Accentuating CircRNA-miRNA-Transcription Factors Axis: A Conundrum in Cancer Research

Mucin 1 expression is regulated by hsa_circ_0055054/microRNA‑122‑5p and promotes hepatocellular carcinoma development

The abnormal expression of mucin 1 (MUC1) is a major cause of poor prognosis in patients with hepatocellular carcinoma (HCC). Competitive endogenous RNA demonstrates a novel regulatory mechanism that can affect the biological behavior of tumors. In the present study, the regulatory functions of hsa_circ_0055054 as well as those of microRNA (miR/miRNA) 122-5p on MUC1 expression and its role in HCC cell proliferation, migration and invasion, were evaluated. MUC1 expression was assessed using western blotting and reverse transcription-quantitative PCR. The phenotypic functions of the HCC cell lines were evaluated following MUC1 knockdown using Cell Counting Kit-8, wound healing and Transwell assays. Bioinformatics tools were used to identify specific miRNAs and circular (circ)RNAs that interact with and can regulate MUC1. The stability of circRNAs was assessed using a Ribonuclease R assay. The binding of circRNA/miRNA/MUC1 was assessed using dual-luciferase reporter assays and cellular function tests. Finally, in vivo experiments were performed using animal models. The results demonstrated that in MHCC97L cells, MUC1 and hsa_circ_0055054 were expressed at high levels while miR-122-5p was downregulated. The proliferation, migration and invasion of MHCC97L cells were suppressed by low MUC1 expression. hsa_circ_0055054 knockdown or miR-122-5p overexpression both led to a decrease in MUC1 expression. In MHCC97L cells with a low MUC1 expression caused by hsa_circ_0055054 knockdown, miR-122-5p inhibition resulted in the increased proliferation, migration and invasion of MHCC97L cells. In combination, the results of the present study indicate that hsa_circ_0055054 knockdown in MHCC97L cells leads to an increased expression of miR-122-5p and decreased expression of MUC1, which results in the inhibition of MHCC97L cell proliferation, migration and invasion.

Roles and mechanisms of circular RNA in respiratory system cancers

Circular RNAs (circRNAs) constitute a class of endogenous non-coding RNAs (ncRNAs) that lack a 5'-ended cap and 3'-ended poly (A) tail and form a closed ring structure with covalent bonds. Due to its special structure, circRNA is resistant to Exonuclease R (RNaseR), making its distribution in the cytoplasm quite rich. Advanced high-throughput sequencing and bioinformatics methods have revealed that circRNA is highly conserved, stable, and disease- and tissue-specific. Furthermore, increasing research has confirmed that circRNA, as a driver or suppressor, regulates cancer onset and progression by modulating a series of pathophysiological mechanisms. As a result, circRNA has emerged as a clinical biomarker and therapeutic intervention target. This article reviews the biological functions and regulatory mechanisms of circRNA in the context of respiratory cancer onset and progression.

Competitive endogenous RNA networks: Decoding the role of long non-coding RNAs and circular RNAs in colorectal cancer chemoresistance

Colorectal cancer (CRC) is recognized as one of the most common gastrointestinal malignancies across the globe. Despite significant progress in designing novel treatments for CRC, there is a pressing need for more effective therapeutic approaches. Unfortunately, many patients undergoing chemotherapy develop drug resistance, posing a significant challenge for cancer treatment. Non-coding RNAs (ncRNAs) have been found to play crucial roles in CRC development and its response to chemotherapy. However, there are still gaps in our understanding of interactions among various ncRNAs, such as long non-coding RNAs (lncRNAs), circular RNAs (circRNAs) and microRNAs (miRNAs). These ncRNAs can act as either oncogenes or tumour suppressors, affecting numerous biological functions in different cancers including CRC. A class of ncRNA molecules known as competitive endogenous RNAs (ceRNAs) has emerged as a key player in various cellular processes. These molecules form networks through lncRNA/miRNA/mRNA and circRNA/miRNA/mRNA interactions. In CRC, dysregulation of ceRNA networks has been observed across various cellular processes, including proliferation, apoptosis and angiogenesis. These dysregulations are believed to play a significant role in the progression of CRC and, in certain instances, may contribute to the development of chemoresistance. Enriching our knowledge of these dysregulations holds promise for advancing the field of diagnostic and therapeutic modalities for CRC. In this review, we discuss lncRNA- and circRNA-associated ceRNA networks implicated in the emergence and advancement of drug resistance in colorectal carcinogenesis.

Epithelial-to-mesenchymal transition in cancer progression: unraveling the immunosuppressive module driving therapy resistance

Cancer cells undergo phenotypic switching (cancer cell plasticity) in response to microenvironmental cues, including exposure to therapy/treatment. Phenotypic plasticity enables the cancer cells to acquire more mesenchymal traits promoting cancer cells' growth, survival, therapy resistance, and disease recurrence. A significant program in cancer cell plasticity is epithelial-to-mesenchymal transition (EMT), wherein a comprehensive reprogramming of gene expression occurs to facilitate the translational shift from epithelial-to-mesenchymal phenotypes resulting in increased invasiveness and metastasis. In addition, EMT plays a pivotal role in facilitating cancer cells' escape from the body's immune system using several mechanisms, such as the downregulation of major histocompatibility complex-mediated antigen presentation, upregulation of immune checkpoint molecules, and recruitment of immune-suppressive cells. Cancer cells' ability to undergo phenotypic switching and EMT-driven immune escape presents a formidable obstacle in cancer management, highlighting the need to unravel the intricate mechanisms underlying these processes and develop novel therapeutic strategies. This article discusses the role of EMT in promoting immune evasion and therapy resistance. We also discuss the ongoing research on developing therapeutic approaches targeting intrinsic and induced cell plasticity within the immune suppressive microenvironment. We believe this review article will update the current research status and equip researchers, clinicians, and other healthcare professionals with valuable insights enhancing their existing knowledge and shedding light on promising directions for future cancer research. This will facilitate the development of innovative strategies for managing therapy-resistant cancers and improving patient outcomes.

The Circular RNA circFOXK2 Enhances the Tumorigenesis of Non-Small Cell Lung Cancer Through the miR-149-3p/IL-6 Axis

Circular RNAs (circRNAs) are the non-coding types of RNAs and are thoughts to be linked with human cancer progression. circFOXK2 is believed to be associated with cancers, however, the molecular mechanisms of circFOXK2 in non-small cell lung cancer (NSCLC) are still unclear. Here we firstly reported that circFOXK2 enhances the tumorigenesis of NSCLC through the miR-149-3p/IL-6 axis. The expression of circFOXK2, microRNA-149-3p (miR-149-3p) and IL-6 were assessed by qRT-PCR and western blot. Transwell, colony formation, wound healing, and CCK-8 assays were used to elucidate NSCLC cells' proliferation, migration, and invasion. MiR-149-3p interaction with circFOXK2 was confirmed by dual-luciferase reporter gene assay (DLRGA). Furthermore, the biological effect of circFOXK2 on NSCLC progression was detected by tumor xenograft assay. CircFOXK2 were upregulated in NSCLC tissues and cells, miR-149-3p were downregulated in NSCLC tissues and cells. In addition, circFOXK2 stimulated NSCLC cell proliferation, migration and invasion in vitro. Mechanical analysis indicated that circFOXK2 modulated IL-6 via miR-149-3p sponging. Furthermore, circFOXK2 overexpression promoted tumor growth in vivo. Overall, this research verified that circFOXK2 enhances the tumorigenesis of NSCLC through the miR-149-3p/IL-6 axis.

The emerging role of circRNAs on skeletal muscle development in economical animals

CircRNAs are a novel type of closed circular molecules formed through a covalent bond lacking a 5'cap and 3' end tail, which mainly arise from mRNA precursor. They are widely distributed in plants and animals and are characterized by stable structure, high conservativeness in cells or tissues, and showed the expression specificity at different stages of development in different tissues. CircRNAs have been gradually attracted wide attention with the development of RNA sequencing, which become a new research hotspot in the field of RNA. CircRNAs play an important role in gene expression regulation. Presently, the related circRNAs research in the regulation of animal muscle development is still at the initial stage. In this review, the formation, properties, biological functions of circRNAs were summarized. The recent research progresses of circRNAs in skeletal muscle growth and development from economic animals including livestock, poultry and fishes were introduced. Finally, we proposed a prospective for further studies of circRNAs in muscle development, and we hope our research could provide new ideas, some theoretical supports and helps for new molecular genetic markers exploitation and animal genetic breeding in future.

A spotlight on the interplay between Wnt/β-catenin signaling and circular RNAs in hepatocellular carcinoma progression

Hepatocellular carcinoma (HCC) is one of the deadliest cancers due to multifocal development and distant metastasis resulting from late diagnosis. Consequently, new approaches to HCC diagnosis and treatment are required to reduce mortality rates. A large body of evidence suggests that non-coding RNAs (ncRNAs) are important in cancer initiation and progression. Cancer cells release many of these ncRNAs into the blood or urine, enabling their use as a diagnostic tool. Circular RNAs (CircRNAs) are as a members of the ncRNAs that regulate cancer cell expansion, migration, metastasis, and chemoresistance through different mechanisms such as the Wnt/β-catenin Signaling pathway. The Wnt/β-catenin pathway plays prominent roles in several biological processes including organogenesis, stem cell regeneration, and cell survival. Aberrant signaling of both pathways mentioned above could affect the progression and metastasis of many cancers, including HCC. Based on several studies investigated in the current review, circRNAs have an effect on HCC formation and progression by sponging miRNAs and RNA-binding proteins (RBPs) and regulating the Wnt/β-catenin signaling pathway. Therefore, circRNAs/miRNAs or RBPs/Wnt/β-catenin signaling pathway could be considered promising prognostic and therapeutic targets in HCC.

Roles of circRNA dysregulation in esophageal squamous cell carcinoma tumor microenvironment

Esophageal squamous cell carcinoma (ESCC) is the most prevalent histological esophageal cancer characterized by advanced diagnosis, metastasis, resistance to treatment, and frequent recurrence. In recent years, numerous human disorders such as ESCC, have been linked to abnormal expression of circular RNAs (circRNAs), suggesting that they are fundamental to the intricate system of gene regulation that governs ESCC formation. The tumor microenvironment (TME), referring to the area surrounding the tumor cells, is composed of multiple components, including stromal cells, immune cells, the vascular system, extracellular matrix (ECM), and numerous signaling molecules. In this review, we briefly described the biological purposes and mechanisms of aberrant circRNA expression in the TME of ESCC, including the immune microenvironment, angiogenesis, epithelial-to-mesenchymal transition, hypoxia, metabolism, and radiotherapy resistance. As in-depth research into the processes of circRNAs in the TME of ESCC continues, circRNAs are promising therapeutic targets or delivery systems for cancer therapy and diagnostic and prognostic indicators for ESCC.

GLUT1 transporter-facilitated solid lipid nanoparticles loaded with anti-cancer therapeutics for ovarian cancer targeting

The therapeutics available for cancer treatment have the major hurdle of site-specific delivery of anti-cancer drugs to the tumor site and non-target specific side effects. The standard therapy for ovarian cancer still poses numerous pitfalls due to the irrational use of drugs affecting healthy cells. As an appealing approach, nanomedicine could revamp the therapeutic profile of anti-cancer agents. Owing to the low manufacturing cost, increased biocompatibility, and modifiable surface properties, lipid-based nanocarriers, particularly solid lipid nanoparticles (SLN), have remarkable drug delivery properties in cancer treatment. Given the extra-ordinary benefits, we developed anti-neoplastic (paclitaxel) drug-loaded SLN (PTX-SLN) and functionalized with N-acetyl-d-glucosamine (GLcNAc) (GLcNAc-PTX-SLN) to reduce the rate of proliferation, growth, and metastasis of ovarian cancer cells over-expressing GLUT1 transporters. The particles presented considerable size and distribution while demonstrating haemocompatibility. Using GLcNAc modified form of SLNs, confocal microscopy, MTT assay, and flow cytometry study demonstrated higher cellular uptake and significant cytotoxic effect. Also, molecular docking results established excellent binding affinity between GLcNAc and GLUT1, complimenting the feasibility of the therapeutic approach in targeted cancer therapy. Following the compendium of target-specific drug delivery by SLN, our results demonstrated a significant response for ovarian cancer therapy.

Emerging landscape of circFNDC3B and its role in human malignancies

In recent years, more attention has been paid to expanding the abundance of Circular RNAs (circRNAs), while the circRNAs that have been found to have significant functions have not been studied in different diseases. CircFNDC3B is one of the most researched circRNAs generated from fibronectin type III domain-containing protein 3B (FNDC3B) gene. Accumulating researches have reported the multiple functions of circFNDC3B in different cancer types and other non-neoplastic diseases, and predicted that circFNDC3B might be a potential biomarker. Notably, circFNDC3B can play roles in different diseases by binding to various microRNAs (miRNAs), binding to RNA-binding proteins (RBPs), or encoding functional peptides. This paper systematically summarizes the biogenesis and function of circRNAs, reviews and discusses the roles and molecular mechanisms of circFNDC3B and its target genes in different cancers and non-neoplastic diseases, which will do favor to broaden our comprehension of the function of circRNAs and facilitate subsequent research on circFNDC3B.

Key circRNAs from goat: discovery, integrated regulatory network and their putative roles in the differentiation of intramuscular adipocytes

BACKGROUND

The procession of preadipocytes differentiation into mature adipocytes involves multiple cellular and signal transduction pathways. Recently. a seirces of noncoding RNAs (ncRNAs), including circular RNAs (circRNAs) were proved to play important roles in regulating differentiation of adipocytes.

RESULT

In this study, we aimed to identificate the potential circRNAs in the early and late stages of goat intramuscular adipocytes differentiation. Using bioinformatics methods to predict their biological functions and map the circRNA-miRNA interaction network. Over 104 million clean reads in goat intramuscular preadipocytes and adipocytes were mapped, of which16 circRNAs were differentially expressed (DE-circRNAs). Furthermore, we used real-time fluorescent quantitative PCR (qRT-PCR) technology to randomly detect the expression levels of 8 circRNAs among the DE-circRNAs, and our result verifies the accuracy of the RNA-seq data. From the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of the DE-circRNAs, two circRNAs, circ_0005870 and circ_0000946, were found in Focal adhesion and PI3K-Akt signaling pathway. Then we draw the circRNA-miRNA interaction network and obtained the miRNAs that possibly interact with circ_0005870 and circ_0000946. Using TargetScan, miRTarBase and miR-TCDS online databases, we further obtained the mRNAs that may interact with the miRNAs, and generated the final circRNA-miRNA-mRNA interaction network. Combined with the following GO (Gene Ontology) and KEGG enrichment analysis, we obtained 5 key mRNAs related to adipocyte differentiation in our interaction network, which are FOXO3(forkhead box O3), PPP2CA (protein phosphatase 2 catalytic subunit alpha), EEIF4E (eukaryotic translation initiation factor 4), CDK6 (cyclin dependent kinase 6) and ACVR1 (activin A receptor type 1).

CONCLUSIONS

By using Illumina HiSeq and online databases, we generated the final circRNA-miRNA-mRNA interaction network that have valuable functions in adipocyte differentiation. Our work serves as a valuable genomic resource for in-depth exploration of the molecular mechanism of ncRNAs interaction network regulating adipocyte differentiation.

Circular RNA Sec61 subunit alpha isoform 1 by competitive absorption of microRNA-513a-5p mediates peroxisomal biogenesis factor 5 expression and promotes the malignant phenotype of non-small cell lung cancer

Circular RNAs (circRNAs) are functional RNAs in the development and metabolism of non-small cell lung cancer (NSCLC). Therein, this paper particularly elucidated the circRNA SEC61 subunit alpha isoform 1 (circSEC61A1) in NSCLC has not been fully elucidated. Clinical analysis of circSEC61A1 expression was performed on specimens collected from 51 patients with primary NSCLC, together with patients' survival. Cell experiments were performed after interfering with circSEC61A1, microRNA (miR)-513a-5p, and peroxisomal biogenesis factor 5 (PEX5) expression, respectively, and cell malignant phenotypes and aerobic glycolysis were evaluated, as well as epithelial-to-mesenchymal transition (EMT)-related markers and Wnt/β-catenin pathway. Xenografts experiments studied the performance of circSEC61A1 in vivo. The downstream molecules of circSEC61A1 were searched. Our data demonstrated that circSEC61A1 was upregulated in NSCLC patients, showing an association with poorer survival outcomes. In cell experiments, circSEC61A1 overexpression promoted NSCLC malignant phenotypes, glycolysis, EMT, and Wnt/β-catenin pathway activation, whereas circSEC61A1 underexpression did the opposite. Knockdown of circSEC61A1 limited tumor growth and metastasis. Furthermore, circSEC61A1 could regulate PEX5 expression through competitive absorption of miR-513a-5p. Generally, circSEC61A1 is a potential biomarker for NSCLC, and circSEC61A1 serves tumor-promoting action in the progression of NSCLC.

Functions and clinical significance of circular RNAs in acute myeloid leukemia

Circular RNAs (circRNAs) are a class of covalently closed single-stranded RNA molecules. Four types of circRNAs have been reported in animal cells, and they have typical characteristics in their biogenesis, nuclear export and degradation. Advances in our understanding of the molecular functions of circRNAs in sponging microRNAs, modulating transcription, regulating RNA-binding proteins, as well as encoding proteins have been made very recently. Dysregulated circRNAs are associated with human diseases such as acute myeloid leukemia (AML). In this review, we focus on the recently described mechanisms, role and clinical significance of circRNAs in AML. Although great progress of circRNAs in AML has been achieved, substantial efforts are still required to explore whether circRNAs exert their biological function by other mechanisms such as regulation of gene transcription or serving as translation template in AML. It is also urgent that researchers study the machineries regulating circRNAs fate, the downstream effectors of circRNAs modulatory networks, and the clinical application of circRNAs in AML.

Folic acid engineered sulforaphane loaded microbeads for targeting breast cancer

Non-targeted cancer therapy poses a huge risk to the cancer patients' life due to high toxicity offered by chemotherapy. Breast carcinoma is one of such deleterious disease, demanding a highly effectual treatment option which could reduce the toxicity and extend survival rate. Since, folate receptors extensively display themselves on the cancer cell surface, targeting them would help to ameliorate the progression and metastasis. Considering this, we envisaged and developed sulforaphane loaded folate engineered microbeads to target breast cancer cells over-expressing folate receptors. The surface engineered microbeads were optimized and developed using emulsion gelation technique, among which the best developed preparation demonstrated the particle size of 1302 ± 3.98 µm, % EE of 84.1 ± 3.32% and in vitro drug release of 98.1 ± 4.42%@24h. The spherical sized microbead showed controlled release with improved haem-compatibility in comparison to the bare drug. Free radical scavenging activity by ABTS assay showed strong anti-oxidant activity (IC₅₀ 20.62 µg/ml) of the targeted microbeads with profound cancer cell sup pressing effect (IC₅₀ 17.48 ± 3.5 µM) as observed in MCF-7 cells by MTT assay. Finally, in comparison to lone SFN, the targeted therapy showed enhanced uptake by the intestinal villi indicating a suitable oral targeted therapy against breast carcinoma.

Emerging innovations in cold plasma therapy against cancer: A paradigm shift

Cancer is one of the major causes of mortality, accounting for ∼ 9.5 million deaths globally in 2018. The spectrum of conventional treatment for cancer includes surgery, chemotherapy and radiotherapy. Recently, cold plasma therapy surfaced as a novel technique in the treatment of cancer. The FDA approval of the first trial for the use of cold atmospheric plasma (CAP) in cancer therapy in 2019 is evidence of this. This review highlights the mechanisms of action of CAP. Additionally, its applications in anticancer therapy have been reviewed. In summary, this article will introduce the readers to the exciting field of plasma oncology and help them understand the current status and prospects of plasma oncology.

Critical Roles of Circular RNA in Tumor Metastasis via Acting as a Sponge of miRNA/isomiR

Circular RNAs (circRNAs), a class of new endogenous non-coding RNAs (ncRNAs), are closely related to the carcinogenic process and play a critical role in tumor metastasis. CircRNAs can lay the foundation for tumor metastasis via promoting tumor angiogenesis, make tumor cells gain the ability of migration and invasion by regulating epithelial-mesenchymal transition (EMT), interact with immune cells, cytokines, chemokines, and other non-cellular components in the tumor microenvironment, damage the normal immune function or escape the immunosuppressive network, and further promote cell survival and metastasis. Herein, based on the characteristics and biological functions of circRNA, we elaborated on the effect of circRNA via circRNA-associated competing endogenous RNA (ceRNA) network by acting as miRNA/isomiR sponges on tumor angiogenesis, cancer cell migration and invasion, and interaction with the tumor microenvironment (TME), then explored the potential interactions across different RNAs, and finally discussed the potential clinical value and application as a promising biomarker. These results provide a theoretical basis for the further application of metastasis-related circRNAs in cancer treatment. In summary, we briefly summarize the diverse roles of a circRNA-associated ceRNA network in cancer metastasis and the potential clinical application, especially the interaction of circRNA and miRNA/isomiR, which may complicate the RNA regulatory network and which will contribute to a novel insight into circRNA in the future.

Circular RNAs and Their Role in Exosomes

As a novel class of endogenous non-coding RNAs discovered in recent years, circular RNAs (circRNAs) are highly conserved and stable covalently closed ring structures with no 5'-end cap or 3'-end poly(A) tail. CircRNAs are formed by reverse splicing, mainly by means of a noose structure or intron complementary pairing. Exosomes are tiny discoid vesicles with a diameter of 40-100 nm that are secreted by cells under physiological and pathological conditions. Exosomes play an important role in cell-cell communication by carrying DNA, microRNAs, mRNAs, proteins and circRNAs. In this review, we summarize the biological functions of circRNAs and exosomes, and further reveal the potential roles of exosomal circRNAs in different diseases, providing a scientific basis for the diagnosis, treatment, and prognosis of a wide variety of diseases.

Clinical progress of therapeutics and vaccines: Rising hope against COVID-19 treatment

Cases of deaths due to COVID-19 (COrona VIrus Disease-19) infection are increasing gradually worldwide. Immense research is ongoing to control this pandemic condition. Continual research outcomes are indicating that therapeutic and prophylactic agents are the possible hope to prevent the pandemic from spreading and to combat this increasing death count. Experience gained from previous coronavirus infections (eg., SARS (Severe Acute Respiratory Syndrome), MERS (Middle Ease Respiratory Syndrome), accumulated clinical knowledge during this pandemic, and research helped to identify a few therapeutic agents for emergency treatment of COVID-19. Thereby, monoclonal antibodies, antivirals, broad-spectrum antimicrobials, immunomodulators, and supplements are being suggested for treatment depending on the stage of the disease. These recommended treatments are authorized under medical supervision in emergency conditions only. Urgent need to control the pandemic condition had resulted in various approaches of repurposing the existing drugs, However, poorly designed clinical trials and associated outcomes do not provide enough evidence to fully approve treatments against COVID-19. So far, World Health Organization (WHO) authorized three vaccines as prophylactic against SARS-CoV-2. Here, we discussed about various therapeutic agents, their clinical trials, and limitations of trials for the management of COVID-19. Further, we have also spotlighted different vaccines in research in combating COVID-19.