells. miR-346 expression was upregulated in NSCLC tissues and cells, and miR-346 worked as a target of circ_0006427. VGLL4 was down-regulated in NSCLC tissues and cells, and knockdown of VGLL4 accelerated multiplication, migration, invasion and EMT of NSCLC cells. Circ_0006427 enhanced VGLL4 expression by competitively binding with miR-346.

Conclusion

Circ_0006427/miR-346/VGLL4 axis regulated NSCLC progression.

Circular RNA MTCL1 promotes advanced laryngeal squamous cell carcinoma progression by inhibiting C1QBP ubiquitin degradation and mediating beta-catenin activation

Background

Circular RNAs (circRNAs) are involved in regulatory processes of ubiquitination and deubiquitination in various tumors at post-transcriptional epigenetic modification level. However, the underlying mechanism and its biological functions of circRNAs in the advanced laryngeal squamous cell carcinoma (LSCC) remain obscure.

Methods

RNA sequencing and quantitative real-time PCR (qRT-PCR) assays were applied to screen for circRNAs differentially expressed in LSCC tissues and cell lines. The candidate RNA-binding proteins and target signalling pathway were detected by RNA pull-down and mass spectrometry, in situ hybridization (ISH), immunohistochemistry (IHC), qRT-PCR assays, and bioinformatics analysis. The functional roles of these molecules were investigated using in vitro and in vivo experiments including EdU, transwell, wound healing, western blot assays, and the xenograft mice models. The molecular mechanisms were identified using RNA pull-down assays, RNA immunoprecipitation (RIP), Co-IP, ISH, Ubiquitination assay, bioinformatics analysis, and the rescue experiments.

Results

Here, we unveil that microtubule cross-linking factor 1 circRNA (circMTCL1, circ0000825) exerts its critical oncogenic functions by promoting complement C1q-binding protein (C1QBP)-dependent ubiquitin degradation and subsequently activating Wnt/β-catenin signalling in laryngeal carcinoma initiation and development. Specifically, circMTCL1 was remarkably up-regulated in the paired tissues of patients with LSCC (n = 67), which predicted a worse clinical outcome. Functionally, circMTCL1 exerted oncogenic biological charactersistics by promoting cell proliferative capability and invasive and migrative abilities. Ectopic circMTCL1 augumented cell proliferation, migration, and invasion of LSCC cells, and this effect could be reversed by C1QBP knocking down in vitro and in vivo. Mechanistically, circMTCL1 directly recruited C1QBP protein by harboring the specific recognized sequence (+ 159 − + 210), thereby accelerating the translation of C1QBP expression by inhibiting its ubiquitin–proteasome-mediated degradation. Importantly, the direct interaction of C1QBP with β-catenin protein was enhanced via suppressing the β-catenin phosphorylation and accelerating its accumulation in cytoplasm and nucleus.

Conclusion

Our findings manifested a novel circMTCL1-C1QBP-β-catenin signaling axis involving in LSCC tumorigenesis and progression, which shed new light on circRNAs-ubiquitous acidic glycoprotein mediated ubiquitin degradation and provided strategies and targets in the therapeutic intervention of LSCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-022-01570-4.

Circular RNAs Modulate Cancer Hallmark and Molecular Pathways to Support Cancer Progression and Metastasis

Simple Summary

Circular RNAs (circRNA) are a type of RNA molecule of circular shape that are now being extensively studied due to the important roles they play in different biological processes. In addition, they were also shown to be implicated in disease such as cancer. Cancer is a complex process which is often defined by a combination of specific processes called cancer hallmarks. In this review, we summarize the literature on circRNAs in cancer and classify them as being implicated in specific cancer hallmarks.

Abstract

Circular RNAs (circRNAs) are noncoding products of backsplicing of pre-mRNAs which have been established to possess potent biological functions. Dysregulated circRNA expression has been linked to diseases including different types of cancer. Cancer progression is known to result from the dysregulation of several molecular mechanisms responsible for the maintenance of cellular and tissue homeostasis. The dysregulation of these processes is defined as cancer hallmarks, and the molecular pathways implicated in them are regarded as the targets of therapeutic interference. In this review, we summarize the literature on the investigation of circRNAs implicated in cancer hallmark molecular signaling. First, we present general information on the properties of circRNAs, such as their biogenesis and degradation mechanisms, as well as their basic molecular functions. Subsequently, we summarize the roles of circRNAs in the framework of each cancer hallmark and finally discuss the potential as therapeutic targets.

Cervical cancer progression is regulated by SOX transcription factors: Revealing signaling networks and therapeutic strategies

Cervical cancer is the fourth common gynecologic cancer and is considered as second leading cause of death among women. Various strategies are applied in treatment of cervical cancer including radiotherapy, chemotherapy and surgery. However, cervical cancer cells demonstrate aggressive behavior in advanced phases, requiring novel strategies in their elimination. On the other hand, SOX proteins are transcription factors capable of regulating different molecular pathways and their expression varies during embryogenesis, disease development and carcinogenesis. In the present review, our aim is to reveal role of SOX transcription factors in cervical cancer. SOX transcription factors play like a double-edged sword in cancer. For instance, SOX9 possesses both tumor-suppressor and tumor-promoting role in cervical cancer. Therefore, exact role of each SOX members in cervical cancer has been discussed to direct further experiments for revealing other functions. SOX proteins can regulate proliferation and metastasis of cervical cancer cells. Furthermore, response of cervical cancer cells to chemotherapy and radiotherapy is tightly regulated by SOX transcription factors. Different downstream targets of SOX proteins such as Wnt signaling, EMT and Hedgehog have been identified. Besides, upstream mediators such as microRNAs, lncRNAs and circRNAs can regulate SOX expression in cervical cancer. In addition to pre-clinical studies, role of SOX transcription factors as prognostic and diagnostic tools in cervical cancer has been shown.

DLX6-AS1 activated by H3K4me1 enhanced secondary cisplatin resistance of lung squamous cell carcinoma through modulating miR-181a-5p/miR-382-5p/CELF1 axis

Cisplatin (CDDP) based chemotherapy is widely used as the first-line strategy in treating non-small cell lung cancer (NSCLC), especially lung squamous cell carcinoma (LUSC). However, secondary cisplatin resistance majorly undermines the cisplatin efficacy leading to a worse prognosis. In this respect, we have identified the role of the DLX6-AS1/miR-181a-5p/miR-382-5p/CELF1 axis in regulating cisplatin resistance of LUSC. qRT-PCR and Western blot analysis were applied to detect gene expression. Transwell assay was used to evaluate the migration and invasion ability of LUSC cells. CCK-8 assay was used to investigate the IC50 of LUSC cells. Flow cytometry was used to test cell apoptosis rate. RNA pull-down and Dual luciferase reporter gene assay were performed to evaluate the crosstalk. DLX6-AS1 was aberrantly high expressed in LUSC tissues and cell lines, and negatively correlated with miR-181a-5p and miR-382-5p expression. DLX6-AS1 expression was enhanced by H3K4me1 in cisplatin resistant LUSC cells. Besides, DLX6-AS1 knockdown led to impaired IC50 of cisplatin resistant LUSC cells. Furthermore, DLX6-AS1 interacted with miR-181a-5p and miR-382-5p to regulate CELF1 expression and thereby mediated the cisplatin sensitivity of cisplatin resistant LUSC cells. DLX6-AS1 induced by H3K4me1 played an important role in promoting secondary cisplatin resistance of LUSC through regulating the miR-181a-5p/miR-382-5p/CELF1 axis. Therefore, targeting DLX6-AS1 might be a novel way of reversing secondary cisplatin resistance in LUSC.

CircRNAs as potent biomarkers in ovarian cancer: a systematic scoping review

More powerful prognostic and diagnostic tools are urgently needed for identifying and treating ovarian cancer (OC), which is the most fatal malignancy in women in developed countries. Circular RNAs (circRNAs) are conservative and stable looped molecules that can regulate gene expression by competing with other endogenous microRNA sponges. This discovery provided new insight into novel methods for regulating genes that are involved in many disorders and cancers. This review focuses on the dysregulated expression of circRNAs as well as their diagnostic and prognostic values in OC. We found that studies have identified twenty-one downregulated circRNAs and fifty-seven upregulated ones. The results of these studies confirm that circRNAs might be potent biomarkers with diagnostic, prognostic and therapeutic target value for OC. We also consider the connection between circRNAs and OC cell proliferation, apoptosis, metastasis, and chemotherapy resistance and sensitivity.

lncRNA TUG1 promotes atherosclerosis progression by targeting miR-382-5p

OBJECTIVE

Atherosclerosis is a key risk factor for the initiation of cardiovascular disease, which results in high morbidity and mortality. lncRNA taurine upregulated gene 1 (TUG1) has been reported to participate in the development of atherosclerosis. Here, we aimed to investigate the interaction of TUG1 and miR-382-5p in regulating atherosclerosis progression.

METHODS

The levels of TUG1 and miR-382-5p in atherosclerotic serum samples and a cell model were determined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Pearson correlation analysis was then applied to TUG1 and miR-382-5p expression. Moreover, the interaction between TUG1 and miR-382-5p was confirmed by luciferase assay. The biological interaction between TUG1 and miR-382-5p was also dissected by loss of function analyses, including cell counting kit-8 (CCK-8) and Caspase-3 assays for cell proliferation and apoptosis, respectively, in oxidized low-density lipoprotein (ox-LDL)-treated human vascular smooth muscle cells (VSMCs).

RESULTS

TUG1 and miR-382-5p expressions were significantly increased and decreased, respectively, in both atherosclerotic serum samples and a cell model. In addition, the expression of TUG1 was negatively correlated with the level of miR-382-5p in atherosclerotic serum samples. Moreover, silencing of TUG1 reduced cell growth and enhanced the apoptosis of ox-LDL-treated VSMCs. Notably, a miR-382-5p inhibitor significantly reversed the effect of TUG1 downregulation on ox-LDL-treated VSMCs, which aggravates the process of atherosclerosis.

CONCLUSION

TUG1 can aggravate atherosclerosis progression by reducing the expression of miR-382-5p. This study provides an effective treatment target of atherosclerosis patients based on the TUG1-miR-382-5p axis.

CircITGA7 Suppresses Gastric Cancer Progression Through miR-1471/MTDH Axis

In recent years, there have been reports about the involvement of circular RNAs (circRNAs) in the pathogenesis of gastric cancer (GC), but the molecular mechanism in cell proliferation, invasion, and migration is still unclear. Based on The Cancer Genome Atlas (TCGA) database, we analyzed differentially expressed circRNAs between GC and non-tumor tissues. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis were used to clarify the functional role in GC. Here, we showed that circITGA7 was lowly expressed in GC tissues based on the TCGA database. In vitro, silencing the expression of circITGA7 increased cell proliferation and metastasis, whereas overexpression did the opposite. Mechanistically, miR-1471 has circITGA7 as a sponge, and miR-1471 has metadherin (MTDH) as a target gene. Consequently, functional analysis showed that the tumor suppressor effect of circITGA7 was the result of regulating the miR-1471/MTDH axis. Overall, the circITGA7/miR-1471/MTDH signaling pathway may play a crucial role in GC, providing a new potential mechanism involved in GC progression.

Hsa-circ_0000064 accelerates the malignant progression of gastric cancer via sponging microRNA-621

Gastric cancer (GC) is one of the most common digestive system tumors in the world. Many circular RNAs (circRNAs) are involved in the progression of GC. The purpose of this study was to delve into the expression characteristics and biological functions of circ_0000064 in GC, and further study its mechanisms. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect circ_0000064 expression in 61 GC tissues and cell lines. Circ_0000064 knockdown was successfully modeled with siRNA. The effects of circ_0000064 on the biological functions of GC cells were analyzed by CCK-8, BrdU, and Transwell assays. Bioinformatics and dual-luciferase reporter gene assay were adopted to explore the relations between circ_0000064 and microRNA-621 (miR-621). Western blot was used to examine the regulatory function of circ_0000064 and miR-621 on SYF2 pre-mRNA splicing factor 2. Cric_0000064 expression was elevated in GC tissues and cell lines. Knocking down cric_0000064 could inhibit the viability, migration, and invasion of GC cells. Dual-luciferase reporter gene assay showed that miR-621 could bind circ_0000064 and SYF2 3'UTR; in addition, miR-621 overexpression or SYF2 knockdown could partially weaken the cancer-promoting effect of circ_0000064 on GC cells. Circ_0000064 expression was negatively correlated with miR-621 expression in GC tissues while positively with SYF2 expression. Circ_0000064 can participate in the GC progression via modulating miR-621/SYF2 axis. This implies that circ_0000064 may be a new diagnosed biomarker or a new therapeutic target of GC.

LINC00707 Regulates miR-382-5p/VEGFA Pathway to Enhance Cervical Cancer Progression

Long noncoding RNAs (LncRNAs) are reported to exhibit crucial roles in cancer progression. LINC00707 is recently indicated to be a significant oncogene in various cancers. Up to now, the mechanism of LINC00707 in cervical cancer is still unclear. In this study, our present work was designed to study the biological effects of LINC00707 in cervical cancer. Firstly, the expression level of LINC00707 in cervical cancer was tested. We observed LINC00707 expression was greatly increased in cervical cancer. Then, we assessed the detailed effect of LINC00707 on the development of cervical cancer using CCK-8 assay, Transwell assays, and tumor xenograft experiments. Gain-of-function and loss-of-function assays revealed the function of LINC00707 in cervical cancer progression. In addition, the action of LINC00707 in cervical cancer cells was studied using bioinformatic tools and luciferase reporter experiment. It was displayed that loss of LINC00707 significantly repressed cell growth of cervical cancer. Meanwhile, restoration of LINC00707 expression obviously induced cervical cancer cell growth. Then, we predicted that LINC00707 could serve as a molecular sponge for miR-382-5p to modulate VEGFA expression in cervical cancer. Subsequently, lack of VEGFA expression reversed the influence of miR-382-5p knockdown on cervical cancer cells. In conclusion, our findings evidenced the significant role of LINC00707-miR-382-5p-VEGFA network in cervical cancer and it can provide an attractive target.

Lidocaine Promoted Ferroptosis by Targeting miR-382-5p /SLC7A11 Axis in Ovarian and Breast Cancer

Ovarian and breast cancer are prevalent female malignancies with increasing occurrence incidence and metastasis, significantly affecting the health and life quality of women globally. Anesthetic lidocaine has presented anti-tumor activities in the experimental conditions. However, the effect of lidocaine on ovarian and breast cancer remains elusive. We identified the important function of lidocaine in enhancing ferroptosis and repressing progression of ovarian and breast cancer. Our data showed that lidocaine further repressed erastin-inhibited ovarian and breast cancer cell viabilities. The treatment of lidocaine induced accumulation of Fe²⁺, iron and lipid reactive oxygen species (ROS) in ovarian and breast cancer cells. The ovarian and breast cancer cell proliferation was suppressed while cell apoptosis was induced by lidocaine in vitro. Lidocaine attenuated invasion and migration of ovarian and breast cancer cells as well. Regarding the mechanism, we found that lidocaine downregulated solute carrier family 7 member 11 (SLC7A11) expression by enhancing microRNA-382-5p (miR-382-5p) in the cells. The inhibition of miR-382-5p blocked lidocaine-induced ferroptosis of ovarian and breast cancer cells. MiR-382-5p/SLC7A11 axis was involved in lidocaine-mediated inhibition of ovarian and breast cancer cell proliferation in vitro. The miR-382-5p expression was down-regulated but SLC7A11 expression was up-regulated in clinical ovarian and breast cancer samples. Furthermore, the treatment of lidocaine repressed tumor growth of ovarian cancer cells in vivo, in which the miR-382-5p expression was increased while SLC7A11 expression was decreased. Consequently, we concluded that the lidocaine promoted ferroptosis by miR-382-5p/SLC7A11 axis in ovarian and breast cancer cells. The clinical value of lidocaine in the treatment of ovarian and breast cancer deserves to be proved in detail.

Circular RNA circ_0084927 regulates proliferation, apoptosis, and invasion of breast cancer cells via miR-142-3p/ERC1 pathway

OBJECTIVE

We aimed to investigate the mechanism of circular RNA circ_0084927 in the progression of breast cancer (BC).

METHODS

The levels of circ_0084927, miR-142-3p, and ELKS/RAB6-interacting/CAST family member-1 (ERC1) mRNA in the BC tissues and cells were detected by qRT-PCR. CCK8, colony formation, Transwell, and flow cytometry assays were performed to examine the cell proliferation, colony formation, cell invasion, and apoptosis, respectively, in the BC cells with regulated expressions of circ_0084927, miR-142-3p, and ERC1. RNase R treatment was employed to verify the circular structure of circ_0084927. Nucleocytoplasmic separation experiment, bioinformatics analysis, dual-luciferase reporter assay, and RNA immunoprecipitation were performed to investigate the ceRNA mechanism of circ_0084927.

RESULTS

High levels of circ_0084927 and ERC1 and low levels of miR-142-3p were detected in the BC tissues and cells. Knockdown of circ_0084927 promoted apoptosis and inhibited proliferation, colony formation, and invasion of BC cells (all P<0.05), whereas overexpression of circ_0084927 in the BC cells achieved the opposite effects. miR-142-3p is the target of circ_0084927. Overexpression of miR-142-3p could inhibit BC cell proliferation, colony formation, and cell invasion and induce apoptosis of the BC cells (all P<0.05), and the effects of miR-142-3p knockout on the BC cells could be reversed by silencing circ_0084927. miR-142-3p could target ERC1. Both ERC1 silencing and circ_0084927 knockout in the BC cells could achieve the tumor-suppressing effect, and this effect could be more remarkable under simultaneous ERC1 silencing and circ_0084927 knockout (all P<0.05).

CONCLUSION

Circ_0084927 can promote the progression of BC by regulating the miR-142-3p/ERC1 axis.

Circular RNA circPVT1 Contributes to Doxorubicin (DXR) Resistance of Osteosarcoma Cells by Regulating TRIAP1 via miR-137

Background

Chemoresistance is a major obstacle to the treatment of osteosarcoma patients. Circular RNA (circRNA) circPVT1 has been reported to be related to the doxorubicin (DXR) resistance in osteosarcoma. This study is designed to explore the role and mechanism of circPVT1 in the DXR resistance of osteosarcoma.

Methods

circPVT1, microRNA-137 (miR-137), and TP53-regulated inhibitor of apoptosis 1 (TRIAP1) levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). The protein levels of ATP-binding cassette, subfamily C, member 1 (ABCC1), multidrug resistance-associated protein 1 (MRP-1), cleaved- (c-) caspase-3, B-cell lymphoma-2 (Bcl-2), and TRIAP1 were examined by a western blot assay. Cell viability, proliferation, and apoptosis were detected by cell counting kit-8 (CCK-8), colony formation, and flow cytometry assays, severally. The binding relationship between miR-137 and circPVT1 or TRIAP1 was predicted by starbase 3.0 and then verified by dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays. The biological role of circPVT1 in osteosarcoma tumor growth and drug resistance was examined by the xenograft tumor model in vivo. Results. circPVT1 and TRIAP1 were highly expressed, and miR-137 was decreased in DXR-resistant osteosarcoma tissues and cells. Moreover, circPVT1 knockdown could boost DXR sensitivity by inhibiting DXR-caused proliferation and DXR-induced apoptosis in DXR-resistant osteosarcoma cells in vitro. The mechanical analysis discovered that circPVT1 acted as a sponge of miR-137 to regulate TRIAP1 expression. circPVT1 silencing increased the drug sensitivity of osteosarcoma in vivo. Conclusion. circPVT1 boosted DXR resistance of osteosarcoma cells partly by regulating the miR-137/TRIAP1 axis, hinting a promising therapeutic target for the osteosarcoma treatment.

Non-coding RNA in cancer

Majority of the human genome is transcribed to RNAs that do not encode proteins. These non-coding RNAs (ncRNAs) play crucial roles in regulating the initiation and progression of various cancers. Given the importance of the ncRNAs, the roles of ncRNAs in cancers have been reviewed elsewhere. Thus, in this review, we mainly focus on the recent studies of the function, regulatory mechanism and therapeutic potential of the ncRNAs including microRNA (miRNA), long ncRNA (lncRNA), circular RNA (circRNA) and PIWI interacting RNA (piRNA), in different type of cancers.

Regulation of Nuclear Factor-KappaB (NF-κB) signaling pathway by non-coding RNAs in cancer: Inhibiting or promoting carcinogenesis?

The nuclear factor-kappaB (NF-κB) signaling pathway is considered as a potential therapeutic target in cancer therapy. It has been well established that transcription factor NF-κB is involved in regulating physiological and pathological events including inflammation, immune response and differentiation. Increasing evidences suggest that deregulated NF-κB signaling can enhance cancer cell proliferation, metastasis and also mediate radio-as well as chemo-resistance. On the contrary, non-coding RNAs (ncRNAs) have been found to modulate NF-κB signaling pathway under different settings. MicroRNAs (miRNAs) can dually inhibit/induce NF-κB signaling thereby affecting the growth and migration of cancer cells. Furthermore, the response of cancer cells to radiotherapy and chemotherapy may also be regulated by miRNAs. Regulation of NF-κB by miRNAs may be mediated via binding to 3^/-UTR region. Interestingly, anti-tumor compounds can increase the expression of tumor-suppressor miRNAs in inhibiting NF-κB activation and the progression of cancers. Long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) can also effectively modulate NF-κB signaling thus affecting tumorigenesis. It is noteworthy that several studies have demonstrated that lncRNAs and circRNAs can affect miRNAs in targeting NF-κB activation. They can act as competing endogenous RNA (ceRNA) thereby reducing miRNA expression to induce NF-κB activation that can in turn promote cancer progression and malignancy.

Hsa_circ_0015326 Promotes the Proliferation, Invasion and Migration of Ovarian Cancer Through miR-127-3p/MYB

Background

More and more evidences show that circular RNA (circRNA) has an important role in ovarian cancer (OC). Hsa_circ_0015326 is a newly discovered upregulated circRNA in OC, but its role and mechanism in OC have not been studied yet.

Methods

Quantitative real-time PCR was used to detect the expression of hsa_circ_0015326, microRNA (miR)-127-3p and MYB. The viability, colony number, cell cycle process, invasion, migration and apoptosis of cells were determined using cell counting kit 8 assay, colony formation assay, flow cytometry, transwell assay and wound healing assay. Moreover, the protein expression levels of metastasis, proliferation, apoptosis markers and MYB were assessed using Western blot analysis. The interaction between miR-127-3p and hsa_circ_0015326 or MYB was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay. Xenograft tumors were built to explore the role of hsa_circ_0015326 in OC tumor growth in vivo.

Results

Elevated expression of hsa_circ_0015326 was identified in OC tissues and cells. Loss-of-function experiments suggested that silenced hsa_circ_0015326 inhibited the proliferation, invasion, migration, and promoted the apoptosis of OC cells in vitro, as well as inhibited OC tumorigenesis in vivo. Mechanically, hsa_circ_0015326 sponged miR-127-3p and miR-127-3p targeted MYB. The rescue experiments revealed that miR-127-3p inhibitor reversed the inhibitory effect of hsa_circ_0015326 silencing on OC progression, and MYB overexpression reversed the suppressive effect of miR-127-3p on OC progression. In addition, our data indicated that MYB expression was positively regulated by hsa_circ_0015326.

Conclusion

This study showed that hsa_circ_0015326 could facilitate OC progression by regulating the miR-127-3p/MYB axis, which suggested that it might become a potential target for the treatment of OC.

The Interplay between Long Noncoding RNAs and Proteins of the Epigenetic Machinery in Ovarian Cancer

Comprehensive large-scale sequencing and bioinformatics analyses have uncovered a myriad of cancer-associated long noncoding RNAs (lncRNAs). Aberrant expression of lncRNAs is associated with epigenetic reprogramming during tumor development and progression, mainly due to their ability to interact with DNA, RNA, or proteins to regulate gene expression. LncRNAs participate in the control of gene expression patterns during development and cell differentiation and can be cell and cancer type specific. In this review, we described the potential of lncRNAs for clinical applications in ovarian cancer (OC). OC is a complex and heterogeneous disease characterized by relapse, chemoresistance, and high mortality rates. Despite advances in diagnosis and treatment, no significant improvements in long-term survival were observed in OC patients. A set of lncRNAs was associated with survival and response to therapy in this malignancy. We manually curated databases and used bioinformatics tools to identify lncRNAs implicated in the epigenetic regulation, along with examples of direct interactions between the lncRNAs and proteins of the epigenetic machinery in OC. The resources and mechanisms presented herein can improve the understanding of OC biology and provide the basis for further investigations regarding the selection of novel biomarkers and therapeutic targets.