Exosomes loaded with circPARD3 promotes EBV-miR-BART4-induced stemness and cisplatin resistance in nasopharyngeal carcinoma side population cells through the miR-579-3p/SIRT1/SSRP1 axis

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.

Exosomes: a significant medium for regulating drug resistance through cargo delivery

Exosomes are small lipid nanovesicles with a diameter of 30-150 nm. They are present in all body fluids and are actively secreted by the majority of cells through the process of exocytosis. Exosomes play an essential role in intercellular communication and act as significant molecular carriers in regulating various physiological and pathological processes, such as the emergence of drug resistance in tumors. Tumor-associated exosomes transfer drug resistance to other tumor cells by releasing substances such as multidrug resistance proteins and miRNAs through exosomes. These substances change the cell phenotype, making it resistant to drugs. Tumor-associated exosomes also play a role in impacting drug resistance in other cells, like immune cells and stromal cells. Exosomes alter the behavior and function of these cells to help tumor cells evade immune surveillance and form a tumor niche. In addition, exosomes also export substances such as tumoricidal drugs and neutralizing antibody drugs to help tumor cells resist drug therapy. In this review, we summarize the mechanisms of exosomes in promoting drug resistance by delivering cargo in the context of the tumor microenvironment (TME).

Targeting histone deacetylases in head and neck squamous cell carcinoma: molecular mechanisms and therapeutic targets

The onerous health and economic burden associated with head and neck squamous cell carcinoma (HNSCC) is a global predicament. Despite the advent of novel surgical techniques and therapeutic protocols, there is an incessant need for efficacious diagnostic and therapeutic targets to monitor the invasion, metastasis and recurrence of HNSCC due to its substantial morbidity and mortality. The differential expression patterns of histone deacetylases (HDACs), a group of enzymes responsible for modifying histones and regulating gene expression, have been demonstrated in neoplastic tissues. However, there is limited knowledge regarding the role of HDACs in HNSCC. Consequently, this review aims to summarize the existing research findings and explore the potential association between HDACs and HNSCC, offering fresh perspectives on therapeutic approaches targeting HDACs that could potentially enhance the efficacy of HNSCC treatment. Additionally, the Cancer Genome Atlas (TCGA) dataset, CPTAC, HPA, OmicShare, GeneMANIA and STRING databases are utilized to provide supplementary evidence on the differential expression of HDACs, their prognostic significance and predicting functions in HNSCC patients.

Emerging roles of circular RNAs in nasopharyngeal carcinoma: functions and implications

Nasopharyngeal carcinoma (NPC) is a distinct malignancy primarily prevalent in Southern China and Southeast Asia. Circular RNAs (circRNAs), a class of non-coding RNAs, are evolutionarily conserved and exhibit remarkable stability. Their dysregulation has been observed in various cancers, including NPC. In this review, we investigate the pivotal role of circRNAs in NPC, focusing specifically on their involvement in tumor proliferation, apoptosis, metastasis, angiogenesis, stemness, metabolism, and the tumor microenvironment. We highlight the diagnostic and prognostic potential of circRNAs in NPC, emphasizing their utility as biomarkers for early detection, disease monitoring, and prediction of treatment outcomes. Additionally, we explore the therapeutic implications of circRNAs in NPC, highlighting their potential for targeted therapies.

Androgen-repressed lncRNA LINC01126 drives castration-resistant prostate cancer by regulating the switch between O-GlcNAcylation and phosphorylation of androgen receptor

BACKGROUND

Prostate cancer (PCa) initially shows satisfactory response to therapies targeting the androgen receptor (AR). However, progression to a castration-resistant stage indicates poor prognosis in PCa patients. AR signalling still plays a central role in most castration-resistant prostate cancers (CRPC). Therefore, unveiling the mechanisms of AR reactivation under androgen-deprived conditions is imperative to discover novel therapeutic targets for CRPC.

METHODS

Using an integrative analysis of the transcriptomics of three independent PCa cohorts and a published landscape of AR-regulated long non-coding RNA (lncRNA), lncRNA LINC01126 was selected as a candidate gene that could drive CRPC progression for further study. Quantitative reverse transcription polymerase chain reaction, in situ hybridisation (ISH) and fluorescent ISH were performed to detect LINC01126 in PCa tissues and cells. The functional role and mechanism of LINC01126 were further investigated using in vitro and in vivo gain and loss of function assays.

RESULTS

LINC01126, identified as an AR-repressed lncRNA, was significantly upregulated after AR-targeted therapies. In addition, we found that LINC01126 was upregulated in CRPC and was associated with poor prognosis. We also proved that LINC01126 stabilised AR protein and enhanced AR nuclear translocation and transactivation by promoting the transition from O-GlcNAcylation at threonine 80 to phosphorylation at serine 81 (S81) within the AR protein. Mechanism analysis revealed that LINC01126 facilitates the interaction of CDK9 with AR and impedes the binding of O-linked N-acetylglucosamine (O-GlcNAc) transferase to AR. Consequently, LINC01126 expression was sufficient to activate AR signalling without androgen. LINC01126 overexpression increased, whereas LINC01126 knockdown decreased castration resistance traits in PCa cells in vitro and in vivo. Furthermore, our data showed that LINC01126-targeting antisense oligonucleotides (ASO) substantially inhibited CRPC cells in vitro.

CONCLUSIONS

Our research expands the functions of AR-regulated lncRNA in sustaining androgen-independent AR activity and promoting CRPC progression and reveals that LINC01126 may be a new therapeutic target for PCa.

Recent advances of exosomal circRNAs in cancer and their potential clinical applications

Circular RNA (circRNA) is a type of non-coding RNA that forms a covalently closed, uninterrupted loop. The expression of circRNA differs among cell types and tissues, and various circRNAs are aberrantly expressed in a variety of diseases, including cancer. Aberrantly expressed circRNAs contribute to disease progression by acting as microRNA sponges, functional protein sponges, or novel templates for protein translation. Recent studies have shown that circRNAs are enriched in exosomes. Exosomes are spherical bilayer vesicles released by cells into extracellular spaces that mediate intercellular communication by delivering cargoes. These cargoes include metabolites, proteins, lipids, and RNA molecules. Exosome-mediated cell-cell or cell-microenvironment communications influence the progression of carcinogenesis by regulating cell proliferation, angiogenesis, metastasis as well as immune escape. In this review, we summarize the current knowledge about exosomal circRNAs in cancers and discuss their specific functions in tumorigenesis. Additionally, we discuss the potential value of exosomal circRNAs as diagnostic biomarkers and the potential applications of exosomal circRNA-based cancer therapy.

Exosomal circular RNAs: A chief culprit in cancer chemotherapy resistance

Chemotherapy is one of the primary treatments for malignant tumors. However, the acquired drug resistance hinders clinical efficacy and leads to treatment failure in most patients. Exosomes are cell-derived vesicles with a diameter of 30-150 nm carrying and delivering substances such as DNAs, RNAs, lipids, and proteins for cellular communication in tumor development. Circular RNAs (circRNAs) present covalently closed-loop RNA structures, which regulate tumor cell proliferation, apoptosis, and metastasis by controlling different genes and signaling pathways. CircRNAs are abundant and stably expressed in exosomes. Recent studies have shown that they play critical roles in chemotherapy resistance in various cancers. In this review, we summarized the origin of exosomes and discussed the regulation mechanism of exosomal circRNAs in cancer drug resistance.

Circ_0000182 promotes cholesterol synthesis and proliferation of stomach adenocarcinoma cells by targeting miR-579-3p/SQLE axis

BACKGROUND

Circular RNAs (circRNAs) or cholesterol metabolism have been demonstrated to participate in stomach adenocarcinoma (STAD) progression. However, the relationship between circRNAs and cholesterol metabolism in STAD and its underlined mechanism remain unclear.

METHODS

RNA and protein expression levels were detected by qRT-PCR and Western blot. Cell proliferation was assessed by CCK-8, EdU incorporation and colony formation assays. Total cholesterol (TC) and free cholesterol (FC) levels were measured by the corresponding kits. The relationships between circ_0000182 and miR-579-3p or squalene epoxidase (SQLE) mRNA were investigated by bioinformatics analysis, RNA-RNA pull-down, luciferase reporter and RIP assays.

RESULTS

We found that circ_0000182 expression was significantly up-regulated in both STAD tissues and cell lines, and high circ_0000182 expression was correlated with increased tumor size. Circ_0000182 promoted cell proliferation and cholesterol synthesis of STAD cells. Accordingly, cell proliferation, cholesterol synthesis and SQLE expression were significantly inhibited by circ_0000182 knockdown in STAD cells, and these effects were partly reversed by miR-579-3p inhibition or SQLE over-expression. Furthermore, we identified that circ_0000182 acted as a competing endogenous RNA (ceRNA) by sponging miR-579-3p, thereby facilitating SQLE expression, cholesterol synthesis and cell proliferation.

CONCLUSION

Circ_0000182 promotes cholesterol synthesis and proliferation of STAD cells by enhancing SQLE expression via sponging miR-579-3p.

Transcriptomic and Proteomic Profiles for Elucidating Cisplatin Resistance in Head-and-Neck Squamous Cell Carcinoma

To identify the novel genes involved in chemoresistance in head and neck squamous cell carcinoma (HNSCC), we explored the expression profiles of the following cisplatin (CDDP) resistant (R) versus parental (sensitive) cell lines by RNA-sequencing (RNA-seq): JHU029, HTB-43 and CCL-138. Using the parental condition as a control, 30 upregulated and 85 downregulated genes were identified for JHU029-R cells; 263 upregulated and 392 downregulated genes for HTB-43-R cells, and 154 upregulated and 68 downregulated genes for CCL-138-R cells. Moreover, we crossed-checked the RNA-seq results with the proteomic profiles of HTB-43-R (versus HTB-43) and CCL-138-R (versus CCL-138) cell lines. For the HTB-43-R cells, 21 upregulated and 72 downregulated targets overlapped between the proteomic and transcriptomic data; whereas in CCL-138-R cells, four upregulated and three downregulated targets matched. Following an extensive literature search, six genes from the RNA-seq (CLDN1, MAGEB2, CD24, CEACAM6, IL1B and ISG15) and six genes from the RNA-seq and proteomics crossover (AKR1C3, TNFAIP2, RAB7A, LGALS3BP, PSCA and SSRP1) were selected to be studied by qRT-PCR in 11 HNSCC patients: six resistant and five sensitive to conventional therapy. Interestingly, the high MAGEB2 expression was associated with resistant tumours and is revealed as a novel target to sensitise resistant cells to therapy in HNSCC patients.

Exosomes in the tumor microenvironment: Promoting cancer progression

Exosomes, which are extracellular vesicles produced by endosomes, are important performers of intercellular communication functions. For more than three decades, there has been a growing awareness of exosomes as the contents of the tumor microenvironment and their intimate connection to the development of cancer. The composition, generation, and uptake of exosomes as well as their roles in tumor metastasis, angiogenesis, and immunosuppression are discussed in this paper. In order to stop the progression of cancer, it is crucial to find new diagnostic biomarkers and therapeutic targets for the disease. Knowing the biological characteristics of exosomes and their functions in tumor development helps in this endeavor.