Exosome-derived circCCAR1 promotes CD8 + T-cell dysfunction and anti-PD1 resistance in hepatocellular carcinoma

Biological functions and molecular mechanisms of exosome-derived circular RNAs and their clinical implications in digestive malignancies: the vintage in the bottle

BACKGROUND

Circular RNAs (circRNAs) are identified as a novel family of endogenous RNA molecules through 'back-splicing' and covalently linked at the 5' and 3' ends. Emerging researches have demonstrated circRNAs are stable and abundant in exosomes called exosomal circRNAs (exo-circRNA).

MATERIALS AND METHODS

We searched recent studies and references to summary the research progress of exosomal circRNA.

RESULTS

Recent studies have revealed that exosome-derived circRNAs including exo-CDR1as, exo-circRanGAP1, exo-circIAR play vital roles in cell proliferation and apoptosis, epithelial mesenchymal transition, invasion and metastasis, angiogenesis, immune evasion, cellular crosstalk, cancer cachexia through a variety of biological mechanisms, such as serving as microRNA sponges, interacting with RNA binding proteins, regulating gene transcription, N6-Methyladenosine modification and so on. Due to their characteristics of origin, structure, properties and biological functions, exo-circRNAs are expected to apply in precious diagnosis and prognostic indicators, improving drug and radiation resistance and sensitivity, becoming biological therapeutic targets.

CONCLUSION

We summarize the update of digestive malignancies associated exo-circRNAs in biogenesis, biological functions, molecular mechanisms, clinical implications, potential applications and experimental technique in order to effectively promote transformation and application in the future.

The landscape of circRNAs in gliomas temozolomide resistance: Insights into molecular pathways

As the deadliest type of primary brain tumor, gliomas represent a significant worldwide health concern. Circular RNA (circRNA), a unique non-coding RNA molecule, seems to be one of the most alluring target molecules involved in the pathophysiology of many kinds of cancers. CircRNAs have been identified as prospective targets and biomarkers for the diagnosis and treatment of numerous disorders, particularly malignancies. Recent research has established a clinical link between temozolomide (TMZ) resistance and certain circRNA dysregulations in glioma tumors. CircRNAs may play a therapeutic role in controlling or overcoming TMZ resistance in gliomas and may provide guidance for a novel kind of individualized glioma therapy. To address the biological characteristics of circRNAs and their potential to induce resistance to TMZ, this review has highlighted and summarized the possible roles that circRNAs may play in molecular pathways of drug resistance, including the Ras/Raf/ERK PI3K/Akt signaling pathway and metabolic processes in gliomas.

Mechanism research of non-coding RNA in immune checkpoint inhibitors therapy

Immune checkpoint inhibitor (ICI) therapies for tumors of different systems have attained significant achievements and have changed the current situation of tumor treatment due to their therapeutic characteristics of high specificity and low side effects. The immune checkpoint Programmed death 1/Programmed cell death-Ligand 1 (PD-1/PD-L1) axis exerts a vital role in the immune escape of tumor cells. As a result, it has become a key target for tumor immunotherapy. Therefore, to perfect research into potential regulatory factors for the PD-1/PD-L1 axis, in order to understand and illustrate tumor ICI therapy mechanisms, is a significant goal. Moreover, ncRNA has been verified to regulate the PD-1/PD-L1 axis in the tumor immune microenvironment to regulate tumor genesis and development. ncRNAs can improve or decrease the efficacy of ICI therapy by modulating PD-L1 expression. This review aimed to investigate the mechanisms of action of ncRNA in regulating the PD-1/PD-L1 axis in ICI therapy, to provide more efficient immunotherapy for tumors of different systems.

The interaction between m6A modification and noncoding RNA in tumor microenvironment on cancer progression

Cancer development is thought to be closely related to aberrant epigenetic regulation, aberrant expression of specific non-coding RNAs (ncRNAs), and tumor microenvironment (TME). The m6A methylation is one of the most abundant RNA modifications found in eukaryotes, and it can determine the fate of RNA at the post-transcriptional level through a variety of mechanisms, which affects important biological processes in the organism. The m6A methylation modification is involved in RNA processing, regulation of RNA nuclear export or localisation, RNA degradation and RNA translation. This process affects the function of mRNAs and ncRNAs, thereby influencing the biological processes of cancer cells. TME accelerates and promotes cancer generation and progression during tumor development. The m6A methylation interacting with ncRNAs is closely linked to TME formation. Mutual regulation and interactions between m6A methylation and ncRNAs in TME create complex networks and mediate the progression of various cancers. In this review, we will focus on the interactions between m6A modifications and ncRNAs in TME, summarising the molecular mechanisms by which m6A interacts with ncRNAs to affect TME and their roles in the development of different cancers. This work will help to deepen our understanding of tumourigenesis and further explore new targets for cancer therapy.

m6A-modified exosome-derived circHIF1α binding to KH domain of IGF2BP3 mediates DNA damage and arrests G1/S transition phase to resists bacterial infection in bacteremia

BACKGROUND

Animal and human health are seriously threatened by bacterial infections, which can lead to bacteremia and extremely high rates of morbidity and mortality. Recently, there have been reports indicating the involvement of exosomal circular RNAs (circRNAs) in a range of human disorders and tumor types. However, the role of exosomal circRNAs in bacterial infection remains elusive.

METHODS

We extracted and identified exosomes from the culture medium of PIEC cells infected with or without Glaesserella parasuis. RNA sequencing analysis was performed on the exosomes to screen and identify circRNAs (circHIF1α) associated with Glaesserella parasuis infection. PIEC cells were infected with Staphylococcus aureus or Streptococcus suis 2 to further determine whether exosome-derived circHIF1α was the crucial circHIF1α associated with bacterial infections. The transmission process of exosomes and their circHIF1α between cells was clarified via exosome tracing and co-culture assay. Moreover, the mechanism of circHIF1α being packaged into exosomes was explored, and the effects of exosomes and their circHIF1α on cell proliferation, DNA damage and cell cycle were analyzed. In addition, the binding mode and site of interacting proteins with circHIF1α were further determined. In vivo and in vitro, the role of exosomes and their circHIF1α in host resistance to bacterial infection was confirmed.

RESULTS

We first discovered a new circHIF1α that was very stable and detectable, encapsulated into exosomes by hnRNPA2B1, and whose expression in exosomes of bacterially infected PIEC cells significantly decreased. Additionally, exosomal circHIF1α reduced bacterial infection both in vitro and in vivo and suppressed the growth of reception cells. Mechanistically, the circHIF1α interacted with the KH domain of IGF2BP3 in an m6A-modified manner, which mediated DNA damage to arrest the cells at the G1/S phase through the interaction between the regulator of Chromosome Condensation 2 (RCC2) and γ-H2AX protein. Exosomal circHIF1α is a unique therapeutic target for bacterial infection since this work highlights its critical function in fighting bacterial infection.

Insights about exosomal circular RNAs as novel biomarkers and therapeutic targets for hepatocellular carcinoma

One of the most prevalent pathological types of Primary Liver Cancer (PLC) is the Hepatocellular Carcinoma (HCC) poses a global health issue. The high recurrence and metastasis rate of HCC, coupled with a low 5-year survival rate, result in a bleak prognosis. Exosomes, small extracellular vesicles released by various cells, contain diverse non-coding RNA molecules, including circular RNAs (circRNAs), which play a significant role in intercellular communication and can impact HCC progression. Studies have revealed the potential clinical applications of exosomal circRNAs as biomarkers and therapeutic targets for HCC. These circRNAs can be transferred via exosomes to nearby non-cancerous cells, thereby regulating HCC progression and influencing malignant phenotypes, such as cell proliferation, invasion, metastasis, and drug resistance. This review provides a comprehensive overview of the identified exosomal circRNAs, highlighting their potential as non-invasive biomarkers for HCC, and suggesting new perspectives for HCC diagnosis and treatment. The circRNA from exosomal organelles promotes metastasis and immune scape because of their unique chirality which is different from the Biomolecular Homochirality.

Tumor Microenvironment-Derived Exosomes: A Double-Edged Sword for Advanced T Cell-Based Immunotherapy

The tumor microenvironment (TME) plays a crucial role in cancer progression and immune evasion, partially mediated by the activity of the TME-derived exosomes. These extracellular vesicles are pivotal in shaping immune responses through the transfer of proteins, lipids, and nucleic acids between cells, facilitating a complex interplay that promotes tumor growth and metastasis. This review delves into the dual roles of exosomes in the TME, highlighting both their immunosuppressive functions and their emerging therapeutic potential. Exosomes can inhibit T cell function and promote tumor immune escape by carrying immune-modulatory molecules, such as PD-L1, yet they also hold promise for cancer therapy as vehicles for delivering tumor antigens and costimulatory signals. Additionally, the review discusses the intricate crosstalk mediated by exosomes among various cell types within the TME, influencing both cancer progression and responses to immunotherapies. Moreover, this highlights current challenges and future directions. Collectively, elucidating the detailed mechanisms by which TME-derived exosomes mediate T cell function offers a promising avenue for revolutionizing cancer treatment. Understanding these interactions allows for the development of targeted therapies that manipulate exosomal pathways to enhance the immune system's response to tumors.

Global research trends in the tumor microenvironment of hepatocellular carcinoma: insights based on bibliometric analysis

Objective

This study aimed to use visual mapping and bibliometric analysis to summarize valuable information on the tumor microenvironment (TME)-related research on hepatocellular carcinoma (HCC) in the past 20 years and to identify the research hotspots and trends in this field.

Methods

We screened all of the relevant literature on the TME of HCC in the Web of Science database from 2003 to 2023 and analysed the research hotspots and trends in this field via VOSviewer and CiteSpace.

Results

A total of 2,157 English studies were collected. According to the prediction, the number of papers that were published in the past three years will be approximately 1,394, accounting for 64.63%. China published the most papers (n=1,525) and had the highest total number of citations (n=32,253). Frontiers In Immunology published the most articles on the TME of HCC (n=75), whereas, Hepatology was the journal with the highest total number of citations (n=4,104) and average number of citations (n=91). The four clusters containing keywords such as "cancer-associated fibroblasts", "hepatic stellate cells", "immune cells", "immunotherapy", "combination therapy", "landscape", "immune infiltration", and "heterogeneity" are currently hot research topics in this field. The keywords "cell death", "ferroptosis", "biomarkers", and "prognostic features" have emerged relatively recently, and these research directions are becoming increasingly popular.

Conclusions

We identified four key areas of focus in the study of the TME in HCC: the main components and roles in the TME, immunotherapy, combination therapy, and the microenvironmental landscape. Moreover, the result of our study indicate that effect of ferroptosis on the TME in HCC may become a future research trend.

RNAs in tumour-derived extracellular vesicles and their significance in the tumour microenvironment

Small extracellular vesicles (sEVs) secreted by various types of cells serve as crucial mediators of intercellular communication within the complex tumour microenvironment (TME). Tumour-derived small extracellular vesicles (TDEs) are massively produced and released by tumour cells, recapitulating the specificity of their cell of origin. TDEs encapsulate a variety of RNA species, especially messenger RNAs, microRNAs, long non-coding RNAs, and circular RNAs, which release to the TME plays multifaced roles in cancer progression through mediating cell proliferation, invasion, angiogenesis, and immune evasion. sEVs act as natural delivery vehicles of RNAs and can serve as useful targets for cancer therapy. This review article provides an overview of recent studies on TDEs and their RNA cargo, with emphasis on the role of these RNAs in carcinogenesis.

Downregulation of the m6A reader YTHDC2 upregulates exosome content in lung adenocarcinoma via inhibiting IFIT and OAS family members

N6-Methyladenosine (m6A) is the most prevalent mRNA modification. Its biological function primarily relies on its "Reader" protein, such as YTHDC2. Previous studies have shown that YTHDC2 downregulation is a procarcinogenic phenomenon in lung adenocarcinoma (LUAD). However, further investigation is needed to understand the molecular mechanisms of downstream genes and the associated biological phenomena following YTHDC2 downregulation. Here, we found that YTHDC2 knockout upregulated exosome content in LUAD. Following YTHDC2 knockout, the mRNA levels of OAS family members (OASs) and IFIT family members (IFITs) also decreased; and inhibition of OASs and IFITs could promote exosome content. Several m6A modification sites on the NT domain of OASs and the TPR12 domain of IFITs were found to increase the stability of OASs and IFITs in a YTHDC2-dependent manner. OASs and IFITs affected exosome content through target genes including RAB5A, RAB7, and RAB11A, and three arginine (R) amino acids on IFITs were critical for combination IFITs with targeted RAB mRNAs and subsequent degradation. Simultaneously, OASs degraded targeted RABs through RNAseL. Additionally, mutual bindings between OASs and IFITs were critical for their target gene degradation. Collectively, the above findings might provide a theoretical basis for the treatment of LUAD patients with low YTHDC2 expression.

Advances in exosomes utilization for clinical applications in cancer

Exosomes are regarded as having transformative potential for clinical applications. Exosome-based liquid biopsies offer a noninvasive method for early cancer detection and real-time disease monitoring. Clinical trials are underway to validate the efficacy of exosomal biomarkers for enhancing diagnostic accuracy and predicting treatment responses. Additionally, engineered exosomes are being developed as targeted drug delivery systems that can navigate the bloodstream to deliver therapeutic agents to tumor sites, thus enhancing treatment efficacy while minimizing systemic toxicity. Exosomes also exhibit immunomodulatory properties, which are being harnessed to boost antitumor immune responses. In this review, we detail the latest advances in clinical trials and research studies, underscoring the potential of exosomes to revolutionize cancer care.

Enhanced efficacy of combined VEGFR peptide-drug conjugate and anti-PD-1 antibody in treating hepatocellular carcinoma

This study aimed to design a VEGFR-targeting peptide-drug conjugate with the ability to decrease tumor burden and suppress tumor angiogenesis, and to further evaluate the therapeutic effect of anti-PD-1 antibody in HCC therapy. A VEGFR-targeting peptide VEGF125 - 136 (QR) was conjugated with a lytic peptide (KLU) to form a peptide-drug conjugate QR-KLU. And the efficacy of QR-KLU in combination with anti-PD-1 antibody for HCC therapy in vivo and in vitro were evaluated. QR-KLU inhibited the proliferation and migration of mouse HCC cell line (Hepa1-6) cells under normoxic and hypoxic conditions in a dose-dependent manner. In the subcutaneous Hepa1-6 tumor model, QR-KLU combined with the anti-PD-1 antibody substantially inhibited tumor growth, promoted tumor necrosis, and prolonged the survival time of tumor-bearing mice. QR-KLU substantially inhibited hypoxia-induced expression of VEGF, promoted tumor vascular normalization, and increased cluster of differentiation 8+ (CD8+) T cell infiltration in the tumor. In addition, QR-KLU and anti-PD-1 antibody demonstrated a strong synergistic effect in promoting the activation of intratumoral CD8+ T cells, reducing the expression of immune-inhibitory factors, and increasing the expression of immune-stimulatory factors. This study proposed a novel approach for enhancing the efficacy of anti-PD-1 antibody using a VEGFR-targeting peptide-drug conjugate in HCC therapy.

Extracellular vesicles in the HCC microenvironment: Implications for therapy and biomarkers

Hepatocellular carcinoma (HCC) stands as the sixth most prevalent cancer and the third leading cause of cancer mortality globally. Despite surgical resection being the preferred approach for early-stage HCC, most patients are diagnosed at intermediate to advanced stages, limiting treatment options to chemotherapy and immunotherapy, which often yield poor outcomes. Extracellular vesicles (EVs), minute lipid-bilayered particles released by diverse cells under various physiological and pathological conditions, are crucial for mediating communication between cells. Mounting evidence indicates that EVs sourced from different cells can profoundly influence the HCC tumor microenvironment (TME), thereby affecting the progression of HCC. Given their immunogenicity and liver-targeting properties, these EVs not only hold promise for HCC treatment but also provide avenues for advancing early diagnostic methods and assessing prognosis. This review not only describes the function of EVs within the HCC tumor microenvironment but also analyzes their therapeutic advantages and explores their significance in various therapeutic approaches for HCC, including chemotherapy, immunotherapy, combination therapy, and their role as innovative drug delivery carriers. Furthermore, it highlights the potential of EVs as biomarkers for the diagnosis and prognosis of HCC.

Dual role of exosomal circCMTM3 derived from GSCs in impeding degradation and promoting phosphorylation of STAT5A to facilitate vasculogenic mimicry formation in glioblastoma

Background: Glioblastoma (GBM) is characterized by abundant neovascularization as an essential hallmark. Vasculogenic mimicry (VM) is a predominant pattern of GBM neovascularization. However, the biological functions of circRNAs prompting VM formation in GBM remains unclarified. Methods: The circular RNA circCMTM3 was identified through high-throughput sequencing and bioinformatics analysis. The expression of circCMTM3 in exosomes in glioma tissues and cells was verified via RT-qPCR and FISH. In vitro and in vivo assays, such as EdU, MTS, Transwell, and tube formation assays were performed to investigate functional roles of circCMTM3. Meanwhile, in situ tumorigenesis assay were implemented to explore the influences of circCMTM3 on the GBM progression. Additionally, RNA pull-down, RIP, ChIP, and dual-luciferase reporter gene assays were executed to confirm the underlying regulation mechanism of circCMTM3. Results: CircCMTM3, as a novel circular RNA, was packaged into exosomes derived from glioblastoma stem cells (GSCs), which facilitates the phenotypic transition of differentiated glioma cells (DGCs) to VM. Mechanistically, exosomal circCMTM3 is internalized by DGCs and disrupt the ubiquitination degradation of STAT5A and STAT5B by E3 ubiquitin ligase CNOT4. Additionally, through molecular scaffold function of circCMTM3, STAT5A is activated and triggers transcriptional regulation of target genes including the pro-vasculogenic factor CHI3L2 and the RNA-binding protein SRSF1. Subsequently, circCMTM3/STAT5A/SRSF1 positive feedback loop sustainably enhances VM formation and accelerates tumor progression in GBM. Conclusion: Exosomal circCMTM3 possessing growth factor-mimetic property activates the JAK2/STAT5A pathway via non-canonical manner, and promotes VM formation in GBM. The molecular communications between GSCs and DGCs offers a therapeutic strategy for targeting the neovascularization of GBM.

Exosomes: Key Factors in Ovarian Cancer Peritoneal Metastasis and Drug Resistance

Ovarian cancer remains a leading cause of death among gynecological cancers, largely due to its propensity for peritoneal metastasis and the development of drug resistance. This review concentrates on the molecular underpinnings of these two critical challenges. We delve into the role of exosomes, the nano-sized vesicles integral to cellular communication, in orchestrating the complex interactions within the tumor microenvironment that facilitate metastatic spread and thwart therapeutic efforts. Specifically, we explore how exosomes drive peritoneal metastasis by promoting epithelial-mesenchymal transition in peritoneal mesothelial cells, altering the extracellular matrix, and supporting angiogenesis, which collectively enable the dissemination of cancer cells across the peritoneal cavity. Furthermore, we dissect the mechanisms by which exosomes contribute to the emergence of drug resistance, including the sequestration and expulsion of chemotherapeutic agents, the horizontal transfer of drug resistance genes, and the modulation of critical DNA repair and apoptotic pathways. By shedding light on these exosome-mediated processes, we underscore the potential of exosomal pathways as novel therapeutic targets, offering hope for more effective interventions against ovarian cancer's relentless progression.

Non-coding RNAs in hepatocellular carcinoma metastasis: Remarkable indicators and potential oncogenic mechanism

Non-coding RNAs (ncRNAs), as key regulators involving in intercellular biological processes, are more prominent in many malignancies, especially for hepatocellular carcinoma (HCC). Herein, we conduct a comprehensive review to summarize diverse ncRNAs roles in HCC metastatic mechanism. We focus on four signaling pathways that predominate in HCC metastatic process, including Wnt/β-catenin, HIF-1α, IL-6, and TGF-β pathways. MicroRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) employed different mechanisms to participate in the regulation of the key genes in these pathways, typical as interaction with DNA to control transcription, with RNA to control translation, and with protein to control stability. Therefore, ncRNAs may become potential biomarkers and therapeutic targets for HCC metastasis.

Circular RNA in cancer

Over the past decade, circular RNA (circRNA) research has evolved into a bona fide research field shedding light on the functional consequence of this unique family of RNA molecules in cancer. Although the method of formation and the abundance of circRNAs can differ from their cognate linear mRNA, the spectrum of interacting partners and their resultant cellular functions in oncogenesis are analogous. However, with 10 times more diversity in circRNA variants compared with linear RNA variants, combined with their hyperstability in the cell, circRNAs are equipped to influence every stage of oncogenesis. This is an opportune time to address the breadth of circRNA in cancer focused on their spatiotemporal expression, mutations in biogenesis factors and contemporary functions through each stage of cancer. In this Review, we highlight examples of functional circRNAs in specific cancers, which satisfy critical criteria, including their physical co-association with the target and circRNA abundance at stoichiometrically valid quantities. These considerations are essential to develop strategies for the therapeutic exploitation of circRNAs as biomarkers and targeted anticancer agents.

N6-methyladenosine (m6A) Writer WTAP Potentiates Hepatocellular Carcinoma Immune Evasion and Aerobic Glycolysis

Hepatocellular carcinoma (HCC) is one of most prevalent malignant tumors with poor prognosis and a high mortality rate. Recent research indicates that N6-methyladenosine (m6A) and tumor immunotherapy are important factors in HCC. More research is still needed to fully understand the profound roles that m6A writer Wilms tumor 1-associated protein (WTAP) and CD8+ T cells play in the antitumor immunity that prevents HCC from progressing. According to the findings of our investigation, WTAP was significantly elevated in HCC cells and was associated with a poor prognosis. Functionally, WTAP accelerated HCC immune evasion and aerobic glycolysis while suppressing the tumor-killing ability of CD8+ T cells. On the other hand, WTAP knockdown had the opposite effect. WTAP targets the m6A site on the 3'-UTR of PD-L1 mRNA, which mechanistically increases the stability of PD-L1 mRNA. These results showed that WTAP inhibited CD8+ T cells' antitumor activity, which in turn deteriorated HCC immune evasion and aerobic glycolysis. In conclusion, our research uncovers a novel mechanism for WTAP on the tumor-killing ability of CD8+ T cells, which helps to overcome HCC immune evasion.

Role of N6-methyladenosine RNA modification in cancer

N6-methyladenosine (m6A) is the most abundant modification of RNA in eukaryotic cells. Previous studies have shown that m6A is pivotal in diverse diseases especially cancer. m6A corelates with the initiation, progression, resistance, invasion, and metastasis of cancer. However, despite these insights, a comprehensive understanding of its specific roles and mechanisms within the complex landscape of cancer is still elusive. This review begins by outlining the key regulatory proteins of m6A modification and their posttranslational modifications (PTMs), as well as the role in chromatin accessibility and transcriptional activity within cancer cells. Additionally, it highlights that m6A modifications impact cancer progression by modulating programmed cell death mechanisms and affecting the tumor microenvironment through various cancer-associated immune cells. Furthermore, the review discusses how microorganisms can induce enduring epigenetic changes and oncogenic effect in microorganism-associated cancers by altering m6A modifications. Last, it delves into the role of m6A modification in cancer immunotherapy, encompassing RNA therapy, immune checkpoint blockade, cytokine therapy, adoptive cell transfer therapy, and direct targeting of m6A regulators. Overall, this review clarifies the multifaceted role of m6A modification in cancer and explores targeted therapies aimed at manipulating m6A modification, aiming to advance cancer research and improve patient outcomes.

Circular RNAs in human diseases

Circular RNAs (circRNAs) are a unique class of RNA molecules formed through back-splicing rather than linear splicing. As an emerging field in molecular biology, circRNAs have garnered significant attention due to their distinct structure and potential functional implications. A comprehensive understanding of circRNAs' functions and potential clinical applications remains elusive despite accumulating evidence of their involvement in disease pathogenesis. Recent research highlights their significant roles in various human diseases, but comprehensive reviews on their functions and applications remain scarce. This review provides an in-depth examination of circRNAs, focusing first on their involvement in non-neoplastic diseases such as respiratory, endocrine, metabolic, musculoskeletal, cardiovascular, and renal disorders. We then explore their roles in tumors, with particular emphasis on exosomal circular RNAs, which are crucial for cancer initiation, progression, and resistance to treatment. By detailing their biogenesis, functions, and impact on disease mechanisms, this review underscores the potential of circRNAs as diagnostic biomarkers and therapeutic targets. The review not only enhances our understanding of circRNAs' roles in specific diseases and tumor types but also highlights their potential as novel diagnostic and therapeutic tools, thereby paving the way for future clinical investigations and potential therapeutic interventions.

KLF4-induced upregulation of SOCS1 ameliorates myocardial ischemia/reperfusion injury by attenuating AC16 cardiomyocyte damage and enhancing M2 macrophage polarization

Reperfusion strategies, the standard therapy for acute myocardial infarction (AMI), may result in ischemia/reperfusion (I/R) damage. Suppressor of cytokine signaling1 (SOCS1) exerts a cardioprotective function in myocardial I/R damage. Here, we investigated epigenetic modulators that deregulate SOCS1 in cardiomyocytes under hypoxia/reoxygenation (H/R) conditions. Human AC16 cardiomyocytes were exposed to H/R conditions to generate a cell model of myocardial I/R damage. Expression of mRNA and protein was detected by quantitative PCR and western blot analysis, respectively. Cell migratory and invasive abilities were evaluated by transwell assay. Cell apoptosis and M2 macrophage polarization were assessed by flow cytometry. TNF-α, IL-1β, and IL-6 levels were examined by ELISA. The interaction of KLF4 with SOCS1 was verified by chromatin immunoprecipitation and luciferase assays. SOCS1 and transcription factor KLF4 protein levels were underexpressed by 75% and 57%, respectively, in H/R-exposed AC16 cardiomyocytes versus control cells. Under H/R conditions, forced SOCS1 expression (2.7 times) induced cell migration (2.2 times) and invasion (1.9 times) and hindered cell apoptosis (by 45%) of AC16 cardiomyocytes as well as enhanced M2 macrophage polarization (4.6 times). Mechanistically, KLF4 upregulation promoted SOCS1 transcription (2.6 times) and expression (2.6 times) by binding to the SOCS1 promoter. Decrease of SOCS1 (by 51%) reversed the effects of KLF4 upregulation on cardiomyocyte migration, invasion and apoptosis, and M2 macrophage polarization under H/R conditions. Additionally, SOCS1 and KLF4 were underexpressed by 56% and 63%, respectively, in AMI serum. Our study indicates that KLF4-induced upregulation of SOCS1 can attenuate H/R-triggered apoptosis of AC16 cardiomyocytes and enhance M2 macrophage polarization.

Mechanisms of Tolerance Induction in Liver Transplantation: Lessons Learned from Fetomaternal Tolerance, Autoimmunity and Tumor Immunity

Since the first published report of experimental kidney transplantation in dogs in 1902, there were many experimental and clinical trials of organ transplantation, with many sacrifices. After the establishment of the surgical technique and the discovery of immunosuppressive drugs, transplantation became the definitive treatment strategy for patients with terminal organ failure. However, this is not a common therapy method due to the difficulty of solving the fundamental issues behind organ transplantation, including the shortage of donor graft, potential risks of transplant surgery and economic capability. The pre- and post-transplant management of recipients is another critical issue that may affect transplant outcome. Most liver transplant recipients experience post-transplant complications, including infection, acute/chronic rejection, metabolic syndrome and the recurrence of hepatocellular carcinoma. Therefore, the early prediction and diagnosis of these complications may improve overall and disease-free survival. Furthermore, how to induce operational tolerance is the key to achieving the ultimate goal of transplantation. In this review, we focus on liver transplantation, which is known to achieve operational tolerance in some circumstances, and the mechanical similarities and differences between liver transplant immunology and fetomaternal tolerance, autoimmunity or tumor immunity are discussed.

Interplay among extracellular vesicles, cancer stemness and immune regulation in driving hepatocellular carcinoma progression

The intricate interplay among extracellular vesicles, cancer stemness properties, and the immune system significantly impacts hepatocellular carcinoma (HCC) progression, treatment response, and patient prognosis. Extracellular vesicles (EVs), which are membrane-bound structures, play a pivotal role in conveying proteins, lipids, and nucleic acids between cells, thereby serving as essential mediators of intercellular communication. Since a lot of current research focuses on small extracellular vesicles (sEVs), with diameters ranging from 30 nm to 200 nm, this review emphasizes the role of sEVs in the context of interactions between HCC stemness-bearing cells and the immune cells. sEVs offer promising opportunities for the clinical application of innovative diagnostic and prognostic biomarkers in HCC. By specifically targeting sEVs, novel therapeutics aimed at cancer stemness can be developed. Ongoing investigations into the roles of sEVs in cancer stemness and immune regulation in HCC will broaden our understanding and ultimately pave the way for groundbreaking therapeutic interventions.

Exosome nanovesicles: biomarkers and new strategies for treatment of human diseases

Exosomes are nanoscale vesicles of cellular origin. One of the main characteristics of exosomes is their ability to carry a wide range of biomolecules from their parental cells, which are important mediators of intercellular communication and play an important role in physiological and pathological processes. Exosomes have the advantages of biocompatibility, low immunogenicity, and wide biodistribution. As researchers' understanding of exosomes has increased, various strategies have been proposed for their use in diagnosing and treating diseases. Here, we provide an overview of the biogenesis and composition of exosomes, describe the relationship between exosomes and disease progression, and focus on the use of exosomes as biomarkers for early screening, disease monitoring, and guiding therapy in refractory diseases such as tumors and neurodegenerative diseases. We also summarize the current applications of exosomes, especially engineered exosomes, for efficient drug delivery, targeted therapies, gene therapies, and immune vaccines. Finally, the current challenges and potential research directions for the clinical application of exosomes are also discussed. In conclusion, exosomes, as an emerging molecule that can be used in the diagnosis and treatment of diseases, combined with multidisciplinary innovative solutions, will play an important role in clinical applications.

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.

Identification of mechanism of the oncogenic role of FGFR1 in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most prevalent malignancy of the thyroid. Fibroblast growth factor receptor 1 (FGFR1) is highly expressed in PTC and works as an oncogenic protein in this disease. In this report, we wanted to uncover a new mechanism that drives overexpression of FGFR1 in PTC. Analysis of FGFR1 expression in clinical specimens and PTC cells revealed that FGFR1 expression was enhanced in PTC. Using siRNA/shRNA silencing experiments, we found that FGFR1 downregulation impeded PTC cell growth, invasion, and migration and promoted apoptosis in vitro, as well as suppressed tumor growth in vivo. Bioinformatic analyses predicted the potential USP7-FGFR1 interplay and the potential binding between YY1 and the FGFR1 promoter. The mechanism study found that USP7 stabilized FGFR1 protein via deubiquitination, and YY1 could promote the transcription of FGFR1. Our rescue experiments showed that FGFR1 re-expression had a counteracting effect on USP7 downregulation-imposed in vitro alterations of cell functions and in vivo suppression of xenograft growth. In conclusion, our study identifies the deubiquitinating enzyme USP7 and the oncogenic transcription factor YY1 as potent inducers of FGFR1 overexpression. Designing inhibitors targeting FGFR1 or its upstream inducers USP7 and YY1 may be foreseen as a promising strategy to control PTC development.

Silencing Exosomal circ102927 Inhibits Foot Melanoma Metastasis via Regulating Invasiveness, Epithelial-Mesenchymal Transition and Apoptosis

Background

Exosomes contain abundant circular RNAs (circRNAs), playing an important role in intercellular communication. However, the function and underlying molecular mechanism of exosomal circRNAs in foot metastatic melanoma remain unclear.

Methods

Twelve differentially expressed exosomal circRNAs between patients with metastatic and primary foot melanoma were screened through high-throughput sequencing, and their expression levels were detected by the real-time reverse transcriptase-polymerase chain reaction (RT-qPCR). CircRNA102927 silencing and overexpression A2058 cell line was constructed, and the effects of circRNA102927 on cell proliferation, apoptosis, migration, invasion, and epithelial-mesenchymal transition (EMT) were assessed using cell counting kit-8 (CCK-8), flow cytometry, wound healing, Transwell, and Western blot assays, respectively.

Results

Twelve differentially expressed exosomal circRNAs were screened and ROC curve showed that six circRNAs could be used as the diagnostic biomarkers for metastatic melanoma. Melanoma-secreted exosomes induced the differentiation of CD4+ T cells into Treg cells. CircRNA102927 was highly expressed in metastatic melanomas. Functionally, circRNA102927 silencing inhibited proliferation, EMT, migration, and invasion in metastatic melanoma cells, while promoting apoptosis. Meanwhile, overexpression of circRNA102927 had the opposite effects.

Conclusion

Our investigation suggests that silencing exosomal circRNA102927 may suppress foot melanoma metastasis by inhibiting invasiveness, EMT and promoting apoptosis.

Exosomes: a review of biologic function, diagnostic and targeted therapy applications, and clinical trials

Exosomes are extracellular vesicles generated by all cells and they carry nucleic acids, proteins, lipids, and metabolites. They mediate the exchange of substances between cells,thereby affecting biological properties and activities of recipient cells. In this review, we briefly discuss the composition of exocomes and exosome isolation. We also review the clinical applications of exosomes in cancer biology as well as strategies in exosome-mediated targeted drug delivery systems. Finally, the application of exosomes in the context of cancer therapeutics both in practice and literature are discussed.

Developing an advanced diagnostic model for hepatocellular carcinoma through multi-omics integration leveraging diverse cell-death patterns

Introduction

Hepatocellular carcinoma (HCC), representing more than 80% of primary liver cancer cases, lacks satisfactory etiology and diagnostic methods. This study aimed to elucidate the role of programmed cell death-associated genes (CDRGs) in HCC by constructing a diagnostic model using single-cell RNA sequencing (scRNA-seq) and RNA sequencing (RNA-seq) data.

Methods

Six categories of CDRGs, including apoptosis, necroptosis, autophagy, pyroptosis, ferroptosis, and cuproptosis, were collected. RNA-seq data from blood-derived exosomes were sourced from the exoRBase database, RNA-seq data from cancer tissues from the TCGA database, and scRNA-seq data from the GEO database. Subsequently, we intersected the differentially expressed genes (DEGs) of the HCC cohort from exoRBase and TCGA databases with CDRGs, as well as DEGs obtained from single-cell datasets. Candidate biomarker genes were then screened using clinical indicators and a machine learning approach, resulting in the construction of a seven-gene diagnostic model for HCC. Additionally, scRNA-seq and spatial transcriptome sequencing (stRNA-seq) data of HCC from the Mendeley data portal were used to investigate the underlying mechanisms of these seven key genes and their association with immune checkpoint blockade (ICB) therapy. Finally, we validated the expression of key molecules in tissues and blood-derived exosomes through quantitative Polymerase Chain Reaction (qPCR) and immunohistochemistry experiments.

Results

Collectively, we obtained a total of 50 samples and 104,288 single cells. Following the meticulous screening, we established a seven-gene diagnostic model for HCC, demonstrating high diagnostic efficacy in both the exoRBase HCC cohort (training set: AUC = 1; testing set: AUC = 0.847) and TCGA HCC cohort (training set: AUC = 1; testing set: AUC = 0.976). Subsequent analysis revealed that HCC cluster 3 exhibited a higher stemness index and could serve as the starting point for the differentiation trajectory of HCC cells, also displaying more abundant interactions with other cell types in the microenvironment. Notably, key genes TRIB3 and NQO1 displayed elevated expression levels in HCC cells. Experimental validation further confirmed their elevated expression in both tumor tissues and blood-derived exosomes of cancer patients. Additionally, stRNA analysis not only substantiated these findings but also suggested that patients with high TRIB3 and NQO1 expression might respond more favorably to ICB therapy.

Conclusions

The seven-gene diagnostic model demonstrated remarkable accuracy in HCC screening, with TRIB3 emerging as a promising diagnostic tool and therapeutic target for HCC.

Advances and challenges of exosome-derived noncoding RNAs for hepatocellular carcinoma diagnosis and treatment

Exosomes, also termed extracellular vesicles (EVs), are an important component of the tumor microenvironment (TME) and exert versatile effects on the molecular communications in the TME of hepatocellular carcinoma (HCC). Exosome-mediated intercellular communication is closely associated with the tumorigenesis and development of HCC. Exosomes can be extracted through ultracentrifugation and size exclusion, followed by molecular analysis through sequencing. Increasing studies have confirmed the important roles of exosome-derived ncRNAs in HCC, including tumorigenesis, progression, immune escape, and treatment resistance. Due to the protective membrane structure of exosomes, the ncRNAs carried by exosomes can evade degradation by enzymes in body fluids and maintain good expression stability. Thus, exosome-derived ncRNAs are highly suitable as biomarkers for the diagnosis and prognostic prediction of HCC, such as exosomal miR-21-5p, miR-221-3p and lncRNA-ATB. In addition, substantial studies revealed that the up-or down-regulation of exosome-derived ncRNAs had an important impact on HCC progression and response to treatment. Exosomal biomarkers, such as miR-23a, lncRNA DLX6-AS1, miR-21-5p, lncRNA TUC339, lncRNA HMMR-AS1 and hsa_circ_0004658, can reshape immune microenvironment by regulating M2-type macrophage polarization and then promote HCC development. Therefore, by controlling exosome biogenesis and modulating exosomal ncRNA levels, HCC may be inhibited or eliminated. In this current review, we summarized the recent findings on the role of exosomes in HCC progression and analyzed the relationship between exosome-derived ncRNAs and HCC diagnosis and treatment.

Recent advances in the reciprocal regulation of m6A modification with non-coding RNAs and its therapeutic application in acute myeloid leukemia

N6-methyladenosine (m6A) is one of the most common modifications of RNA in eukaryotic cells and is involved in mRNA metabolism, including stability, translation, maturation, splicing, and export. m6A also participates in the modification of multiple types of non-coding RNAs, such as microRNAs, long non-coding RNAs, and circular RNAs, thereby affecting their metabolism and functions. Increasing evidence has revealed that m6A regulators, such as writers, erasers, and readers, perform m6A-dependent modification of ncRNAs, thus affecting cancer progression. Moreover, ncRNAs modulate m6A regulators to affect cancer development and progression. In this review, we summarize recent advances in understanding m6A modification and ncRNAs and provide insights into the interaction between m6A modification and ncRNAs in cancer. We also discuss the potential clinical applications of the mechanisms underlying the interplay between m6A modifications and ncRNAs in acute myeloid leukemia (AML). Therefore, clarifying the mutual regulation between m6A modifications and ncRNAs is of great significance to identify novel therapeutic targets for AML and has great clinical application prospects.

Extracellular vesicles in anti-tumor drug resistance: Mechanisms and therapeutic prospects

Drug resistance presents a significant challenge to achieving positive clinical outcomes in anti-tumor therapy. Prior research has illuminated reasons behind drug resistance, including increased drug efflux, alterations in drug targets, and abnormal activation of oncogenic pathways. However, there's a need for deeper investigation into the impact of drug-resistant cells on parental tumor cells and intricate crosstalk between tumor cells and the malignant tumor microenvironment (TME). Recent studies on extracellular vesicles (EVs) have provided valuable insights. EVs are membrane-bound particles secreted by all cells, mediating cell-to-cell communication. They contain functional cargoes like DNA, RNA, lipids, proteins, and metabolites from mother cells, delivered to other cells. Notably, EVs are increasingly recognized as regulators in the resistance to anti-cancer drugs. This review aims to summarize the mechanisms of EV-mediated anti-tumor drug resistance, covering therapeutic approaches like chemotherapy, targeted therapy, immunotherapy and even radiotherapy. Detecting EV-based biomarkers to predict drug resistance assists in bypassing anti-tumor drug resistance. Additionally, targeted inhibition of EV biogenesis and secretion emerges as a promising approach to counter drug resistance. We highlight the importance of conducting in-depth mechanistic research on EVs, their cargoes, and functional approaches specifically focusing on EV subpopulations. These efforts will significantly advance the development of strategies to overcome drug resistance in anti-tumor therapy.

The role of RNA methylation in tumor immunity and its potential in immunotherapy

RNA methylation, a prevalent post-transcriptional modification, has garnered considerable attention in research circles. It exerts regulatory control over diverse biological functions by modulating RNA splicing, translation, transport, and stability. Notably, studies have illuminated the substantial impact of RNA methylation on tumor immunity. The primary types of RNA methylation encompass N6-methyladenosine (m6A), 5-methylcytosine (m5C), N1-methyladenosine (m1A), and N7-methylguanosine (m7G), and 3-methylcytidine (m3C). Compelling evidence underscores the involvement of RNA methylation in regulating the tumor microenvironment (TME). By affecting RNA translation and stability through the "writers", "erasers" and "readers", RNA methylation exerts influence over the dysregulation of immune cells and immune factors. Consequently, RNA methylation plays a pivotal role in modulating tumor immunity and mediating various biological behaviors, encompassing proliferation, invasion, metastasis, etc. In this review, we discussed the mechanisms and functions of several RNA methylations, providing a comprehensive overview of their biological roles and underlying mechanisms within the tumor microenvironment and among immunocytes. By exploring how these RNA modifications mediate tumor immune evasion, we also examine their potential applications in immunotherapy. This review aims to provide novel insights and strategies for identifying novel targets in RNA methylation and advancing cancer immunotherapy efficacy.

Exosomal noncoding RNAs: decoding their role in thyroid cancer progression

Exosomes, as pivotal entities within the tumor microenvironment, orchestrate intercellular communication through the transfer of diverse molecules, among which non-coding RNAs (ncRNAs) such as miRNAs, lncRNAs, and circRNAs play a crucial role. These ncRNAs, endowed with regulatory functions, are selectively incorporated into exosomes. Emerging evidence underscores the significance of exosomal ncRNAs in modulating key oncogenic processes in thyroid cancer (TC), including proliferation, metastasis, epithelial-mesenchymal transition (EMT), angiogenesis, and immunoediting. The unique composition of exosomes shields their cargo from enzymatic and chemical degradation, ensuring their integrity and facilitating their specific expression in plasma. This positions exosomal ncRNAs as promising candidates for novel diagnostic and prognostic biomarkers in TC. Moreover, the potential of exosomes in the therapeutic landscape of TC is increasingly recognized. This review aims to elucidate the intricate relationship between exosomal ncRNAs and TC, fostering a deeper comprehension of their mechanistic involvement. By doing so, it endeavors to propel forward the exploration of exosomal ncRNAs in TC, ultimately paving the way for innovative diagnostic and therapeutic strategies predicated on exosomes and their ncRNA content.

CircRNA Regulation of T Cells in Cancer: Unraveling Potential Targets

T lymphocytes play a critical role in antitumor immunity, but their exhaustion poses a significant challenge for immune evasion by malignant cells. Circular RNAs (circRNAs), characterized by their covalently closed looped structure, have emerged as pivotal regulators within the neoplastic landscape. Recent studies have highlighted their multifaceted roles in cellular processes, including gene expression modulation and protein function regulation, which are often disrupted in cancer. In this review, we systematically explore the intricate interplay between circRNAs and T cell modulation within the tumor microenvironment. By dissecting the regulatory mechanisms through which circRNAs impact T cell exhaustion, we aim to uncover pathways crucial for immune evasion and T cell dysfunction. These insights can inform innovative immunotherapeutic strategies targeting circRNA-mediated molecular pathways. Additionally, we discuss the translational potential of circRNAs as biomarkers for therapeutic response prediction and as intervention targets. Our comprehensive analysis aims to enhance the understanding of immune evasion dynamics in the tumor microenvironment by facilitating the development of precision immunotherapy.

Exosomal circSIPA1L3-mediated intercellular communication contributes to glucose metabolic reprogramming and progression of triple negative breast cancer

BACKGROUND

Breast cancer is the most common malignant tumor, and metastasis remains the major cause of poor prognosis. Glucose metabolic reprogramming is one of the prominent hallmarks in cancer, providing nutrients and energy to support dramatically elevated tumor growth and metastasis. Nevertheless, the potential mechanistic links between glycolysis and breast cancer progression have not been thoroughly elucidated.

METHODS

RNA-seq analysis was used to identify glucose metabolism-related circRNAs. The expression of circSIPA1L3 in breast cancer tissues and serum was examined by qRT-PCR, and further assessed its diagnostic value. We also evaluated the prognostic potential of circSIPA1L3 by analyzing a cohort of 238 breast cancer patients. Gain- and loss-of-function experiments, transcriptomic analysis, and molecular biology experiments were conducted to explore the biological function and regulatory mechanism of circSIPA1L3.

RESULTS

Using RNA-seq analysis, circSIPA1L3 was identified as the critical mediator responsible for metabolic adaption upon energy stress. Gain- and loss-of-function experiments revealed that circSIPA1L3 exerted a stimulative effect on breast cancer progression and glycolysis, which could also be transported by exosomes and facilitated malignant behaviors among breast cancer cells. Significantly, the elevated lactate secretion caused by circSIPA1L3-mediated glycolysis enhancement promoted the recruitment of tumor associated macrophage and their tumor-promoting roles. Mechanistically, EIF4A3 induced the cyclization and cytoplasmic export of circSIPA1L3, which inhibited ubiquitin-mediated IGF2BP3 degradation through enhancing the UPS7-IGF2BP3 interaction. Furthermore, circSIPA1L3 increased mRNA stability of the lactate export carrier SLC16A1 and the glucose intake enhancer RAB11A through either strengthening their interaction with IGF2BP3 or sponging miR-665, leading to enhanced glycolytic metabolism. Clinically, elevated circSIPA1L3 expression indicated unfavorable prognosis base on the cohort of 238 breast cancer patients. Moreover, circSIPA1L3 was highly expressed in the serum of breast cancer patients and exhibited high diagnostic value for breast cancer patients.

CONCLUSIONS

Our study highlights the oncogenic role of circSIPA1L3 through mediating glucose metabolism, which might serve as a promising diagnostic and prognostic biomarker and potential therapeutic target for breast cancer.

Nomograms incorporating hsa_circ_0029325 highly expressed in exosomes of hepatocellular carcinoma predict the postoperative outcomes

BACKGROUND

Liquid biopsies, for example, exosomal circular RNA (circRNA) can be used to assess potential predictive markers for hepatocellular carcinoma (HCC) in patients after curative resection. This study aimed to search for effective prognostic biomarkers for HCC in patients after surgical resection based on exosomal circRNA expression profiles. We developed two nomograms incorporating circRNAs to predict the postoperative recurrence-free survival (RFS) and overall survival (OS) of HCC patients.

METHOD

Plasma exosomes isolated from HCC patients and healthy individuals were used for circRNA microarray analysis to explore differentially expressed circRNAs. Pearson correlation analysis was used to evaluate the correlation between circRNAs and clinicopathological features. Cox regression analysis was used to explore the correlation between circRNA and postoperative survival time as well as recurrence time. A nomogram based on circRNA and clinicopathological characteristics was established and further evaluated to predict prognosis and recurrence.

RESULT

Among 60 significantly upregulated circRNAs and 25 downregulated circRNAs, hsa_circ_0029325 was selected to verify its power for predicting HCC outcomes. The high expression level of exosomal hsa_circ_0029325 was significantly correlated with OS (P = 0.001, HR = 2.04, 95% CI 1.41-3.32) and RFS (P = 0.009, HR = 1.62, 95% CI 1.14-2.30). Among 273 HCC patients, multivariate regression analysis showed that hsa_circ_0029325 (HR = 1.96, 95% CI 1.21-3.18), tumor size (HR = 2.11, 95% CI 1.33-3.32), clinical staging (HR = 2.31, 95% CI 1.54-3.48), and tumor thrombus (HR = 1.74, 95% CI 1.12-2.7) were independent risk factors for poor prognosis in HCC patients after radical resection. These independent predictors of prognosis were incorporated into the two nomograms. The AUCs under the 1-year, 3-year, and 5-year survival and recurrence curves of the OS and RFS nomograms were 0.755, 0.749, and 0.742 and 0.702, 0.685, and 0.642, respectively. The C-index, calibration curves, and clinical decision curves showed that the two prediction models had good predictive performance. These results were verified in the validation cohort with 90 HCC patients.

CONCLUSION

Our study established two reliable nomograms for predicting recurrence and prognosis in HCC patients. We also show that it is feasible to screen potential predictive markers for HCC after curative resection through exosomal circRNA expression profile analysis.

Exosome-derived circUPF2 enhances resistance to targeted therapy by redeploying ferroptosis sensitivity in hepatocellular carcinoma

BACKGROUND

Advanced hepatocellular carcinoma (HCC) can be treated with sorafenib, which is the primary choice for targeted therapy. Nevertheless, the effectiveness of sorafenib is greatly restricted due to resistance. Research has shown that exosomes and circular RNAs play a vital role in the cancer's malignant advancement. However, the significance of exosomal circular RNAs in the development of resistance to sorafenib in HCC remains uncertain.

METHODS

Ultracentrifugation was utilized to isolate exosomes (Exo-SR) from the sorafenib-resistant HCC cells' culture medium. Transcriptome sequencing and differential expression gene analysis were used to identify the targets of Exo-SR action in HCC cells. To identify the targets of Exo-SR action in HCC cells, transcriptome sequencing and analysis of differential expression genes were employed. To evaluate the impact of exosomal circUPF2 on resistance to sorafenib in HCC, experiments involving gain-of-function and loss-of-function were conducted. RNA pull-down assays and mass spectrometry analysis were performed to identify the RNA-binding proteins interacting with circUPF2. RNA immunoprecipitation (RIP), RNA pull-down, electrophoretic mobility shift assay (EMSA), immunofluorescence (IF) -fluorescence in situ hybridization (FISH), and rescue assays were used to validate the interactions among circUPF2, IGF2BP2 and SLC7A11. Finally, a tumor xenograft assay was used to examine the biological functions and underlying mechanisms of Exo-SR and circUPF2 in vivo.

RESULTS

A novel exosomal circRNA, circUPF2, was identified and revealed to be significantly enriched in Exo-SR. Exosomes with enriched circUPF2 enhanced sorafenib resistance by promoting SLC7A11 expression and suppressing ferroptosis in HCC cells. Mechanistically, circUPF2 acts as a framework to enhance the creation of the circUPF2-IGF2BP2-SLC7A11 ternary complex contributing to the stabilization of SLC7A11 mRNA. Consequently, exosomal circUPF2 promotes SLC7A11 expression and enhances the function of system Xc- in HCC cells, leading to decreased sensitivity to ferroptosis and resistance to sorafenib.

CONCLUSIONS

The resistance to sorafenib in HCC is facilitated by the exosomal circUPF2, which promotes the formation of the circUPF2-IGF2BP2-SLC7A11 ternary complex and increases the stability of SLC7A11 mRNA. Focusing on exosomal circUPF2 could potentially be an innovative approach for HCC treatment.

CircDCAF8 promotes the progression of hepatocellular carcinoma through miR-217/NAP1L1 Axis, and induces angiogenesis and regorafenib resistance via exosome-mediated transfer

BACKGROUND

Circular RNAs (circRNAs), which are a new type of single-stranded circular RNA, have significant involvement in progression of many diseases, including tumors. Currently, multiple circRNAs have been identified in hepatocellular carcinoma (HCC). Our study aims to investigate the function and mechanism of circDCAF8 in HCC.

METHODS

The expression of circDCAF8 (hsa_circ_0014879) in HCC and para-carcinoma tissue samples was determined using quantitative real-time polymerase chain reaction (qRT-PCR). The biological function of circDCAF8 in HCC was confirmed by experiments conducted both in vitro and in vivo. And the relationship between circDCAF8, miR-217 and NAP1L1 was predicted by database and verified using qRT-PCR, RNA-binding protein immunoprecipitation (RIP) and dual-luciferase reporter assays. Exosomes isolated from HCC cells were utilized to assess the connection of exosomal circDCAF8 with HCC angiogenesis and regorafenib resistance.

RESULTS

CircDCAF8 is upregulated in HCC tissues and cell lines, and is linked to an unfavourable prognosis for HCC patients. Functionally, circDCAF8 was proved to facilitate proliferation, migration, invasion and Epithelial-Mesenchymal Transformation (EMT) in HCC cells. Animal examinations also validated the tumor-promoting characteristics of circDCAF8 on HCC. Besides, exosomal circDCAF8 promoted angiogenesis in HUVECs. Mechanistically, circDCAF8 interacted with miR-217 and NAP1L1 was a downstream protein of miR-217. CircDCAF8 promoted NAP1L1 expression by sponging miR-217. In addition, exosomes may transfer circDCAF8 from regorafenib-resistant HCC cells to sensitive cells, where it would confer a resistant phenotype.

CONCLUSION

CircDCAF8 facilitates HCC proliferation and metastasis via the miR-217/NAP1L1 axis. Meanwhile, circDCAF8 can promote angiogenesis and drive resistance to regorafenib, making it a viable therapeutic target for HCC patients.

Exosomal microRNAs in hepatocellular carcinoma, expanding research field

In this editorial we comment on the review by Wang et al published in the recent issue of the World Journal of Gastroenterology in 2023. Small extracellular vesicles (exosomes) play important roles in the tumor microenvironment. In this review, the authors introduce the following points: (1) The composition and function of exosomal microRNAs (miRNAs) of different cell origins in hepatocellular carcinoma (HCC); (2) the crosstalk between exosomal miRNAs from stromal cells and immune cells in the tumor microenvironment and the progression of HCC; and (3) the potential applicability of exosomal miRNAs derived from mesen-chymal stem cells in the treatment of HCC. In addition, the potential applicability of exosomal miRNAs derived from mesenchymal stem cells in the treatment of HCC was introduced. In this review, the authors give us an overview of the exosomal RNA and summarize the function of exosomal RNA in HCC, which provides a deeper understanding of exosomal miRNAs to the readers.

Role of Exosomes in Cancer and Aptamer-Modified Exosomes as a Promising Platform for Cancer Targeted Therapy

Exosomes are increasingly recognized as important mediators of intercellular communication in cancer biology. Exosomes can be derived from cancer cells as well as cellular components in tumor microenvironment. After secretion, the exosomes carrying a wide range of bioactive cargos can be ingested by local or distant recipient cells. The released cargos act through a variety of mechanisms to elicit multiple biological effects and impact most if not all hallmarks of cancer. Moreover, owing to their excellent biocompatibility and capability of being easily engineered or modified, exosomes are currently exploited as a promising platform for cancer targeted therapy. In this review, we first summarize the current knowledge of roles of exosomes in risk and etiology, initiation and progression of cancer, as well as their underlying molecular mechanisms. The aptamer-modified exosome as a promising platform for cancer targeted therapy is then briefly introduced. We also discuss the future directions for emerging roles of exosome in tumor biology and perspective of aptamer-modified exosomes in cancer therapy.

Role of T cells in liver metastasis

The liver is a major metastatic site (organ) for gastrointestinal cancers (such as colorectal, gastric, and pancreatic cancers) as well as non-gastrointestinal cancers (such as lung, breast, and melanoma cancers). Due to the innate anatomical position of the liver, the apoptosis of T cells in the liver, the unique metabolic regulation of hepatocytes and other potential mechanisms, the liver tends to form an immunosuppressive microenvironment and subsequently form a pre-metastatic niche (PMN), which can promote metastasis and colonization by various tumor cells(TCs). As a result, the critical role of immunoresponse in liver based metastasis has become increasingly appreciated. T cells, a centrally important member of adaptive immune response, play a significant role in liver based metastases and clarifying the different roles of the various T cells subsets is important to guide future clinical treatment. In this review, we first introduce the predisposing factors and related mechanisms of liver metastasis (LM) before introducing the PMN and its transition to LM. Finally, we detail the role of different subsets of T cells in LM and advances in the management of LM in order to identify potential therapeutic targets for patients with LM.

Involvement of circ_0029407 in Caerulein-Evoked Cytotoxicity in Human Pancreatic Cells via the miR-579-3p/TLR4/NF-κB Pathway

Acute pancreatitis (AP) is the most prevalent gastrointestinal inflammatory disease. Circular RNAs (circRNAs) are implicated in the development of AP. Here, we identified the precise action of circ_0029407 in AP development. Human pancreatic epithelial cells (HPECs) were stimulated with caerulein. Cell viability, proliferation, and apoptosis were gauged by Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), and flow cytometry assays, respectively. Circ_0029407, microRNA (miR)-579-3p, and toll-like receptor 4 (TLR4) were quantified by a qRT-PCR or western blot assay. Dual-luciferase reporter and RNA pull-down assays were performed to evaluate the direct relationship between miR-579-3p and circ_0029407 or TLR4. Our results indicated that circ_0029407 was markedly overexpressed in AP serum samples and caerulein-stimulated HPECs. Reduction of circ_0029407 attenuated caerulein-imposed HPEC damage by promoting cell proliferation and repressing cell apoptosis and inflammation. Mechanistically, circ_0029407 contained a miR-579-3p binding site, and miR-579-3p downregulation reversed the effect of circ_0029407 reduction on caerulein-imposed HPEC damage. TLR4 was identified as a direct and functional target of miR-579-3p, and TLR4 overexpression reversed the impact of miR-579-3p upregulation on attenuating caerulein-imposed HPEC damage. Moreover, circ_0029407 regulated the TLR4/nuclear factor NF-kappaB (NF-κB) signaling by acting as a competing endogenous RNA (ceRNA) for miR-579-3p. Our study suggests that circ_0029407 regulates caerulein-imposed cell injury in human pancreatic cells at least in part via the TLR4/NF-κB signaling pathway by functioning as a ceRNA for miR-579-3p.

The role of circular RNAs in regulating resistance to cancer immunotherapy: mechanisms and implications

Cancer immunotherapy has rapidly transformed cancer treatment, yet resistance remains a significant hurdle, limiting its efficacy in many patients. Circular RNAs (circRNAs), a novel class of non-coding RNAs, have emerged as pivotal regulators of gene expression and cellular processes. Increasing evidence indicates their involvement in modulating resistance to cancer immunotherapy. Notably, certain circRNAs function as miRNA sponges or interact with proteins, influencing the expression of immune-related genes, including crucial immune checkpoint molecules. This, in turn, shapes the tumor microenvironment and significantly impacts the response to immunotherapy. In this comprehensive review, we explore the evolving role of circRNAs in orchestrating resistance to cancer immunotherapy, with a specific focus on their mechanisms in influencing immune checkpoint gene expression. Additionally, we underscore the potential of circRNAs as promising therapeutic targets to augment the effectiveness of cancer immunotherapy. Understanding the role of circRNAs in cancer immunotherapy resistance could contribute to the development of new therapeutic strategies to overcome resistance and improve patient outcomes.

Crosstalk between m6A modification and non-coding RNAs in HCC

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide, with high morbidity and occurrence. Although various therapeutic approaches have been rapidly developed in recent years, the underlying molecular mechanisms in the pathogenesis of HCC remain enigmatic. The N6-methyladenosine (m6A) RNA modification is believed to regulate RNA metabolism and further gene expression. This process is intricately regulated by multiple regulators, such as methylases and demethylases. Non-coding RNAs (ncRNAs) are involved in the regulation of the epigenetic modification, mRNA transcription and other biological processes, exhibiting crucial roles in tumor occurrence and development. The m6A-ncRNA interaction has been implicated in the malignant phenotypes of HCC and plays an important role in drug resistance. This review summarizes the effect of m6A-ncRNA crosstalk on HCC progression and their clinical implications as prognostic markers and therapeutic targets in this disease.

Current advances in circular RNA detection and investigation methods: Are we running in circles?

Circular RNAs (circRNAs), characterized by their closed-loop structure, have emerged as significant transcriptomic regulators, with roles spanning from microRNA sponging to modulation of gene expression and potential peptide coding. The discovery and functional analysis of circRNAs have been propelled by advancements in both experimental and bioinformatics tools, yet the field grapples with challenges related to their detection, isoform diversity, and accurate quantification. This review navigates through the evolution of circRNA research methodologies, from early detection techniques to current state-of-the-art approaches that offer comprehensive insights into circRNA biology. We examine the limitations of existing methods, particularly the difficulty in differentiating circRNA isoforms and distinguishing circRNAs from their linear counterparts. A critical evaluation of various bioinformatics tools and novel experimental strategies is presented, emphasizing the need for integrated approaches to enhance our understanding and interpretation of circRNA functions. Our insights underscore the dynamic and rapidly advancing nature of circRNA research, highlighting the ongoing development of analytical frameworks designed to address the complexity of circRNAs and facilitate the assessment of their clinical utility. As such, this comprehensive overview aims to catalyze further advancements in circRNA study, fostering a deeper understanding of their roles in cellular processes and potential implications in disease. This article is categorized under: RNA Methods > RNA Nanotechnology RNA Methods > RNA Analyses in Cells RNA Methods > RNA Analyses In Vitro and In Silico.

Exosome secretion related gene signature predicts chemoresistance in patients with colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is a highly heterogeneous malignancy, and patients often have different responses to treatment. In this study, the genetic characteristics related to exosome formation and secretion procedure were used to predict chemoresistance and guide the individualized treatment of patients.

METHODS

Firstly, seven microarray datasets in Gene Expression Omnibus (GEO) and RNA-Seq dataset from the Cancer Genome Atlas (TCGA) were used to analysis the transcriptome profiles and associated characteristics of CRC patients. Then, a predictive model based on gene features linked to exosome formation and secretion was created and validated using Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis and Support Vector Machine-Recursive Feature Elimination (SVM-RFE) machine learning. Finally, we evaluated the model using chemoresistant/chemosensitive cells and tissues by immunofluorescence (IF), western blot (WB), quantitative real-time PCR (qRT-PCR) and immunocytochemistry (IHC) experiments, and the predictive value of integrated model in the clinical validation cohort were performed by Receiver Operating Characteristic (ROC) and Kaplan-Meier (K-M) curves analyses.

RESULTS

We established a risk score signature based on three genes related to exosome secretion in CRC. Better Overall Survival (OS) and greater chemosensitivity were seen in the low-risk group, whereas the high-risk group exhibited chemoresistance and a subpar response to immune checkpoint blockade (ICB) therapy. Higher expression of the model genes EXOC2, EXOC3 and STX4 were observed in chemoresistant cells and specimens. The AUC of 5-year disease-free survival (DFS) was 0.804. Compared with that in the low-risk group, patients' DFS was found to be significantly worse in the high-risk group.

CONCLUSIONS

In summary, the gene signature related to exosome formation and secretion could reliably predict patients' chemosensitivity and ICB treatment response, which providing new independent biomarkers for the treatment of CRC.

Targeting non-coding RNAs and N6-methyladenosine modification in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the most common form of primary liver cancers, accounts for a significant portion of cancer-related death globally. However, the molecular mechanisms driving the onset and progression of HCC are still not fully understood. Emerging evidence has indicated that non-protein-coding regions of genomes could give rise to transcripts, termed non-coding RNA (ncRNA), forming novel functional driving force for aberrant cellular activity. Over the past decades, overwhelming evidence has denoted involvement of a complex array of molecular function of ncRNAs at different stages of HCC tumorigenesis and progression. In this context, several pre-clinical studies have highlighted the potentials of ncRNAs as novel therapeutic modalities in the management of human HCC. Moreover, N6-methyladenosine (m6A) modification, the most prevalent form of internal mRNA modifications in mammalian cells, is essential for the governance of biological processes within cells. Dysregulation of m6A in ncRNAs has been implicated in human carcinogenesis, including HCC. In this review, we will discuss dysregulation of several hallmark ncRNAs (miRNAs, lncRNAs, and circRNAs) in HCC and address the latest advances for their involvement in the onset and progression of HCC. We also focus on dysregulation of m6A modification and various m6A regulators in the etiology of HCC. In the end, we discussed the contemporary preclinical and clinical application of ncRNA-based and m6A-targeted therapies in HCC.

Clinical Application of Different Liquid Biopsy Components in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer, usually occurring in the background of chronic liver disease. HCC lethality rate is in the third highest place in the world. Patients with HCC have concealed early symptoms and possess a high-level of heterogeneity. Once diagnosed, most of the tumors are in advanced stages and have a poor prognosis. The sensitivity and specificity of existing detection modalities and protocols are suboptimal. HCC calls for more sophisticated and individualized therapeutic regimens. Liquid biopsy is non-invasive, repeatable, unaffected by location, and can be monitored dynamically. It has emerged as a useable aid in achieving precision malignant tumor treatment. Circulating tumor cells (CTCs), circulating nucleic acids, exosomes and tumor-educated platelets are the commonest components of a liquid biopsy. It possesses the theoretical ability to conquer the high heterogeneity and the difficulty of early detection for HCC patients. In this review, we summarize the common enrichment techniques and the clinical applications in HCC for different liquid biopsy components. Tumor recurrence after HCC-related liver transplantation is more insidious and difficult to treat. The clinical use of liquid biopsy in HCC-related liver transplantation is also summarized in this review.

Extracellular Vesicle-Related Non-Coding RNAs in Hepatocellular Carcinoma: An Overview

Hepatocellular carcinoma (HCC) is the most common primary liver cancer. It is a major public health problem worldwide, and it is often diagnosed at advanced stages, when no effective treatment options are available. Extracellular vesicles (EVs) are nanosized double-layer lipid vesicles containing various biomolecule cargoes, such as lipids, proteins, and nucleic acids. EVs are released from nearly all types of cells and have been shown to play an important role in cell-to-cell communication. In recent years, many studies have investigated the role of EVs in cancer, including HCC. Emerging studies have shown that EVs play primary roles in the development and progression of cancer, modulating tumor growth and metastasis formation. Moreover, it has been observed that non-coding RNAs (ncRNAs) carried by tumor cell-derived EVs promote tumorigenesis, regulating the tumor microenvironment (TME) and playing critical roles in the progression, angiogenesis, metastasis, immune escape, and drug resistance of HCC. EV-related ncRNAs can provide information regarding disease status, thus encompassing a role as biomarkers. In this review, we discuss the main roles of ncRNAs present in HCC-derived EVs, including micro(mi) RNAs, long non-coding (lnc) RNAs, and circular (circ) RNAs, and their potential clinical value as biomarkers and therapeutic targets.