circ_PPAPDC1A promotes Osimertinib resistance by sponging the miR-30a-3p/ IGF1R pathway in non-small cell lung cancer (NSCLC).

BACKGROUND: Recent evidence has demonstrated that abnormal expression and regulation of circular RNA (circRNAs) are involved in the occurrence and development of a variety of tumors. The aim of this study was to investigate the effects of circ_PPAPDC1A in Osimertinib resistance in NSCLC. METHODS: Human circRNAs microarray analysis was conducted to identify differentially expressed (DE) circRNAs in Osimertinib-acquired resistance tissues of NSCLC. The effect of circ_PPAPDC1A on cell proliferation, invasion, migration, and apoptosis was assessed in both in vitro and in vivo. Dual-luciferase reporter assay, RT-qPCR, Western-blot, and rescue assay were employed to confirm the interaction between circ_PPAPDC1A/miR-30a-3p/IGF1R axis. RESULTS: The results revealed that circ_PPAPDC1A was significantly upregulated in Osimertinib acquired resistance tissues of NSCLC. circ_PPAPDC1A reduced the sensitivity of PC9 and HCC827 cells to Osimertinib and promoted cell proliferation, invasion, migration, while inhibiting apoptosis in Osimertinib-resistant PC9/OR and HCC829/OR cells, both in vitro and in vivo. Silencing circ_PPAPDC1A partially reversed Osimertinib resistance. Additionally, circ_PPAPDC1A acted as a competing endogenous RNA (ceRNA) by targeting miR-30a-3p, and Insulin-like Growth Factor 1 Receptor (IGF1R) was identified as a functional gene for miR-30a-3p in NSCLC. Furthermore, the results confirmed that circ_PPAPDC1A/miR-30a-3p/IGF1R axis plays a role in activating the PI3K/AKT/mTOR signaling pathway in NSCLC with Osimertinib resistance. CONCLUSIONS: Therefore, for the first time we identified that circ_PPAPDC1A was significantly upregulated and exerts an oncogenic role in NSCLC with Osimertinib resistance by sponging miR-30a-3p to active IGF1R/PI3K/AKT/mTOR pathway. circ_PPAPDC1A may serve as a novel diagnostic biomarker and therapeutic target for NSCLC patients with Osimertinib resistance.

CircHIF1A induces cetuximab resistance in colorectal cancer by promoting HIF1α-mediated glycometabolism alteration.

Epidermal growth factor receptor (EGFR)-targeted therapy is an important treatment for RAS wild-type metastatic colorectal cancer (mCRC), but the resistance mechanism remains unclear. Here, the differential expression of circRNAs between Cetuximab sensitive and resistant cell lines was analyzed using whole-transcriptome sequencing. We identified that the expression of circHIF1A was significantly higher in LIM1215-R than in LIM1215. When treated with Cetuximab, downregulation of circHIF1A level weakened the proliferation and clonal formation ability of LIM1215-R, caused more cells to enter G0-G1 phase, and significantly reduced the basal respiration, ATP production, and maximal respiration, as well as the glycolytic capacity and glycolytic reserve. The response rate and prognosis of circHIF1A-positive patients were inferior to those of negative patients. Mechanistically, circHIF1A can upregulate the level of hypoxia-inducible factor 1 A (HIF1A) by competitively binding to miR-361-5p, inducing the overexpression of enzymes such as glucose transporter 1 (GLUT1) and lactate dehydrogenase A (LDHA). In a xenograft model, inhibition of circHIF1A expression increased the sensitivity to Cetuximab treatment. In conclusion, circHIF1A can promote HIF1α-mediated glycometabolism alteration to induce Cetuximab resistance in CRC. It has the potential to become a screening indicator for the Cetuximab beneficial population in mCRC and a new therapeutic target for enhancing treatment efficacy.

FOXA1 co-activates circODC1 and ODC1 in HPV-positive cervical cancer cell growth.

As demonstrated in previous research, hsa_circ_0052602 (circODC1) is dynamically expressed in HPV-positive cervical cancer (CC). CircODC1 expression was quantified using qRT-PCR, and its role in CC cell growth was assessed via loss-of-function assays. Interactions between miR-607 and circODC1 or ODC1 were confirmed using bioinformatics and mechanistic assays. The association of FOXA1 with the circODC1 promoter was validated through ChIP and luciferase reporter assays. CircODC1 was highly expressed in HPV-positive CC cell lines, and its depletion significantly impeded malignant processes such as proliferation, migration, and invasion. We found that ODC1 also played an oncogenic role in HPV-positive CC cells. CircODC1 was shown to positively regulate ODC1 as a ceRNA, competitively binding to miR-607 to counteract its suppression of ODC1. HPV-associated FOXA1 was identified as a potential transcription factor of circODC1. Restoration experiments showed that overexpression of circODC1 could counterbalance the inhibitory effect of FOXA1 knockdown. These findings offer new insights into therapeutic strategies for HPV-positive CC patients.

Hsa_Circ_0002762 may be a New Marker for the Gastric Cancer Diagnosis and Prognosis.

BACKGROUND: The global incidence and mortality rate of gastric carcinoma (GC) persists at elevated levels, often manifesting no overt symptoms in its early stages. Hsa_circ_0002762 has been identified as an important modulator in cervical cancer. This study aims to explore its role in the context of GC. METHODS: A quantitative real-time polymerase chain reaction (qPCR) was implemented to assess the expression level of hsa_circ_0002762. The over-expression was confirmed through an examination of 28 cases of gastric cancer and their corresponding adjacent tissues. In addition, plasma samples from 78 healthy individuals, from 45 benign gastritis patients, and from 106 gastric cancer patients were collected, and the diagnostic efficacy was assessed by analyzing the receiver operating characteristic (ROC) curve. Simultaneously, postoperative specimens from 36 GC cases were collected, and a Kaplan-Meier survival analysis curve was used to evaluate the prognosis of GC. RESULTS: The study revealed an up-regulation in the expression of hsa_circ_0002762 in gastric cancer plasma and tissues. The area under the receiver operating characteristic (ROC) curve for serum hsa_circ_0002762 was 0.784 (95% CI: 0.719 - 0.851), indicating a higher diagnostic efficiency compared to CEA (0.687, 95% CI: 0.611 - 0.763) and CA199 (0.699, 95% CI: 0.625 - 0.744). Combining these three biomarkers demonstrated an increased sensitivity in the diagnostic effectiveness. Finally, postoperative dynamic monitoring revealed a practical utility in predicting the clinical prognosis using serum has_circ_0002762. CONCLUSIONS: The findings from our study suggest that hsa_circ_0002762 holds promise as a novel diagnostic and prognostic marker for individuals with GC.

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.

CircSCNN1A inhibits the proliferation, migration and invasion of renal cell carcinoma cells by decreasing CLDN8 expression through miR-590-5p.

BACKGROUND: Increasing evidence suggests that circular RNA (circRNA) plays a regulatory role in the progression of renal cell carcinoma (RCC). However, the precise function and underlying mechanism of circSCNN1A in RCC progression still remain unclear. METHODS: The expression levels of circSCNN1A, microRNA-590-5p (miR-590-5p), claudin 8 (CLDN8), cyclin D1, matrix metalloprotein 2 (MMP2), MMP9, E-cadherin, N-cadherin and vimentin were detected by a quantitative real-time polymerase chain reaction and Western blotting analysis. Immunohistochemistry assay was performed to analyze the positive expression rate of CLDN8. Cell proliferation was investigated by cell colony formation, 5-Ethynyl-2'-deoxyuridine and DNA content quantitation assays. Cell migration and invasion were assessed by wound-healing and transwell invasion assays. Interactions among circSCNN1A, miR-590-5p and CLDN8 were identified by dual-luciferase reporter assay, RNA immunoprecipitation assay and RNA pull-down assay. Xenograft mouse model assay was conducted to verify the effect of circSCNN1A on tumor formation in vivo. RESULTS: CircSCNN1A and CLDN8 expression were significantly downregulated, while miR-590-5p was upregulated in both RCC tissues and cells. CircSCNN1A overexpression inhibited RCC cell proliferation, migration and invasion, accompanied by decreases of cyclin D1, MMP2, MMP9, N-cadherin and vimentin expression and an increase of E-cadherin expression. CircSCNN1A acted as a miR-590-5p sponge and regulated RCC cell processes by binding to miR-590-5p. CLDN8, a target gene of miR-590-5p, was involved in the regulation of the biological behaviors of RCC cells by miR-590-5p. In addition, circSCNN1A induced CLDN8 production by interacting with miR-590-5p. Further, circSCNN1A suppressed tumor formation in vivo. CONCLUSION: CircSCNN1A inhibited RCC cell proliferation, migration and invasion by regulating the miR-590-5p/CLDN8 pathway.

Involvement of circRNA Regulators MBNL1 and QKI in the Progression of Esophageal Squamous Cell Carcinoma.

OBJECTIVES: To investigate the role of circRNA regulators MBNL1 and QKI in the progression of esophageal squamous cell carcinoma. BACKGROUND: MBNL1 and QKI are pivotal regulators of pre-mRNA alternative splicing, crucial for controlling circRNA production - an emerging biomarker and functional regulator of tumor progression. Despite their recognized roles, their involvement in ESCC progression remains unexplored. METHODS: The expression levels of MBNL1 and QKI were examined in 28 tissue pairs from ESCC and adjacent normal tissues using data from the GEO database. Additionally, a total of 151 ESCC tissue samples, from stage T1 to T4, consisting of 13, 43, 87, and 8 cases per stage, respectively, were utilized for immunohistochemical (IHC) analysis. RNA sequencing was utilized to examine the expression profiles of circRNAs, lncRNAs, and mRNAs across 3 normal tissues, 3 ESCC tissues, and 3 pairs of KYSE150 cells in both wildtype (WT) and those with MBNL1 or QKI knockouts. Transwell, colony formation, and subcutaneous tumorigenesis assays assessed the impact of MBNL1 or QKI knockout on ESCC cell migration, invasion, and proliferation. RESULTS: ESCC onset significantly altered MBNL1 and QKI expression levels, influencing diverse RNA species. Elevated MBNL1 or QKI expression correlated with patient age or tumor invasion depth, respectively. MBNL1 or QKI knockout markedly enhanced cancer cell migration, invasion, proliferation, and tumor growth. Moreover, the absence of either MBNL1 or QKI modulated the expression profiles of multiple circRNAs, causing extensive downstream alterations in the expression of numerous lncRNAs and mRNAs. While the functions of circRNA and lncRNA among the top 20 differentially expressed genes remain unclear, mRNAs like SLCO4C1, TMPRSS15, and MAGEB2 have reported associations with tumor progression. CONCLUSIONS: This study underscores the tumor-suppressive roles of MBNL1 and QKI in ESCC, proposing them as potential biomarkers and therapeutic targets for ESCC diagnosis and treatment.

CircCOX6A1 suppresses osteogenic differentiation and aggravates osteoporosis via miR-512-3p/DYRK2 axis.

BACKGROUND: Osteoporosis (OP), characterized by compromised bone integrity and increased fracture risk, poses a significant health challenge. Circular RNAs (circRNAs) have emerged as crucial regulators in various pathophysiological processes, prompting investigation into their role in osteoporosis. This study aimed to elucidate the involvement of circCOX6A1 in OP progression and understand its underlying molecular mechanisms. The primary objective was to explore the impact of circCOX6A1 on bone marrow-derived mesenchymal stem cells (BMSCs) and its potential interactions with miR-512-3p and DYRK2. METHODS: GSE161361 microarray analysis was employed to assess circCOX6A1 expression in OP patients. We utilized in vitro and in vivo models, including BMSC cultures, osteogenic differentiation assays, and an OVX-induced mouse model of OP. Molecular techniques such as quantitative RT-PCR, western blotting, and functional assays like alizarin red staining (ARS) were employed to evaluate circCOX6A1 effects on BMSC proliferation, apoptosis, and osteogenic differentiation. The interaction between circCOX6A1, miR-512-3p, and DYRK2 was investigated through dual luciferase reporter assays, RNA immunoprecipitation, and RNA pull-down assays. RESULTS: CircCOX6A1 was found to be upregulated in osteoporosis patients, and its expression inversely correlated with osteogenic differentiation of BMSCs. CircCOX6A1 knockdown enhanced osteogenic differentiation, as evidenced by increased mineralized nodule formation and upregulation of osteogenic markers. In vivo, circCOX6A1 knockdown ameliorated osteoporosis progression in OVX mice. Mechanistically, circCOX6A1 acted as a sponge for miR-512-3p, subsequently regulating DYRK2 expression. CONCLUSION: This study provides compelling evidence for the role of circCOX6A1 in osteoporosis pathogenesis. CircCOX6A1 negatively regulates BMSC osteogenic differentiation through the miR-512-3p/DYRK2 axis, suggesting its potential as a therapeutic target for mitigating OP progression.

CircPRELID2 functions as a promoter of renal cell carcinoma through the miR-22-3p/ETV1 cascade.

BACKGROUND: Emerging evidence has indicated that a number of circular RNAs (circRNAs) participate in renal cell carcinoma (RCC) carcinogenesis. Nevertheless, the activity and molecular process of circPRELID2 (hsa_circ_0006528) in RCC progression remain unknown. METHODS: CircPRELID2, miR-22-3p and ETS variant 1 (ETV1) levels were gauged by qRT-PCR. Effect of the circPRELID2/miR-22-3p/ETV1 axis was evaluated by detecting cell growth, motility, and invasion. Immunoblotting assessed related protein levels. The relationships of circPRELID2/miR-22-3p and miR-22-3p/ETV1 were confirmed by RNA immunoprecipitation (RIP), luciferase reporter or RNA pull-down assay. RESULTS: CircPRELID2 was up-regulated in RCC. CircPRELID2 silencing suppressed RCC cell growth, motility and invasion. Moreover, circPRELID2 silencing weakened M2-type macrophage polarization in THP1-induced macrophage cells. CircPRELID2 sequestered miR-22-3p, and circPRELID2 increased ETV1 expression through miR-22-3p. Moreover, the inhibitory impact of circPRELID2 silencing on RCC cell malignant behaviors was mediated by the miR-22-3p/ETV1 axis. Furthermore, circPRELID2 knockdown in vivo hampered growth of xenograft tumors. CONCLUSION: Our study demonstrates that circPRELID2 silencing can mitigate RCC malignant development through the circPRELID2/miR-22-3p/ETV1 axis, highlighting new therapeutic targets for RCC treatment.

The potential role of circular RNAs -regulated PI3K signaling in non-small cell lung cancer: Molecular insights and clinical perspective.

Non-small cell lung cancer (NSCLC), accounting for more than 80% of all cases, is the predominant form of lung cancer and the leading cause of cancer-related deaths worldwide. Significant progress has been made in diagnostic techniques, surgical interventions, chemotherapy protocols, and targeted therapies at the molecular level, leading to enhanced treatment outcomes in patients with NSCLC. Extensive evidence supports the use of circular RNAs (circRNAs), a specific category of naturally occurring non-coding small RNAs (ncRNAs), for the diagnosis, monitoring of treatment efficacy, and assessment of survival in NSCLC. CircRNAs have been identified to play significant roles in various aspects of cancer formation, either as tumor suppressors or tumor promoters, contributing to cancer development through several signaling pathways, including the phosphoinositide 3-kinases (PI3Ks) pathway. This pathway is well-established because of its regulatory role in essential cellular processes. CircRNAs regulate the PI3K/AKT pathway by targeting diverse cellular elements. This review aims to provide insight into the involvement of several circRNAs linked to the PI3K/AKT pathway in NSCLC.

circCDK13-loaded small extracellular vesicles accelerate healing in preclinical diabetic wound models.

Chronic wounds are a major complication in patients with diabetes. Here, we identify a therapeutic circRNA and load it into small extracellular vesicles (sEVs) to treat diabetic wounds in preclinical models. We show that circCDK13 can stimulate the proliferation and migration of human dermal fibroblasts and human epidermal keratinocytes by interacting with insulin-like growth factor 2 mRNA binding protein 3 in an N6-Methyladenosine-dependent manner to enhance CD44 and c-MYC expression. We engineered sEVs that overexpress circCDK13 and show that local subcutaneous injection into male db/db diabetic mouse wounds and wounds of streptozotocin-induced type I male diabetic rats could accelerate wound healing and skin appendage regeneration. Our study demonstrates that the delivery of circCDK13 in sEVs may present an option for diabetic wound treatment.

Subcellular localization of circular RNAs: Where and why.

Localization of RNAs at specific subcellular locations regulating various local cellular events has gained much attention recently. Like most other classes of RNAs, the function of newly discovered circular RNAs (circRNAs) is predominantly determined by their association with different cellular factors in the cell. CircRNAs function as transcriptional and posttranscriptional regulators of gene expression by interacting with transcription factors, splicing regulators, RNA-binding proteins, and microRNAs or by translating into functional polypeptides. Hence, studying their subcellular localization to assess their function is essential. The discovery of more than a million circRNA and increasing evidence of their involvement in development and diseases require a thorough analysis of their subcellular localization linking to their biological functions. Here, we summarize current knowledge of circRNA localization in cells and extracellular vesicles, factors regulating their subcellular localization, and the implications of circRNA localization on their cellular functions. Given the discovery of many circRNAs in all life forms and their implications in pathophysiology, we discuss the challenges in studying circRNA localization and the opportunities for unlocking the mystery of circRNA functions.

Exosome-transmitted circular RNA circ-LMO7 facilitates the progression of osteosarcoma by regulating miR-21-5p/ARHGAP24 axis.

The potential function and mechanism of circRNAs in regulating malignant performances of Osteosarcoma (OS) cells have not been well investigated. The expression level of CircLMO7, miR-21-5p and ARHGAP24 were detected by RT-qPCR. The relationship between miR-21-5p and circ-LMO7, as well as between miR-21-5p and ARHGAP24, was predicted and examined through bioinformatics analysis and luciferase reporter gene experiments. Moreover, OS cell growth, invasion, migration, and apoptosis were detected using the cell counting kit-8 (CCK-8), transwell and flow cytometry assays, respectively. ARHGAP24 protein level was measured using western blotting. In present study, we choose to investigate the role and mechanism of circ-LOM7 on OS cell proliferation, migration and invasion. circ-LOM7 was found to be down-regulated in OS tissues and cell lines. Enforced expression of circ-LOM7 suppressed the growth, invasion, and migration of OS cells. In contrast, decreasing circ-LMO7 expression had opposite effects. Furthermore, miR-21-5p was predicted to be sponged by circ-LMO7, and had an opposite role of circ-LMO7 in OS. Moreover, ARHGAP24 served as miR-21-5p's downstream target. Mechanistically, circ-LMO7 was packed in exosomes and acted as a cancer-suppresser on OS by sponging miR-21-5p and upregulating the expression of ARHGAP24. The exosomal circ-LMO7 expression was significantly decreased in OS cell exosomes, and co-culture experiments showed that exosomal circ-LMO7 suppressed the proliferation ability of OS cells. Circ-LMO7 exerts as a tumor suppressor in OS, and the circ-LMO7/miR-21-5P/ARHGAP24 axis is involved in OS progression.

ALKBH5-mediated m6A modification of circFOXP1 promotes gastric cancer progression by regulating SOX4 expression and sponging miR-338-3p.

Circular RNAs (circRNAs) have recently been suggested as potential functional modulators of cellular physiology processes in gastric cancer (GC). In this study, we demonstrated that circFOXP1 was more highly expressed in GC tissues. High circFOXP1 expression was positively associated with tumor size, lymph node metastasis, TNM stage, and poor prognosis in patients with GC. Cox multivariate analysis revealed that higher circFOXP1 expression was an independent risk factor for disease-free survival (DFS) and overall survival (OS) in GC patients. Functional studies showed that increased circFOXP1 expression promoted cell proliferation, cell invasion, and cell cycle progression in GC in vitro. In vivo, the knockdown of circFOXP1 inhibited tumor growth. Mechanistically, we observed ALKBH5-mediated m6A modification of circFOXP1 and circFOXP1 promoted GC progression by regulating SOX4 expression and sponging miR-338-3p in GC cells. Thus, our findings highlight that circFOXP1 could serve as a novel diagnostic and prognostic biomarker and potential therapeutic target for GC.

circATAD2 mitigates CD8+ T cells antitumor immune surveillance in breast cancer via IGF2BP3/m6A/PD-L1 manner.

Immune surveillance and chemotherapy sensitivity play critical functions in the tumorigenesis of breast cancer (BC). Emerging findings have indicated that circular RNA (circRNA) and N6-methyladenosine (m6A) both participate in the BC tumorigenesis. Here, present study aimed to investigate the roles of m6A-modified circATAD2 on BC and explore better understanding for BC precision therapeutic. Results reported that m6A-modifid circRNA (m6A-circRNA) microarray revealed the m6A-circRNA landscape in BC. M6A-modifid circATAD2 upregulated in BC samples and was closely correlated to poor prognosis. Functionally, circATAD2 promoted the immune evasion of BC cells and reduced the CD8+ T cells' killing effect. Mechanistically, MeRIP-seq unveiled the m6A modification in the 3'-UTR of PD-L1 mRNA, which was bound by circATAD2 and recognized by m6A reader IGF2BP3 to enhance PD-L1 mRNA stability and expression. In summary, these findings revealed the circATAD2/m6A/IGF2BP3/PD-L1 axis in BC immune surveillance, suggesting the potential that circATAD2 as a potential target for PD-L1-mediated BC.

Simultaneous detection of breast cancer biomarkers circROBO1 and BRCA1 based on a CRISPR-Cas13a/Cas12a system.

Breast cancer is reported to be one of the most lethal cancers in women, and its multi-target detection can help improve the accuracy of diagnosis. In this work, a cluster regularly interspaced short palindromic repeats (CRISPR)-Cas13a/Cas12a-based system was established for the simultaneous fluorescence detection of breast cancer biomarkers circROBO1 and BRCA1. CRISPR-Cas13a and CRISPR-Cas12a were directly activated by their respective targets, resulting in the cleavage of short RNA and DNA reporters, respectively, thus the signals of 6-carboxyfluorescein (FAM) and 6-carboxy-xrhodamine (ROX) were restored. As the fluorescence intensities of FAM and ROX were dependent on the concentrations of circROBO1 and BRCA1, respectively, synchronous fluorescence scanning could achieve one-step detection of circROBO1 and BRCA1 with detection limits of 0.013 pM and 0.26 pM, respectively. The system was highly sensitive and specific, holding high diagnostic potential for the detection of clinical samples. Furthermore, the competing endogenous RNA mechanism between circROBO1 and BRCA1 was also explored, providing a reliable basis for the intrinsic regulatory mechanism of breast cancer.

CircAGFG1 Promotes Ovarian Cancer Progression Through the miR-409-3 p/ZEB1 Axis.

OBJECTIVES: Circular RNAs (circRNAs) serve a crucial regulatory role in ovarian cancer (OC). Circular RNA ArfGAP with FG repeats 1 (circAGFG1) has been shown to be involved in promoting the progression of several cancers, containing triple-negative breast cancer, esophageal cancer and colorectal cancer. However, the function of circAGFG1 in OC is unclear. METHODS: Quantitative real-time reverse transcription PCR (RT-qPCR) was conducted to determine the expression levels of circAGFG1 and miR-409-3p. The proliferation and metastasis of cells were determined by colony formation assays, EdU assays, transwell assays and wound healing assays. In addition, a dual-luciferase reporter assay was performed to validate the mechanism between circAGFG1, miR-409-3p, and ZEB1. RESULTS: Our data suggested that circAGFG1 was significantly overexpressed in OC tissues compared to normal ovarian epithelial tissues. Overexpression of circAGFG1 was correlated with intraperitoneal metastasis, tumor recurrence and advanced stage. Additionally, circAGFG1 overexpression revealed a poor prognosis in OC patients. Knockdown of circAGFG1 suppressed the proliferation, invasion and migration of OC cells. Mechanistically, circAGFG1 acted as a sponge of miR-409-3p to enhance the expression level of zinc finger E-box binding homeobox 1 (ZEB1), thereby conferring OC cell proliferation, invasion and migration. Importantly, re-expression of ZEB1 effectively reversed the effects of circAGFG1 knockdown on OC cells. CONCLUSIONS: In summary, our study indicated that circAGFG1 may act as a prognostic biomarker and potential therapeutic target for patients with OC.

Cholangiocarcinoma combined with biliary obstruction: an exosomal circRNA signature for diagnosis and early recurrence monitoring.

Cholangiocarcinoma (CCA) is a highly malignant biliary tract cancer with currently suboptimal diagnostic and prognostic approaches. We present a novel system to monitor CCA using exosomal circular RNA (circRNA) via serum and biliary liquid biopsies. A pilot cohort consisting of patients with CCA-induced biliary obstruction (CCA-BO, n = 5) and benign biliary obstruction (BBO, n = 5) was used to identify CCA-derived exosomal circRNAs through microarray analysis. This was followed by a discovery cohort (n = 20) to further reveal a CCA-specific circRNA complex (hsa-circ-0000367, hsa-circ-0021647, and hsa-circ-0000288) in both bile and serum exosomes. In vitro and in vivo studies revealed the three circRNAs as promoters of CCA invasiveness. Diagnostic and prognostic models were established and verified by two independent cohorts (training cohort, n = 184; validation cohort, n = 105). An interpreter-free diagnostic model disclosed the diagnostic power of biliary exosomal circRNA signature (Bile-DS, AUROC = 0.947, RR = 6.05) and serum exosomal circRNA signature (Serum-DS, AUROC = 0.861, RR = 4.04) compared with conventional CA19-9 (AUROC = 0.759, RR = 2.08). A prognostic model of CCA undergoing curative-intent surgery was established by calculating early recurrence score, verified with bile samples (Bile-ERS, C-index=0.783) and serum samples (Serum-ERS, C-index = 0.782). These models, combined with other prognostic factors revealed by COX-PH model, enabled the establishment of nomograms for recurrence monitoring of CCA. Our study demonstrates that the exosomal triple-circRNA panel identified in both bile and serum samples serves as a novel diagnostic and prognostic tool for the clinical management of CCA.

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.

Human circular RNA hsa_circ_0000231 clinical diagnostic effectiveness as a new tumor marker in gastric cancer.

BACKGROUND: Owing to the subtlety of initial symptoms associated with gastric cancer (GC), the majority of patients are diagnosed at later stages. Given the absence of reliable diagnostic markers, it is imperative to identify novel markers that exhibit high sensitivity and specificity. Circular RNA, a non-coding RNA, plays an important role in tumorigenesis and development and is well expressed in body fluids. AIMS: In this study, we aimed to identify hsa_circ_0000231 as a new biomarker for the diagnosis of GC and to assess its clinical diagnostic value in serum. METHODS AND RESULTS: The stability and correctness of hsa_circ_0000231 was determined by agarose gel electrophoresis, Rnase R assay and Sanger sequencing. Real-time quantitative polymerase chain reaction (qRT-PCR) was designed to discover the expression level of hsa_circ_0000231 and whether it has dynamic serum monitoring capability. The correlation between hsa_circ_0000231 and clinicopathological parameters was analyzed by collecting clinical and pathological data from GC patients. In addition, diagnostic efficacy was assessed by constructing receiver operating characteristic curves (ROC). Hsa_circ_0000231 exhibits a stable and consistently expressed structure. In GC serum, cells, and tissues, it demonstrates reduced expression levels. Elevated expression levels observed postoperatively suggest its potential for dynamic monitoring. Additionally its expression level correlates with TNM staging and neuro/vascular differentiation. The area under ROC curve (AUC) for hsa_circ_0000231 is 0.781, indicating its superior diagnostic value compared to CEA, CA19-9, and CA72-4. The combination of these four indicators enhances diagnostic accuracy, with an AUC of 0.833. CONCLUSIONS: The stable expression of hsa_circ_0000231 in the serum of gastric cancer patients holds promise as a novel biomarker for both the diagnosis and dynamic monitoring of GC.