Circular RNA circ_0000517 regulates hepatocellular carcinoma development via miR-326/IGF1R axis

Identification of Safety Biomarkers for Autologous Blood Transfusion in Hepatocellular Carcinoma Patients

Hepatocellular carcinoma (HCC) represents the predominant form of primary liver cancer, constituting 75%-85% of all liver cancer cases. Despite advances in understanding HCC mechanisms and treatment options, challenges remain and further research is needed to uncover new therapeutic targets and improve patient outcomes. intraoperative cell salvage (IOCS) is an important surgical method that minimises the necessity for transfusions of donor blood, improves haemodynamic stability and may enhance recovery. This study aims to identify safety biomarkers for autologous blood transfusion in HCC patients. We conducted a prospective case-control study on 80 HCC patients undergoing radical surgery. Blood and tumour tissues were collected for analysis. The control group provided blood directly from the surgical site without IOCS processing, while the experimental group used blood collected through the IOCS system. Dual-Luciferase reporter gene assays, immunofluorescence, Western blot and qRT-PCR techniques were employed to assess the expression of key proteins and microRNAs. Comparable demographic and baseline clinical characteristics were observed between groups. The experimental group showed significantly improved pathological features, with an increase in PTEN-positive cells and upregulated protein expression of PTEN, mTOR, c-Met and IGF1R. Additionally, miRNA levels (miRNA-21, miRNA-122, miRNA-223, miRNA-199a and miRNA-375) were significantly reduced in the experimental group (p < 0.05), while mRNA levels for PTEN, mTOR, c-Met, YAP1 and IGF1R were significantly upregulated (p < 0.05). IOCS has a positive impact on liver tissue pathology in HCC patients by reducing apoptosis and modulating key molecular pathways. These findings suggest that IOCS could be a valuable therapeutic strategy for HCC, potentially guiding future treatment approaches and improving patient outcomes.

Circ-EIF3I Promotes Hepatocellular Carcinoma Progression Through Modulating miR-361-3p/DUSP2 Axis

Hepatocellular carcinoma (HCC) is one of the most common malignant cancers globally. Circular RNAs (circRNAs) have been implicated in the development of HCC. Previous studies have confirmed that circ-EIF3I plays an important role in the progress of lung cancer. Nevertheless, the biological functions of circ-EIF3I and the underlying mechanisms by which they regulate HCC progression remain unclear. In this study, the regulatory mechanism and targets were studied with bioinformatics analysis, luciferase reporting analysis, transwell migration, Cell Counting Kit-8, and 5-Ethynyl-2'-deoxyuridine analysis. In addition, in vivo tumorigenesis and metastasis assays were employed to evaluate the roles of circ-EIF3I in HCC. The result shows that the circ-EIF3I expression was increased in HCC cell line, which means that circ-EIF3I plays a role in the progression of HCC. Downregulation of circ-EIF3I suppressed HCC cells' proliferation and migration in both in vivo and in vitro experiments. Bioinformatics and luciferase report analysis confirmed that both miR-361-3p and Dual-specificity phosphatase 2 (DUSP2) were the downstream target of circ-EIF3I. The overexpression of DUSP2 or inhibition of miR-361-3p restored HCC cells' proliferation and migration ability after silence circ-EIF3I. Taken together, our study found that downregulation of circ-EIF3I suppressed the progression of HCC through miR-361-3p/DUSP2 Axis.

Epigenetic regulation of hepatocellular carcinoma progression: MicroRNAs as therapeutic, diagnostic and prognostic factors

Hepatocellular carcinoma (HCC), a significant challenge for public healthcare systems in developed Western countries including the USA, Canada, and the UK, is influenced by different risk factors including hepatitis virus infections, alcoholism, and smoking. The disruption in the balance of microRNAs (miRNAs) plays a vital function in tumorigenesis, given their function as regulators in numerous signaling networks. These miRNAs, which are mature and active in the cytoplasm, work by reducing the expression of target genes through their impact on mRNAs. MiRNAs are particularly significant in HCC as they regulate key aspects of the tumor, like proliferation and invasion. Additionally, during treatment phases such as chemotherapy and radiotherapy, the levels of miRNAs are key determinants. Pre-clinical experiments have demonstrated that altered miRNA expression contributes to HCC development, metastasis, drug resistance, and radio-resistance, highlighting related molecular pathways and processes like MMPs, EMT, apoptosis, and autophagy. Furthermore, the regulatory role of miRNAs in HCC extends beyond their immediate function, as they are also influenced by other epigenetic factors like lncRNAs and circular RNAs (circRNAs), as discussed in recent reviews. Applying these discoveries in predicting the prognosis of HCC could mark a significant advancement in the therapy of this disease.

CircSNX6 promotes proliferation, metastasis, and angiogenesis in hepatocellular carcinoma via miR-383-5p/VEGFA signaling pathway

The role of circular RNA (circRNAs) in hepatocellular carcinoma (HCC) has been extensively studied. Previous research has highlighted the regulatory role of circSNX6 in HCC cells and tissues. However, the precise mechanism underlying HCC progression still requires comprehensive investigation. The study initially utilized quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to assess circSNX6 expression levels in HCC cell lines and tissues. Subsequently, the stability of circRNA was evaluated through Ribonuclease R and actinomycin D treatment assays. The impact of circSNX6 knockdown on proliferation, migration, invasion, and angiogenesis abilities was determined using various assays including colony formation, Transwell culture system, tube formation assay, and cell counting kit (CCK)-8 assays. Additionally, RNA immunoprecipitation chip and dual-luciferase reporter assays were employed to investigate the interactions between circSNX6 and miR-383-5p. Finally, an HCC xenograft tumor model in mice was established to assess the in vivo expression of circSNX6 and its functional role in HCC. Our findings revealed an elevated circSNX6 expression in HCC tissues, which was correlated with poor patient prognosis. Knockdown of circSNX6 suppressed HCC cell growth, invasion, metastasis, and angiogenesis. The downregulation of miR-383-5p, a target of circSNX6, significantly attenuated the tumor-suppressive effects induced by circSNX6 knockdown. Moreover, circSNX6 was found to modulate VEGFA expression by targeting miR-383-5p. The inhibition of HCC cell proliferation by miR-383-5p could be partially reversed by overexpressing VEGFA. Silencing circSNX6 also suppressed tumor formation and the metastasis of HCC cells in a mouse model. In summary, our findings suggest that circSNX6 promotes cell proliferation, metastasis, and angiogenesis in HCC by regulating the miR-383-5p/VEGFA pathway.

Involvement of CircRNAs in regulating The "New Generation of Cancer Hallmarks": A Special Depiction on Hepatocellular Carcinoma

The concept of 'Hallmarks of Cancer' is an approach of reducing the enormous complexity of cancer to a set of guiding principles. As the underlying mechanism of cancer are portrayed, we find that we gain insight and additional aspects of the disease arise. The understanding of the tumor microenvironment (TME) brought a new dimension and led to the discovery of novel hallmarks such as senescent cells, non-mutational epigenetic reprogramming, polymorphic microbiomes and unlocked phenotypic plasticity. Circular RNAs (circRNAs) are single-stranded, covalently closed RNA molecules that are ubiquitous across all species. Recent studies on the circRNAs have highlighted their crucial function in regulating the formation of human malignancies through a range of biological processes. The primary goal of this review is to clarify the role of circRNAs in the most common form of liver cancer, hepatocellular carcinoma (HCC). This review also addressed the topic of how circRNAs affect HCC hallmarks, including the new generation hallmarks. Finally, the enormous applications that these rapidly expanding ncRNA molecules serve in the functional and molecular development of effective HCC diagnostic biomarkers and therapeutic targets.

RUSC1-AS1 promotes the malignant progression of breast cancer depending on the regulation of the miR-326/XRCC5 pathway

BACKGROUND

Many long noncoding RNAs (lncRNAs) are the key regulators for cancer progression, including breast cancer (BC). RUSC1 antisense 1 (RUSC1-AS1) has been found to be highly expressed in BC, but its role and potential molecular mechanism in BC remain to be further elucidated.

METHODS

Quantitative reverse transcription-polymerase chain reaction (RT-PCR) was utilized to measure RUSC1-AS1, microRNA (miR)-326 and X-ray repair cross-complementing group 5 (XRCC5) expression. Cell proliferation, metastasis, cell cycle, apoptosis and angiogenesis were determined by cell counting kit-8, colony formation, transwell, flow cytometry and tube formation assays. Protein expression was detected by western blot analysis. The targeted relationship between miR-326 and RUSC1-AS1 or XRCC5 was validated using dual-luciferase reporter assay and RIP assay. Xenograft models were constructed to uncover the effect of RUSC1-AS1 on BC tumorigenesis.

RESULTS

RUSC1-AS1 was upregulated in BC, and its downregulation suppressed BC proliferation, metastasis, cell cycle, angiogenesis, and tumor growth. MiR-326 was confirmed to be sponged by RUSC1-AS1, and its inhibitor reversed the regulation of RUSC1-AS1 silencing on BC progression. XRCC5 could be targeted by miR-326. Overexpression of XRCC5 reversed the inhibitory impacts of miR-326 on BC progression.

CONCLUSION

RUSC1-AS1 could serve as a sponge of miR-326 to promote BC progression by targeting XRCC5, suggesting that RUSC1-AS1 might be a target for BC treatment.

Hsa-circ-0006091 modulates the proliferation of hepatocellular carcinoma via the miR-622/CCNB1 axis

Background/aim

Hepatocellular carcinoma (HCC) is a common type of cancer. We hypothesize that circular RNA-0006091 (circ-0006091) affects the progression of HCC. The study aims to investigate the effect of circ-0006091 in HCC cells.

Materials and methods

The levels of circ-0006091, microRNA-622 (miR-622), and cyclin B1 (CCNB1) were assayed using qRT-PCR and western blotting. The metastasis of the HCC cells was measured with wound healing and transwell assays. The protein expression levels of MMP-2 and MMP-9 were assayed with western blotting. Dual-luciferase reporter and RNA-pulldown assays were used to determine the link between miR-622 and circ-0006091 or CCNB1. Mice-based tests were used to determine the effect of circ-0006091 on the proliferation of HCC cells.

Results

The levels of circ-0006091 and CCNB1 were increased in the HCC cells, but miR-622 was down-regulated. Deficiency of circ-0006091 reduced the metastasis of the HCC cells, and silencing of circ-0006091 decreased the activities of MMP-2 and MMP-9 in the same cells. Circ-0006091 modulated the CCNB1 level in the HCC cells via miR-622. Silencing of circ-0006091 suppressed the proliferation of the HCC cells in vivo.

Conclusion

Circ-0006091 regulated HCC cell metastasis via the miR-622/CCNB1 axis, a possible therapeutic target in managing HCC.

The Tumorigenic Role of Circular RNA-MicroRNA Axis in Cancer

Circular RNAs (circRNAs) are a class of endogenous RNAs that control gene expression at the transcriptional and post-transcriptional levels. Recent studies have increasingly demonstrated that circRNAs act as novel diagnostic biomarkers and promising therapeutic targets for numerous cancer types by interacting with other non-coding RNAs such as microRNAs (miRNAs). The miRNAs are presented as crucial risk factors and regulatory elements in cancer by regulating the expression of their target genes. Some miRNAs are derived from transposable elements (MDTEs) that can transfer their location to another region of the genome. Genetic interactions between miRNAs and circular RNAs can form complex regulatory networks with various carcinogenic processes that play critical roles in tumorigenesis and cancer progression. This review focuses on the biological regulation of the correlative axis among circular RNAs, miRNAs, and their target genes in various cancer types and suggests the biological importance of MDTEs interacting with oncogenic or tumor-suppressive circRNAs in tumor progression.

Circ_0003489 facilitates multiple myeloma progression by targeting miR-433-3p/PBX3 axis

BACKGROUND

Multiple myeloma (MM) is a relatively common hematologic tumor, and the study of non-coding RNAs in MM is gradually increasing. Our study aimed to reveal the regulatory mechanism of circular RNA_0003489 (circ_0003489)/microRNA-433-3p (miR-433-3p)/Pre-B-cell leukemia homeobox 3 (PBX3) axis in MM.

METHODS

Circ_0003489, miR-433-3p and PBX3 contents were measured by real-time quantitative PCR or western blot. Functionally, MM cell proliferation and apoptosis were evaluated using cell counting kit-8, flow cytometry and EdU assays. Interaction between miR-433-3p and circ_0003489 or PBX3 was confirmed with the application of dual-luciferase reporter assay and RNA pull down assay.

RESULTS

Circ_0003489 and PBX3 were upregulated, while miR-433-3p was downregulated in MM tissues. Circ_0003489 knockdown or miR-433-3p overexpression remarkably suppressed MM proliferation and increased apoptosis in vitro. In terms of mechanism, circ_0003489 could sponge miR-433-3p to regulate PBX3. Besides, miR-433-3p downregulation or PBX3 overexpression reversed the inhibition effect of circ_0003489 knockdown on MM progression.

CONCLUSION

Circ_0003489 facilitated MM progression by targeting miR-433-3p/PBX3 axis, suggesting that it might be a potential target for MM.

Circular RNAs Involved in the Regulation of the Age-Related Pathways

Circular RNAs (circRNAs) are a class of covalently circular noncoding RNAs that have been extensively studied in recent years. Aging is a process related to functional decline that is regulated by signal transduction. An increasing number of studies suggest that circRNAs can regulate aging and multiple age-related diseases through their involvement in age-related signaling pathways. CircRNAs perform several biological functions, such as acting as miRNA sponges, directly interacting with proteins, and regulating transcription and translation to proteins or peptides. Herein, we summarize research progress on the biological functions of circRNAs in seven main age-related signaling pathways, namely, the insulin-insulin-like, PI3K-AKT, mTOR, AMPK, FOXO, p53, and NF-κB signaling pathways. In these pathways, circRNAs mainly function as miRNA sponges. In this review, we suggest that circRNAs are widely involved in the regulation of the main age-related pathways and are potential biomarkers for aging and age-related diseases.

Assessment of circulating levels of microRNA-326, microRNA-424, and microRNA-511 as biomarkers for hepatocellular carcinoma in Egyptians

BACKGROUND

Hepatocellular carcinoma (HCC) is the fifth most common cancer. Differential expression of microRNAs (miRNAs)-326, miRNA-424, and miRNA-511 has been associated with the diagnosis and prognosis of HCC in different populations. However, limited information is available regarding their expression in Egyptian HCC patients.

AIM

To assess the role of circulating miRNAs-326, miRNA-424, and miRNA-511 in Egyptian HCC patients.

METHODS

This prospective observational study included 70 HCC patients and 25 healthy controls. The circulating levels of these three miRNAs were evaluated by real-time PCR. Receiver operating characteristic curve analysis was used to test the diagnostic accuracy of microRNA expression levels.

RESULTS

All miRNAs were differentially expressed in HCC patients; miRNAs326 and miRNA-424 were upregulated, while miRNA-511 was downregulated. Both miRNA-326 and miRNA-424 showed sensitivity and specificity of 97%, 71.4%, and 52%, 60%, respectively, to differentiate HCC from controls. Moreover, miRNA-326 was associated with survival and could differentiate between Child grades (A vs B); miRNA-424 significantly differentiated early vs intermediate stages of HCC; while miRNA-511 was significantly correlated with response to modified Response Evaluation Criteria in Solid Tumors (mRECIST).

CONCLUSION

We conclude that miRNA-326, miRNA-424, and miRNA-511 have diagnostic and prognostic roles in Egyptian patients with hepatitis C virus-related HCC and should be considered for better disease management.

Circular BANP knockdown inhibits the malignant progression of residual hepatocellular carcinoma after insufficient radiofrequency ablation

BACKGROUND

Circular RNAs (circRNAs) are endogenous non-coding RNAs, some of which have pathological roles. The current study aimed to explore the role of circRNA BTG3-associated nuclear protein (circ-BANP) binding with let-7f-5p and its regulation of the toll-like receptor 4 (TLR4)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in residual hepatocellular carcinoma (HCC) after insufficient radiofrequency ablation (RFA).

METHODS

Circ-BANP, let-7f-5p, and TLR4 expressions in HCC samples were assessed using reverse transcription- quantitative polymerase chain reaction (RT-qPCR) and Western blotting. Bioinformatics prediction, RNA pull-down assay, and dual luciferase reporter gene assay were used to analyze the relationships among circ-BANP, let-7f-5p, and TLR4. Huh7 cells were used to generate an in vitro model of residual HCC, defined as Huh7-H cells, which were transfected with either a plasmid or the sequence of circ-BANP, let-7f-5p, or TLR4. Expression of circ-BANP, let-7f-5p, and TLR4 mRNA was determined by RT-qPCR. TLR4, STAT3, p-STAT3, vascular endothelial growth factor A, vascular endothelial growth factor receptor-2, and epithelial-mesenchymal transformation (EMT)-related factors proteins were determined by Western blotting. Cell proliferation was determined by cell counting kit-8 and 5-Ethynyl-2'-deoxyuridine (EdU) assay and cell migration and invasion by Transwell assay. Animal studies were performed by inducing xenograft tumors in nude mice.

RESULTS

Circ-BANP and TLR4 mRNAs were upregulated in HCC tissues (the fold change for circ-BANP was 1.958 and that for TLR4 was 1.736 relative to para-tumors) and expression further increased following insufficient RFA (fold change for circ- BANP was 2.407 and that of TLR4 was 2.224 relative to para-tumors). Expression of let-7f-5p showed an opposite tendency (fold change for let-7f-5p in HCC tissues was 0.491 and that in tumors after insufficient RFA was 0.300 relative to para-tumors). Competitive binding of circ-BANP to let-7f-5p was demonstrated and TLR4 was identified as a target of let-7f-5p (P < 0.01). Knockdown of circ-BANP or elevation of let-7f-5p expression inhibited the TLR4/STAT3 signaling pathway, proliferation, invasion, migration, angiogenesis, and EMT in Huh7 and Huh7-H cells (P < 0.01). The effects induced by circ-BANP knockdown were reversed by let-7f-5p inhibition. Overexpression of TLR4 reversed the impact of let-7f-5p upregulation on the cells (P < 0.01). Silencing of circ-BANP inhibited the in vivo growth of residual HCC cells after insufficient RFA (P < 0.01).

CONCLUSIONS

Knockdown of circ-BANP upregulated let-7f-5p to inhibit proliferation, migration, and EMT formation in residual HCC remaining after insufficient RFA. Effects occur via regulation of the TLR4/STAT3 signaling pathway.

CircMMP9 accelerates the progression of hepatocellular carcinoma through the miR-149/CCND2 axis

BACKGROUND

This study aimed to verify the hypothesis that circular RNA MMP9 (circMMP9) promotes hepatocellular carcinoma (HCC) progression through targeting miR-149 and regulating cyclin D2 (CCND2) expression.

METHODS

Expression of circMMP9, miR-149 and CCND2 was detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR) or protein blotting. Cell Counting Kit-8 (CCK-8) was used to evaluate cell proliferation. The HCC cell migration and invasion were evaluated using wound healing and transwell assays. The interaction among circMMP9, miR-149, and CCND2 was evaluated using luciferase, RNA-pull down, and RNA immunoprecipitation (RIP) assays, respectively. Cell apoptosis and cycle were examined by flow cytometry. A subcutaneous HCC xenograft mouse model was established for analyzing the role of circMMP9 in regulating the progression of HCC in vivo.

RESULTS

The expression of circMMP9 was elevated in HCC tissues and its high expression correlated with poor prognosis (P<0.05). Knockdown of circMMP9 restrained the proliferation, migration, and invasion of HCC cells and led to arrested cell cycle and increased apoptosis (all P<0.05). Furthermore, knockdown of circMMP9 attenuated HCC growth in vivo (P<0.05). Mechanically, circMMP9 acted as a sponge for miR-149 and enhanced CCND2 expression in HCC cells (P<0.05). Inhibition of miR-149 or overexpression of CCND2 abrogated knockdown of circMMP9-mediated alleviation of the malignant phenotypes of HCC (P<0.05).

CONCLUSIONS

For the first time, we demonstrated that circMMP9 exacerbated HCC progression through the miR-149/CCND2 axis, which suggested that circMMP9 could be potentially targeted for HCC treatment.

A six-miRNA signature as a novel biomarker for improving prediction of prognosis and patterns of immune infiltration in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the leading causes of tumor-related death. MicroRNAs (miRNAs) belong to a subfamily of functional non-coding RNAs (ncRNAs) and are essential regulators of tumorigenesis. They affect tumor-related therapeutic response, tumor metastasis, and clinical outcomes of several human malignant tumors. However, the prognostic value of miRNAs and their role in the tumor immune microenvironment (TIME) of HCC have not been clarified.

MATERIALS AND METHODS

Raw RNA-sequencing data (mRNA and miRNA) and clinicopathological characteristics of HCC samples were downloaded from the TCGA-GDC database. The Perl programming language, R software, Cytoscape software, and several online databases were used to clarify the clinical significance and biological functions of miRNAs and their target genes in HCC.

RESULTS

A total of 424 mRNA-sequencing samples and 425 miRNA-sequencing samples were obtained from the TCGA database. There were 344 HCC cases with complete information in the TCGA dataset and they were randomly categorized into two subgroups. Six miRNAs were identified as independent prognostic biomarkers for HCC patients by univariate and multivariate Cox regression analysis. The constructed prognostic signature, which contains these six miRNAs, was significantly correlated with overall survival (OS). In addition, this prognostic signature is superior to single miRNA in predicting short-term prognosis of HCC patients. We also found that the prognostic signature was significantly associated with tumor-related immune cell infiltration, TIME, and immunotherapeutic response. Furthermore, a total of 4568 potential target genes of six miRNAs were identified. The miRNA-mRNA co-expression network, protein-protein interaction (PPI) network, and functional and pathway enrichment analysis demonstrated that these miRNA-related target genes have important biological effects during the initiation and progression of HCC.

CONCLUSIONS

This study demonstrates that the miRNA signature can accurately predict the prognosis of HCC patients and provide a basis for novel immunotherapy treatments.

circSYPL1 Promotes the Proliferation and Metastasis of Hepatocellular Carcinoma via the Upregulation of EZH2 Expression by Competing with hsa-miR-506-3p

Objective. Circular RNAs (circRNAs) and microRNAs are crucial for progressing of hepatocellular carcinoma (HCC). Nonetheless, the function or mechanisms of a newly discovered circRNA, circSYPL1, as well as miR-506-3p, in the progression of HCC are mostly unexplained. The purpose of this research was to determine the mechanisms by which circSYPL1 and miR-506-3p regulate the malignant features of HCC. Methods. The expression level of circSYPL1 was indeed detected using real-time PCR in HCC cell lines, primary as well as metastatic cancers. To assess the functionality of circSYPL1 upregulation and knockdown, we used proliferation and apoptosis, in addition to migration assays, as well as tumor xenograft and lung metastasis assays. The mechanisms of competing endogenous RNAs with circSYPL1/miR-506-3p/EZH2 were investigated using luciferase as well as RNA pull-down experiments. Lastly, cell proliferation and migration, in addition to tumor xenograft tests, were used to validate the biological significance of the circSYPL1/miR-506-3p/EZH2 signaling axis through overexpression or otherwise silencing. Results. circSYPL1 expression was significantly upregulated in HCC cell lines, in addition to primary and metastatic tumors of patients with HCC. Additionally, it may promote HCC initiation, development as well as progression. By knocking down circSYPL1 siRNA, we were able to drastically decrease the aggressiveness of HCC cells. circSYPL1 sponged miR-506-3p to boost EZH2 expression levels, as indicated by luciferase and RNA pull-down assays. Furthermore, circSYPL1 overexpression could upregulate EZH2 expression, while miR-506-3p mimics or EZH2 shRNAs could reverse the circSYPL1-induced malignancy of HCC cells. Conclusion. On a mechanistic level, circSYPL1 can interact with miR-506-3p in a competitive manner to upregulate EZH2, hence increasing the aggressiveness of tumors.

Hsa_circ_0005230 is up-regulated and promotes gastric cancer cell invasion and migration via regulating the miR-1299/RHOT1 axis

Gastric cancer (GC) is one of the most common cancers in the world. Circular RNAs (circRNAs) are a class of non-coding RNAs that are widely expressed in eukaryotic cells. However, their role has been poorly understood in GC. This report aimed to explore the biological functions of hsa_circ_0005230 and its action mechanism in GC. This study validated that hsa_circ_0005230 was significantly up-regulated in 130 cases of GC tissues using qRT-PCR, and clinicopathological feature analysis revealed that its high expression was positively associated with histological grade, lymph node metastasis, TNM stages, and poor prognosis. In vitro, functional experiments showed that silencing hsa_circ_0005230 significantly decreased GC cell proliferation, invasion and migration capabilities. In addition, the major proteins of EMT (epithelial-mesenchymal transition) relevance have changed. In mechanism studies, bioinformatics analyses were used to predict the hsa_circ_0005230/miR-1299/RHOT1 axis and hsa_circ_0005230 may serve as a sponge for miR-1299 and indirectly regulate the expression of RHOT1. The regulated relationships between the molecules on the axis were verified using qRT-PCR and correlation analysis. Dual-luciferase reporter gene assay has been used to verify the binding site between miR-1299 and RHOT1. WB (Western blotting) and IHC (Immunohistochemical) were used to verify that RHOT1 may play the role of oncoprotein and affect the biological behavior of GC. Overall, hsa_circ_0005230 could enhance the EMT phenotype by promoting RHOT1 expression through sponging miR-1299, thus affecting the biological behavior of GC. Hsa_circ_0005230 can be easily identified as a potential diagnostic biomarker and assessment prognosis target for GC.

The novel circular RNA HIPK3 accelerates the proliferation and invasion of hepatocellular carcinoma cells by sponging the micro RNA-124 or micro RNA-506/pyruvate dehydrogenase kinase 2 axis

Circular RNAs (circRNAs) have been confirmed to be associated with the progression of various cancers, including hepatocellular carcinoma (HCC). However, the role and mechanism of circHIPK3 in HCC are still unclear. To investigate its function, circHIPK3 expression was first determined by RT–qPCR in HCC tissues or cells. Functionally, cell proliferation and invasion were investigated by CCK-8, EdU, or Transwell assays. In terms of understanding the mechanism, the interaction of the circRNA HIPK3/micro RNA 124 (miRNA 124) or micro RNA 506 (miRNA506) /PDK2 regulatory loop was verified by dual-luciferase reporter gene assay. In addition, a xenograft tumor model was established to confirm the impact of circHIPK3 on the growth of HCC cells in vivo. We found that circHIPK3 was upregulated in HCC patients and associated with clinical characteristics, while miR-124 and miR-506 were downregulated in HCC patients. Additionally, we proved that knock down of circHIPK3 remarkably suppressed the proliferation and invasion of HCC cells. Mechanistically, circHIPK3 directly bound to miR-124 or miR-506 and inhibited their expression, and PDK2 was a target gene of miR-124 or miR-506. Moreover, circHIPK3 overexpression reversed the inhibitory effect of miR-124 or miR-506 on HCC progression. miR-124 or miR-506 could also suppress tumorigenesis of HCC cells by PDK2. Furthermore, in vivo evidence confirmed that knock down of circHIPK3 inhibited tumor formation. We suggest that circHIPK3 can accelerate the proliferation and invasion of HCC cells by sponging miR-124 or miR-506 to upregulate PDK2, which is the underlying mechanism of circHIPK3-induced HCC progression.

Identification of Circular RNA-Based Immunomodulatory Networks in Colorectal Cancer

BACKGROUND

Circular RNAs (circRNAs) have been recently proposed as hub molecules in various diseases, especially in tumours. We found that circRNAs derived from ribonuclease P RNA component H1 (RPPH1) were highly expressed in colorectal cancer (CRC) samples from Gene Expression Omnibus (GEO) datasets.

OBJECTIVE

We sought to identify new circRNAs derived from RPPH1 and investigate their regulation of the competing endogenous RNA (ceRNA) and RNA binding protein (RBP) networks of CRC immune infiltration.

METHODS

The circRNA expression profiles miRNA and mRNA data were extracted from the GEO and The Cancer Genome Atlas (TCGA) datasets, respectively. The differentially expressed (DE) RNAs were identified using R software and online server tools, and the circRNA-miRNA-mRNA and circRNA-protein networks were constructed using Cytoscape. The relationship between targeted genes and immune infiltration was identified using the GEPIA2 and TIMER2 online server tools.

RESULTS

A ceRNA network, including eight circRNAs, five miRNAs, and six mRNAs, was revealed. Moreover, a circRNA-protein network, including eight circRNAs and 49 proteins, was established. The targeted genes, ENOX1, NCAM1, SAMD4A, and ZC3H10, are closely related to CRC tumour-infiltrating macrophages.

CONCLUSIONS

We analysed the characteristics of circRNA from RPPH1 as competing for endogenous RNA binding miRNA or protein in CRC macrophage infiltration. The results point towards the development of a new diagnostic and therapeutic paradigm for CRC.

Circular BANP knockdown inhibits the malignant progression of residual hepatocellular carcinoma after insufficient radiofrequency ablation

BACKGROUND

Circular RNAs (circRNAs) are endogenous non-coding RNAs, some of which have pathological roles. The current study aimed to explore the role of circRNA BTG3-associated nuclear protein (circ-BANP) binding with let-7f-5p and its regulation of the toll-like receptor 4 (TLR4)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in residual hepatocellular carcinoma (HCC) after insufficient radiofrequency ablation (RFA).

METHODS

Circ-BANP, let-7f-5p, and TLR4 expressions in HCC samples were assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blotting. Bioinformatics prediction, RNA pull-down assay, and dual luciferase reporter gene assay were used to analyze the relationships among circ-BANP, let-7f-5p, and TLR4. Huh7 cells were used to generate an in vitro model of residual HCC, defined as Huh7-H cells, which were transfected with either a plasmid or the sequence of circ-BANP, let-7f-5p, or TLR4. Expression of circ-BANP, let-7f-5p, and TLR4 mRNA was determined by RT-qPCR. TLR4, STAT3, p-STAT3, vascular endothelial growth factor A, vascular endothelial growth factor receptor-2, and epithelial-mesenchymal transformation (EMT)-related factors proteins were determined by Western blotting. Cell proliferation was determined by cell counting kit-8 and 5-Ethynyl-2'-deoxyuridine (EdU) assay and cell migration and invasion by Transwell assay. Animal studies were performed by inducing xenograft tumors in nude mice.

RESULTS

Circ-BANP and TLR4 mRNAs were upregulated in HCC tissues (the fold change for circ-BANP was 1.958 and that for TLR4 was 1.736 relative to para-tumors) and expression further increased following insufficient RFA (fold change for circ-BANP was 2.407 and that of TLR4 was 2.224 relative to para-tumors). Expression of let-7f-5p showed an opposite tendency (fold change for let-7f-5p in HCC tissues was 0.491 and that in tumors after insufficient RFA was 0.300 relative to para-tumors). Competitive binding of circ-BANP to let-7f-5p was demonstrated and TLR4 was identified as a target of let-7f-5p (P < 0.01). Knockdown of circ-BANP or elevation of let-7f-5p expression inhibited the TLR4/STAT3 signaling pathway, proliferation, invasion, migration, angiogenesis, and EMT in Huh7 and Huh7-H cells (P < 0.01). The effects induced by circ-BANP knockdown were reversed by let-7f-5p inhibition. Overexpression of TLR4 reversed the impact of let-7f-5p upregulation on the cells (P < 0.01). Silencing of circ-BANP inhibited the in vivo growth of residual HCC cells after insufficient RFA (P < 0.01).

CONCLUSIONS

Knockdown of circ-BANP upregulated let-7f-5p to inhibit proliferation, migration, and EMT formation in residual HCC remaining after insufficient RFA. Effects occur via regulation of the TLR4/STAT3 signaling pathway.

Circular RNA circ_0000517 Facilitates The Growth and Metastasis of Non-Small Cell Lung Cancer by Sponging miR-326/miR-330-5p

OBJECTIVE

There is growing evidence showing that circular RNAs (circRNAs) are crucial regulators in modulating the biological behavior of tumors. This work is aimed to probe the role of circ_0000517 in non-small cell lung cancer (NSCLC) and to elucidate its mechanism of action.

MATERIALS AND METHODS

In this experimental study, the differentially expressed circRNAs in NSCLC were screened using the GEO database (GSE158695). Circ_0000517, miR-326, miR-330-5p, and MMP2 expression levels were determined by quantitative real-time polymerase chain reaction (qRT-PCR) analysis and Western blot. The proliferation, apoptosis, migration, and invasion of NSCLC cells were detected by CCK-8, flow cytometry, and transwell assays. RNA immunoprecipitation (RIP), RNA pull-down, and dual-luciferase reporter gene assays were performed to clarify the association between the circ_0000517 and miR-326/miR-330-5p.

RESULTS

Circ_0000517 was shown to be up-regulated in NSCLC tissues and cell lines. The up-regulation of circ_0000517 is closely associated with advanced clinical stage of cancer, lymph node metastasis, and poor prognosis in NSCLC patients. Circ_0000517 knockdown impeded the proliferation, migration, and invasion of NSCLC cells and enhanced their apoptosis. Mechanistically, circ_0000517 was demonstrated to up-regulate MMP2 expression via decoying miR-326 and miR-330-5p to facilitate the malignant biological behaviors of NSCLC cells.

CONCLUSION

This work reveals that circ_0000517 is implicated in NSCLC cell growth and metastasis through the modulation of miR-326/miR-330-5p/MMP2, providing novel insights into the role of circRNAs in NSCLC progression.

Silencing of circ_0000517 suppresses proliferation, glycolysis, and glutamine decomposition of non-small cell lung cancer by modulating miR-330-5p/YY1 signal pathway

In recent years, circular RNA (circRNA) has been found to be involved in a variety of cancer processes. More and more attention has been paid to the research of circRNA in lung cancer. This study aims to investigate whether circ_0000517 affected the physiology of non-small cell lung cancer (NSCLC) and the underlying mechanism. The results demonstrated that circ_0000517 was highly expressed in lung cancer tissues and cells, and overexpression of circ_0000517 was negatively correlated with the prognosis of NSCLC patients. Silencing of circ_0000517 significantly inhibited the proliferation, glycolysis, and glutamine decomposition of NSCLC cells in vitro and repressed the growth of xenografted tumors in vivo. Moreover, knockdown of circ_0000517 attenuated the expression of PCNA, HK2, LDHA, ASCT2, and GLS1. Further study found that circ_0000517 targeted miR-330-5p and miR-330-5p targeted YY1. In addition, miR-330-5p inhibitor reversed inhibition of cancer cell proliferation, glycolysis, and glutamine decomposition induced by si-circ_0000517. In conclusion, our study revealed that silencing of circ_0000517 improved the progression of NSCLC through regulating miR-330-5p/YY1 axis.

Circular RNAs Regulate Glucose Metabolism in Cancer Cells

Circular RNAs (circRNAs) were originally thought to result from RNA splicing errors. However, it has been shown that circRNAs can regulate cancer onset and progression in various ways. They can regulate cancer cell proliferation, differentiation, invasion, and metastasis. Moreover, they modulate glucose metabolism in cancer cells through different mechanisms such as directly regulating glycolytic enzymes and glucose transporter (GLUT) or indirectly regulating signal transduction pathways. In this review, we elucidate on the role of circRNAs in regulating glucose metabolism in cancer cells, which partly explains the pathogenesis of malignant tumors, and provides new therapeutic targets or new diagnostic and prognostic markers for human cancers.

Current Molecular Biology and Therapeutic Strategy Status and Prospects for circRNAs in HBV-Associated Hepatocellular Carcinoma

Circular RNAs (circRNAs) are newly classified noncoding RNA (ncRNA) members with a covalently closed continuous loop structure that are involved in immune responses against hepatitis B virus (HBV) infections and play important biological roles in the occurrence and pathogenesis of HCC progression. The roles of circRNAs in HBV-associated HCC (HBV-HCC) have gained increasing attention. Substantial evidence has revealed that both tissue and circulating circRNAs may serve as potential biomarkers for diagnostic, prognostic and therapeutic purposes. So far, at least four circRNA/miRNA regulatory axes such as circRNA_101764/miR-181, circRNA_100338/miR-141-3p, circ-ARL3/miR-1305, circ-ATP5H/miR-138-5p, and several circulating circRNAs were reported to be associated with HBV-HCC development. Notably, TGF/SMAD, JAK/STAT, Notch and Wnt/β-catenin signaling pathways may play pivotal roles in this HBV-driven HCC via several circRNAs. Moreover, in non-HBV HCC patients or HCC patients partially infected by HBV, numerous circRNAs have been identified to be important regulators impacting the malignant biological behavior of HCC. Furthermore, the role of circRNAs in HCC drug resistance has become a focus of research with the aim of reversing chemoresistance and immune resistance. Herein, we review the molecular biology of circRNAs in HBV-HCC and their potential in therapeutic strategies.

Dysregulated circ_0004913, circ_0008160, circ_0000517, and their potential as biomarkers for disease monitoring and prognosis in hepatocellular carcinoma

OBJECTIVE

Circular RNA_0004913 (circ_0004913), circular RNA_0008160 (circ_0008160), and circular RNA_0000517 (circ_0000517) are shown to be dysregulated in HCC tissues and cell lines, and also show potential in regulating hepatocellular carcinoma (HCC) pathogenesis. This current study attempted to find possible associations of circ_0004913, circ_0008160, and circ_0000517 with clinical features and prognosis of HCC patients.

METHODS

A hundred and fifty HCC patients who received hepatectomy were retrospectively reviewed, and their resected specimens including tumor tissues and paired adjacent tissues were obtained, in which the circ_0004913, circ_0008160, and circ_0000517 expressions were detected. Overall survival (OS) data were collected according to the clinical visit records.

RESULTS

Circ_0004913 (p < 0.001) and circ_0008160 (p < 0.001) were downregulated, while circ_0000517 (p < 0.001) was upregulated in tumor tissue compared with paired adjacent tissue. Additionally, tumor circ_0004913 was negatively associated with largest tumor size (p = 0.009) and Barcelona clinic liver cancer (BCLC) stage (p = 0.020), while tumor circ_0008160 and circ_0000517 were not correlated with any clinicopathological features of HCC patients (all p > 0.05). Tumor circ_0004913 high expression was associated with prolonged OS in total HCC patients (p = 0.008) and in subgroup of patients with largest tumor size <5 cm (p = 0.008). Tumor circ_0008160 high expression was correlated with longer OS in patients with BCLC stage B (p = 0.026). Univariate Cox's analysis disclosed that tumor circ_0004913 high expression was correlated with longer OS; while after adjustment by multivariate Cox's analysis, it failed to predict OS independently.

CONCLUSION

Circ_0004913 was downregulated in tumor tissue and may serve as a biomarker for evaluating disease severity and prognosis in HCC patients.

Circular RNAs in Hepatocellular Carcinoma: Emerging Functions to Clinical Significances

Hepatocellular carcinoma (HCC) is the most common primary cancer of the liver and carries high morbidity and mortality. Diagnosing HCC at an early stage is challenging. Therefore, finding new, highly sensitive and specific diagnostic biomarkers for the diagnosis and prognosis of HCC patients is extremely important. Circular RNAs (circRNAs) are a class of non-coding RNAs with covalently closed loop structures. They are characterized by remarkable stability, long half-life, abundance and evolutionary conservation. Recent studies have shown that many circRNAs are expressed aberrantly in HCC tissues and have important regulatory roles during the development and progression of HCC. Hence, circRNAs are promising biomarkers for the diagnosis and prognosis of HCC. This review: (i) summarizes the biogenesis, categories, and functions of circRNAs; (ii) focuses on current progress of dysregulated expression of circRNAs in HCC with regard to regulation of the tumor hallmarks, “stemness” of cancer cells, and immunotherapy; (iii) highlights circRNAs as potential biomarkers and therapeutic targets for HCC; and (iv) discusses some of the challenges, questions and future perspectives of circRNAs research in HCC.

lncRNA PCAT6 facilitates cell proliferation and invasion via regulating the miR-326/hnRNPA2B1 axis in liver cancer

Liver cancer is one of the most common malignant human tumors with the highest morbidity and mortality rates of all cancer types in China. Evidence suggests that long non-coding RNA prostate cancer-associated transcript 6 (PCAT6) plays an essential role in tumor progression. However, the roles and mechanism of PCAT6 in liver cancer remain unclear. The present study showed that the expression of PCAT6 and heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1) was upregulated in liver cancer tissues compared with non-cancerous tissues and were associated with poor overall survival time, whereas microRNA (miR)-326 expression was downregulated. Moreover, knockdown of PCAT6 significantly inhibited the proliferation and invasion of liver cancer cells in vitro and in vivo. A dual-luciferase reporter gene assay demonstrated that PCAT6 could bind to miR-326 and that hnRNPA2B1 was a direct target gene of miR-326. Mechanistically, silenced PCAT6 suppressed the malignant phenotype of liver cancer cells through upregulating the inhibitory effect of miR-326 on hnRNPA2B1 expression. Taken together, these data demonstrated that knockdown of PCAT6 inhibited liver cancer progression through regulation of the miR-326/hnRNPA2B1 axis, suggesting that PCAT6 functions as an oncogene and may be a useful biomarker for the future diagnosis and treatment of liver cancer.

WITHDRAWN: Circ_0000517 contributes to hepatocellular carcinoma progression by upregulating ARID4B via sponging miR-328-3p

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MiR-325-3p mediate the CXCL17/CXCR8 axis to regulate angiogenesis in hepatocellular carcinoma

INTRODUCTION

MicroRNA-325-3p (miR-325-3p) is involved in the progression of a great number of tumors. However, the regulatory mechanism of miR-325-3p on hepatocellular carcinoma (HCC) remains unclear.

AIM

In this paper, we aim to investigate the underlying mechanism by which miR-325-3p regulate the progression of HCC.

METHODS

RT-qPCR was performed to detect the levels of miR-325-3p, CXCL17, and CXCR8. Western bolt was conducted to determine the levels of pro-angiogenic factors VEGF, FGF2, Ang-1 and PDGF-B. Immunohistochemistry was carried to detect the distribution and expression of Ki-67 and CD34 in HCC tissues. MTT and colony formation were carried to evaluate cell proliferation, endothelial tube-formation assay was used detect tubule formation, and transwell assay was performed to evaluate cell migration and invasion ability. Dual-luciferase activity assay was used to verify the relationship between miR-325-3p and CXCL17.

RESULTS

MiR-325-3p was down-regulated in HCC cells and tissues, miR-325-3p overexpression inhibited the proliferation, migration and invasion of HCC cells. Besides, miR-325-3p overexpression inhibited angiogenesis of HCC. CXCL17 is a direct target of miR-325-3p and partially mediates the effect of miR-325-3p on proliferation, migration, invasion and angiogenesis of HCC.

CONCLUSION

MiR-325-3p regulated angiogenesis of HCC via mediating CXCL17/CXCR8 axis, indicating miR-325-3p may serve as a promising therapy biomarker for HCC.

Recent Update on the Role of Circular RNAs in Hepatocellular Carcinoma

After being overlooked for decades, circular RNAs (circRNAs) have recently generated considerable interest. circRNAs play a role in a variety of normal and pathological biological processes, including hepatocarcinogenesis. Many circRNAs contribute to hepatocarcinogenesis through sponging of microRNAs (miRs) and disruption of cellular signaling pathways that play a part in control of cell proliferation, metastasis and apoptosis. In most cases, overexpressed circRNAs sequester miRs to cause de-repressed translation of mRNAs that encode oncogenic proteins. Conversely, low expression of circRNAs has also been described in hepatocellular carcinoma (HCC) and is associated with inhibited production of tumor suppressor proteins. Other functions of circRNAs that contribute to hepatocarcinogenesis include translation of truncated proteins and acting as adapters to regulate influence of transcription factors on target gene expression. circRNAs also affect hepatocyte transformation indirectly. For example, the molecules regulate immune surveillance of cancerous cells and influence the liver fibrosis that commonly precedes HCC. Marked over- or under-expression of circRNA expression in HCC, with correlating plasma concentrations, has diagnostic utility and assays of these RNAs are being developed as biomarkers of HCC. Although knowledge in the field has recently surged, the myriad of described effects suggests that not all may be vital to hepatocarcinogenesis. Nevertheless, investigation of the role of circRNAs is providing valuable insights that are likely to contribute to improved management of a serious and highly aggressive cancer.