Circle RNA circABCB10 Modulates PFN2 to Promote Breast Cancer Progression, as Well as Aggravate Radioresistance Through Facilitating Glycolytic Metabolism Via miR-223-3p

CircZCCHC2 decreases pirarubicin sensitivity and promotes triple-negative breast cancer development via the miR-1200/TPR axis

Triple-negative breast cancer (TNBC) has attracted attention due to its poor prognosis and limited treatment options. The mechanisms underlying the association between circular RNAs (circRNAs) and the occurrence and development of TNBC remain unclear. CircZCCHC2 is observed to be upregulated in TNBC cells, tissues, and plasma exosomes. Knockdown of circZCCHC2 inhibited the proliferation, migration, invasion, and epithelial-mesenchymal transition of TNBC cells in vitro and in vivo. Pirarubicin (THP) treatment downregulated circZCCHC2, and circZCCHC2 affected the sensitivity to THP. CircZCCHC2/miR-1200/translocated promoter region, the nuclear basket protein (TPR) pathway was cascaded and verified. It is demonstrated that circZCCHC2 plays a crucial role in the malignant progression of TNBC via the miR-1200/TPR axis, thereby activating the RAS-RAF-MEK-ERK pathway. The present results indicate that circZCCHC2 has the potential to serve as a novel prognostic biomarker for TNBC.

Knockdown of circ-ADAM9 inhibits malignant phenotype and enhances radiosensitivity in breast cancer cells via acting as a sponge for miR-383-5p

BACKGROUND

Circular RNA (circRNA) has been proven to play a critical role in breast cancer progression. Therefore, this study was designed to clarify the role and underlying molecular mechanisms of circ-disintegrin and metalloproteinase 9 (circ-ADAM9) in breast cancer.

METHODS

A quantitative real-time polymerase chain reaction (RT-qPCR) was conducted to assess the expression levels of circ-ADAM9, microRNA-383-5p (miR-383-5p), and profilin 2 (PFN2). Cellular growth curves of breast cancer cells were determined by colony-forming assay. Cell viability and apoptosis were measured by MTT and flow cytometry, respectively. The protein expression level was analyzed by western blot. Cell migration and invasion were evaluated by wound healing and Transwell assays. A xenograft experiment was established to clarify the functional role of circ-ADAM9 inhibition in vivo. The interactions among circ-ADAM9, miR-383-5p, and PFN2 were analyzed by dual-luciferase reporter, RNA immunoprecipitation (RIP), and RNA pull-down assays.

RESULTS

We found that circ-ADAM9 was upregulated in breast cancer tissues and cells compared to controls. Inhibition of circ-ADAM9 expression impaired proliferation, migration, and invasion, but increased radiosensitivity and apoptosis in breast cancer cells; besides, radiotherapy combined with circ-ADAM9 inhibition showed significant inhibitory effects on tumor growth. The functional effects of circ-ADAM9 were related to miR-383-5p, a target of circ-ADAM9. Overexpression of miR-383-5p-mediated malignant behaviors and radiosensitivity of breast cancer cells were dependent on PFN2.

CONCLUSION

Circ-ADAM9 was found to participate in breast cancer progression through targeting the miR-383-5p/PFN2 axis.

CircRNAs in Tumor Radioresistance

Circular RNAs (circRNAs) are endogenous, non-coding RNAs, which are derived from host genes that are present in several species and can be involved in the progression of various diseases. circRNAs’ leading role is to act as RNA sponges. In recent years, the other roles of circRNAs have been discovered, such as regulating transcription and translation, regulating host genes, and even being translated into proteins. As some tumor cells are no longer radiosensitive, tumor radioresistance has since become a challenge in treating tumors. In recent years, circRNAs are differentially expressed in tumor cells and can be used as biological markers of tumors. In addition, circRNAs can regulate the radiosensitivity of tumors. Here, we list the mechanisms of circRNAs in glioma, nasopharyngeal carcinoma, and non-small cell lung cancer; further, these studies also provide new ideas for the purposes of eliminating radioresistance in tumors.

Metabolic Pathways in Breast Cancer Reprograming: An Insight to Non-Coding RNAs

Cancer cells reprogram their metabolisms to achieve high energetic requirements and produce precursors that facilitate uncontrolled cell proliferation. Metabolic reprograming involves not only the dysregulation in glucose-metabolizing regulatory enzymes, but also the enzymes engaging in the lipid and amino acid metabolisms. Nevertheless, the underlying regulatory mechanisms of reprograming are not fully understood. Non-coding RNAs (ncRNAs) as functional RNA molecules cannot translate into proteins, but they do play a regulatory role in gene expression. Moreover, ncRNAs have been demonstrated to be implicated in the metabolic modulations in breast cancer (BC) by regulating the metabolic-related enzymes. Here, we will focus on the regulatory involvement of ncRNAs (microRNA, circular RNA and long ncRNA) in BC metabolism, including glucose, lipid and glutamine metabolism. Investigation of this aspect may not only alter the approaches of BC diagnosis and prognosis, but may also open a new avenue in using ncRNA-based therapeutics for BC treatment by targeting different metabolic pathways.

MicroRNAs as Potential Tools for Predicting Cancer Patients’ Susceptibility to SARS-CoV-2 Infection and Vaccination Response

Coronavirus disease (COVID-19) is an infectious disease that is caused by a highly contagious and severe acute respiratory syndrome—coronavirus 2 (SARS-CoV-2). This infection started to spread across the world in 2019 and rapidly turned into a global pandemic, causing an urgent necessity for treatment strategies development. The mRNA vaccines against SARS-CoV-2 can trigger an immune response, providing genetic information that allows the production of spike glycoproteins. MiRNAs play a crucial role in diverse key cellular processes, including antiviral defense. Several miRNAs are described as key factors in SARS-CoV-2 human infection through the regulation of ACE2 levels and by the inhibition of SARS-CoV-2 replication and spike expression. Consequently, these molecules have been considered as highly promising biomarkers. In numerous human malignancies, it has been recognized that miRNAs expression is dysregulated. Since miRNAs can target SARS-CoV-2-associated mRNAs, in cancer patients, the deregulation of these molecules can impair the immune response to the vaccines. Therefore, in this review, we propose a miRNA profile of seven SARS-CoV-2-related miRNAs, namely miR-214, miR-98-5p, miR-7-5p, miR-24-3p, miR-145-5p, miR-223-3p and miR-15b-5p, that are deregulated in a high number of cancers and have the potential to be used as prognostic biomarkers to stratify cancer patients.

Mutual regulation between N6-methyladenosine (m6A) modification and circular RNAs in cancer: impacts on therapeutic resistance

The resistance of tumor cells to therapy severely impairs the efficacy of treatment, leading to recurrence and metastasis of various cancers. Clarifying the underlying mechanisms of therapeutic resistance may provide new strategies for overcoming cancer resistance. N6-methyladenosine (m6A) is the most prevalent RNA modification in eukaryotes, and is involved in the regulation of RNA splicing, translation, transport, degradation, stability and processing, thus affecting several physiological processes and cancer progression. As a novel type of multifunctional non-coding RNAs (ncRNAs), circular RNAs (circRNAs) have been demonstrated to play vital roles in anticancer therapy. Currently, accumulating studies have revealed the mutual regulation of m6A modification and circRNAs, and their interaction can further influence the sensitivity of cancer treatment. In this review, we mainly summarized the recent advances of m6A modification and circRNAs in the modulation of cancer therapeutic resistance, as well as their interplay and potential mechanisms, providing promising insights and future directions in reversal of therapeutic resistance in cancer.

The Emerging Roles of Circ-ABCB10 in Cancer

Circular RNAs (circRNAs) are non-coding RNAs (ncRNAs) without 5′ caps and 3′ tails, which are formed from precursor mRNAs (pre-mRNAs) that are inversely back-spliced by exons. CircRNAs are characterized by a covalently closed circular structure and are abundantly expressed in eukaryotic cells. With the development of RNA-sequencing, it was discovered that circRNAs play important roles in the regulation of numerous human genes and are related to the occurrence, development, and prognosis of diseases. Studies in various cancers have revealed that circRNAs have both positive and negative effects on the occurrence and development of tumors. Circ-ABCB10, a circular RNA originating from exons of ABCB10 located on chromosome 1q42, has been proven to play an important role in different types of cancers. Here, we report the primary findings of recent research studies by many contributors about the roles of circ-ABCB10 in cancer and clearly formulate its influence and functions in different aspects of cancer biology, which gives us a broad picture of circ-ABCB10. Thus, this study aimed to generalize the roles of circ-ABCB10 in the diagnosis and treatment of different types of tumors and its related miRNA genes. In this way, we wish to provide a sufficient understanding and assess the future development direction of the research on circ-ABCB10.

Deciphering a Novel Necroptosis-Related miRNA Signature for Predicting the Prognosis of Clear Cell Renal Carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common histological and devastating subtype of renal cell carcinoma. Necroptosis is a form of programmed cell death that causes prominent inflammatory responses. miRNAs play a significant role in cancer progression through necroptosis. However, the prognostic value of necroptosis-related miRNAs remains ambiguous. In this study, 39 necroptosis-related miRNAs (NRMs) were extracted and 17 differentially expressed NRMs between normal and tumor samples were identified using data form The Cancer Genome Atlas (TCGA). After applying univariate Cox proportional hazard regression analysis and LASSO Cox regression model, six necroptosis-related miRNA signatures were identified in the training cohort and their expression levels were verified by qRT-PCR. Using the expression levels of these miRNAs, all patients were divided into the high- and low-risk groups. Patients in the high-risk group showed poor overall survival (P < 0.0001). Time-dependent ROC curves confirmed the good performance of our signature. The results were verified in the testing cohort and the entire TCGA cohort. Univariate and multivariate Cox regression models demonstrated that the risk score was an independent prognostic factor. Additionally, a predictive nomogram with good performance was constructed to enhance the implementation of the constructed signature in a clinical setting. We then employed miRBD, miRTarBase, and TargetScan to predict the target genes of six necroptosis-related miRNAs. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses indicated that 392 potential target genes were enriched in cell proliferation-related biological processes. Six miRNAs and 59 differentially expressed target genes were used to construct an miRNA–mRNA interaction network, and 11 hub genes were selected for survival and tumor infiltration analysis. Drug sensitivity analysis revealed potential drugs that may contribute to cancer management. Hence, necroptosis-related genes play an important role in cancer biology. We developed, for the first time, a necroptosis-related miRNA signature to predict ccRCC prognosis.

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.

Circular RNAs as Potential Biomarkers in Breast Cancer

Due to the high heterogeneity and initially asymptomatic nature of breast cancer (BC), the management of this disease depends on imaging together with immunohistochemical and molecular evaluations. These tests allow early detection of BC and patient stratification as they guide clinicians in prognostication and treatment decision-making. Circular RNAs (circRNAs) represent a class of newly identified long non-coding RNAs. These molecules have been described as key regulators of breast carcinogenesis and progression. Moreover, circRNAs play a role in drug resistance and are associated with clinicopathological features in BC. Accumulating evidence reveals a clinical interest in deregulated circRNAs as diagnostic, prognostic and predictive biomarkers. Furthermore, due to their covalently closed structure, circRNAs are highly stable and easily detectable in body fluids, making them ideal candidates for use as non-invasive biomarkers. Herein, we provide an overview of the biogenesis and pleiotropic functions of circRNAs, and report on their clinical relevance in BC.

Circ_0008500 Knockdown Improves Radiosensitivity and Inhibits Tumorigenesis in Breast Cancer Through the miR-758-3p/PFN2 Axis

Breast cancer is one of the most common malignancies worldwide. Circular RNAs (CircRNAs) were revealed to be implicated in the development of breast cancer. In this research, we aimed to investigate the role and underlying mechanism of circ_0008500 in the development and radiosensitivity of breast cancer. Using real-time quantitative PCR (RT-qPCR) and western blot, we found that hsa_circ_0008500 (circ_0008500) and profilin 2 (PFN2) were increased, while microRNA-758-3p (miR-758-3p) was decreased in breast cancer tissues and cells. Cell viability, the number of colonies, proliferation and apoptosis were detected using CCK-8, colony formation, EdU assays and flow cytometry, respectively. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were devoted to test the interaction between miR-758-3p and circ_0008500 or PFN2. The results showed that circ_0008500 knockdown inhibited cell growth, and facilitated cell apoptosis and radiosensitivity in breast cancer cells in vitro. Moreover, circ_0008500 regulated PFN2 expression by sponging miR-758-3p. Functionally, circ_0008500 knockdown regulated cell behaviors and radiosensitivity by targeting miR-758-3p to downregulate PFN2 expression in vitro. Additionally, in vivo tumor formation assay and immunohistochemistry (IHC) assay demonstrated that circ_0008500 knockdown enhanced the radiosensitivity and repressed tumor growth in vivo. In conclusion, circ_0008500 inhibition promoted the radiosensitivity and restrained the development of breast cancer by downregulating PFN2 expression via targeting miR-758-3p.

Circular RNA circ_IRAK3 contributes to tumor growth through upregulating KIF2A via adsorbing miR-603 in breast cancer

Background

Breast cancer (BC) threatens the health of women around the world. Researchers have proved that hsa_circ_0005505 (circ_IRAK3) facilitates BC cell invasion and migration, but the regulatory mechanisms of circ_IRAK3 in BC remain mostly unknown. We aim to explore a new mechanism by which circ_IRAK3 promotes BC progression.

Methods

Levels of circ_IRAK3, microRNA (miR)-603, and kinesin family member 2A (KIF2A) mRNA in BC tissues and cells were examined by quantitative real-time polymerase chain reaction (qRT-PCR). The cell cycle progression, colony formation, and proliferation of BC cells were evaluated by flow cytometry, plate clone, or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assays. The migration, invasion, and apoptosis of BC cells were determined by transwell or flow cytometry assays. Several protein levels were detected using western blotting. The targeting relationship between circ_IRAK3 or KIF2A and miR-603 was verified via dual-luciferase reporter assay. The role of circ_IRAK3 in vivo was verified by xenograft assay.

Results

We observed higher levels of circ_IRAK3 in BC tissues and cell lines than their respective controls. Functional experiments presented that circ_IRAK3 silencing induced BC cell apoptosis, curbed cell proliferation, migration, and invasion in vitro, and decreased tumor growth in vivo. Mechanistically, circ_IRAK3 could modulate kinesin family member 2A (KIF2A) expression through acting as a microRNA (miR)-603 sponge. miR-603 silencing impaired the effects of circ_IRAK3 inhibition on the malignant behaviors of BC cells. Also, the repressive effects of miR-603 mimic on the malignant behaviors of BC cells were weakened by KIF2A overexpression.

Conclusions

circ_IRAK3 exerted a promoting effect on BC progression by modulating the miR-603/KIF2A axis, providing a piece of novel evidence for circ_IRAK3 as a therapeutic target for BC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02497-y.

Non-Coding RNAs Regulate the Resistance to Anti-EGFR Therapy in Colorectal Cancer

Colorectal cancer (CRC) is the third prevalent cancer worldwide, the morbidity and mortality of which have been increasing in recent years. As molecular targeting agents, anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (McAbs) have significantly increased the progression-free survival (PFS) and overall survival (OS) of metastatic CRC (mCRC) patients. Nevertheless, most patients are eventually resistant to anti-EGFR McAbs. With the intensive study of the mechanism of anti-EGFR drug resistance, a variety of biomarkers and pathways have been found to participate in CRC resistance to anti-EGFR therapy. More and more studies have implicated non-coding RNAs (ncRNAs) primarily including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are widely involved in tumorigenesis and tumor progression. They function as essential regulators controlling the expression and function of oncogenes. Increasing data have shown ncRNAs affect the resistance of molecular targeted drugs in CRC including anti-EGFR McAbs. In this paper, we have reviewed the advance in mechanisms of ncRNAs in regulating anti-EGFR McAbs therapy resistance in CRC. It provides insight into exploring ncRNAs as new molecular targets and prognostic markers for CRC.

miR-223-3p targets FBXW7 to promote epithelial-mesenchymal transition and metastasis in breast cancer

BACKGROUND

Breast cancer is the most common malignant tumor diagnosed in women. It is the second leading cause of cancer-related death among women in the world. Aberrant expression of microRNAs (miRNAs) have been identified to be involved in the development and progression of breast cancer. The aim of this study was to investigate the function of miR-223-3p in breast cancer progression and metastasis.

METHODS

qRT-PCR was used to analyze the expression levels of miR-223-3p in breast cancer tissues and cell lines. Wound healing and Matrigel assays were used to examine cell motility and invasiveness. FBXW7 3'-UTR construct and luciferase reporter assays were performed for the target gene.

RESULTS

miR-223-3p was overexpressed in breast cancer tissue and cell lines. A high level of miR-223-3p was associated with poor prognosis in breast cancer patients. In addition, overexpressed miR-223-3p promoted the migration and invasion of breast cancer cells in vitro and in vivo. Mechanistically, we found that tumor suppressor gene FBXW7 is a target of miR-223-3p. Luciferase activity reporter assay indicated miR-223-3p could directly bind with the 3'-UTR of FBXW7. miR-223-3p exhibited its oncogenic role partly by decreasing FBXW7 expression, and consequently promoted the invasion and metastasis of breast cancer cells.

CONCLUSIONS

Our study revealed a physical and functional relationship among miR-223-3p and FBXW7. By negatively regulating FBXW7 expression, miR-223-3p exerts a tumor promotion role promoting cell invasion and metastasis in breast cancer.

The Regulation Network and Clinical Significance of Circular RNAs in Breast Cancer

Breast cancer is one of the most common malignant tumors in women worldwide. Circular RNA (circRNA) is a class of structurally stable non-coding RNA with a covalently closed circular structure. In recent years, with the development of high-throughput RNA sequencing, many circRNAs have been discovered and have proven to be clinically significant in the development and progression of breast cancer. Importantly, several regulators of circRNA biogenesis have been discovered. Here, we systematically summarize recent progress regarding the network of regulation governing the biogenesis, degradation, and distribution of circRNAs, and we comprehensively analyze the functions, mechanisms, and clinical significance of circRNA in breast cancer.

Circular RNAs Regulate Glucose Metabolism in Cancer Cells

Circular RNAs (circRNAs) were originally thought to result from RNA splicing errors. However, it has been shown that circRNAs can regulate cancer onset and progression in various ways. They can regulate cancer cell proliferation, differentiation, invasion, and metastasis. Moreover, they modulate glucose metabolism in cancer cells through different mechanisms such as directly regulating glycolytic enzymes and glucose transporter (GLUT) or indirectly regulating signal transduction pathways. In this review, we elucidate on the role of circRNAs in regulating glucose metabolism in cancer cells, which partly explains the pathogenesis of malignant tumors, and provides new therapeutic targets or new diagnostic and prognostic markers for human cancers.

The biogenesis, function and clinical significance of circular RNAs in breast cancer

Circular RNAs (circRNAs) are noncoding RNAs that form covalently closed loop structures. CircRNAs are dysregulated in cancer and play key roles in tumorigenesis, diagnosis, and tumor therapy. CircRNAs function as competing endogenous RNAs or microRNA sponges that regulate transcription and splicing, binding to proteins, and translation. CircRNAs may serve as novel biomarkers for cancer diagnosis, and they show potential as therapeutic targets in cancers including breast cancer (BC). In women, BC is the most common malignant tumor worldwide and the second leading cause of cancer death. Although evidence indicates that circRNAs play a critical role in BC, the mechanisms regulating the function of circRNAs in BC remain poorly understood. Here, we provide literature review aiming to clarify the role of circRNAs in BC and summarize the latest research. We provide a systematic overview of the biogenesis and biological functions of circRNAs, elaborate on the functional roles of circRNAs in BC, and highlight the value of circRNAs as diagnostic and therapeutic targets in BC.

Tip of the Iceberg: Roles of CircRNAs in Cancer Glycolysis

Warburg effect reflects that tumor cells tend to generate energy by aerobic glycolysis rather than oxidative phosphorylation (OXPHOS), thus promoting the development of malignant tumors. As a kind of non-coding RNA, circular RNA (circRNA) is characterized by a closed ring structure and emerges as a regulator of cancer metabolism. Mounting studies revealed that circRNA can regulate the cancer metabolism process through affecting the expression of glycolysis relevant enzymes, transcription factors (TFs), and signaling pathways. In this review, we comprehensively analyzed and concluded the mechanism of circRNA regulating glycolysis, hoping to deepen the cognition of the cancer metabolic regulatory network and to reap huge fruits in targeted cancer treatment.

Circular RNA circ_ABCB10 in cancer

Circular RNA (circRNA), a newly discovered type of endogenous noncoding RNA, has become a focus and hotspot in biological research in recent years. It exists widely and possesses a stable structure, is highly conserved and has cell-specific expression. circRNA is associated with disease occurence in general and cancer specifically due to its role in cell differentiation, proliferation, invasion and metastasis. Recently, circ_ABCB10, an increasingly studied member of the annular RNA family, has attracted considerable attention due to the fact that its expression is upregulated in various tumors, ie, esophageal cancer, breast cancer, lung cancer, and glioma, and may be of prognostic value. Molecular regulation and mechanism of circ_ABCB10 action in cancer are reviewed and its potential as a molecular marker and novel target for diagnosis and treatment are explored..

Hypoxia-Induced Cancer Cell Responses Driving Radioresistance of Hypoxic Tumors: Approaches to Targeting and Radiosensitizing

Simple Summary

Some regions of aggressive malignancies experience hypoxia due to inadequate blood supply. Cancer cells adapting to hypoxic conditions somehow become more resistant to radiation exposure and this decreases the efficacy of radiotherapy toward hypoxic tumors. The present review article helps clarify two intriguing points: why hypoxia-adapted cancer cells turn out radioresistant and how they can be rendered more radiosensitive. The critical molecular targets associated with intratumoral hypoxia and various approaches are here discussed which may be used for sensitizing hypoxic tumors to radiotherapy.

Abstract

Within aggressive malignancies, there usually are the “hypoxic zones”—poorly vascularized regions where tumor cells undergo oxygen deficiency through inadequate blood supply. Besides, hypoxia may arise in tumors as a result of antiangiogenic therapy or transarterial embolization. Adapting to hypoxia, tumor cells acquire a hypoxia-resistant phenotype with the characteristic alterations in signaling, gene expression and metabolism. Both the lack of oxygen by itself and the hypoxia-responsive phenotypic modulations render tumor cells more radioresistant, so that hypoxic tumors are a serious challenge for radiotherapy. An understanding of causes of the radioresistance of hypoxic tumors would help to develop novel ways for overcoming this challenge. Molecular targets for and various approaches to radiosensitizing hypoxic tumors are considered in the present review. It is here analyzed how the hypoxia-induced cellular responses involving hypoxia-inducible factor-1, heat shock transcription factor 1, heat shock proteins, glucose-regulated proteins, epigenetic regulators, autophagy, energy metabolism reprogramming, epithelial–mesenchymal transition and exosome generation contribute to the radioresistance of hypoxic tumors or may be inhibited for attenuating this radioresistance. The pretreatments with a multitarget inhibition of the cancer cell adaptation to hypoxia seem to be a promising approach to sensitizing hypoxic carcinomas, gliomas, lymphomas, sarcomas to radiotherapy and, also, liver tumors to radioembolization.