Circular RNA circPBX3 promotes cisplatin resistance of ovarian cancer cells via interacting with IGF2BP2 to stabilize ATP7A mRNA expression

The emerging role of circular RNAs in cisplatin resistance in ovarian cancer: From molecular mechanism to future potential

Ovarian cancer (OC) is the most common cause of death in female cancers. The prognosis of OC is very poor due to delayed diagnosis and identification of most patients in advanced stages, metastasis, recurrence, and resistance to chemotherapy. As chemotherapy with platinum-based drugs such as cisplatin (DDP) is the main treatment in most OC cases, resistance to DDP is an important obstacle to achieving satisfactory therapeutic efficacy. Consequently, knowing the different molecular mechanisms involved in resistance to DDP is necessary to achieve new therapeutic approaches. According to numerous recent studies, non-coding RNAs (ncRNAs) could regulate proliferation, differentiation, apoptosis, and chemoresistance in many cancers, including OC. Most of these ncRNAs are released by tumor cells into human fluid, allowing them to be used as tools for diagnosis. CircRNAs are ncRNA family members that have a role in the initiation, progression, and chemoresistance regulation of various cancers. In the current study, we investigated the roles of several circRNAs and their signaling pathways on OC progression and also on DDP resistance during chemotherapy.

Novel insights into cuproptosis inducers and inhibitors

Cuproptosis is a new pattern of Cu-dependent cell death distinct from classic cell death pathways and characterized by aberrant lipoylated protein aggregation in TCA cycle, Fe-S cluster protein loss, HSP70 elevation, proteotoxic and oxidative stress aggravation. Previous studies on Cu homeostasis and Cu-induced cell death provide a great basis for the discovery of cuproptosis. It has gradually gathered enormous research interests and large progress has been achieved in revealing the metabolic pathways and key targets of cuproptosis, due to its role in mediating some genetic, neurodegenerative, cardiovascular and tumoral diseases. In terms of the key targets in cuproptosis metabolic pathways, they can be categorized into three types: oxidative stress, mitochondrial respiration, ubiquitin-proteasome system. And strategies for developing cuproptosis inducers and inhibitors involved in these targets have been continuously improved. Briefly, based on the essential cuproptosis targets and metabolic pathways, this paper classifies some relevant inducers and inhibitors including small molecule compounds, transcription factors and ncRNAs with the overview of principle, scientific and medical application, in order to provide reference for the cuproptosis study and target therapy in the future.

The Emerging Role of IGF2BP2 in Cancer Therapy Resistance: From Molecular Mechanism to Future Potential

Tumor resistance is one of the primary reasons for cancer treatment failure, significantly limiting the options and efficacy of cancer therapies. Therefore, overcoming resistance has become a critical factor in improving cancer treatment outcomes. IGF2BP2, as a reader of m6A methylation, plays a pivotal role in the post-transcriptional regulation of RNA through the methylation of m6A sites. It not only contributes to cancer initiation and progression but also plays a key role in tumor drug resistance. This review provides a comprehensive summary of the mechanisms by which IGF2BP2 contributes to therapy resistance, with the aim of improving the efficacy of chemotherapy in cancer treatment. Advancing research in this area is crucial for developing more effective therapies that could significantly improve the quality of life for cancer patients.

The role of circular RNA targeting IGF2BPs in cancer-a potential target for cancer therapy

Circular RNAs (circRNAs) are an interesting class of conserved single-stranded RNA molecules derived from exon or intron sequences produced by the reverse splicing of precursor mRNA. CircRNAs play important roles as microRNA sponges, gene splicing and transcriptional regulators, RNA-binding protein sponges, and protein/peptide translation factors. Abnormal functions of circRNAs and RBPs in tumor progression have been widely reported. Insulin-like growth factor-2 mRNA-binding proteins (IGF2BPs) are a highly conserved family of RBPs identified in humans that function as post-transcriptional fine-tuners of target transcripts. Emerging evidence suggests that IGF2BPs regulate the processing and metabolism of RNA, including its stability, translation, and localization, and participate in a variety of cellular functions and pathophysiology. In this review, we have summarized the roles and molecular mechanisms of circRNAs and IGF2BPs in cancer development and progression. In addition, we briefly introduce the role of other RNAs and IGF2BPs in cancer, discuss the current clinical applications and challenges faced by circRNAs and IGF2BPs, and propose future directions for this promising research field.

Molecular mechanisms of cisplatin resistance in ovarian cancer

Ovarian cancer is one of the most common malignant tumors of the female reproductive system. The majority of patients with advanced ovarian cancer are mainly treated with cisplatin-based chemotherapy. As the most widely used first-line anti-neoplastic drug, cisplatin produces therapeutic effects through multiple mechanisms. However, during clinical treatment, cisplatin resistance has gradually emerged, representing a challenge for patient outcome improvement. The mechanism of cisplatin resistance, while known to be complex and involve many processes, remains unclear. We hope to provide a new direction for pre-clinical and clinical studies through this review on the mechanism of ovarian cancer cisplatin resistance and methods to overcome drug resistance.

Epithelial splicing regulatory protein 1 promotes peritoneal dissemination of ovarian cancer by inducing the formation of circular RNAs modulating epithelial plasticity

Peritoneal metastases prevalently occur in ovarian cancer, deteriorating patient prognosis. During the metastatic cascade, tumor plasticity enables cells to adapt to environmental changes, thereby facilitating dissemination. We previously found that epithelial splicing regulatory protein 1 (ESRP1) is linked to peritoneal metastasis and epithelial-mesenchymal plasticity in ovarian cancer. This study delves into the underlying mechanism. We found that ESRP1 preserves epithelial plasticity in ovarian cancer cells in vitro and in vivo. Functionally, ESRP1 enhances ovarian cancer cell growth and peritoneal dissemination. High-throughput sequencing revealed several ESRP1-related epithelial RNAs, encompassing both linear and circular forms. Specifically, ESRP1 triggers the cyclization of circPAFAH1B2 and circUBAP2 through binding to the GGU sequences in adjacent introns. The two ESRP1-induced circular RNAs stabilize DKK3 and AHR mRNAs, which are critical for epithelial plasticity, through interaction with IGF2BP2. Collectively, ESRP1 triggers the formation of circPAFAH1B2 and circUBAP2, which in turn stabilizes DKK3 and AHR through IGF2BP2 binding, thereby modulating the epithelial plasticity and aiding the peritoneal spread of ovarian cancer cells. The findings unveiled a biological network, orchestrated by ESRP1, that governs the epithelial-mesenchymal plasticity of ovarian cancer cells, emphasizing the therapeutic potential of ESRP1 and its induced circular RNAs for ovarian cancer treatment.

Nanodrugs based on co-delivery strategies to combat cisplatin resistance

Cisplatin (CDDP), as a broad-spectrum anticancer drug, is able to bind to DNA and inhibit cell division. Despite the widespread use of cisplatin since its discovery, cisplatin resistance developed during prolonged chemotherapy, similar to other small molecule chemotherapeutic agents, severely limits its clinical application. Cisplatin resistance in cancer cells is mainly caused by three reasons: DNA repair, decreased cisplatin uptake/increased efflux, and cisplatin inactivation. In earlier combination therapies, the emergence of multidrug resistance (MDR) in cancer cells prevented the achievement of the desired therapeutic effect even with the accurate combination of two chemotherapeutic drugs. Therefore, combination therapy using nanocarriers for co-delivery of drugs is considered to be ideal for alleviating cisplatin resistance and reducing cisplatin-related toxicity in cancer cells. This article provides an overview of the design of cisplatin nano-drugs used to combat cancer cell resistance, elucidates the mechanisms of action of cisplatin and the pathways through which cancer cells develop resistance, and finally discusses the design of drugs and related carriers that can synergistically reduce cancer resistance when combined with cisplatin.

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.

Circular RNAs in EMT-driven metastasis regulation: modulation of cancer cell plasticity, tumorigenesis and therapy resistance

The non-coding RNAs comprise a large part of human genome lack of capacity in encoding functional proteins. Among various members of non-coding RNAs, the circular RNAs (circRNAs) have been of importance in the pathogenesis of human diseases, especially cancer. The circRNAs have a unique closed loop structure and due to their stability, they are potential diagnostic and prognostic factors in cancer. The increasing evidences have highlighted the role of circRNAs in the modulation of proliferation and metastasis of cancer cells. On the other hand, metastasis has been responsible for up to 90% of cancer-related deaths in patients, requiring more investigation regarding the underlying mechanisms modulating this mechanism. EMT enhances metastasis and invasion of tumor cells, and can trigger resistance to therapy. The cells demonstrate dynamic changes during EMT including transformation from epithelial phenotype into mesenchymal phenotype and increase in N-cadherin and vimentin levels. The process of EMT is reversible and its reprogramming can disrupt the progression of tumor cells. The aim of current review is to understanding the interaction of circRNAs and EMT in human cancers and such interaction is beyond the regulation of cancer metastasis and can affect the response of tumor cells to chemotherapy and radiotherapy. The onco-suppressor circRNAs inhibit EMT, while the tumor-promoting circRNAs mediate EMT for acceleration of carcinogenesis. Moreover, the EMT-inducing transcription factors can be controlled by circRNAs in different human tumors.

RNA binding proteins in cancer chemotherapeutic drug resistance

Drug resistance has been a major obstacle in the quest for a cancer cure. Many chemotherapeutic treatments fail to overcome chemoresistance, resulting in tumor remission. The exact process that leads to drug resistance in many cancers has not been fully explored or understood. However, the discovery of RNA binding proteins (RBPs) has provided insight into various pathways and post-transcriptional gene modifications involved in drug tolerance. RBPs are evolutionarily conserved proteins, and their abnormal gene expression has been associated with cancer progression. Additionally, RBPs are aberrantly expressed in numerous neoplasms. RBPs have also been implicated in maintaining cancer stemness, epithelial-to-mesenchymal transition, and other processes. In this review, we aim to provide an overview of RBP-mediated mechanisms of drug resistance and their implications in cancer malignancy. We discuss in detail the role of major RBPs and their correlation with noncoding RNAs (ncRNAs) that are associated with the inhibition of chemosensitivity. Understanding and exploring the pathways of RBP-mediated chemoresistance will contribute to the development of improved cancer diagnosis and treatment strategies.

The role of circRNAs in regulation of drug resistance in ovarian cancer

Ovarian cancer is one of the female reproductive system tumors. Chemotherapy is used for advanced ovarian cancer patients; however, drug resistance is a pivotal cause of chemotherapeutic failure. Hence, it is critical to explore the molecular mechanisms of drug resistance of ovarian cancer cells and to ameliorate chemoresistance. Noncoding RNAs (ncRNAs) have been identified to critically participate in drug sensitivity in a variety of human cancers, including ovarian cancer. Among ncRNAs, circRNAs sponge miRNAs and prevent miRNAs from regulation of their target mRNAs. CircRNAs can interact with DNA or proteins to modulate gene expression. In this review, we briefly describe the biological functions of circRNAs in the development and progression of ovarian cancer. Moreover, we discuss the underneath regulatory molecular mechanisms of circRNAs on governing drug resistance in ovarian cancer. Furthermore, we mention the novel strategies to overcome drug resistance via targeting circRNAs in ovarian cancer. Due to that circRNAs play a key role in modulation of drug resistance in ovarian cancer, targeting circRNAs could be a novel approach for attenuation of chemoresistance in ovarian cancer.

Insulin-like growth factor 2 mRNA-binding protein 2 is a therapeutic target in ovarian cancer

Ovarian cancer (OC) is a fatal gynecologic disease. The most common treatment for OC patients is surgery combined with chemotherapy but most patients at advanced stages eventually develop relapse due to chemoresistance. This study examined the role and function of insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) in OC. We observed that the expression of IGF2BP2 mRNA and protein was up-regulated in OC cells and tissues using quantitative real-time polymerase chain reaction (qRT-PCR) and western blot, respectively. An increase in IGF2BP2 expression at mRNA and protein levels was verified by the analyses of The Cancer Genome Atlas (TCGA) and Clinical Proteomic Tumor Analysis Consortium (CPTAC), respectively. Gene Expression Omnibus (GEO) and Cancer Cell Line Encyclopedia (CCLE) databases were applied to analyze the expression and clinical value of IGF2BP2. Gene set enrichment analysis (GSEA), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Ontology (GO) analyses explored biological functions and the involvement of IGF2BP2 in cell growth. Indeed, the knockdown of IGF2BP2 resulted in the inhibition of OC cell proliferation evaluated by the Cell Counting Kit-8 assay. Genomic amplification of IGF2BP2 partly accounted for its overexpression. High expression of IGF2BP2 was associated with signal transducer and activator of transcription 1 (STAT1) and drug sensitivity and was correlated with an unfavorable survival outcome in OC patients. Furthermore, the responsiveness of chemotherapy and immunotherapy were analyzed using the "pRRophetic" R package and The Cancer Immune Atlas (TCIA) database, respectively. The low expression of IGF2BP2 was associated with chemoresistance but with high tumor microenvironment scores and tumor-infiltrating immune cells, suggesting that immunotherapy may apply in chemoresistant patients. The alteration of IGF2BP2 expression may respond to chemotherapy and immunotherapy. Thus, IGF2BP2 shows potential as a therapeutic target and diagnostic biomarker for OC.

Circ-AMOTL1 enhances cardiac fibrosis through binding with EIF4A3 and stabilizing MARCKS expression in diabetic cardiomyopathy

OBJECTIVE

To evaluate the effects and possible mechanisms of circular RNAs (circRNAs) on diabetic myocardial fibrosis (DMF).

METHODS

We used an in vivo mice model of streptozotocin (STZ)-induced diabetes and conducted in vitro studies using cultured mouse cardiac fibroblast cells (CFs).

RESULTS

We found that the expression of circ-AMOTL1 was significantly upregulated in the myocardial tissue of diabetic mice compared to that in normal tissues. Inhibition of circ-AMOTL1 improved cardiac function in mice with type I diabetes and significantly repressed STZ-induced myocardial mesenchymal and perivascular fibrosis. In addition, silencing circ-AMOTL1 inhibited cell proliferation, decreased the expression levels of TGF-β1, collagen 1, collagen III, and α-SMA, and reduced the levels of ROS and NO in HG-treated CFs. Our data also indicated that silencing circ-AMOTL1 significantly reduced the expression of myristoylated alanine-rich C-kinase substrate (MARCKS). Finally, circ-AMOTL1 combined with the RNA-binding protein EIF4A3 to improve MARCKS stability. Moreover, co-transfection with si-circ-AMOTL1 and MARCKS reversed the effects of si-circ-AMOTL1 on cell proliferation, fibrotic marker proteins, and ROS and NO levels in vitro.

CONCLUSION

Our data suggest that circ-AMOTL1 plays a key role in STZ-induced DMF by modulating MARCKS, and that targeting circ-AMOTL1 may be a potential strategy to treat DMF.

The mechanism of copper transporters in ovarian cancer cells and the prospect of cuproptosis

Copper transporters can not only carry copper (Cu) to maintain the homeostasis of Cu in cells but also transport platinum-based chemotherapy drugs. The effect of copper transporters on chemosensitivity has been demonstrated in a variety of malignancies. In addition, recent studies have reported that copper transporters can act as vectors to induce cuproptosis. Therefore, copper transporters can act on cells through different mechanisms to achieve different purposes. This review mainly describes the current research progress of the intracellular transport mechanism of copper transporters and cuproptosis, and prospects for the application of them in the treatment of ovarian cancer (OC).

RNA epigenetic modifications in ovarian cancer: The changes, chances, and challenges

Ovarian cancer (OC) is the most common female cancer worldwide. Patients with OC have high mortality because of its complex and poorly understood pathogenesis. RNA epigenetic modifications, such as m6 A, m1 A, and m5 C, are closely associated with the occurrence and development of OC. RNA modifications can affect the stability of mRNA transcripts, nuclear export of RNAs, translation efficiency, and decoding accuracy. However, there are few overviews that summarize the link between m6 A RNA modification and OC. Here, we discuss the molecular and cellular functions of different RNA modifications and how their regulation contributes to the pathogenesis of OC. By improving our understanding of the role of RNA modifications in the etiology of OC, we provide new perspectives for their use in OC diagnosis and treatment. This article is categorized under: RNA Processing > RNA Editing and Modification RNA in Disease and Development > RNA in Disease.

Circular RNAs in gynecologic cancers: mechanisms and implications for chemotherapy resistance

Chemotherapy resistance remains a major challenge in the treatment of gynecologic malignancies. Increasing evidence suggests that circular RNAs (circRNAs) play a significant role in conferring chemoresistance in these cancers. In this review, we summarize the current understanding of the mechanisms by which circRNAs regulate chemotherapy sensitivity and resistance in gynecologic malignancies. We also discuss the potential clinical implications of these findings and highlight areas for future research. CircRNAs are a novel class of RNA molecules that are characterized by their unique circular structure, which confers increased stability and resistance to degradation by exonucleases. Recent studies have shown that circRNAs can act as miRNA sponges, sequestering miRNAs and preventing them from binding to their target mRNAs. This can lead to upregulation of genes involved in drug resistance pathways, ultimately resulting in decreased sensitivity to chemotherapy. We discuss several specific examples of circRNAs that have been implicated in chemoresistance in gynecologic cancers, including cervical cancer, ovarian cancer, and endometrial cancer. We also highlight the potential clinical applications of circRNA-based biomarkers for predicting chemotherapy response and guiding treatment decisions. Overall, this review provides a comprehensive overview of the current state of knowledge regarding the role of circRNAs in chemotherapy resistance in gynecologic malignancies. By elucidating the underlying mechanisms by which circRNAs regulate drug sensitivity, this work has important implications for improving patient outcomes and developing more effective therapeutic strategies for these challenging cancers.

Establishment and experimental validation of a novel cuproptosis-related gene signature for prognostic implication in cholangiocarcinoma

Background

Cholangiocarcinoma (CCA) is a highly malignant, heterogeneous bile duct malignancy with poor treatment options. A novel type of cell death termed cuproptosis was recently demonstrated to closely correlate with tumor progression. To gain more insight into the role of cuproptosis in CCA, we investigated the prognostic implications of cuproptosis related genes (CRGs) and their relationship to the development of CCA.

Methods

Gene expression data for CCA were obtained from the European Bioinformatics Institute (EMBL-EBI) database. Least absolute shrinkage and selection operator (LASSO) penalized Cox regression was used to construct a prognostic risk model based on CRGs. RNA-seq, qRT-PCR and immunohistochemistry staining were used to verify the expression of CRGs in human CCA tissues or cell lines. Further in vitro experiments were performed to demonstrate the role of cuproptosis in CCA.

Results

We established a 4-gene signature (ATP7A, FDX1, DBT and LIAS) that exhibited good stability and was an independent prognostic factor for CCA. Seventy-five CCA samples were divided into high- and low-risk groups based on the risk score. Enrichment analysis revealed increased extracellular activity in the high-risk group and increased lipid metabolic activity in the low-risk group. Moreover, the 4 signature genes were verified in clinical samples and cell lines by RNA-seq, qRT-PCR and immunohistochemistry. Further experiments confirmed that cuproptosis can significantly inhibit the viability of CCA cells. Knockdown of the key gene LIAS ameliorated the toxicity of cuproptosis to CCA cells.

Conclusion

We established a 4-gene prognostic signature based on cuproptosis and explored the role of cuproptosis in CCA. The results provide an effective indicator for predicting the prognosis of cuproptosis in CCA.

Circular RNAs in Epithelial Ovarian Cancer: From Biomarkers to Therapeutic Targets

Epithelial ovarian cancer (EOC) is the most lethal gynecological cancer, and more than 70% of patients are diagnosed at advanced stages. Despite the application of surgery and chemotherapy, the prognosis remains poor due to the high relapse rate. It is urgent to identify novel biomarkers and develop novel therapeutic strategies for EOC. Circular RNAs (circRNAs) are a class of noncoding RNAs generated from the "back-splicing" of precursor mRNA. CircRNAs exert their functions via several mechanisms, including acting as miRNA sponges, interacting with proteins, regulating transcription, and encoding functional proteins. Recent studies have identified many circRNAs that are dysregulated in EOC and may be used as diagnostic and prognostic markers. Increasing evidence has revealed that circRNAs play a critical role in ovarian cancer progression by regulating various cellular processes, including proliferation, apoptosis, metastasis, and chemosensitivity. The circRNA-based therapy may be a novel strategy that is worth exploring in the future. Here, we provide an overview of EOC and circRNA biogenesis and functions. We then discuss the dysregulations of circRNAs in EOC and the possibility of using them as diagnostic/prognostic markers. We also summarize the role of circRNAs in regulating ovarian cancer development and speculate their potential as therapeutic targets.