CircCPA4 Promotes the Malignant Phenotypes in Glioma via miR-760/MEF2D Axis

Circ_0082374 Promotes the Tumorigenesis and Suppresses Ferroptosis in Non-small Cell Lung Cancer by Up-Regulating GPX4 Through Sequestering miR-491-5p

Circular RNAs (circRNAs) have been identified to be dysregulated in non-small cell lung cancer (NSCLC) and implicated in the progression of this cancer. Here, this work aimed to investigate the role and mechanism of circ_0082374 on NSCLC progression. Levels of circ_0082374, miR-491-5p, GPX4 (glutathione peroxidase 4) and epithelial-mesenchymal transition (EMT)-related proteins were examined by quantitative real-time PCR or western blotting, respectively. Cell proliferation and metastasis were detected using cell counting kit-8, colony formation, EdU, transwell, and Scratch assays. Cell ferroptosis was evaluated by measuring cell survival after the treatment of different ferroptosis inducers or inhibitors, as well as the accumulation of intracellular reactive oxygen species (ROS), ferrous iron (Fe2+) and malondialdehyde (MDA). The binding between miR-491-5p and circ_0082374 or GPX4 was confirmed using dual-luciferase reporter and RNA pull-down assays. In vivo experiments were conducted using murine xenograft assay and immunohistochemistry. Circ_0082374 was a stable circRNA with high expression in NSCLC tissues and cells. Functionally, circ_0082374 silencing suppressed NSCLC cell proliferation and metastasis. Moreover, its down-regulation enhanced ferroptosis by decreasing iron and lipid peroxidation accumulation. Mechanistically, circ_0082374 could indirectly up-regulate GPX4 expression via miR-491-5p, indicating the circ_0082374/miR-491-5p/GPX4 competitive endogenous RNAs (ceRNA) network. Rescue experiments demonstrated that the miR-491-5p/GPX4 axis mediated the regulatory effects of circ_0082374 exerted on NSCLC cells. Moreover, knockdown of circ_0082374 impeded NSCLC growth and EMT via regulating miR-491-5p and GPX4. Circ_0082374 silencing could suppress NSCLC cell proliferation, metastasis and induce ferroptosis through miR-491-5p/GPX4 axis, suggesting a novel therapeutic approach for NSCLC patients.

CircCPA4 induces ASCT2 expression to promote tumor property of non-small cell lung cancer cells in a miR-145-5p-dependent manner

BACKGROUND

Non-small cell lung cancer (NSCLC) is a type of lung cancer that occurs in the cells of the respiratory tract, and its development is influenced by the regulation of circular RNAs (circRNAs). However, the role of circRNA carboxypeptidase A4 (circCPA4) in the progression of NSCLC and the underlying mechanism remain relatively clear.

METHODS

The study utilized both real-time quantitative polymerase chain reaction (RT-qPCR) and western blot techniques to evaluate the levels of circCPA4, microRNA-145-5p (miR-145-5p), alanine, serine, or cysteine-preferring transporter 2 (ASCT2). To assess cell proliferation, cell counting kit-8 (CCK8) and 5-ethynyl-2'-deoxyuridine (EdU) assays were performed. Apoptosis was determined using flow cytometry, while cell migration and invasive capacity were evaluated through transwell and wound-healing assays. Intracellular levels of glutamine, glutamate, and α-KG were measured using specific kits. The relationship between miR-145-5p and circCPA4 or ASCT2 was confirmed using dual-luciferase reporter assay and RNA immunoprecipitation assay.

RESULTS

CircCPA4 and ASCT2 RNA levels were elevated, while miR-145-5p was downregulated in both NSCLC tissues and cells. Depletion of circCPA4 significantly inhibited NSCLC cell proliferation, migration, invasion, and intracellular levels of glutamine, glutamate, and α-KG, and promoted apoptosis. Moreover, circCPA4 knockdown delayed tumor growth in vivo. Furthermore, circCPA4 was found to bind to miR-145-5p, thereby regulating the progression of NSCLC in vitro. ASCT2 was also identified as a downstream target of miR-145-5p, and its upregulation rescued the effects of miR-145-5p overexpression on NSCLC cell processes.

CONCLUSION

CircCPA4 knockdown inhibited tumor property of NSCLC cells by modulating the miR-145-5p/ASCT2 axis.

Circular RNAs in glioma: Molecular functions and pathological implications

Circular RNAs (circRNAs) are a special class of non-coding RNAs with the ring structure. They are stable, abundant and conservative across mammals. The biogenesis and molecular properties of circRNAs are being elucidated, which exert regulatory functions not only through miRNA and protein sponge, but also via translation and exosomal interaction. Accumulating studies have demonstrated that circRNAs are aberrantly expressed in various diseases, especially in cancer. Glioma is one of the most common malignant cerebral neoplasms with poor prognosis. The accurate diagnosis and effective therapies of glioma have always been challenged, there is an urgent need for developing promising therapeutic intervention. Therefore, exploring novel biomarkers is crucial for diagnosis, treatment and prognosis of the glioma which can provide better assistance in guiding treatment. Recent findings found that circRNAs are systematically altered in glioma and may play critical roles in glioma tumorigenesis, proliferation, invasion and metastasis. Due to their distinct functional properties, they are considered as the potential therapeutic targets, diagnostic and prognostic biomarkers. This review elaborates on current advances towards the biogenesis, translation and interaction of circRNAs in many diseases and focused on the role of their involvement in glioma progression, highlighting the potential value of circRNAs in glioma.

circCPA4 induces malignant behaviors of prostate cancer via miR-491-5p/SHOC2 feedback loop

OBJECTIVE

circCPA4 has been defined to be an oncogenic gene. This study examined whether circCPA4 regulates Prostate Cancer (PC) development and revealed its molecular mechanism.

METHODS

PC tissues and PC cell lines were collected, in which circCPA4/miR-491-5p/SHOC2 levels were evaluated by RT-qPCR and immunoblot. Colony formation assay and EdU assay assessed cell proliferation, flow cytometry measured apoptosis, and Transwell assessed invasion and migration. Ki-67, cleaved caspase-3, E-cadherin, and N-cadherin were evaluated by immunoblot. Based on the luciferase reporter assay and RIP assay the authors investigated the targeting relationship between circCPA4/miR-491-5p/SHOC2. The effect of circCPA4 on tumor growth was evaluated by xenotransplantation in nude mice.

RESULTS

circCPA4 and SHOC2 levels were abundant while miR-491-5p expression was low in PC. Loss of circCPA4 decreased the proliferation and EdU-positive rate of PC cells, enhanced apoptosis, and inhibited invasion, migration, and EMT. Upregulation of circCPA4 forced the malignant behaviors of PC cells, and this promotion could be abolished when miR-491-5p was overexpressed or SHOC2 was silenced. CircCAP4 competitively decoyed miR-491-5p mediating SHOC2 expression. circCAP4 suppression inhibited PC tumor growth.

CONCLUSION

circCAP4 acts as a novel oncogenic factor in PC, accelerating the malignant behavior of PC cells via miR-491-5p/SHOC2 interaction. This novel ceRNA axis may be a potential target for PC drug development and targeted therapy in the future.

Roles of circular RNAs in regulating the development of glioma

BACKGROUND

Glioma is the most common malignant tumor in the central nervous system. In patients with glioma, the prognosis is poor and median survival is only 12-15 months. With the recent development of sequencing technology, important roles of noncoding RNAs are being discovered in cells, especially those of circular RNAs (circRNAs). Because circRNAs are stable, abundant, and highly conserved, they are regarded as novel biomarkers in the early diagnosis and prognosis of diseases.

PURPOSE

In this review, roles and mechanisms of circRNAs in the development of glioma are summarized.

METHODS

This paper collects and reviews relevant PubMed literature.

CONCLUSION

Several classes of circRNAs are highly expressed in glioma and are associated with malignant biological behaviors of gliomas, including proliferation, migration, invasion, apoptosis, angiogenesis, and drug resistance. Further studies are needed to clarify the roles of circRNAs in glioma and to determine whether it is possible to increase therapeutic effects on tumors through circRNA intervention.

CircYIPF6 regulates glioma cell proliferation, apoptosis, and glycolysis through targeting miR-760 to modulate PTBP1 expression

Background

Recent studies have highlighted that circular RNAs regulate cancer-related genes' expression by functioning as microRNA sponges in cancers. Herein, we investigated the function and molecular mechanism of circYIPF6 in glioma.

Methods

5-Ethynyl-2'-deoxyuridine assay, colony formation, and flow cytometry were performed to assess the proliferation and apoptosis of glioma cells. The levels of glycolytic metabolism were evaluated by measuring the glucose uptake and lactate production. The protein levels of Bax, Bcl2, GLUT1, LDHA, and PTBP1 were examined by western blot. The interplay between miR-760 and circYIPF6 or PTBP1 was confirmed by a dual-luciferase reporter. The effect of circYIPF6 silencing on the growth of glioma in vivo was determined by a xenograft experiment.

Results

circYIPF6 was significantly upregulated in glioma. Knockdown of circYIPF6 suppressed glioma cell proliferation and glycolysis while promoting cell apoptosis. Mechanistic studies revealed that circYIPF6 targeted miR-760 and could abundantly sponge miR-760 to inhibit the expression of its downstream target gene PTBP1. Functional rescue experiments showed that both miR-760 inhibition and PTBP1 overexpression could attenuate the regulatory effect of circYIPF6 silencing on glioma cells. Furthermore, circYIPF6 knocking down effectively impeded glioma growth in vivo.

Conclusion

These findings suggested that circYIPF6 participated in the proliferation, apoptosis, and glycolysis of glioma through the miR-760/PTBP1 axis.

Diagnostic and therapeutic potential of circular RNA in brain tumors

Circular RNAs (circRNAs) are a class of RNA with a stable cyclic structure. They are expressed in various tissues and cells with conserved, specific characteristics. CircRNAs have been found to play critical roles in a wide range of cellular processes by regulating gene expression at the epigenetic, transcriptional, and posttranscriptional levels. There is an accumulation of evidence on newly discovered circRNAs, their molecular interactions, and their roles in the development and progression of human brain tumors, including cell proliferation, cell apoptosis, invasion, and chemoresistance. Here we summarize the current state of knowledge of the circRNAs that have been implicated in brain tumor pathogenesis, particularly in gliomas and medulloblastomas. In providing a comprehensive overview of circRNA studies, we highlight how different circRNAs have oncogenic or tumor-suppressive roles in brain tumors, making them attractive therapeutic targets and biomarkers for personalized therapy and precision diagnostics. This review article discusses circRNAs' functional roles and the prospect of using them as diagnostic biomarkers and therapeutic targets in patients with brain tumors.

CircRNAs in Malignant Tumor Radiation: The New Frontier as Radiotherapy Biomarkers

World Health Organization (WHO) data show that of the top 20 factors that threaten human life and health, cancer is at the forefront, and the therapeutic approaches for cancer consist of surgery, radiotherapy, chemotherapy and immunotherapy. For most highly metastatic and recurrent cancer, radiation therapy is an essential modality to mitigate tumor burden and improve patient survival. Despite the great accomplishments that have been made in clinical therapy, an inevitable challenge in effective treatment is radioresistance, the mechanisms of which have not yet been completely elucidated. In addition, radiosensitization methods based on molecular mechanisms and targets, and clinical applications are still inadequate. Evidence indicates that circular RNAs (circRNAs) are important components in altering tumor progression, and in influencing resistance and susceptibility to radiotherapy. This review summarizes the reasons for tumor radiotherapy resistance induced by circRNAs, and clarifies the molecular mechanisms and targets of action. Moreover, we determine the potential value of circRNAs as clinical indicators in radiotherapy, providing a theoretical basis for circRNAs-based strategies for cancer radiotherapy.

Research Progress on Circular RNA in Glioma

The discovery of circular RNA (circRNA) greatly complements the traditional gene expression theory. CircRNA is a class of non-coding RNA with a stable cyclic structure. They are highly expressed, spatiotemporal-specific and conservative across species. Importantly, circRNA participates in the occurrence of many kinds of tumors and regulates the tumor development. Glioma is featured by limited therapy and grim prognosis. Cancer-associated circRNA compromises original function or creates new effects in glioma, thus contributing to oncogenesis. Therefore, this article reviews the biogenesis, metabolism, functions and properties of circRNA as a novel potential biomarker for gliomas. We elaborate the expression characteristics, interaction between circRNA and other molecules, aiming to identify new targets for early diagnosis and treatment of gliomas.

Sevoflurane suppresses glioma tumorigenesis via regulating circ_0079593/miR-633/ROCK1 axis

BACKGROUND

Sevoflurane is a common inhalational anesthetic, which has been revealed to have anticancer effect in glioma. However, the mechanisms of sevoflurane in glioma progression remain largely unclear.

METHODS

Cell proliferation, cell cycle, apoptosis and metastasis were monitored by cell counting kit-8 (CCK-8), flow cytometry, Transwell and Western blot assays. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot assays were used to examine the expression levels of circ_0079593, microRNA (miR)-633 and ROCK1 (Rho Associated Coiled-Coil Containing Protein Kinase 1). The dual-luciferase reporter assay was employed to confirm the targeting relationship between miR-633 and circ_0079593 or ROCK1. Animal experiment was conducted to explore the effect of sevoflurane in vivo.

RESULTS

Sevoflurane inhibited glioma cell proliferation, metastasis and induced apoptosis in vitro as well as impeded tumor growth in vivo. The expression of circ_0079593 was higher in glioma tissues and cells, and was decreased by sevoflurane treatment in glioma cells. Functional experiments showed that circ_0079593 overexpression in glioma cells reversed the inhibitory effects of sevoflurane on cell growth and metastasis. In a mechanism analysis, circ_0079593 acted as a sponge for miR-633 to elevate ROCK1 expression in glioma cells, and sevoflurane could regulate ROCK1 expression via circ_0079593/miR-633 axis. Besides that, circ_0079593/miR-633/ROCK1 axis mediated the protective effects of sevoflurane on glioma cell tumorigenesis.

CONCLUSION

Sevoflurane repressed glioma tumorigenesis via regulating circ_0079593/miR-633/ROCK1 axis, suggesting a new insight into the application of sevoflurane in glioma therapy.

Competing Endogenous RNA Networks in Glioma

Gliomas are the most common and malignant primary brain tumors. Various hallmarks of glioma, including sustained proliferation, migration, invasion, heterogeneity, radio- and chemo-resistance, contribute to the dismal prognosis of patients with high-grade glioma. Dysregulation of cancer driver genes is a leading cause for these glioma hallmarks. In recent years, a new mechanism of post-transcriptional gene regulation was proposed, i.e., "competing endogenous RNA (ceRNA)." Long non-coding RNAs, circular RNAs, and transcribed pseudogenes act as ceRNAs to regulate the expression of related genes by sponging the shared microRNAs. Moreover, coding RNA can also exert a regulatory role, independent of its protein coding function, through the ceRNA mechanism. In the latest glioma research, various studies have reported that dysregulation of certain ceRNA regulatory networks (ceRNETs) accounts for the abnormal expression of cancer driver genes and the establishment of glioma hallmarks. These achievements open up new avenues to better understand the hidden aspects of gliomas and provide new biomarkers and potential efficient targets for glioma treatment. In this review, we summarize the existing knowledge about the concept and logic of ceRNET and highlight the emerging roles of some recently found ceRNETs in glioma progression.