CircRNA_103948 inhibits autophagy in colorectal cancer in a ceRNA manner

Hsa_circ_0057104, by competitive adsorption of miR-627-5p, mediates CCND2 expression to promote malignant proliferation and Warburg effect of colorectal cancer

OBJECTIVE

hsa_circ_0057104 (circPDK1) has been elucidated to regulate malignant behavior in pancreatic and renal cell carcinoma. The study functionally aimed at how circPDK1 modifies colorectal cancer (CRC) progression, along with its potential molecular mechanism.

METHODS

circPDK1 expression patterns in CRC tissues and cell lines were analyzed by RT-qPCR. circPDK1/miR-627-5p/CCND2 expression levels were changed by transient transfection. CCK-8 assay, flow cytometry, Transwell, immunoblotting, and commercial kits were utilized to measure CRC cell proliferation, apoptosis, invasion/migration, and glycolysis processes. Dual luciferase reporting assay and RIP assay were employed to evaluate the targeting relationship between circPDK1/miR-627-5p/CCND2.

RESULTS

circPDK1 was highly expressed in CRC. circPDK1 knockdown inhibited CRC cell proliferation, invasion/migration, and warburg effect and forced apoptosis. Overexpressing circPDK1 had the opposite effect. The effects of circPDK1 knockdown or circPDK1 overexpression on CRC cells were mitigated by downregulating miR-627-5p or CCND2, respectively. CircPDK1, by competitive adsorption of miR-627-5p, mediated CCND2 expression.

CONCLUSION

CircPDK1 induces the malignant behavior of CRC by competitive adsorption of miR-627-5p mediating CCND2 expression, offering new insights into the future development of CRC-targeted drugs.

A tumor-promotional molecular axis CircMAPKBP1/miR-17-3p/TGFβ2 activates autophagy pathway to drive tongue squamous cell carcinoma cisplatin chemoresistance

Platinum-based chemotherapy is the first-line treatment for tongue squamous cell carcinoma (TSCC), but most patients rapidly develop resistance. Circular RNAs (circRNAs) are a class of critical regulators in the pathogenesis of several tumors, but their role in cisplatin resistance in TSCC has not been fully elucidated. Here we found that circMAPKBP1 was enriched in cisplatin resistant TSCC cells and was closely associated with enhanced autophagic activity. Functionally, silencing circMAPKBP1 significantly restored the chemosensitivity of cisplatin-resistant TSCC cells both in vitro and in vivo by suppressing autophagy. Mechanistically, circMAPKBP1 enhanced cisplatin sensitivity through the miR-17-3p/TGFβ2 axis by activating autophagy pathway. Data from clinical studies revealed that high expression of circMAPKBP1 and TGFβ2 was closely linked to a poor outcome in TSCC patients. We thus concluded that circMAPKBP1 is a tumor promoting factor and confers cisplatin sensitivity by activating the miR-17-3p/TGFβ2 axis-mediated autophagy. We propose that circMAPKBP1 may be a potential therapeutic target for TSCC.

Circular RNAs in programmed cell death: Regulation mechanisms and potential clinical applications in cancer: A review

Circular RNAs (circRNAs) are a novel class of non-coding RNAs with covalently closed structures formed by reverse splicing of precursor mRNAs. The widespread expression of circRNAs across species has been revealed by high-throughput sequencing and bioinformatics approaches, indicating their unique properties and diverse functions including acting as microRNA sponges and interacting with RNA-binding proteins. Programmed cell death (PCD), encompassing various forms such as apoptosis, necroptosis, pyroptosis, autophagy, and ferroptosis, is an essential process for maintaining normal development and homeostasis in the human body by eliminating damaged, infected, and aging cells. Many studies have demonstrated that circRNAs play crucial roles in tumourigenesis and development by regulating PCD in tumor cells, showing that circRNAs have the potential to be biomarkers and therapeutic targets in cancer. This review aims to comprehensively summarize the intricate associations between circRNAs and diverse PCD pathways in tumor cells, which play crucial roles in cancer development. Additionally, this review provides a detailed overview of the underlying mechanisms by which circRNAs modulate various forms of PCD for the first time. The ultimate objective is to offer valuable insights into the potential clinical significance of developing novel strategies based on circRNAs and PCD for cancer diagnosis, prognosis, and treatment.

The role of epigenetics in women's reproductive health: the impact of environmental factors

This paper explores the significant role of epigenetics in women's reproductive health, focusing on the impact of environmental factors. It highlights the crucial link between epigenetic modifications-such as DNA methylation and histones post-translational modifications-and reproductive health issues, including infertility and pregnancy complications. The paper reviews the influence of pollutants like PM2.5, heavy metals, and endocrine disruptors on gene expression through epigenetic mechanisms, emphasizing the need for understanding how dietary, lifestyle choices, and exposure to chemicals affect gene expression and reproductive health. Future research directions include deeper investigation into epigenetics in female reproductive health and leveraging gene editing to mitigate epigenetic changes for improving IVF success rates and managing reproductive disorders.

CircCOL5A1 is involved in proliferation, invasion, and inhibition of ferroptosis of colorectal cancer cells via miR-1287-5p/SLC7A11

Colorectal cancer (CRC) is the leading cause of cancer-related death globally. Circular RNA circCOL5A1 plays an oncogene function in a variety of tumors. However, the function of circCOL5A1 in CRC is still unknown. Here, we aimed to elucidate the function and mechanism of circCOL5A1 in CRC. The correlation between circCOL5A1 and CRC clinicopathological was assessed through chi-square. The relevance between circCOL5A1 and CRC patient survival time was evaluated by Kaplan-Meier analysis. The expressions of circCOL5A1 in CRC were determined via quantitative real-time PCR. The function of circCOL5A1 in CRC was analyzed with Cell Counting Kit-8, EdU assay, Transwell, detection of reactive oxygen species and Fe2+ levels, and Western blot analysis. Moreover, the mechanism of circCOL5A1 was determined by dual-luciferase reporter assay, RNA immunoprecipitation, and RNA pull-down. Finally, the role of circCOL5A1 in vivo was elucidated through a mouse xenograft model, hematoxylin-eosin staining, and immunohistochemistry. CircCOL5A1 expression was increased in CRC, and increased circCOL5A1 levels were related to TNM stage, lymph node metastasis, distant metastasis, and tumor differentiation in CRC patients, and CRC patients with high circCOL5A1 levels had a low overall survival rate. For the circCOL5A1 function in CRC, we found that circCOL5A1 knockdown weakened CRC cell proliferation and invasion, and enhanced cell ferroptosis. For the circCOL5A1 mechanism in CRC, we further confirmed that circCOL5A1 bound to miR-1287-5p, miR-1287-5p bound to SLC7A11. SLC7A11 was negatively interrelated to miR-1287-5p and was positively interrelated to circCOL5A1 in CRC tissues. Furthermore, interfering circCOL5A1 decreased SLC7A11 expression, and this trend was abolished through miR-1287-5p cotransfection. Rescue assays further demonstrated that circCOL5A1 knockdown alleviated CRC cell malignant phenotype via miR-1287-5p/SLC7A11. Moreover, interference with circCOL5A1 reduced CRC growth in vivo. CircCOL5A1 functioned as an oncogene in CRC via miR-1287-5p/SLC7A11.

Effect of circ_0000009 on lung adenocarcinoma progression by regulating PDZD2 in a ceRNA- and RBP- dependent manner

Accumulating evidence now demonstrated that circular RNAs (circRNAs) are closely related to the pathogenesis of lung adenocarcinoma (LUAD). Through GEO2R online analysis, we screened hsa_circ_0000009 (circ_0000009) from the GEO database (GSE158695), and its expression in LUAD cancer tissues and cell lines was detected by RT-qPCR. The looping structure of circ_0000009 was tested by RNase R and actinomycin D experiments. The changes of proliferation were tested by CCK-8 or EdU assay. And the changes of apoptosis in A549 and H1299 cells were measured via flow cytometry. The A549 BALB/c tumor model was established to evaluate the influence of circ_0000009 on LUAD cell growth in vivo. In addition, experiments connected with ceRNA direction (mainly including bioinformatics prediction and luciferase reporter assay) and RNA Binding Protein (RBP) direction (mainly including RNA pull-down assay, RIP assay and mRNA stability assay) were further developed to reveal the regulatory mechanism of circ_0000009. The gene and protein levels in this project were assessed by RT-qPCR and western blotting analysis, respectively. The data manifested that circ_0000009 was in low expression in LUAD. The in vitro and in vivo experiments threw light on that overexpression of circ_0000009 dramatically suppressing LUAD tumorigenesis. Mechanistically, circ_0000009 promoted the expression of PDZD2 by sponging miR-154-3p. Furthermore, circ_0000009 stabilized PDZD2 by recruiting IGF2BP2. This study illustrated the mechanism that overexpressing of circ_0000009 suppressed LUAD progression by upregulating PDZD2 expression, providing an original treatment direction for LUAD.

Circular RNA circ_0000212 accelerates cervical cancer progression by acting as a miR-625-5p sponge to upregulate PTP4A1

Cervical cancer is one of the most common malignant tumors in women. Circular RNA (circRNA) has been shown to play a crucial role in cervical cancer. Here, the aim of this study was to explore the functions and a novel miRNA/mRNA network underlying circ_0000212 in cervical cancer regulation. The expression of circ_000212, miR-625-5p and Protein Tyrosine Phosphatase 4A1 (PTP4A1) mRNA was measured by quantitative real-time PCR (qRT-PCR). 5-ethynyl-2'-deoxyuridine assay was conducted to detect the proliferation of cervical cancer cells. Wound healing and transwell assays were employed to assess cell migration and invasion. The angiogenesis abilities of cervical cancer cells were evaluated by tube formation assay. Flow cytometry was performed for analyzing cell apoptosis. The expression of PTP4A1 protein and apoptosis-relative protein were detected via western blot. The dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were employed to clarify the interaction between circ_0000212 or PTP4A1 and miR-625-5p. The impact of circ_0000212 on cervical cancer growth in vivo was detected by xenograft assay. Circ_0000212 and PTP4A1 were highly expressed and miR-625-5p expression level was decreased in cervical cancer. Circ_0000212 silencing suppressed cervical cancer cell proliferation, migration, invasion and angiogenesis while promoting apoptosis. MiR-625-5p was targeted by circ_0000212, and miR-625-5p inhibition reversed the effects of circ_0000212 knockdown. MiR-625-5p directly targeted PTP4A1, and the inhibitory effect of miR-625-5p on the malignant progression of cervical cancer was reversed after PTP4A1 overexpression. In-vivo assays validated that circ_0000212 promoted cervical cancer tumor growth in vivo . circ_0000212 acted as an oncogene in cervical cancer progression, and knockdown of circ_0000212 repressed cervical cancer development by increasing miR-625-5p and decreasing PTP4A1.

Targeting a novel circITCH/miR-421/BTG1 axis is effective to suppress the malignant phenotypes in hepatocellular carcinoma (HCC) cells

Circular RNA-based competing endogenous RNA (ceRNA) networks contribute to the initiation and development of various types of cancer, including hepatocellular carcinoma (HCC). Although a novel circular RNA itchy E3 ubiquitin protein ligase (circITCH) is identified as a tumor suppressor in HCC, its detailed molecular mechanisms have not been fully delineated. The present study was designed to resolve this issue, and we firstly verified that circITCH suppressed the malignant phenotypes in HCC cells by regulating a novel miR-421/B-cell translocation gene 1 (BTG1) axis. Specifically, through performing the Real-Time qPCR analysis, we noticed that circITCH expression in HCC tumor tissues or cell lines were significantly lower than that in adjacent normal tissues or normal hepatocytes, and the expression levels of circITCH were negatively correlated with tumor size and TNM stage in HCC patients. Next, our functional experiments confirmed that overexpression of circITCH induced cell cycle arrest and apoptosis, and reduced cell viability and colony forming ability in Hep3B and Huh7 cells. Mechanically, bioinformatics analysis, RNA immunoprecipitation and luciferase reporter assay demonstrated that circITCH served as RNA sponges for miR-421 to elevate BTG1 levels in HCC cells. The rescuing experiments verified that upregulation of miR-421 promoted cell viability and colony formation, and reduced apoptosis, which were abrogated by overexpression of circITCH or BTG1. In conclusion, this study identified a novel circITCH/miR-421/BTG1 axis that restrained the development of HCC, and our findings provided novel biomarkers for the treatment of this disease.

Exosomal circCOL1A2 from cancer cells accelerates colorectal cancer progression via regulating miR-665/LASP1 signal axis

Circular RNAs (circRNAs) have been demonstrated to exert pivotal functions in cancer progression but are poorly understood in colorectal cancer (CRC). This work intends to investigate the effect and mechanism of a novel cirRNA (circCOL1A2) in CRC. Exosomes were identified via transmission electron microscope (TEM) and nanoparticle tracking analysis (NTA). Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot were used to analyze the levels of genes and proteins. Proliferation, migration, and invasion were detected via cell counting kit-8 (CCK8), 5-Ethynyl-2'-deoxyuridine (EDU), and transwell experiments. RNA pull-down, luciferase reporter, and RNA immunoprecipitation (RIP) assays were performed to assess the binding between genes. Animal studies were carried out to evaluate the function of circCOL1A2 in vivo. We found that circCOL1A2 was highly expressed in CRC cells. And circCOL1A2 was packaged from cancerous cells into exosomes. The proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) properties were inhibited after the reduction of exosomal circCOL1A2. Mechanism studies proved the binding of miR-665 with circCOL1A2 or LASP1 Rescue experiments validated the reverse effects of miR-665 knockdown on circCOL1A2 silencing and LASP1 overexpression on miR-665. Animal studies further confirmed the oncogenic function of exosomal circCOL1A2 in CRC tumorigenesis. In conclusion, exosomal circCOL1A2 sponges miR-665 to enhance LASP1 expression and modulated CRC phenotypes. Thus, circCOL1A2 might be a valuable therapeutic target for CRC, offering novel insight into CRC treatment.

Emerging roles of non-coding RNAs in colorectal cancer oxaliplatin resistance and liquid biopsy potential

Colorectal cancer (CRC) is one of the most common malignancies of the digestive tract, with the annual incidence and mortality increasing consistently. Oxaliplatin-based chemotherapy is a preferred therapeutic regimen for patients with advanced CRC. However, most patients will inevitably develop resistance to oxaliplatin. Many studies have reported that non-coding RNAs (ncRNAs), such as microRNAs, long non-coding RNAs, and circular RNAs, are extensively involved in cancer progression. Moreover, emerging evidence has revealed that ncRNAs mediate chemoresistance to oxaliplatin by transcriptional and post-transcriptional regulation, and by epigenetic modification. In this review, we summarize the mechanisms by which ncRNAs regulate the initiation and development of CRC chemoresistance to oxaliplatin. Furthermore, we investigate the clinical application of ncRNAs as promising biomarkers for liquid CRC biopsy. This review provides new insights into overcoming oxaliplatin resistance in CRC by targeting ncRNAs.

Epigenetic regulation of autophagy by non-coding RNAs in gastrointestinal tumors: Biological functions and therapeutic perspectives

Cancer is the manifestation of changes and mutations in genetic and epigenetic levels. Non-coding RNAs (ncRNAs) are commonly dysregulated in disease pathogenesis, and their role in cancer has been well-documented. The ncRNAs regulate various molecular pathways and mechanisms in cancer that can lead to induction/inhibition of carcinogenesis. Autophagy is a molecular "self-digestion" mechanism its function can be pro-survival or pro-death in tumor cells. The aim of the present review is to evaluate the role of ncRNAs in regulating autophagy in gastrointestinal tumors. The role of the ncRNA/autophagy axis in affecting the progression of gastric, liver, colorectal, pancreatic, esophageal, and gallbladder cancers is investigated. Both ncRNAs and autophagy mechanisms can function as oncogenic or onco-suppressor and this interaction can determine the growth, invasion, and therapy response of gastrointestinal tumors. ncRNA/autophagy axis can reduce/increase the proliferation of gastrointestinal tumors via the glycolysis mechanism. Furthermore, related molecular pathways of metastasis, such as EMT and MMPs, are affected by the ncRNA/autophagy axis. The response of gastrointestinal tumors to chemotherapy and radiotherapy can be suppressed by pro-survival autophagy, and ncRNAs are essential regulators of this mechanism. miRNAs can regulate related genes and proteins of autophagy, such as ATGs and Beclin-1. Furthermore, lncRNAs and circRNAs down-regulate miRNA expression via sponging to modulate the autophagy mechanism. Moreover, anti-cancer agents can affect the expression level of ncRNAs regulating autophagy in gastrointestinal tumors. Therefore, translating these findings into clinics can improve the prognosis of patients.

Roles of N6-methyladenosine (m6A) modifications in gynecologic cancers: mechanisms and therapeutic targeting

Uterine and ovarian cancers are the most common gynecologic cancers. N6−methyladenosine (m6A), an important internal RNA modification in higher eukaryotes, has recently become a hot topic in epigenetic studies. Numerous studies have revealed that the m6A-related regulatory factors regulate the occurrence and metastasis of tumors and drug resistance through various mechanisms. The m6A-related regulatory factors can also be used as therapeutic targets and biomarkers for the early diagnosis of cancers, including gynecologic cancers. This review discusses the role of m6A in gynecologic cancers and summarizes the recent advancements in m6A modification in gynecologic cancers to improve the understanding of the occurrence, diagnosis, treatment, and prognosis of gynecologic cancers.

The emerging roles of circular RNA-mediated autophagy in tumorigenesis and cancer progression

Circular RNA (circRNA) is characterized by a specific covalently closed ring structure. The back-splicing of precursor mRNA is the main way of circRNA generation, and various cis/trans-acting elements are involved in regulating the process. circRNAs exhibit multiple biological functions, including serving as sponges of microRNAs, interacting with proteins to regulate their stabilities and abilities, and acting as templates for protein translation. Autophagy participates in many physiological and pathological processes, especially it plays a vital role in tumorigenesis and carcinoma progression. Increasing numbers of evidences have revealed that circRNAs are implicated in regulating autophagy during tumor development. Until now, the roles of autophagy-associated circRNAs in carcinoma progression and their molecular mechanisms remain unclear. Here, the emerging regulatory roles and mechanisms of circRNAs in autophagy were summarized. Furtherly, the effects of autophagy-associated circRNAs on cancer development were described. We also prospected the potential of autophagy-associated circRNAs as novel therapeutic targets of tumors and as biomarkers for cancer diagnosis and prognosis.

Circular RNA-regulated autophagy is involved in cancer progression

Circular RNAs (circRNAs) are a sort of long, non-coding RNA molecules with a covalently closed continuous ring structure without 5'-3' polarity and poly-A tail. The modulative role of circRNAs in malignant diseases has been elucidated by many studies in recent years via bioinformatics and high-throughput sequencing technologies. Generally, circRNA affects the proliferative, invasive, and migrative capacity of malignant cells via various mechanisms, exhibiting great potential as novel biomarkers in the diagnoses or treatments of malignancies. Meanwhile, autophagy preserves cellular homeostasis, serving as a vital molecular process in tumor progression. Mounting studies have demonstrated that autophagy can not only contribute to cancer cell survival but can also induce autophagic cell death in specific conditions. A growing number of research studies have indicated that there existed abundant associations between circRNAs and autophagy. Herein, we systemically reviewed and discussed recent studies on this topic in different malignancies and concluded that the circRNA–autophagy axis played crucial roles in the proliferation, metastasis, invasion, and drug or radiation resistance of different tumor cells.

CircSV2b participates in oxidative stress regulation through miR-5107-5p-Foxk1-Akt1 axis in Parkinson's disease

As a novel type of non-coding RNAs, covalently closed circular RNAs (circRNAs) are ubiquitously expressed in eukaryotes. Emerging studies have indicated that dysregulation of circRNAs was related to neurological diseases. However, the biogenesis, regulation, function, and mechanism of circRNAs in Parkinson's disease (PD) remain largely unclear. In this study, thirty-three differentially expressed circRNAs (DECs) were detected by RNA-sequencing between the MPTP-induced PD mice model and the wild-type mice. Quantitative real-time PCR was used to determine the RNA level of DECs in the striatum (STR), substantia nigra pars compacta (SNpc), and serum exosomes, and it was found that circSV2b was downregulated in PD mice. Then, functional experiments in vivo were employed to explore the effect of circSV2b in PD. For the mechanism study, dual-luciferase reporter, fluorescence in situ hybridization (FISH), RNA immunoprecipitation (RIP), RNA pull-down, gene editing, and CUT & Tag were performed in vitro to confirm that circSV2b directly sponged miR-5107-5p and alleviated the suppression of the expression of the target gene Foxk1, and then positively regulated Akt1 transcription. In vivo, the mechanistic analysis demonstrated that circSV2b overexpression resisted oxidative stress damage through the ceRNA-Akt1 axis in PD models. Taken together, these findings suggested that the miR-5107-5p-Foxk1-Akt1 axis might serve as a key target of circSV2b overexpression in PD treatment, and highlighted the significant change of circSV2b in serum exosomes. Therefore, circSV2b might be a novel biomarker for the diagnosis and treatment of PD.

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CircSV2b in serum exosomes can be used as a biomarker for the diagnosis of PD.

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CircSV2b participates in the progress of PD through the ceRNA-Akt1 axis.

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CircSV2b overexpression is neuroprotective by resisting oxidative stress injury.

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Foxk1 can regulate Akt1 transcription.

Integrated analysis of the functions and clinical implications of exosome circRNAs in colorectal cancer

Background

Exosome circRNAs (Exo-circRNAs) regulate cancer progression and intercellular crosstalk in the tumor microenvironment. However, their biological functions and potential clinical importance in colorectal cancer (CRC) remain unknown.

Methods

We used exoRBase 2.0 data to identify significant differentially expressed Exo-circRNAs (Exo-DEcircRNAs) in CRC patients and healthy individuals. The least absolute shrinkage and selector operation algorithm, support vector machine-recursive feature elimination, and multivariate Cox regression analyses were used to select candidate Exo-circRNAs and constructed a diagnostic model. Quantitative reverse transcription-polymerase chain reaction analysis was performed to confirm the expression of Exo-circRNAs in the serum samples of patients. Furthermore, we constructed an exosome circRNA-miRNA-mRNA network for CRC. Upregulated target mRNAs in the exosome competing endogenous RNA (Exo-ceRNA) network were used for functional and pathway enrichment analyses. We identified 22 immune cell types in CRC patients using CIBERSORT. Correlation analysis revealed the relationship between Exo-ceRNA networks and immune-infiltrating cells. The relationship between target mRNAs and immunotherapeutic response was also explored. Finally, using the Kaplan–Meier survival curve, a prognostic upregulated target mRNA was screened. We constructed a survival-related Exo-ceRNA subnetwork and explored the correlation between the Exo-ceRNA subnetwork and immune-infiltrating cells.

Results

The constructed diagnostic model had a high area under the curve (AUC) value in both the training and validation sets (AUC = 0.744 and AUC = 0.741, respectively). qRT-PCR confirmed that the Exo-circRNAs were differentially expressed in CRC serum samples. We constructed Exo-ceRNA networks based on the interactions among seven upregulated Exo-DEcircRNAs, eight differentially expressed miRNAs, and twenty-two differentially expressed mRNAs in CRC. Functional enrichment analysis revealed that the upregulated target mRNAs were significantly enriched in cytoskeletal motor activity and the PI3K-Akt signaling pathway. Co-expression analysis showed a significant correlation between the Exo-ceRNA networks and immune cells. The significant correlation was observed between target mRNAs and the immunotherapeutic response. Additionally, based on the prognostic upregulated target gene (RGS2), we constructed a survival-related Exo-ceRNA subnetwork (Exosome hsa_circ_0050334-hsa_miR_182_5p-RGS2). CIBERSORT results revealed that the Exo-ceRNA subnetwork correlated with M2 macrophages (P = 4.6e-07, R = 0.31).

Conclusions

Our study identified an Exo-diagnostic model, established Exo-ceRNA networks, and explored the correlation between Exo-ceRNA networks and immune cell infiltration in CRC. These findings elucidated the biological functions of Exo-circRNAs and their potential clinical implications.

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.

Hsa_circ_0060927 participates in the regulation of Caudatin on colorectal cancer malignant progression by sponging miR-421/miR-195-5p

BACKGROUND

Caudatin is extracted from radix cynanchi bungei and has an inhibitory effect on cancer progression. The study aims to reveal the impacts of hsa_circ_0060927 on Caudatin-mediated colorectal cancer (CRC) development and the underneath mechanism.

METHODS

The expression levels of hsa_circ_0060927, microRNA-421 (miR-421) and miR-195-5p were detected by quantitative real-time reverse transcription-polymerase chain reaction. The protein expression was analyzed by Western blot or immunohistochemistry assay. Cell viability and proliferation were analyzed by 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide or 5-Ethynyl-29-deoxyuridine assay. Cell apoptosis was quantified by flow cytometry analysis. Cell migration and invasion were investigated by transwell assay. The putative associations among hsa_circ_0060927, miR-421 and miR-195-5p were predicted by the starbase online database, and identified by dual-luciferase reporter, RNA pull-down and RNA immunoprecipitation (RIP) assays. The impacts of Caudatin treatment on tumor growth in vivo were revealed by a xenograft tumor model assay.

RESULTS

Hsa_circ_0060927 expression was significantly upregulated, whereas miR-421 and miR-195-5p were downregulated in CRC tissues and cells compared with control groups. Hsa_circ_0060927 expression was closely associated with lymph node metastasis and tumor-node-metastasis stage. Caudatin treatment significantly decreased hsa_circ_0060927 expression but increased miR-421 and miR-195-5p expression. Caudatin exposure suppressed CRC cell proliferation, migration and invasion, and induced cell apoptosis; however, hsa_circ_0060927 overexpression hindered these impacts. Additionally, hsa_circ_0060927 was associated with miR-421/miR-195-5p. Depletion of miR-421 or miR-195-5p attenuated the influences of hsa_circ_0060927 silencing on CRC development. Furthermore, Caudatin treatment repressed tumor growth in vivo.

CONCLUSION

Caudatin inhibited CRC cell malignancy through the hsa_circ_0060927/miR-421/miR-195-5p pathway, which provided a potential therapeutic agent for CRC.

CircRNA circ_0023984 promotes the progression of esophageal squamous cell carcinoma via regulating miR-134-5p/cystatin-s axis

Recent studies have shown that circRNAs can act as oncogenic factors or tumor suppressors by sponging microRNAs (miRNAs). The upregulation of circ_0023984 was reported in esophageal squamous cell carcinoma (ESCC). However, its functional role in ESCC remain unclear. In the present study, circ_0023984 expression in ESCC cells and tissues were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting (WB). Subcellular fraction experiment was performed to determine relative nuclear-cytoplasmic localization. The loss-of-function effects of circ_0023984 in ESCC cell lines were investigated by shRNA-mediated knockdown. Functional assays including cell Counting Kit-8 (CCK-8), 5-Ethynyl-2’-deoxyuridine (EDU) incorporation, colony formation and Transwell migration assays were conducted to assess the malignant phenotype. The interaction between the two molecules was analyzed by RNA pull-down, luciferase reporter assay and RNA immunoprecipitation (RIP). The subcutaneous tumor model in nude mice was used to assess the role of circ-0023984 in tumorigenesis. We found that ESCC patients with high circ_0023984 expression was associated with a poor prognosis. The knockdown of circ_0023984 suppressed cell growth, invasion, and migration in ESCC cells. Circ_0023984 interacted with miR-134-5p and inhibited its activity, which promoted the expression of CST4 (Cystatin-S). Circ_0023984 also regulated tumorigenesis in a CST4-dependent manner. Together, our study indicates that the oncogenic role of Circ_0023984 is mediated by miR-134-5p/CST4 Axis in ESCC, which could serve as potential targets for future therapeutic strategies.

hsa_circ_0000231 Promotes colorectal cancer cell growth through upregulation of CCND2 by IGF2BP3/miR-375 dual pathway

Background

Circular RNAs (circRNAs) have emerged as vital regulators of the initiation and progression of diverse kinds of human cancers. In this study, we explored the role of hsa_circ_0000231 and its downstream pathway in CRC.

Methods

The expression profile of circRNAs in 5 pairs of CRC tissues and adjacent normal tissues were analyzed by Microarray. Quantitative real-time PCR and in situ hybridization and Base Scope Assay were used to determine the level and prognostic values of hsa_circ_0000231. Then, functional experiments in vitro and in vivo were performed to investigate the effects of hsa_circ_0000231 on cell proliferation. Mechanistically, fluorescent in situ hybridization, dual luciferase reporter assay, RNA pull-down and RNA immunoprecipitation experiments were performed to confirm the interaction between hsa_circ_0000231 and IGF2BP3 or has_miR-375.

Results

We acquired data through circRNA microarray profiles, showing that the expression of hsa_circ_0000231 was upregulated in CRC primary tissues compared to adjacent normal tissues, which was indicated poor prognosis of patients with CRC. Functional analysis indicated that inhibition of hsa_circ_0000231 in CRC cell lines could suppress CRC cell proliferation as well as tumorigenesis in vitro and in vivo. The mechanistic analysis showed that hsa_circ_0000231 might, on the one hand, act as a competing endogenous RNA of miR-375 to promote cyclin D2 (CCND2) and, on the other hand, bind to the IGF2BP3 protein to prevent CCND2 degradation.

Conclusions

The findings suggested that hsa_circ_0000231 facilitated CRC progression by sponging miR-375 or binding to IGF2BP3 to modulate CCND2, implying that hsa_circ_0000231 might be a potential new diagnostic and therapeutic biomarker of CRC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02455-8.