hsa_circ_0007919 induces LIG1 transcription by binding to FOXA1/TET1 to enhance the DNA damage response and promote gemcitabine resistance in pancreatic ductal adenocarcinoma

RNA-binding protein quaking: a multifunctional regulator in tumour progression

BACKGROUND

Quaking (QKI) is a member of the signal transduction and activators of RNA (STAR) family, performing a crucial multifunctional regulatory role in alternative splicing, mRNA precursor processing, mRNA transport and localization, mRNA stabilization, and translation during tumour progression. Abnormal QKI expression or fusion mutations lead to aberrant RNA and protein expression, thereby promoting tumour progression. However, in many types of tumour, QKI played a role as tumour suppressor, the regulatory role of QKI in tumour progression remains ambiguous.

OBJECTIVES

This review aims to analyze the isoform and function of QKI, the impact of QKI-regulated gene expression or signalling pathway alterations on tumour progression, and its potential clinical applications as a predictive marker or target for tumour therapy.

METHODS

We reviewed recent studies and summarized the function of QKI alteration in tumour progression.

RESULTS

QKI mediate post-transcriptional gene regulation including alternative splicing, polyadenylation, mRNA stabilization, mRNA subcellular location, and noncoding RNA by binding to the QRE elements of targeted nucleotide. The dysregulation of QKI is intricately correlated to tumour proliferation, metastasis, angiogenesis, tumor stem cells, the tumour microenvironment, and treatment sensitivity, and represents as a potential biological predictor in tumour diagnosis and prognosis.

CONCLUSIONS

QKI play a critical role as tumour suppressor or an oncogene in tumour progression due to the different splicing sites and transcripts with various tumour subtype or tumor micorenvironment. Ongoing research about QKI's functions and mechanisms persist is required to conduct for better understanding the role of QKI in tumour regulation.

Circular RNAs perspective: exploring the direction of immunotherapy for colorectal cancer

Circular RNAs (circRNAs) are multifaceted molecules that play a pivotal role in regulating gene expression at both transcriptional and post-transcriptional levels. Their expression is highly tissue-specific and developmentally regulated, making them critical players in various physiological processes and diseases, particularly cancer. In colorectal cancer, circRNAs exhibit significantly dysregulated expression patterns and profoundly influence disease progression through diverse molecular mechanisms. Unraveling the complex roles of circRNAs in modulating colorectal cancer immunotherapy outcomes highlights their potential as both promising biomarkers and therapeutic targets. Moving forward, advancements in circRNA-based therapeutic strategies and delivery systems are poised to transform precision medicine, enabling early colorectal cancer diagnosis and improving patient prognosis.

Role of noncoding RNA and protein interaction in pancreatic cancer

ABSTRACT

Noncoding RNAs (ncRNAs) are a class of RNA molecules with little or no protein-coding potential. Emerging evidence indicates that ncRNAs are frequently dysregulated and play pivotal roles in the pathogenesis of pancreatic cancer. Their aberrant expression can arise from chromosomal abnormalities, dysregulated transcriptional control, and epigenetic modifications. ncRNAs function as protein scaffolds or molecular decoys to modulate interactions between proteins and other biomolecules, thereby regulating gene expression and contributing to pancreatic cancer progression. In this review, we summarize the mechanisms underlying ncRNA dysregulation in pancreatic cancer, emphasize the biological significance of ncRNA-protein interactions, and highlight their clinical relevance. A deeper understanding of ncRNA-protein interactions is essential to elucidate molecular mechanisms and advance translational research in pancreatic cancer.

Development of a Nomogram Integrating Modified Inflammation-Based Indexes for Predicting Overall Survival in Pancreatic Cancer: A Retrospective Study

Background

Pancreatic cancer (PCA) is a highly malignant tumor with a 5-year survival rate of <10%. It is characterized as a cold tumor with an immunosuppressive microenvironment. Liver dysfunction due to biliary obstruction can affect the inflammation index, an indicator of immune status. Adjusting inflammation indices for liver function may enhance their clinical utility for predicting overall survival (OS) in PCA patients.

Methods

Resected PCA cases were selected using specific criteria. Liver function indicators identified by Spearman's analysis were integrated into a covariance analysis to refine inflammation indices, including modified neutrophil-to-lymphocyte ratio (mNLR), modified platelet-to-lymphocyte ratio (mPLR), modified lymphocyte-to-monocyte ratio (mLMR), modified systemic immune-inflammation index (mSII), and modified C-reactive protein (mCRP). These modified indices and clinicopathological factors were analyzed to identify independent OS predictors. A nomogram was developed and compared with a primary inflammation-based model using calibration curves, decision curve analysis (DCA), and the concordance index (C-index).

Results

Liver function indicators including direct bilirubin (DBIL), indirect bilirubin (IBIL), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), lactate dehydrogenase (LDH), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), and albumin (ALB) were integrated to refine inflammation indices. In PCA patients, higher mNLR, mSII, CA19-9, T stage, and N stage were associated with worse OS, while higher mLMR or PNI levels correlated with better OS. Vascular invasion predicted poor OS, whereas chemotherapy improved OS. The nomogram model's clinical utility surpassed that of the primary inflammation-based model.

Conclusion

The nomogram incorporating modified inflammation indices demonstrated superior clinical utility. Adjusting inflammation indices for liver function is recommended for prognostic prediction, especially in PCA patients with biliary obstruction. For patients with advanced T and N staging or poorly differentiated tumors, intraoperative margin nanoknife ablation and timely postoperative adjuvant chemotherapy are recommended to enhance prognosis.

Skullcapflavone II induces G2/M phase arrest in hepatic stellate cells and suppresses hepatic fibrosis

RESEARCH PURPOSE

This investigation explored the therapeutic effects and mechanisms of Skullcapflavone II in hepatic fibrosis (HF).

MATERIALS AND METHODS

The optimal concentration of Skullcapflavone II for LX2 hepatic stellate cells was determined using the CCK8 assay. EdU staining and flow cytometry were utilised to assess cell proliferation and G2/M phase arrest. Mice with carbon tetrachloride-triggered HF were administered Skullcapflavone II at low (15 mg/day), medium (30 mg/day), and high (60 mg/day) doses. Subsequently, hepatic damage and fibrosis were assessed via body weight, liver index, biochemical markers, and histopathological staining. Immunohistochemistry for Collagen I and α-SMA were utilised to examine hepatic stellate cell (HSC) activation. RNA sequencing was utilised to ascertain differentially expressed genes. Molecular docking simulated interactions among Skullcapflavone II and target proteins as well as outcomes were validated by implementing western blotting, immunohistochemistry, and RT-qPCR.

RESULTS

Skullcapflavone II inhibited LX2 cell proliferation and triggered G2/M phase arrest. Its optimal intervention concentration was 160 μM. In vivo, it ameliorated hepatic function, diminished serum indicators of fibrosis, and suppressed HSC activation. Diminished collagen sediment was validated utilising histopathological examination, whereas immunohistochemistry indicated decreased expression of Collagen I and α-SMA. Additionally, molecular docking showed strong binding of Skullcapflavone II to DNA replication-related proteins. Western blotting and RT-qPCR implied that Skullcapflavone II disrupted DNA replication, which triggered G2/M arrest and hindered HSCs activation and proliferation.

CONCLUSION

The abovementioned mechanisms of action of Skullcapflavone II substantiate its prospective clinical application against HF.

Recent advances and perspectives on the development of circular RNA cancer vaccines

Engineered circular RNAs (circRNAs) are emerging as promising platforms for RNA-based vaccines in cancer treatment. We summarize the recent advances of design, synthesis, and delivery of circRNA-based cancer vaccines, and highlight the applications and challenges of circRNA vaccines in cancer therapy. Further enhancements are required in areas such as antigen selection, targeted delivery, multidimensional crosstalks, and clinical trial assessments to advance the efficacy and safety of circRNA vaccines in cancer.

Circular RNA in Pancreatic Cancer: Biogenesis, Mechanism, Function and Clinical Application

Circular RNAs (circRNAs) are a class of novel RNA molecules featured by single-strand covalently closed circular structure, which not only are extensively found in eukaryotes and are highly conserved, but also conduct paramount roles in the occurrence and progression of pancreatic cancer (PC) through diverse mechanisms. As recent studies have demonstrated, circRNAs typically exhibit tissue-specific and cell specific expression patterns, with strong potential as biomarkers for disease diagnosis and prognosis. On the basis of their localization and specific interactions with DNA, RNA, and proteins, circRNAs are considered to possess specific biological functions by acting as microRNA (miRNA) sponges, RNA binding protein (RBP) sponges, transcriptional regulators, molecular scaffolds and translation templates. On that account, further addressing the technical difficulties in the detection and research of circRNAs and filling gaps in their biological knowledge will definitely push ahead this comparatively young research field and bring circRNAs to the forefront of clinical practice. Thus, this review systematically summarizes the biogenesis, function, molecular mechanisms, biomarkers and therapeutic targets of circRNAs in PC.

Circular RNAs in cancer

Circular RNA (circRNA), a subtype of noncoding RNA, has emerged as a significant focus in RNA research due to its distinctive covalently closed loop structure. CircRNAs play pivotal roles in diverse physiological and pathological processes, functioning through mechanisms such as miRNAs or proteins sponging, regulation of splicing and gene expression, and serving as translation templates, particularly in the context of various cancers. The hallmarks of cancer comprise functional capabilities acquired during carcinogenesis and tumor progression, providing a conceptual framework that elucidates the nature of the malignant transformation. Although numerous studies have elucidated the role of circRNAs in the hallmarks of cancers, their functions in the development of chemoradiotherapy resistance remain unexplored and the clinical applications of circRNA-based translational therapeutics are still in their infancy. This review provides a comprehensive overview of circRNAs, covering their biogenesis, unique characteristics, functions, and turnover mechanisms. We also summarize the involvement of circRNAs in cancer hallmarks and their clinical relevance as biomarkers and therapeutic targets, especially in thyroid cancer (TC). Considering the potential of circRNAs as biomarkers and the fascination of circRNA-based therapeutics, the "Ying-Yang" dynamic regulations of circRNAs in TC warrant vastly dedicated investigations.

MMP13 as an effective target of an active trifluoromethyl quinazoline compound against osteosarcoma

Osteosarcoma (OS) is a highly fatal malignant tumor with a high metastatic rate and poor prognosis. Matrix metalloproteinase-13 (MMP13) is involved in OS metastasis. Its increased expression is closely related to distant metastasis and poor prognosis. The trifluoromethyl quinazoline compound KZL-201 was designed and synthesized, and its inhibitory effect on the progression of OS cells was investigated. The aim of this study was to investigate the underlying mechanism of action of KZL-201 in OS using a combination of bioinformatics analysis, molecular biology, cytology, and zoology. The in vitro experiments showed that KZL-201 inhibited OS cell proliferation, invasion, and migration; KZL-201 induced apoptosis and arrested the cell cycle at the G2/M phase. The results of molecular docking, the cellular thermal shift assay, and gene silencing experiments showed that KZL-201 had a strong affinity for MMP13. KZL-201 inhibited the progression of 143B cells by regulating the TGF-β1/Smad2/3 pathway. Thus, MMP13 is an important target gene of KZL-201 in inhibiting 143B cell progression. The in vivo experiments showed that KZL-201 inhibited the growth of OS tissues and the expression of MMP13 in OS tissues. In summary, KZL-201 targeted MMP13 and inhibited its expression, consequently suppressing the progression of OS by regulating the TGF-β1/Smad2/3 pathway.

Emerging roles of CircRNA-miRNA networks in cancer development and therapeutic response

The complex interplay of epigenetic factors is essential in regulating the hallmarks of cancer and orchestrating intricate molecular interactions during tumor progression. Circular RNAs (circRNAs), known for their covalently closed loop structures, are non-coding RNA molecules exceptionally resistant to enzymatic degradation, which enhances their stability and regulatory functions in cancer. Similarly, microRNAs (miRNAs) are endogenous non-coding RNAs with linear structures that regulate cellular biological processes akin to circRNAs. Both miRNAs and circRNAs exhibit aberrant expressions in various cancers. Notably, circRNAs can function as sponges for miRNAs, influencing their activity. The circRNA/miRNA interaction plays a pivotal role in the regulation of cancer progression, including in brain, gastrointestinal, gynecological, and urological cancers, influencing key processes such as proliferation, apoptosis, invasion, autophagy, epithelial-mesenchymal transition (EMT), and more. Additionally, this interaction impacts the response of tumor cells to radiotherapy and chemotherapy and contributes to immune evasion, a significant challenge in cancer therapy. Both circRNAs and miRNAs hold potential as biomarkers for cancer prognosis and diagnosis. In this review, we delve into the circRNA-miRNA circuit within human cancers, emphasizing their role in regulating cancer hallmarks and treatment responses. This discussion aims to provide insights for future research to better understand their functions and potentially guide targeted treatments for cancer patients using circRNA/miRNA-based strategies.

POU4F1 enhances lung cancer gemcitabine resistance by regulating METTL3-dependent TWF1 mRNA N6 adenosine methylation

This study aimed to investigate the role of POU Class 4 Homeobox 1 (POU4F1) in regulating gemcitabine (GEM) resistance in lung cancer cells. The mRNA and protein expressions were assessed using RT-qPCR, western blot, immunofluorescence, and immunohistochemistry. Cell viability and proliferation were assessed by CCK-8 assay and EdU assay. TUNEL staining and flow cytometry were employed to detect cell apoptosis. The m6A modification of TWF1 was detected using MeRIP assay. The interactions between molecules were validated using dual luciferase reporter gene, ChIP, and RIP assays. POU4F1 knockdown inhibited GEM resistance and autophagy in lung cancer cells. Mechanistically, POU4F1 transcriptionally activated methyltransferase-like protein 3 (METTL3) in GEM-resistant cells by binding to the METTL3 promoter. METTL3 promoted the N6-methyladenosine (m6A) modification and expression level of twinfilin-1 (TWF1). Overexpression of METTL3 and TWF1 weakened the effects of POU4F1 knockdown on GEM resistance and autophagy. Moreover, knockdown POU4F1 also enhanced GEM anti-tumor sensitivity in vivo. In conclusion, POU4F1 upregulation promoted GEM resistance in lung cancer cells by promoting autophagy through increasing METTL3-mediated TWF1 m6A modification.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-04161-w.

Niraparib perturbs autophagosome-lysosome fusion in pancreatic ductal adenocarcinoma and exhibits anticancer potential against gemcitabine-resistant PDAC

While poly (adenosine diphosphate-ribose) polymerase inhibitors (PARPi) have achieved specific clinical benefits in a subset of pancreatic ductal adenocarcinoma (PDAC) patients, the potential role of the PARPi niraparib in PDAC necessitates further exploration. In this study, we demonstrated that Niraparib exhibited a pronounced inhibitory effect on autophagy in PDAC both in vitro and in vivo. Mechanistically, this inhibition was primarily attributed to niraparib's ability to disrupt the fusion process between autophagosomes and lysosomes, while potentially exerting a relatively minor impact on the initial stage of autophagy. The blockade effect observed may be mediated via modulation of the ERK signaling pathway, and this effect can be mitigated by the application of an ERK inhibitor (FR180204). Notably, the combined treatment regimen of niraparib and gemcitabine failed to elicit the anticipated synergistic effects in wild-type PANC-1 cells, instead exhibiting pronounced antagonistic interactions. However, in gemcitabine-resistant PANC-1 cells, the combination of niraparib and gemcitabine exhibited modest additive effects. Furthermore, niraparib demonstrated a heightened cytotoxic potency against gemcitabine-resistant PANC-1 cells compared to wild-type PANC-1 cells, both in vitro and in vivo. Our research established that niraparib inhibits late-stage autophagy in PDAC, potentially representing a valuable salvage therapy for gemcitabine-resistant PDAC. Further clinical studies are justified.

A Novel circ_0075829/miR-326/GOT1 ceRNA Crosstalk Regulates the Malignant Phenotypes and Drug Sensitivity of Gemcitabine-Resistant Pancreatic Cancer Cells

Although gemcitabine (GEM) is the cornerstone of the treatment of pancreatic cancer (PC), GEM resistance frequently arises. Circular RNA (circRNA) circ_0075829 is highly expressed in PC. However, whether circ_0075829 contributes to GEM resistance of PC is largely unknown. To generate GEM-resistant PC cells (BxPC-3/GR and SW1990/GR), we exposed GEM-sensitive PC cells to GEM. Circ_0075829, microRNA (miR)-326, and glutamic-oxaloacetic transaminase 1 (GOT1) were quantified by a qRT-PCR or western blot method. Cell survival and viability were gauged by MTS assay. Cell proliferation, apoptosis, invasion, and migration were assessed by EdU, flow cytometry, transwell, and wound-healing assays, respectively. Dual-luciferase reporter assays were used to verify the relationship between miR-326 and circ_0075829 or GOT1. Mouse xenografts were performed to evaluate the role of circ_0075829 in vivo. Our data showed that circ_0075829 was upregulated in GEM-resistant PC tissues and cells. Knockdown of circ_0075829 impeded the proliferation, invasion, migration, and glutamine metabolism, and promoted cell apoptosis and GEM sensitivity of GEM-resistant PC cells. Moreover, circ_0075829 silencing suppressed the tumorigenicity of SW1990/GR cells and sensitized them to the cytotoxic effect of GME in vivo. Mechanistically, circ_0075829 bound miR-326 and exerted regulatory effects by affecting miR-326 expression. GOT1 was a direct miR-326 target and a key downstream effector of miR-326. Furthermore, circ_0075829 modulated GOT1 expression via miR-326. Our findings establish a novel regulatory network, the circ_0075829/miR-326/GOT1 competing endogenous RNA (ceRNA) crosstalk, in the regulation of GEM resistance in PC.

Bioinformatics-based screening of key genes associated with gemcitabine resistance in advanced pancreatic ductal adenocarcinoma

Background

Pancreatic ductal adenocarcinoma (PDAC) ranks among the deadliest cancers globally. Despite gemcitabine being a primary chemotherapeutic agent, many patients with PDAC develop resistance, significantly limiting treatment efficacy. This study aims to screen and validate key genes associated with gemcitabine resistance in advanced PDAC using bioinformatics analysis and clinical sample validation, thereby providing potential noninvasive biomarkers and therapeutic targets for overcoming chemoresistance.

Methods

This study used bioinformatics approaches to analyze gene expression data from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases, identifying differentially expressed genes (DEGs) associated with gemcitabine resistance in advanced PDAC. A total of 122 patients with advanced PDAC were selected for the study and divided into gemcitabine-sensitive and gemcitabine-resistant groups post-treatment. The expression levels of key genes in patients' serum were measured using enzyme-linked immunosorbent assay, and both univariate and multivariate analyses were performed to assess their potential as noninvasive biomarkers for predicting resistance.

Results

Ten upregulated DEGs related to gemcitabine resistance were identified. Among these genes, cathepsin E (CTSE) was significantly negatively correlated with overall survival, disease-specific survival, and progression-free interval in patients with PDAC and was thus identified as a significant key gene. Further clinical sample validation confirmed that CTSE expression level was significantly higher in the resistant group of patients with advanced PDAC compared to the sensitive group, establishing CTSE as an independent predictor of gemcitabine resistance.

Conclusions

CTSE is a key gene associated with gemcitabine resistance in advanced PDAC and shows promise as a target for enhancing responsiveness to gemcitabine treatment.

Splicing dysregulation: hallmark and therapeutic opportunity in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer characterized by dismal prognosis. Late diagnosis, resistance to chemotherapy, and lack of efficacious targeted therapies render PDAC almost untreatable. Dysregulation of splicing, the process that excises the introns from nascent transcripts, is emerging as a hallmark of PDAC and a possible vulnerability of this devastating cancer. Splicing factors are deregulated in PDAC and contribute to all steps of tumorigenesis, from inflammation-related early events to metastasis and acquisition of chemoresistance. At the same time, splicing dysregulation offers a therapeutic opportunity to target cancer-specific vulnerabilities. We discuss mounting evidence that splicing plays a key role in PDAC and the opportunities that this essential process offers for developing new targeted therapies.

The crosstalk between alternative splicing and circular RNA in cancer: pathogenic insights and therapeutic implications

RNA splicing is a fundamental step of gene expression. While constitutive splicing removes introns and joins exons unbiasedly, alternative splicing (AS) selectively determines the assembly of exons and introns to generate RNA variants corresponding to the same transcript. The biogenesis of circular RNAs (circRNAs) is inextricably associated with AS. Back-splicing, the biogenic process of circRNA, is a special form of AS. In cancer, both AS and circRNA deviate from the original track. In the present review, we delve into the intricate interplay between AS and circRNAs in the context of cancer. The relationship between AS and circRNAs is intricate, where AS modulates the biogenesis of circRNAs and circRNAs in return regulate AS events. Beyond that, epigenetic and posttranscriptional modifications concurrently regulate AS and circRNAs. On the basis of this modality, we summarize current knowledge on how splicing factors and other RNA binding proteins regulate circRNA biogenesis, and how circRNAs interact with splicing factors to influence AS events. Specifically, the feedback loop regulation between circRNAs and AS events contributes greatly to oncogenesis and cancer progression. In summary, resolving the crosstalk between AS and circRNA will not only provide better insight into cancer biology but also provoke novel strategies to combat cancer.

Circular RNAs in programmed cell death: Regulation mechanisms and potential clinical applications in cancer: A review

Circular RNAs (circRNAs) are a novel class of non-coding RNAs with covalently closed structures formed by reverse splicing of precursor mRNAs. The widespread expression of circRNAs across species has been revealed by high-throughput sequencing and bioinformatics approaches, indicating their unique properties and diverse functions including acting as microRNA sponges and interacting with RNA-binding proteins. Programmed cell death (PCD), encompassing various forms such as apoptosis, necroptosis, pyroptosis, autophagy, and ferroptosis, is an essential process for maintaining normal development and homeostasis in the human body by eliminating damaged, infected, and aging cells. Many studies have demonstrated that circRNAs play crucial roles in tumourigenesis and development by regulating PCD in tumor cells, showing that circRNAs have the potential to be biomarkers and therapeutic targets in cancer. This review aims to comprehensively summarize the intricate associations between circRNAs and diverse PCD pathways in tumor cells, which play crucial roles in cancer development. Additionally, this review provides a detailed overview of the underlying mechanisms by which circRNAs modulate various forms of PCD for the first time. The ultimate objective is to offer valuable insights into the potential clinical significance of developing novel strategies based on circRNAs and PCD for cancer diagnosis, prognosis, and treatment.

CircPDIA3/miR-449a/XBP1 feedback loop curbs pyroptosis by inhibiting palmitoylation of the GSDME-C domain to induce chemoresistance of colorectal cancer

Although oxaliplatin (OXA) is widely used in the frontline treatment of colorectal cancer (CRC), CRC recurrence is commonly observed due to OXA resistance. OXA resistance is associated with a number of factors, including abnormal regulation of pyroptosis. It is therefore important to elucidate the abnormal regulatory mechanism underlying pyroptosis. Here, we identified that the circular RNA circPDIA3 played an important role in chemoresistance in CRC. CircPDIA3 could induce chemoresistance in CRC by inhibiting pyroptosis both in vitro and in vivo. Mechanistically, RIP, RNA pull-down and co-IP assays revealed that circPDIA3 directly bonded to the GSDME-C domain, subsequently enhanced the autoinhibitory effect of the GSDME-C domain through blocking the GSDME-C domain palmitoylation by ZDHHC3 and ZDHHC17, thereby restraining pyroptosis. Additionally, it was found that the circPDIA3/miR-449a/XBP1 positive feedback loop increased the expression of circPDIA3 to induce chemoresistance. Furthermore, our clinical data and patient-derived tumor xenograft (PDX) models supported the positive association of circPDIA3 with development of chemoresistance in CRC patients. Taken together, our findings demonstrated that circPDIA3 could promote chemoresistance by amplifying the autoinhibitory effect of the GSDME-C domain through inhibition of the GSDME-C domain palmitoylation in CRC. This study provides novel insights into the mechanism of circRNA in regulating pyroptosis and providing a potential therapeutic target for reversing chemoresistance of CRC.

New insights into the potential of exosomal circular RNAs in mediating cancer chemotherapy resistance and their clinical applications

Chemotherapy resistance typically leads to tumour recurrence and is a major obstacle to cancer treatment. Increasing numbers of circular RNAs (circRNAs) have been confirmed to be abnormally expressed in various tumours, where they participate in the malignant progression of tumours, and play important roles in regulating the sensitivity of tumours to chemotherapy drugs. As exosomes mediate intercellular communication, they are rich in circRNAs and exhibit a specific RNA cargo sorting mechanism. By carrying and delivering circRNAs, exosomes can promote the efflux of chemotherapeutic drugs and reduce intracellular drug concentrations in recipient cells, thus affecting the cell cycle, apoptosis, autophagy, angiogenesis, invasion and migration. The mechanisms that affect the phenotype of tumour stem cells, epithelial-mesenchymal transformation and DNA damage repair also mediate chemotherapy resistance in many tumours. Exosomal circRNAs are diagnostic biomarkers and potential therapeutic targets for reversing chemotherapy resistance in tumours. Currently, the rise of new fields, such as machine learning and artificial intelligence, and new technologies such as biosensors, multimolecular diagnostic systems and platforms based on circRNAs, as well as the application of exosome-based vaccines, has provided novel ideas for precision cancer treatment. In this review, the recent progress in understanding how exosomal circRNAs mediate tumour chemotherapy resistance is reviewed, and the potential of exosomal circRNAs in tumour diagnosis, treatment and immune regulation is discussed, providing new ideas for inhibiting tumour chemotherapy resistance.

Epigenetic regulation of DNA repair gene program by Hippo/YAP1-TET1 axis mediates sorafenib resistance in HCC

Hepatocellular carcinoma (HCC) is a malignancy that occurs worldwide and is generally associated with poor prognosis. The development of resistance to targeted therapies such as sorafenib is a major challenge in clinical cancer treatment. In the present study, Ten-eleven translocation protein 1 (TET1) was found to be highly expressed in sorafenib-resistant HCC cells and knockdown of TET1 can substantially improve the therapeutic effect of sorafenib on HCC, indicating the potential important roles of TET1 in sorafenib resistance in HCC. Mechanistic studies determined that TET1 and Yes-associated protein 1 (YAP1) synergistically regulate the promoter methylation and gene expression of DNA repair-related genes in sorafenib-resistant HCC cells. RNA sequencing indicated the activation of DNA damage repair signaling was extensively suppressed by the TET1 inhibitor Bobcat339. We also identified TET1 as a direct transcriptional target of YAP1 by promoter analysis and chromatin-immunoprecipitation assays in sorafenib-resistant HCC cells. Furthermore, we showed that Bobcat339 can overcome sorafenib resistance and synergized with sorafenib to induce tumor eradication in HCC cells and mouse models. Finally, immunostaining showed a positive correlation between TET1 and YAP1 in clinical samples. Our findings have identified a previously unrecognized molecular pathway underlying HCC sorafenib resistance, thus revealing a promising strategy for cancer therapy.

CircRNAs in cancer therapy tolerance

The rapidly expanding field of circular RNA (circ-RNA) research has opened new avenues in cancer diagnostics and treatment, highlighting the role of serum circRNAs as potential biomarkers for assessing tumor therapy resistance. This review comprehensively compiles existing knowledge regarding the biogenesis, function, and clinical relevance of circRNAs, emphasizing their stability, abundance, and cell type-specific expression profiles, which make them ideal candidates for noninvasive early biomarkers in cancer treatment. We explored the roles of circRNAs in oncogenesis and tumor progression and their complex interactions with patient responses to various cancer treatments, such as chemotherapy, radiotherapy, targeted therapy, and immunotherapy. Through the analysis of data from recent studies and clinical trials, we underscore the prognostic significance of serum circRNAs in predicting therapeutic outcomes, their involvement in resistance mechanisms, and their capacity to inform personalized treatment approaches. Additionally, this review addresses the obstacles inherent in circRNA research, including the need for standardized protocols for circRNA extraction and quantification and the elucidation of the clinical significance of circRNAs. Furthermore, our investigation extends to future prospects, including embedding circRNA profiling into regular clinical workflows and pioneering circRNA-based therapeutic approaches. We underscore the transformative potential of serum circRNAs in enhancing cancer diagnosis, improving the accuracy of therapy tolerance predictions, and ultimately fostering the advent of precision oncology.

Role of circular RNAs in DNA repair

Circular RNAs (circRNAs) exhibit a wide range of activities that allow them to participate in numerous cellular processes and make them relevant in a variety of diseases. In this regard, a key process in which circRNAs are involved, and which is the focus of this article, is DNA damage repair (DDR). This study aims to illustrate how circRNAs influence different DNA repair pathways, with particular emphasis on the underlying mechanisms. In addition, the potential medical applications of this knowledge are discussed, particularly in the diagnosis, prognosis and treatment of diseases. In this sense, circRNAs were found to play a crucial role in DNA repair processes by regulating the expression and activity of proteins involved in various DNA repair pathways. They influence the expression of DNA repair proteins by interacting with their mRNAs, sponging miRNAs that target these mRNAs, regulating transcription factors that bind to their promoters, modulating upstream signalling pathways, and affecting mRNA translation. Furthermore, circRNAs regulate the activity of DNA repair proteins by interacting directly with them, sequestering them in specific cellular compartments and controlling activation signalling or upstream DDR signalling.