Circ3823 contributes to growth, metastasis and angiogenesis of colorectal cancer: involvement of miR-30c-5p/TCF7 axis

The landscape of epigenetic regulation and therapeutic application of N6-methyladenosine modifications in non-coding RNAs

RNA N6-methyladenosine (m6A) methylation is the most abundant and conserved RNA modification in eukaryotes. It participates in the regulation of RNA metabolism and various pathophysiological processes. Non-coding RNAs (ncRNAs) are defined as small or long transcripts which do not encode proteins and display numerous biological regulatory functions. Similar to mRNAs, m6A deposition is observed in ncRNAs. Studying RNA m6A modifications on ncRNAs is of great importance specifically to deepen our understanding of their biological roles and clinical implications. In this review, we summarized the recent research findings regarding the mutual regulation between RNA m6A modification and ncRNAs (with a specific focus on microRNAs, long non-coding RNAs, and circular RNAs) and their functions. We also discussed the challenges of m6A-containing ncRNAs and RNA m6A as therapeutic targets in human diseases and their future perspective in translational roles.

CircRNA as an Achilles heel of cancer: characterization, biomarker and therapeutic modalities

Circular RNAs (circRNAs) are a class of endogenous noncoding RNAs characterized by their lack of 5' caps and 3' poly(A) tails. These molecules have garnered substantial attention from the scientific community. A wide range of circRNA types has been found to be expressed in various tissues of the human body, exhibiting unique characteristics such as high abundance, remarkable stability, and tissue-specific expression patterns. These attributes, along with their detectability in liquid biopsy samples such as plasma, position circRNAs an ideal choice as cancer diagnostic and prognostic biomarkers. Additionally, several studies have reported that the functions of circRNAs are associated with tumor proliferation, metastasis, and drug resistance. They achieve this through various mechanisms, including modulation of parental gene expression, regulation of gene transcription, acting as microRNA (miRNA) sponges, and encoding functional proteins. In recent years, a large number of studies have focused on synthesizing circRNAs in vitro and delivering them to tumor tissue to exert its effects in inhibit tumor progression. Herein, we briefly discuss the biogenesis, characteristics, functions, and detection of circRNAs, emphasizing their clinical potential as biomarkers for cancer diagnosis and prognosis. We also provide an overview the recent techniques for synthesizing circRNAs and delivery strategies, and outline the application of engineered circRNAs in clinical cancer therapy.

Role of N6-methyladenosine in tumor neovascularization

Tumor neovascularization is essential for the growth, invasion, and metastasis of tumors. Recent studies have highlighted the significant role of N6-methyladenosine (m6A) modification in regulating these processes. This review explores the mechanisms by which m6A influences tumor neovascularization, focusing on its impact on angiogenesis and vasculogenic mimicry (VM). We discuss the roles of m6A writers, erasers, and readers in modulating the stability and translation of angiogenic factors like vascular endothelial growth factor (VEGF), and their involvement in key signaling pathways such as PI3K/AKT, MAPK, and Hippo. Additionally, we outline the role of m6A in vascular-immune crosstalk. Finally, we discuss the current development of m6A inhibitors and their potential applications, along with the contribution of m6A to anti-angiogenic therapy resistance. Highlighting the therapeutic potential of targeting m6A regulators, this review provides novel insights into anti-angiogenic strategies and underscores the need for further research to fully exploit m6A modulation in cancer treatment. By understanding the intricate role of m6A in tumor neovascularization, we can develop more effective therapeutic approaches to inhibit tumor growth and overcome treatment resistance. Targeting m6A offers a novel approach to interfere with the tumor's ability to manipulate its microenvironment, enhancing the efficacy of existing treatments and providing new avenues for combating cancer progression.

Molecular functions of microRNAs in colorectal cancer: recent roles in proliferation, angiogenesis, apoptosis, and chemoresistance

MiRNAs (microRNAs) constitute a group of diminutive molecules of non-coding RNA intricately involved in regulating gene expression. This regulation is primarily accomplished through the binding of miRNAs to complementary sequences situated in the 3'-UTR of the messenger RNA (mRNA) target; as a result, they are degraded or repressed. The multifaceted biogenesis of miRNAs is characterized by a meticulously orchestrated sequence of events encompassing transcription, processing, transportation, and decay. Colorectal cancer stands as a pervasive and formidable ailment, afflicting millions across the globe. Colorectal cancer is not well diagnosed early, and metastasis rates are high, which results in low survival rates in advanced stages. The genesis and progression of colorectal cancer are subject to the influence of genetic and epigenetic factors, among which miRNAs play a pivotal role. When it comes to colorectal cancer, miRNAs have a dual character, depending on the genes they target, functioning as either tumor suppressors or oncogenes and the prevailing cellular milieu. Their impact extends to modulating critical facets of colorectal cancer pathogenesis, including proliferation, angiogenesis, apoptosis, chemoresistance, and radiotherapy response. The discernible potential of miRNAs which are used as biomarkers to diagnose colorectal cancer, prognosis, and treatment response has come to the forefront. Notably, miRNAs are easily found and detected readily in a variety of biological fluids, including saliva, blood, urine, and feces. This prominence is attributed to the inherent advantages of miRNAs over conventional biomarkers, including heightened stability, specificity, sensitivity, and accessibility. Various investigations have pinpointed miRNA signatures or panels capable of differentiating colorectal cancer patients from their healthy counterparts, predicting colorectal cancer stage and survival, and monitoring colorectal cancer recurrence and therapy response. Although there has been research on miRNAs in various diseases, there has been less research on miRNAs in cancer. Moreover, updated results of preclinical and clinical studies on miRNA biomarkers and drugs are required. Nevertheless, the integration of miRNAs as biomarkers for colorectal cancer is not devoid of challenges and limitations. These encompass the heterogeneity prevalent among colorectal cancer subtypes and stages, the variability in miRNA expression across different tissues and individuals, the absence of standardized methodologies for miRNA detection and quantification, and the imperative for validation through extensive clinical trials. Consequently, further research is imperative to conclusively establish the clinical utility and reliability of miRNAs as colorectal cancer biomarkers. MiR-21 demonstrates carcinogenic characteristics by targeting several tumor suppressor genes, which encourages cell division, invasion, and metastasis. On the other hand, by controlling the Wnt/β-catenin pathway, the tumor suppressor miRNA miR-34a prevents CRC cell proliferation, migration, and invasion. Furthermore, in colorectal cancer, the miR-200 family increases chemotherapy sensitivity while suppressing epithelial-mesenchymal transition (EMT). As an oncogene, the miR-17-92 cluster targets elements of the TGF-β signaling pathway to encourage the growth of CRC cells. Finally, miR-143/145, which is downregulated in CRC, influences apoptosis and the progression of the cell cycle. These miRNAs affect pathways like Wnt, TGF-β, PI3K-AKT, MAPK, and EMT, making them potential clinical biomarkers and therapeutic targets. This review summarizes recent research related to miRNAs, their role in tumor progression and metastasis, and their potential as biomarkers and therapeutic targets in colorectal cancer. In addition, we combined miRNAs' roles in tumorigenesis and development with the therapy of CRC patients, leading to novel perspectives on colorectal cancer diagnosis and treatment.

Human Amniotic Epithelial Stem Cells Alleviate Autoimmune Premature Ovarian Insufficiency in Mice by Targeting Granulosa Cells via AKT/ERK Pathways

Autoimmune factors play an important role in premature ovarian insufficiency (POI). Human amniotic epithelial stem cells (hAESCs) have recently shown promising treatment effects on chemotherapy-induced POI. However, the therapeutic efficacy and underlying mechanisms of hAESCs in autoimmune POI remain to be investigated. In this study, we showed for the first time that intravenous transplantation of hAESCs could reside in the ovary of zona pellucida 3 peptide (pZP3) induced autoimmune POI mice model for at least 4 weeks. hAESCs could improve ovarian function and fertility, alleviate inflammation and reduce apoptosis of granulosa cells (GCs) in autoimmune POI mice. The transcriptome analysis of mice ovaries and in vitro co-cultivation experiments suggest that activation of the AKT and ERK pathways may be the key mechanism in the therapeutic effect of hAESCs. Our work provides the theoretical and experimental foundation for optimizing the administration of hAESCs, as well as the clinical application of hAESCs in autoimmune POI patients.

Circular RNA hsa_circ_0000467 promotes colorectal cancer progression by promoting eIF4A3-mediated c-Myc translation

BACKGROUND

Colorectal cancer (CRC) is the second most common malignant tumor worldwide, and its incidence rate increases annually. Early diagnosis and treatment are crucial for improving the prognosis of patients with colorectal cancer. Circular RNAs are noncoding RNAs with a closed-loop structure that play a significant role in tumor development. However, the role of circular RNAs in CRC is poorly understood.

METHODS

The circular RNA hsa_circ_0000467 was screened in CRC circRNA microarrays using a bioinformatics analysis, and the expression of hsa_circ_0000467 in CRC tissues was determined by in situ hybridization. The associations between the expression level of hsa_circ_0000467 and the clinical characteristics of CRC patients were evaluated. Then, the role of hsa_circ_0000467 in CRC growth and metastasis was assessed by CCK8 assay, EdU assay, plate colony formation assay, wound healing assay, and Transwell assay in vitro and in a mouse model of CRC in vivo. Proteomic analysis and western blotting were performed to investigate the effect of hsa_circ_0000467 on c-Myc signaling. Polysome profiling, RT‒qPCR and dual-luciferase reporter assays were performed to determine the effect of hsa_circ_0000467 on c-Myc translation. RNA pull-down, RNA immunoprecipitation (RIP) and immunofluorescence staining were performed to assess the effect of hsa_circ_0000467 on eIF4A3 distribution.

RESULTS

In this study, we found that the circular RNA hsa_circ_0000467 is highly expressed in colorectal cancer and is significantly correlated with poor prognosis in CRC patients. In vitro and in vivo experiments revealed that hsa_circ_0000467 promotes the growth and metastasis of colorectal cancer cells. Mechanistically, hsa_circ_0000467 binds eIF4A3 to suppress its nuclear translocation. In addition, it can also act as a scaffold molecule that binds eIF4A3 and c-Myc mRNA to form complexes in the cytoplasm, thereby promoting the translation of c-Myc. In turn, c-Myc upregulates its downstream targets, including the cell cycle-related factors cyclin D2 and CDK4 and the tight junction-related factor ZEB1, and downregulates E-cadherin, which ultimately promotes the growth and metastasis of CRC.

CONCLUSIONS

Our findings revealed that hsa_circRNA_0000467 plays a role in the progression of CRC by promoting eIF4A3-mediated c-Myc translation. This study provides a theoretical basis and molecular target for the diagnosis and treatment of CRC.

Interaction of the intestinal cytokines-JAKs-STAT3 and 5 axes with RNA N6-methyladenosine to promote chronic inflammation-induced colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers, with a high mortality rate worldwide. Mounting evidence indicates that mRNA modifications are crucial in RNA metabolism, transcription, processing, splicing, degradation, and translation. Studies show that N6-methyladenosine (m6A) is mammalians' most common epi-transcriptomic modification. It has been demonstrated that m6A is involved in cancer formation, progression, invasion, and metastasis, suggesting it could be a potential biomarker for CRC diagnosis and developing therapeutics. Cytokines, growth factors, and hormones function in JAK/STAT3/5 signaling pathway, and they could regulate the intestinal response to infection, inflammation, and tumorigenesis. Reports show that the JAK/STAT3/5 pathway is involved in CRC development. However, the underlying mechanism is still unclear. Signal Transducer and Activator of Transcription 3/5 (STAT3, STAT5) can act as oncogenes or tumor suppressors in the context of tissue types. Also, epigenetic modifications and mutations could alter the balance between pro-oncogenic and tumor suppressor activities of the STAT3/5 signaling pathway. Thus, exploring the interaction of cytokines-JAKs-STAT3 and/or STAT5 with mRNA m6A is of great interest. This review provides a comprehensive overview of the characteristics and functions of m6A and JAKs-STAT3/5 and their relationship with gastrointestinal (GI) cancers.

Cross-talk between circRNAs and m6A modifications in solid tumors

Circular RNAs (circRNAs) possess unique biological properties and distribution characteristics that enable a variety of biological functions. N6-methyladenosine (m6A), a prevalent epigenetic modification in organisms, is regulated by factors including methyltransferases (writers), demethylases (erasers), and m6A-binding proteins (readers). These factors play critical roles in various pathophysiological processes. There is growing evidence that m6A modifications are common within circRNAs, affecting their synthesis, translation, translocation, degradation, and stability. Additionally, circRNAs regulate biological processes that influence m6A modifications. This review explores the metabolism and functions of m6A modifications and circRNAs, their interactions, and their specific regulatory mechanisms in different tumors, offering insights into m6A-circRNA interaction in cancer.

YTHDF1's grip on CRC vasculature: insights into LINC01106 and miR-449b-5p-VEGFA axis

BACKGROUND

Investigating the unexplored territory of lncRNA m6A modification in colorectal cancer (CRC) vasculature, this study focuses on LINC01106 and YTHDF1.

METHODS

Clinical assessments reveal upregulated LINC01106 promoting vascular generation via the miR-449b-5p-VEGFA pathway.

RESULTS

YTHDF1, elevated in CRC tissues, emerges as an adverse prognostic factor. Functional experiments showcase YTHDF1's inhibitory effects on CRC cell dynamics. Mechanistically, Me-CLIP identifies m6A-modified LINC01106, validated as a YTHDF1 target through Me-RIP.

CONCLUSIONS

This study sheds light on the YTHDF1-mediated m6A modification of LINC01106, presenting it as a key player in suppressing CRC vascular generation.

Roles of circRNAs in the progression of colorectal cancer: novel strategies for detection and therapy

Endogenous noncoding RNAs with a covalently closed loop are known as circular RNAs (circRNAs). Recently, published works have revealed that circRNAs, which act as microRNA sponges, are critical for the biological behavior of several kinds of malignancies, including tumor cell proliferation, apoptosis, invasion, and metastasis. Additionally, there is a significant correlation between circRNAs and tumor resistance, stage, prognosis, and size. At present, colorectal cancer (CRC) is one of the most serious malignant tumors for human health. CircRNAs could represent potential targets to use in the prevention, diagnosis, and therapy of CRC, according to many studies. To fully comprehend the role of circRNAs in the incidence and progression of CRC, this review outlines the regulatory role and mechanisms of circRNAs in CRC and assesses their potential relevance as diagnostic and treatment possibilities for CRC. Our goal is to offer meaningful biological information for clinical evaluation and decision-making process for CRC treatment.

Converting "cold" to "hot": epigenetics strategies to improve immune therapy effect by regulating tumor-associated immune suppressive cells

Significant developments in cancer treatment have been made since the advent of immune therapies. However, there are still some patients with malignant tumors who do not benefit from immunotherapy. Tumors without immunogenicity are called "cold" tumors which are unresponsive to immunotherapy, and the opposite are "hot" tumors. Immune suppressive cells (ISCs) refer to cells which can inhibit the immune response such as tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), regulatory T (Treg) cells and so on. The more ISCs infiltrated, the weaker the immunogenicity of the tumor, showing the characteristics of "cold" tumor. The dysfunction of ISCs in the tumor microenvironment (TME) may play essential roles in insensitive therapeutic reaction. Previous studies have found that epigenetic mechanisms play an important role in the regulation of ISCs. Regulating ISCs may be a new approach to transforming "cold" tumors into "hot" tumors. Here, we focused on the function of ISCs in the TME and discussed how epigenetics is involved in regulating ISCs. In addition, we summarized the mechanisms by which the epigenetic drugs convert immunotherapy-insensitive tumors into immunotherapy-sensitive tumors which would be an innovative tendency for future immunotherapy in "cold" tumor.

CircFBXW4 Suppresses Colorectal Cancer Progression by Regulating the MiR-338-5p/SLC5A7 Axis

Dysregulated circular RNAs (circRNAs) contribute to tumourigenesis and cancer progression. However, the expression patterns and biological functions of circRNAs in colorectal cancer (CRC) remain elusive. Here, RNA sequencing and bioinformatics analyses are applied to screen for aberrantly expressed circRNAs. The expression of circFBXW4 in CRC tissues and cell lines is determined by quantitative real-time PCR. A series of in vitro and in vivo biological function assays are implemented to assess the functions of circFBXW4. The regulatory mechanisms linking circFBXW4, miR-338-5p, and SLC5A7 are explored by western blotting, dual luciferase reporter assays, and RNA pull-down assays. CircFBXW4 is dramatically downregulated in CRC tissues and cell lines. circFBXW4 downregulation is clearly correlated with malignant features and patient overall survival in CRC. Functionally, ectopic expression of circFBXW4 strikingly impairs the proliferation, migration, and invasion capacities of CRC cells in vitro and in vivo, whereas circFBXW4 knockdown has the opposite effects. Mechanistically, circFBXW4 competitively binds to miR-338-5p and prevents it from interacting with and repressing its target SLC5A7, thus suppressing the progression of CRC. This study reveals the specific critical role of circFBXW4 in inhibiting CRC progression via the miR-338-5p/SLC5A7 axis and provides an additional target for eradicating CRC.

Nicotine-derived NNK promotes CRC progression through activating TMUB1/AKT pathway in METTL14/YTHDF2-mediated m6A manner

Cigarette smoking substantially promotes tumorigenesis and progression of colorectal cancer; however, the underlying molecular mechanism remains unclear. Among 662 colorectal cancer patients, our investigation revealed a significant correlation between cigarette smoking and factors, such as large tumor size, poor differentiation, and high degree of invasion. Among the nicotine-derived nitrosamines, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) emerged as the most critical carcinogen, which significantly promoted the malignant progression of colorectal cancer both in vivo and in vitro. The results of methylated RNA immunoprecipitation and transcriptome sequencing indicated that NNK upregulated transmembrane and ubiquitin-like domain-containing protein 1 (TMUB1) via N6-adenosine methylation, which was regulated by methyltransferase-like 14 (METTL14) and YTH N6-methyladenosine RNA binding protein 2 (YTHDF2). Elevated TMUB1 levels were associated with a higher risk of cancer invasion and metastasis, leading to a high mortality risk in patients with colorectal cancer. Additionally, TMUB1 promoted lysine63-linked ubiquitination of AKT by interacting with AMFR, which led to the induction of malignant proliferation and metastasis in colorectal cancer cells exposed to NNK. In summary, this study provides a new insight, indicating that targeting TMUB1 expression via METTL14/YTHDF2 mediated N6-adenosine methylation may be a potential therapeutic and prognostic target for patients with colorectal cancer who smoke.

MiR-485-3p/MiR-543/MiR-337-3p is Required for the Oncogenic Potential of the Hsa_circ_0007385-MEMO1 Axis in Colorectal Cancer

Circular RNAs (circRNAs) play regulatory roles in the biological processes of multiple tumors, colorectal cancer (CRC) included. Our previous study probed the impact of circ_0007385 on CRC cell malignant behaviors, while the underlying mechanism remains obscure. In this work, the potential mechanism of hsa_circ_0007385 in CRC was probed. Functional experiments were implemented for probing the function of hsa_circ_0007385 in CRC. Further analysis revealed the relation between hsa_circ_0007385 and miRNAs. A xenograft mouse model was implemented for probing the influence of hsa_circ_0007385 on CRC growth and metastasis in vivo. Hsa_circ_0007385 was up-regulated in CRC. Hsa_circ_0007385 positively regulated its host gene mediator of cell motility 1 (MEMO1). Hsa_circ_0007385 silencing inhibited CRC progression. Hsa_circ_0007385 and MEMO1 bond to miR-485-3p/miR-543/miR-337-3p, and these three miRNAs were lowly expressed in CRC, and negatively modulated by hsa_circ_0007385. Hsa_circ_0007385 functioned as an oncogene in CRC in a miR-485-3p/miR-543/miR-337-3p- or MEMO1-dependent manner. Hsa_circ_0007385 promoted CRC progression via modulating miR-485-3p/miR-543/miR-337-3p/MEMO1 axis. Thus, circ-MEMO1 might be a promising therapeutic target for CRC.

circPVT1 promotes silica-induced epithelial-mesenchymal transition by modulating the miR-497-5p/TCF3 axis

Epithelial-mesenchymal transition (EMT) is a vital pathological feature of silica-induced pulmonary fibrosis. However, whether circRNA is involved in the process remains unclear. The present study aimed to investigate the role of circPVT1 in the silica-induced EMT and the underlying mechanisms. We found that an elevated expression of circPVT1 promoted EMT and enhanced the migratory capacity of silica-treated epithelial cells. The isolation of cytoplasmic and nuclear separation assay showed that circPVT1 was predominantly expressed in the cytoplasm. RNA immunoprecipitation assay and RNA pull-down experiment indicated that cytoplasmic-localized circPVT1 was capable of binding to miR-497-5p. Furthermore, we found that miR-497-5p attenuated the silica-induced EMT process by targeting transcription factor 3 (TCF3), an E-cadherin transcriptional repressor, in the silica-treated epithelial cells. Collectively, these results reveal a novel role of the circPVT1/miR-497-5p/TCF3 axis in the silica-induced EMT process in lung epithelial cells. Once validated, this finding may provide a potential theoretical basis for the development of interventions and treatments for pulmonary fibrosis.

Non-coding RNA-Mediated N6-Methyladenosine (m6A) deposition: A pivotal regulator of cancer, impacting key signaling pathways in carcinogenesis and therapy response

The emergence of RNA modifications has recently been considered as critical post-transcriptional regulations which governed gene expression. N6-methyladenosine (m6A) modification is the most abundant type of RNA modification which is mediated by three distinct classes of proteins called m6A writers, readers, and erasers. Accumulating evidence has been made in understanding the role of m6A modification of non-coding RNAs (ncRNAs) in cancer. Importantly, aberrant expression of ncRNAs and m6A regulators has been elucidated in various cancers. As the key role of ncRNAs in regulation of cancer hallmarks is well accepted now, it could be accepted that m6A modification of ncRNAs could affect cancer progression. The present review intended to discuss the latest knowledge and importance of m6A epigenetic regulation of ncRNAs including mircoRNAs, long non-coding RNAs, and circular RNAs, and their interaction in the context of cancer. Moreover, the current insight into the underlying mechanisms of therapy resistance and also immune response and escape mediated by m6A regulators and ncRNAs are discussed.

METTL16 promotes osteosarcoma progression by downregulating VPS33B in an m6 A-dependent manner

N6-methyladenosine (m6 A) is one of the main epitranscriptomic modifications that accelerates the progression of malignant tumors by modifying RNA. Methyltransferase-like 16 (METTL16) is a newly identified methyltransferase that has been found to play an important oncogenic role in a few malignancies; however, its function in osteosarcoma (OS) remains unclear. In this study, METTL16 was found to be upregulated in OS tissues, and associated with poor prognosis in OS patients. Functionally, METTL16 substantially promoted OS cell proliferation, migration, and invasion in vitro and OS growth in vivo. Mechanistically, vacuolar protein sorting protein 33b (VPS33B) was identified as the downstream target of METTL16, which induced m6 A modification of VPS33B and impaired the stability of the VPS33B transcript, thereby degrading VPS33B. In addition, VPS33B was found to be downregulated in OS tissues, VPS33B knockdown markedly attenuated shMETTL16-mediated inhibition on OS progression. Finally, METTL16/VPS33B might facilitate OS progression through PI3K/AKT pathway. In summary, this study revealed an important role for the METTL16-mediated m6 A modification in OS progression, implying it as a promising target for OS treatment.

The N6-methyladenosine modification in pathologic angiogenesis

The vascular system is a vital circulatory network in the human body that plays a critical role in almost all physiological processes. The production of blood vessels in the body is a significant area of interest for researchers seeking to improve their understanding of vascular function and maintain normal vascular operation. However, an excessive or insufficient vascular regeneration process may lead to the development of various ailments such as cancer, eye diseases, and ischemic diseases. Recent preclinical and clinical studies have revealed new molecular targets and principles that may enhance the therapeutic effect of anti-angiogenic strategies. A thorough comprehension of the mechanism responsible for the abnormal vascular growth in disease processes can enable researchers to better target and effectively suppress or treat the disease. N6-methyladenosine (m6A), a common RNA methylation modification method, has emerged as a crucial regulator of various diseases by modulating vascular development. In this review, we will cover how m6A regulates various vascular-related diseases, such as cancer, ocular diseases, neurological diseases, ischemic diseases, emphasizing the mechanism of m6A methylation regulators on angiogenesis during pathological process.

miR-30c affects the pathogenesis of ulcerative colitis by regulating target gene VIP

MicroRNAs play a crucial role in regulating the epithelial barrier and immune response, which are implicated in the pathogenesis of ulcerative colitis (UC). This study aimed to investigate the role and molecular mechanism of miR-30c in the pathogenesis of UC using a dextran sulfate sodium salt (DSS)-induced colitis model, which is similar to ulcerative colitis. Wild-type (WT) and miR-30c knockout (KO) mice were assigned to either control or DSS-treated groups to evaluate the influence of aberrant miR-30c expression on UC pathogenesis. The disease activity index, inflammatory factors, and the extent of pathological and histological damage in colon tissues were analyzed. The effect of miR-30c on vasoactive intestinal peptide (VIP) gene expression was validated through luciferase reporter assay, qRT-PCR, Western blotting, and immunohistochemistry. The results showed that miR-30c KO mice with DSS-induced colitis model showed more severe phenotypes: significantly higher disease activity indices, significant body weight loss, reduced length of the colon of mice, increased number of aberrant crypt structures, reduced mucus secretion, and significant differences in inflammatory factors. These findings suggested that the absence of miR-30c might promote DSS-induced colitis, and the targe-regulatory effect of miR-30c on VIP might play an important role in the development of colitis.

MPDZ is associated with immune infiltration and regulates migration and invasion by switching YAP1 phosphorylation in colorectal cancer

BACKGROUND

Multiple PDZ Domain Crumbs Cell Polarity Complex Component (MPDZ) is involved in a few human cancers. However, the features and potential mechanisms of MPDZ in progression of colorectal cancer (CRC) remains unknown.

METHODS

The prognostic role of MPDZ in CRC was determined by Kaplan-Meier and univariate regression analysis. Enrichment analysis was performed to characterize crucial pathways of MPDZ. Immune infiltration and immunotherapeutic outcome were further evaluated. CCK8, EDU, transwell, and wound healing assay were used to assess the influence of MPDZ on pernicious performance of CRC cells. CD8+ T cells and CRC cells were co-cultured to explore the effect of MPDZ on the tumor microenvironment. qRT-PCR, western blot, immunoprecipitation (IP), and methylated RNA immunoprecipitation (me-RIP) were implemented in seeking for the potential mechanisms of MPDZ in CRC.

RESULTS

CRC patients with elevated MPDZ expression suffered from significantly worse prognosis. Enrichment analysis revealed that MPDZ involved in pathways related to metastasis and cell cycle in CRC. In addition, MPDZ expression were related to several immunoinhibitors and had the ability to predict immunotherapy response. Finally, in vitro assays demonstrated that MPDZ knockdown inhibited migration, invasion and immune evasion of CRC cells. Mechanistically, MPDZ knockdown enhanced YAP1 phosphorylation by increased LATS1 expression. Moreover, m6A-MPDZ mRNA may be recognized and degraded by m6A recognition protein YTHDF2.

CONCLUSIONS

MPDZ was critical for CRC development and could be a promising candidate for the treatment of CRC patients.

CircFSCN1 induces tumor progression and triggers epithelial-mesenchymal transition in bladder cancer through augmentation of MDM2-mediated p53 silencing

BACKGROUND

Compelling evidences indicated that circular RNA (circRNA) was a novel class of non-coding RNA that played critical and distinct roles in various human cancers. Their roles and underlying mechanisms, however, in bladder cancer (BC) remained largely unknown.

METHODS

A novel circRNA derived from oncogene FSCN1, namely circFSCN1, was selected from a microarray analysis. The phenotypic alterations were assessed with functional experiments in vitro and in vivo. RNA immunoprecipitation, RNA pull-down, luciferase reporter assay, and rescue experiments were sequentially proceeded to clarify the interactions among circFSCN1, miR-145-5p, MDM2, and p53.

RESULTS

We observed that the expression of circFSCN1 was elevated in BC cell lines and tissues. Next, we validated the fundamental properties of circFSCN1. In the meanwhile, we noticed that elevated circFSCN1 level, pathological T stage, and tumor grade were identified as independent factors associated with cancer-specific survivals of patients with BC，as determined by univariate and multivariable COX regression analyses. Phenotype studies demonstrated the promoting effects of circFSCN1 on the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of BC cells. Mechanistically, we elucidated that circFSCN1, primarily localized in the cytoplasm, upregulated the expression of MDM2, a well-known inhibitor of p53, by directly binding to miR-145-5p.

CONCLUSIONS

Elevated circFSCN1 induces tumor progression and EMT in BC via enhancing MDM2-mediated silencing of p53 by sponging miR-145-5p. Targeting circFSCN1, a novel identified target, may be conducive in impeding BC progression and providing survival benefits for patients with BC.

Mechanisms of immune checkpoint inhibitors: insights into the regulation of circular RNAS involved in cancer hallmarks

Current treatment strategies for cancer, especially advanced cancer, are limited and unsatisfactory. One of the most substantial advances in cancer therapy, in the last decades, was the discovery of a new layer of immunotherapy approach, immune checkpoint inhibitors (ICIs), which can specifically activate immune cells by targeting immune checkpoints. Immune checkpoints are a type of immunosuppressive molecules expressed on immune cells, which can regulate the degree of immune activation and avoid autoimmune responses. ICIs, such as anti-PD-1/PD-L1 drugs, has shown inspiring efficacy and broad applicability across various cancers. Unfortunately, not all cancer patients benefit remarkably from ICIs, and the overall response rates to ICIs remain relatively low for most cancer types. Moreover, the primary and acquired resistance to ICIs pose serious challenges to the clinical application of cancer immunotherapy. Thus, a deeper understanding of the molecular biological properties and regulatory mechanisms of immune checkpoints is urgently needed to improve clinical options for current therapies. Recently, circular RNAs (circRNAs) have attracted increasing attention, not only due to their involvement in various aspects of cancer hallmarks, but also for their impact on immune checkpoints in shaping the tumor immune microenvironment. In this review, we systematically summarize the current status of immune checkpoints in cancer and the existing regulatory roles of circRNAs on immune checkpoints. Meanwhile, we also aim to settle the issue in an evidence-oriented manner that circRNAs involved in cancer hallmarks regulate the effects and resistance of ICIs by targeting immune checkpoints.

Regulation of Angiogenesis by Non-Coding RNAs in Cancer

Non-coding RNAs, including microRNAs, long non-coding RNAs, and circular RNAs, have been identified as crucial regulators of various biological processes through epigenetic regulation, transcriptional regulation, and post-transcriptional regulation. Growing evidence suggests that dysregulation and activation of non-coding RNAs are closely associated with tumor angiogenesis, a process essential for tumor growth and metastasis and a major contributor to cancer-related mortality. Therefore, understanding the molecular mechanisms underlying tumor angiogenesis is of utmost importance. Numerous studies have documented the involvement of different types of non-coding RNAs in the regulation of angiogenesis. This review provides an overview of how non-coding RNAs regulate tumor angiogenesis. Additionally, we discuss emerging strategies that exploit non-coding RNAs for anti-angiogenic therapy in cancer treatment. Ultimately, this review underscores the crucial role played by non-coding RNAs in tumor angiogenesis and highlights their potential as therapeutic targets for anti-angiogenic interventions against cancer.

Developing a RiskScore Model based on Angiogenesis-related lncRNAs for Colon Adenocarcinoma Prognostic Prediction

AIM

We screened key angiogenesis-related lncRNAs based on colon adenocarcinoma (COAD) to construct a RiskScore model for predicting COAD prognosis and help reveal the pathogenesis of the COAD as well as optimize clinical treatment.

BACKGROUND

Regulatory roles of lncRNAs in tumor progression and prognosis have been confirmed, but few studies have probed into the role of angiogenesis-related lncRNAs in COAD.

OBJECTIVE

To identify key angiogenesis-related lncRNAs and build a RiskScore model to predict the survival probability of COAD patients and help optimize clinical treatment.

METHODS

Sample data were collected from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. The HALLMARK pathway score in the samples was calculated using the single sample gene set enrichment analysis (ssGSEA) method. LncRNAs associated with angiogenesis were filtered by an integrated pipeline algorithm. LncRNA-based subtypes were classified by ConsensusClusterPlus and then compared with other established subtypes. A RiskScore model was created based on univariate Cox, least absolute shrinkage and selection operator (LASSO) regression and stepwise regression analysis. The Kaplan-Meier curve was drawn by applying R package survival. The time-dependent ROC curves were drawn by the timeROC package. Finally, immunotherapy benefits and drug sensitivity were analyzed using tumor immune dysfunction and exclusion (TIDE) software and pRRophetic package.

RESULTS

Pathway analysis showed that the angiogenesis pathway was a risk factor affecting the prognosis of COAD patients. A total of 66 lncRNAs associated with angiogenesis were screened, and three molecular subtypes (S1, S2, S3) were obtained. The prognosis of S1 and S2 was better than that of S3. Compared with the existing subtypes, the S3 subtype was significantly different from the other two subtypes. Immunoassay showed that immune cell scores of the S2 subtype were lower than those of the S1 and S3 subtypes, which also had the highest TIDE scores. We recruited 8 key lncRNAs to develop a RiskScore model. The high RiskScore group with inferior survival and higher TIDE scores was predicted to benefit limitedly from immunotherapy, but it may be more sensitive to chemotherapeutics. A nomogram designed by RiskScore signature and other clinicopathological characteristics shed light on rational predictive power for COAD treatment.

CONCLUSION

We constructed a RiskScore model based on angiogenesis-related lncRNAs, which could serve as potential prognostic predictors for COAD patients and may offer clues for the intervention of anti-angiogenic application. Our results may help evaluate the prognosis of COAD and provide better treatment strategies.

Multilevel Heterogeneity of Colorectal Cancer Liver Metastasis

Colorectal cancer liver metastasis (CRLM) is a highly heterogeneous disease. Therapies that target both primary foci and liver metastasis are severely lacking. Therefore, understanding the features of metastatic tumor cells in the liver is valuable for the overall control of CRLM patients. In this review, we summarize the heterogeneity exhibited in CRLM from five aspects (gene, transcriptome, protein, metabolism, and immunity). In addition to genetic heterogeneity, the other four aspects exhibit significant heterogeneity. Compared to primary CRC, the dysregulation of epithelial-mesenchymal transition (EMT)-related proteins, the enhanced metabolic activity, and the increased infiltration of immunosuppressive cells are detected in CRLM. Preclinical evidence shows that targeting the EMT process or enhancing cellular metabolism may represent a novel approach to increasing the therapeutic efficacy of CRLM.

New understandings of the genetic regulatory relationship between non-coding RNAs and m6A modification

One of the most frequent epigenetic modifications of RNA in eukaryotes is N6 methyladenosine (m6A), which is mostly present in messenger RNAs. Through the influence of several RNA processing stages, m6A modification is a crucial approach for controlling gene expression, especially in cancer progression. It is universally acknowledged that numerous non-coding RNAs (ncRNAs), such as microRNAs, circular RNAs, long non-coding RNAs, and piRNAs, are also significantly affected by m6A modification, and the complex genetic regulatory relationship between m6A and ncRNAs plays a pivotal role in the development of cancer. The connection between m6A modifications and ncRNAs offers an opportunity to explore the oncogene potential regulatory mechanisms and suggests that m6A modifications and ncRNAs could be vital biomarkers for multiple cancers. In this review, we discuss the mechanisms of interaction between m6A methylation and ncRNAs in cancer, and we also summarize diagnostic and prognostic biomarkers for clinical cancer detection. Furthermore, our article includes some methodologies for identifying m6A sites when assessing biomarker potential.

Effects of RNA methylation on Tumor angiogenesis and cancer progression

Tumor angiogenesis plays vital roles in the growth and metastasis of cancer. RNA methylation is one of the most common modifications and is widely observed in eukaryotes and prokaryotes. Accumulating studies have revealed that RNA methylation affects the occurrence and development of various tumors. In recent years, RNA methylation has been shown to play an important role in regulating tumor angiogenesis. In this review, we mainly elucidate the mechanisms and functions of RNA methylation on angiogenesis and progression in several cancers. We then shed light on the role of RNA methylation-associated factors and pathways in tumor angiogenesis. Finally, we describe the role of RNA methylation as potential biomarker and novel therapeutic target.

Cancer metastasis under the magnifying glass of epigenetics and epitranscriptomics

Most of the cancer-associated mortality and morbidity can be attributed to metastasis. The role of epigenetic and epitranscriptomic alterations in cancer origin and progression has been extensively demonstrated during the last years. Both regulations share similar mechanisms driven by DNA or RNA modifiers, namely writers, readers, and erasers; enzymes responsible of respectively introducing, recognizing, or removing the epigenetic or epitranscriptomic modifications. Epigenetic regulation is achieved by DNA methylation, histone modifications, non-coding RNAs, chromatin accessibility, and enhancer reprogramming. In parallel, regulation at RNA level, named epitranscriptomic, is driven by a wide diversity of chemical modifications in mostly all RNA molecules. These two-layer regulatory mechanisms are finely controlled in normal tissue, and dysregulations are associated with every hallmark of human cancer. In this review, we provide an overview of the current state of knowledge regarding epigenetic and epitranscriptomic alterations governing tumor metastasis, and compare pathways regulated at DNA or RNA levels to shed light on a possible epi-crosstalk in cancer metastasis. A deeper understanding on these mechanisms could have important clinical implications for the prevention of advanced malignancies and the management of the disseminated diseases. Additionally, as these epi-alterations can potentially be reversed by small molecules or inhibitors against epi-modifiers, novel therapeutic alternatives could be envisioned.

Decrypting the circular RNAs does a favor for us: Understanding, diagnosing and treating diabetes mellitus and its complications

Circular RNAs (circRNAs), a novel type of single-stranded noncoding RNAs with a covalently closed loop structure, are generated in a circular conformation via non-canonical splicing or back-splicing events. Functionally, circRNAs have been elucidated to soak up microRNAs (miRNAs) and RNA binding proteins (RBPs), serve as protein scaffolds, maintain mRNA stability, and regulate gene transcription and translation. Notably, circRNAs are strongly implicated in the regulation of β-cell functions, insulin resistance, adipocyte functions, inflammation as well as oxidative stress via acting as miRNA sponges and RBP sponges. Basic and clinical studies have demonstrated that aberrant alterations of circRNAs expressions are strongly associated with the initiation and progression of diabetes mellitus (DM) and its complications. Here in this review, we present a summary of the biogenesis, transportation, degradation and functions of circRNAs, and highlight the recent findings on circRNAs and their action mechanisms in DM and its complications. Overall, this review should contribute greatly to our understanding of circRNAs in DM pathogenesis, offering insights into the further perspectives of circRNAs for DM diagnosis and therapy.

Regulation of Cervical Cancer Development by a Novel Circ_0000212/miR-1236-3p/GREM1 ceRNA Crosstalk

Circular RNAs (circRNAs) possess important functions in cervical carcinogenesis by operating as competing endogenous RNAs (ceRNAs). Our preliminary bioinformatics predicted the potential circ_0000212/microRNA (miR)-1236-3p/gremlin 1 (GREM1) ceRNA crosstalk. Thus, we further elucidated whether the novel ceRNA crosstalk can participate in cervical cancer development. Circ_0000212, miR-1236-3p and GREM1 were quantified by real-time quantitative polymerase chain reaction (qPCR) and immunoblotting. 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry, and tube formation assay were performed to assess cell proliferation, apoptosis and tube formation, respectively. Transwell assay was used to detect cell migration and invasion. Mouse xenografts were established to evaluate the role of circ_0000212 in vivo. Dual-luciferase reporter assay was performed to verify the direct relationship between miR-1236-3p and circ_0000212 or GREM1. Circ_0000212 expression was elevated in human cervical cancer. Silencing of endogenous circ_0000212 hindered cancer cell proliferation, motility and invasion and induced apoptosis, as well as diminished the tube formation of human umbilical vein endothelial cells (HUVECs) in vitro. Circ_0000212 silencing also weakened tumor growth in vivo. Mechanistically, circ_0000212 directly bound to miR-1236-3p, and downregulation of miR-1236-3p reversed these effects of circ_0000212 silencing on cell malignant phenotypes and HUVEC tube formation. GREM1 was a direct miR-1236-3p target, and its expression was regulated by circ_0000212 through miR-1236-3p. Moreover, miR-1236-3p upregulation impeded cancer cell malignant phenotypes and HUVEC tube formation by targeting GREM1. Our findings identify a novel ceRNA regulatory network, circ_0000212/miR-1236-3p/GREM1 axis, in cervical carcinogenesis, and provide potential targets that can be explored for therapeutic interventions.

circSLCO1B7 suppresses the malignant progression of hepatocellular carcinoma via the miR-556-3p/DAB2IP axis

Circular RNAs (circRNAs) are noncoding RNAs with a circular colsed structure that play an important role in the occurrence and development of cancers. The functional mechanism of circRNAs as ceRNAs in hepatocellular carcinoma (HCC) and its effect on the invasion and metastasis of HCC need to be further studied. Five pairs of HCC tissues were selected for high-throughput sequencing, and 19 circRNAs with differential expression were obtained. The expression of circSLCO1B7 was obviously downregulated in 50 pairs of tumor tissues and plasma of HCC patients, which was closely related to the TNM stage, lymph node metastasis and tumor size. Cell functional experiments showed that circSLCO1B7 could inhibit cell growth, migration, invasion and promote cell apoptosis. In the regulatory mechanism, circSLCO1B7 sponged miR-556-3p to regulate the expression of the downstream target gene DAB2IP and induced the Epithelial-mesenchymal transition (EMT) progression. Our results indicated that circSLCO1B7 significantly inhibits the metastasis of HCC via the miR-556-3p/DAB2IP axis. Thus, circSLCO1B7 is a good candidate as a therapeutic target.

Circular RNAs-mediated angiogenesis in human cancers

Circular RNAs (circRNAs) as small non-coding RNAs with cell, tissue, or organ-specific expression accomplish a broad array of functions in physiological and pathological processes such as cancer development. Angiogenesis, a complicated multistep process driving a formation of new blood vessels, speeds up tumor progression by supplying nutrients as well as energy. Abnormal expression of circRNAs reported to affect tumor development through impressing angiogenesis. Such impacts are introduced as constant with different tumorigenic features known as "hallmarks of cancer". In addition, deregulated circRNAs show possibilities to prognosis and diagnosis both in the prophecy of prognosis in malignancies and also their prejudice from healthy individuals. In the present review article, we have evaluated the angiogenic impacts and anti-angiogenic managements of circRNAs in human cancers.

Hsa_circRNA_001676 accelerates the proliferation, migration and stemness in colorectal cancer through regulating miR-556-3p/G3BP2 axis

Circular RNAs (circRNAs) play key roles in colorectal cancer (CRC) progression, but little is known about the biological functions of hsa_circRNA_001676 in CRC. Therefore, we explored the potential role of hsa_circRNA_001676 in CRC development. RT-qPCR was performed to determine hsa_circRNA_001676, miR-556-3p and Ras-GTPase-activating SH3 domain-binding-proteins 2 (G3BP2) levels in CRC tissues. Meanwhile, to evaluate the roles of hsa_circRNA_001676, miR-556-3p and G3BP2 on CRC, functional analysis of cell proliferation, migration and stemness were then performed. Our results showed that compared to normal tissues, hsa_circRNA_001676 and G3BP2 level was elevated, but miR-556-3p level was reduced in CRC tissues. Additionally, luciferase reporter results showed that hsa_circRNA_001676 was shown to target miR-556-3p, and G3BP2 was targeted by miR-556-3p. Hsa_circRNA_001676 or G3BP2 overexpression promoted CRC cell proliferation and migration. Conversely, miR-556-3p overexpression suppressed CRC cell proliferation and migration. Moreover, deficiency of hsa_circRNA_001676 or G3BP2 repressed the CRC cell proliferation, migration and stemness. Meanwhile, hsa_circRNA_001676 deficiency obviously reduced tumor growth and stemness in a CRC mouse xenograft model. Furthermore, hsa_circRNA_001676 deficiency notably reduced G3BP2 level, but elevated miR-556-3p level in tumor tissues from tumor-bearing mice. Mechanistically, hsa_circRNA_001676 targeted miR-556-3p to increase G3BP2 level, contributing to the progression of CRC. Collectively, hsa_circRNA_001676 was able to accelerate proliferation, migration and stemness in CRC through regulating miR-556-3p/G3BP2 axis, suggesting that hsa_circRNA_001676 may become a potential therapeutic target in treating CRC.

Roles of circRNAs in regulating the tumor microenvironment

CircRNAs, a type of non-coding RNA widely present in eukaryotic cells, have emerged as a prominent focus in tumor research. However, the functions of most circRNAs remain largely unexplored. Known circRNAs exert their regulatory roles through various mechanisms, including acting as microRNA sponges, binding to RNA-binding proteins, and functioning as transcription factors to modulate protein translation and coding. Tumor growth is not solely driven by gene mutations but also influenced by diverse constituent cells and growth factors within the tumor microenvironment (TME). As crucial regulators within the TME, circRNAs are involved in governing tumor growth and metastasis. This review highlights the role of circRNAs in regulating angiogenesis, matrix remodeling, and immunosuppression within the TME. Additionally, we discuss current research on hypoxia-induced circRNAs production and commensal microorganisms' impact on the TME to elucidate how circRNAs influence tumor growth while emphasizing the significance of modulating the TME.

MicroRNA-30c-5p arrests bladder cancer G2/M phase and suppresses its progression by targeting PRC1-mediated blocking of CDK1/Cyclin B1 axis

BACKGROUND

MicroRNAs (miRNAs) play a critical role in cancer development and progression, the dis-regulation of miR-30c-5p has been observed in various malignant tumors but no research was done in bladder cancer (BCa). This study aims to investigate the downregulation of miR-30c-5p in BCa, and examine its mechanism and prognostic significance.

METHODS

Bioinformatics analyses and clinical specimens were employed to investigate the relationship between miR-30c-5p and clinical information in BCa patients. The expression levels of miR-30c-5p and its target gene were assessed by real-time PCR and western blot. Cell viability was evaluated through clonogenic capacity, CCK-8, and EdU assays. Cell cycle distribution and cell apoptosis were determined by flow cytometry. The anti-tumor effect of miR-30c-5p was also validated in animal models.

RESULTS

The expression levels of miR-30c-5p were significantly decreased in both bladder tumor tissue and BCa cell lines. Low miR-30c-5p expression was found to be correlated with unfavorable TNM stages and poor prognosis. Over-expressing miR-30c-5p was observed to hinder BCa cell growth, migration, and invasion abilities and causing cell cycle arrest. Mechanistically, miR-30c-5p directly binds and suppresses PRC1, thereby blocking the CDK1/Cyclin B1 axis in BCa, thus impairing BCa cell viability and inducing cell cycle arrest at G2/M phase.

CONCLUSION

Down-regulated miR-30c-5p promotes BCa through its target gene PRC1, miR-30c-5p is a favorable biomarker for predicting clinical outcomes in BCa patients and has the potential to be a therapeutic target.

Circular RNAs: Emerging roles and new insights in human cancers

Circular RNAs (circRNAs) are single-stranded, covalently closed RNA molecules formed by mRNA exon back-splicing. Although the circRNA functions remain largely unknown, their currently known biological activities include: acting as competing endogenous RNA (ceRNA) to adsorb microRNA (miRNA), binding proteins, regulating transcription or splicing, and ability to be translated into proteins or peptides. A growing number of studies have found that many circRNAs are abnormally expressed in various cancers, and their dysregulation is highly correlated with tumor progression. Therefore, diagnosis and treatment using circRNAs as biomarkers and therapeutic targets, respectively, has gradually become an attractive research topic. In this review, we introduced the canonical biogenesis pathways and degradation mechanisms of circRNAs. In addition, we examined the biological functions of circRNAs in vivo. Finally, we discussed the current clinical applications and challenges faced by circRNA, and proposed future directions for this promising research field.

Targeting PI3K/Akt signaling in prostate cancer therapy

Urological cancers have obtained much attention in recent years due to their mortality and morbidity. The most common and malignant tumor of urological cancers is prostate cancer that imposes high socioeconomic costs on public life and androgen-deprivation therapy, surgery, and combination of chemotherapy and radiotherapy are employed in its treatment. PI3K/Akt signaling is an oncogenic pathway responsible for migration, proliferation and drug resistance in various cancers. In the present review, the role of PI3K/Akt signaling in prostate cancer progression is highlighted. The activation of PI3K/Akt signaling occurs in prostate cancer, while PTEN as inhibitor of PI3K/Akt shows down-regulation. Stimulation of PI3K/Akt signaling promotes survival of prostate tumor cells and prevents apoptosis. The cell cycle progression and proliferation rate of prostate tumor cells increase by PI3K/Akt signaling induction. PI3K/Akt signaling stimulates EMT and enhances metastasis of prostate tumor cells. Silencing PI3K/Akt signaling impairs growth and metastasis of prostate tumor cells. Activation of PI3K/Akt signaling mediates drug resistance and reduces radio-sensitivity of prostate tumor cells. Anti-tumor compounds suppress PI3K/Akt signaling in impairing prostate tumor progression. Furthermore, upstream regulators such as miRNAs, lncRNAs and circRNAs regulate PI3K/Akt signaling and it has clinical implications for prostate cancer patients.

Circ-MALAT1 accelerates cell proliferation and epithelial mesenchymal transformation of colorectal cancer through regulating miR-506-3p/KAT6B axis

Colorectal cancer (CRC) is a prevalent malignant tumor of the digestive tract. Circular RNAs may play important roles in the progression of CRC. In this study, we investigated the roles and mechanisms of action of circ-MALAT1 in CRC. Gene expression and protein abundance were determined using qRT-PCR and western blot, respectively. Cell proliferation and migration were assessed by MTT, clone formation, and wound-healing assays. The interactions among the long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (circ-MALAT1), miR-506-3p, and lysine acetyltransferase 6B (KAT6B) were predicted using the StarBase software and confirmed by the luciferase activity assay. Circ-MALAT1 and KAT6B were upregulated, while miR-506-3p was downregulated in CRC cells. We validated that knocking down of circ-MALAT1 suppressed proliferation, migration, and epithelial-mesenchymal transition (EMT) of CRC cells, and these effects were abolished by miR-506-3p downregulation or KAT6B sufficiency. Our study suggests that circ-MALAT1 could sponge miR-506-3p to regulate the expression of KAT6B. Moreover, KAT6B sufficiency could neutralize miR-506-3p-dependent growth arrest, migration, and EMT. Circ-MALAT1 promotes cell proliferation, migration, and EMT of CRC cells via the miR-506-3p/KAT6B axis, thereby acting as a novel potential therapeutic target for the treatment of colorectal cancer.

METTL9 derived circular RNA circ-METTL9 sponges miR-551b-5p to accelerate colorectal cancer progression by upregulating CDK6

Circular RNAs (circRNAs) have been accepted to play key roles in the development and progression of mutiple cancers including colorectal cancer (CRC). Here, we identified circ-METTL9, derived from 2 to 4 exons of METTL9 gene, may promote CRC progression by accelerating cell cycle progression. However, the role and mechanism of circ-METTL9 in CRC remains unclear. Based on our data, the expression of circ-METTL9 was significantly upregulated in CRC tissues and markedly increased in advanced tumors in CRC patients. Functional experiments demonstrated that circ-METTL9 overexpression promoted CRC cells proliferation and migration in vitro, and simultaneously enhanced CRC tumor growth and metastasis in vivo. Mechanistically, RNA immunoprecipitation (RIP) assays proved that circ-METTL9 might be a miRNA sponge, and RNA pulldown assays showed the interaction between circ-METTL9 and miR-551b-5p. Notably, cyclin-dependent kinase 6 (CDK6), a key regulator in cell cycle, is a conserved downstream target of miR-551b-5p. Taken together, our findings highlight a novel oncogenic function of circ-METTL9 in CRC progression via circ-METTL9/miR-551b-5p/CDK6 axis, which may serve as a prognostic biomarker and therapeutic target for CRC patients.

WTAP activates MAPK signaling through m6A methylation in VEGFA mRNA-mediated by YTHDC1 to promote colorectal cancer development

N6-methyladenosine modification, especially Wilms tumor 1-associated protein (WTAP), is reportedly associated with a variety of cancers, including colorectal cancer (CRC). Angiogenesis also plays an important role in the occurrence and development of CRC. However, only a few studies have reported the biological mechanisms underlying this connection. Therefore, tissue microarray and public database were used to explore WTAP levels in CRC. Then, WTAP was down-regulated and over-expressed, respectively. CCK8, EdU, colony formation, and transwell experiments were performed to study the role of WTAP in CRC. Combined RNA sequencing and m6A RNA immunoprecipitation (MeRIP) sequencing, we found downstream molecules VEGFA. Moreover, a tube formation assay was executed for tumor angiogenesis. Finally, a subcutaneous tumorigenesis assay in nude mice was used to examine the tumor-promoting effect of WTAP in vivo. In the present study, WTAP was significantly upregulated in CRC cells and patients with CRC. Moreover, higher WTAP expression was observed in the TCGA and CPATC databases in CRC tissues. WTAP over-expression exacerbates cell proliferation, migration, invasion, and angiogenesis. Conversely, WTAP knockdown inhibited the malignant biological behavior of CRC cells. Mechanistically, WTAP positively regulated VEGFA, as identified using RNA sequencing and MeRIP sequencing. Moreover, we identified YTHDC1 as a downstream effector of the YTHDC1-VEGFA axis in CRC. Furthermore, increased WTAP expression activated the MAPK signaling pathway, which led to enhanced angiogenesis. In conclusion, our study revealed that the WTAP/YTHDC1/VEGFA axis promotes CRC development, especially angiogenesis, suggesting that it may act as a potential biomarker of CRC.

Crosstalk between m6A and coding/non-coding RNA in cancer and detection methods of m6A modification residues

N6-methyladenosine (m6A) is one of the most common and well-known internal RNA modifications that occur on mRNAs or ncRNAs. It affects various aspects of RNA metabolism, including splicing, stability, translocation, and translation. An abundance of evidence demonstrates that m6A plays a crucial role in various pathological and biological processes, especially in tumorigenesis and tumor progression. In this article, we introduce the potential functions of m6A regulators, including "writers" that install m6A marks, "erasers" that demethylate m6A, and "readers" that determine the fate of m6A-modified targets. We have conducted a review on the molecular functions of m6A, focusing on both coding and noncoding RNAs. Additionally, we have compiled an overview of the effects noncoding RNAs have on m6A regulators and explored the dual roles of m6A in the development and advancement of cancer. Our review also includes a detailed summary of the most advanced databases for m6A, state-of-the-art experimental and sequencing detection methods, and machine learning-based computational predictors for identifying m6A sites.

CircRNAs in colorectal cancer: potential biomarkers and therapeutic targets

Globally, colorectal cancer (CRC) is the third most prevalent cancer and the second leading cause of cancer-related deaths. Circular RNAs (circRNAs) are single-stranded RNA with covalently closed-loop structures and are highly stable, conserved, and abundantly expressed in various organs and tissues. Recent research found abnormal circRNA expression in CRC patients' blood/serum, cells, CRC tissues, and exosomes. Furthermore, mounting data demonstrated that circRNAs are crucial to the development of CRC. CircRNAs have been shown to exert biological functions by acting as microRNA sponges, RNA-binding protein sponges, regulators of gene splicing and transcription, and protein/peptide translators. These characteristics make circRNAs potential markers for CRC diagnosis and prognosis, potential therapeutic targets, and circRNA-based therapies. However, further studies are still necessary to improve the understanding of the roles and biological mechanisms of circRNAs in the development of CRC. In this review, up-to-date research on the role of circRNAs in CRC was examined, focusing on their potential application in CRC diagnosis and targeted therapy, which would advance the knowledge of the functions of circRNAs in the development and progression of CRC.

MiR-24-3p regulates the differentiation of adipose-derived stem cells toward pericytes and promotes fat grafting vascularization

Adipose-derived stem cells (ADSCs) enhance fat graft survival by promoting neovascularization. The mechanism that promotes ADSCs differentiation toward pericytes was not known. We treated ADSCs with conditional medium (CM) from endothelial cells (ECs) or human recombinant transforming growth factor β (TGF-β) to induce differentiation into pericytes. Pericytes markers, including platelet-derived growth factor receptor β (PDGFRβ), alpha-smooth muscle actin (α-SMA), and desmin, were examined. Pericytes differentiation markers, migration, and their association with ECs were examined in ADSCs transfected with miR-24-3p mimics and inhibitors. Bioinformatics target prediction platforms and luciferase assays were used to investigate whether PDGFRβ was directly targeted by miR-24-3p. In vivo, fat mixed with ADSCs transfected with miR-24-3p mimics or inhibitors was implanted subcutaneously on the lower back region of nude mice. Fat grafts were harvested and analyzed at 2, 4, 6, and 8 weeks. Results showed that endogenous TGF-β derived from CM from EC or human recombinant TGF-β promoted migration, association with ECs, and induced expression of pericyte markers (PDGFRβ, α-SMA, Desmin) in ADSCs. MiR-24-3p directly targeted PDGFRβ in ADSCs by lucifer reporter assays. Inhibition of miR-24-3p promoted pericytes differentiation, migration, and association with ECs in ADSCs. Inhibition of miR-24-3p in ADSCs promoted survival, integrity, adipocyte viability, vascularization, pericytes association with ECs, and reduced fibrosis, whereas overexpression of miR-24-3p in ADSCs yielded the opposite results. Collectively, TGF-β released by ECs induced ADSCs differentiation toward pericytes through miR-24-3p. Downregulation of miR-24-3p in ADSCs induced survival, integrity, adipocyte viability, vascularization, pericytes association with ECs, and reduced fibrosis after fat grafting.

The significance of N6-methyladenosine-modified non-coding RNAs in different disorders

N6-methyladenosine (m6A) is the most widespread endogenous modification affecting the expression of eukaryotic mRNA transcripts. Recent studies have shown that the m6A marks within non-coding RNAs can affect their functions and expression in a manner similar to that of mRNA-coding genes. Since non-coding RNAs are involved in the pathophysiology of several disorders, identification of the role of m6A marks in the regulation of expression of non-coding RNAs can open a new era for identifying underlying mechanisms of several disorders and designing novel therapeutic modalities for a variety of disorders, particularly cancers. Moreover, a number of non-coding RNAs can affect m6A levels. In the current review, we discuss the impacts of m6A marks on the expression of non-coding RNAs in the context of different disorders, such as bone, gastrointestinal, neurologic, renal, pulmonary, hepatic and other disorders.

The circCDK17/miR-122-5p/ASF1B axis regulates the progression of cervical cancer

BACKGROUND

Cervical cancer (CC) ranks fourth in terms of incidence and fourth in mortality overall in women worldwide. Circular RNAs (circRNAs) have been shown to be involved in the development of CC. However, the function of circRNA cyclin dependent kinase 17 (circCDK17, hsa_circ_0002762) in CC pathogenesis has not been studied.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of related genes. MTT, thymidine analog 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, transwell and wound-healing assays were designed to analyze cell proliferation, cell cycle progression, migration and invasion, respectively. Western blot was utilized to examine the protein levels of Cyclin D1, E-cadherin and Vimentin. The relationship between miR-122-5p and circCDK17 or ASF1B was verified by dual-luciferase reporter assay. The xenograft model was established to study the role of circCDK17 in vivo.

RESULTS

CircCDK17 and anti-silencing function 1B histone chaperone (ASF1B) were highly expressed in CC tissues and cells. Silencing circCDK17 reduced the proliferation, migration and invasion of CC cells. MiR-122-5p was a target of circCDK17. Silencing circCDK17 inhibited the malignant behaviors of CC cells by releasing miR-122-5p. Moreover, ASF1B was a target of miR-122-5p. Overexpression of ASF1B partially restored the inhibitory effects of circCDK17 silencing on cell proliferation, migration and invasion. Animal experiments confirmed the anti-tumor effect of circCDK17 knockdown in vivo.

CONCLUSION

Our study demonstrates that circCDK17 regulates the expression of ASF1B by miR-122-5p competition and thus promotes the development of CC, providing a novel targeted therapy for CC.

Up-regulated Circular RNAs in Colorectal Cancer: New Entities for Therapy and Tools for Identification of Therapeutic Targets

Patients with disseminated colorectal cancer have a dismal prognosis with a 5-year survival rate of only 13%. In order to identify new treatment modalities and new targets, we searched the literature for up-regulated circular RNAs in colorectal cancer which induce tumor growth in corresponding preclinical in vivo models. We identified nine circular RNAs that mediate resistance against chemotherapeutic agents, seven that up-regulate transmembrane receptors, five that induce secreted factors, nine that activate signaling components, five which up-regulate enzymes, six which activate actin-related proteins, six which induce transcription factors and two which up-regulate the MUSASHI family of RNA binding proteins. All of the circular RNAs discussed in this paper induce the corresponding targets by sponging microRNAs (miRs) and can be inhibited by RNAi or shRNA in vitro and in xenograft models. We have focused on circular RNAs with demonstrated activity in preclinical in vivo models because the latter is an important milestone in drug development. All circular RNAs with in vitro activity only data are not referenced in this review. The translational impact of inhibition of these circular RNAs and of the identified targets for treatment of colorectal cancer (CRC) are discussed.

The roles of N6-methyladenosine and its target regulatory noncoding RNAs in tumors: classification, mechanisms, and potential therapeutic implications

N6-methyladenosine (m6A) is one of the epigenetic modifications of RNA. The addition of this chemical mark to RNA molecules regulates gene expression by affecting the fate of the RNA molecules. This posttranscriptional RNA modification is reversible and regulated by methyltransferase "writers" and demethylase "erasers". The fate of m6A-modified RNAs depends on the function of different "readers" that recognize and bind to them. Research on m6A methylation modification has recently increased due to its important role in regulating cancer progression. Noncoding RNAs (ncRNAs) are a class of RNA molecules that are transcribed from the genome but whose roles have been overlooked due to their lack of well-defined potential for translation into proteins or peptides. However, this misconception has now been completely overturned. ncRNAs regulate various diseases, especially tumors, and it has been confirmed that they play either tumor-promoting or tumor-suppressing roles in almost all types of tumors. In this review, we discuss the m6A modification of different types of ncRNA and summarize the mechanisms involved. Finally, we discuss the progress of research on clinical treatment and discuss the important significance of the m6A modification of ncRNAs in the clinical treatment of tumors.

CircSMAD2 accelerates endometrial cancer cell proliferation and metastasis by regulating the miR-1277-5p/MFGE8 axis

OBJECTIVE

Endometrial cancer (EC) is a common gynecological malignant tumor. CircRNAs play crucial roles in cancer progression and metastasis. However, the biological functions of circRNAs in EC remain largely unknown.

METHODS

CircSMAD2, miR-1277-5p, MFGE8 and relative maker protein expression in EC tissues or cell lines were analyzed by quantitative real-time polymerase chain reaction and Western blot. In vitro and in vivo functional assays, including EDU, CCK8, colony formation, transwell, tube formation and tumor xenograft assays, were conduct to explore the effects of circSMAD2 on EC. Mechanism assays were conducted to confirm the binding between miR-1277-5p and circSMAD2 or MFGE8 expression.

RESULTS

Upregulation of circSMAD2 was uncovered in both EC tissues and cell lines. Functionally, silencing of circSMAD2 apparently inhibited the proliferation, migration, invasion and angiogenesis of EC cell lines in vitro. Mechanistically, circSMAD2 sponged miR-1277-5p to upregulate MFGE8 expression. The decrease of miR-1277-5p and increase of MFGE8 were observed both in EC tissues and cell lines. Then MFGE8 knockdown or miR-1277-5p upregulation suppressed EC cell oncogenic biological behavior. Rescue experiments showed that miR-1277-5p mimics countervailed the anticancer effects of circSMAD2 silencing on EC. Besides that, MFGE8 overexpression also attenuated the inhibitory action of miR-1277-5p mimic in EC. Moreover, knockdown of circSMAD2 inhibited EC growth in vivo.

CONCLUSION

CircSMAD2 functions as an oncogene in promoting the progression of EC through miR-1277-5p/MFGE8 axis.

Transcriptomic and Proteomic Analyses of Celery Cytoplasmic Male Sterile Line and Its Maintainer Line

Male sterility is a common phenomenon in the plant kingdom and based on the organelles harboring the male-sterility genes, it can be classified into the genic male sterility (GMS) and the cytoplasmic male sterility (CMS). In every generation, CMS can generate 100% male-sterile population, which is very important for the breeders to take advantage of the heterosis and for the seed producers to guarantee the seed purity. Celery is a cross-pollinated plant with the compound umbel type of inflorescence which carries hundreds of small flowers. These characteristics make CMS the only option to produce the commercial hybrid celery seeds. In this study, transcriptomic and proteomic analyses were performed to identify genes and proteins that are associated with celery CMS. A total of 1255 differentially expressed genes (DEGs) and 89 differentially expressed proteins (DEPs) were identified between the CMS and its maintainer line, then 25 genes were found to differentially expressed at both the transcript and protein levels. Ten DEGs involved in the fleece layer and outer pollen wall development were identified by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, most of which were down-regulated in the sterile line W99A. These DEGs and DEPs were mainly enriched in the pathways of "phenylpropanoid/sporopollenin synthesis/metabolism", "energy metabolism", "redox enzyme activity" and "redox processes". Results obtained in this study laid a foundation for the future investigation of mechanisms of pollen development as well as the reasons for the CMS in celery.

Overview of m6A and circRNAs in human cancers

N⁶-methyladenosine (m⁶A), the richest post-transcriptional modification of RNA in eukaryotic cells, is dynamically installed/uninstalled by the RNA methylase complex ("writer") and demethylase ("eraser") and recognized by the m⁶A-binding protein ("reader"). M⁶A modification on RNA metabolism involves maturation, nuclear export, translation and splicing, thereby playing a critical role in cellular pathophysiology and disease processes. Circular RNAs (circRNAs) are a class of non-coding RNAs with a covalently closed loop structure. Due to its conserved and stable properties, circRNAs could participate in physiological and pathological processes through unique pathways. Despite the recent discovery of m⁶A and circRNAs remains in the initial stage, research has shown that m⁶A modifications are widespread in circRNAs and regulates circRNA metabolism, including biogenesis, cell localization, translation, and degradation. In this review, we describe the functional crosstalk between m⁶A and circRNAs, and illustrate their roles in cancer development. Moreover, we discuss the potential mechanisms and future research directions of m⁶A modification and circRNAs.