circZFR promotes cell proliferation and migration by regulating miR-511/AKT1 axis in hepatocellular carcinoma

Insights about exosomal circular RNAs as novel biomarkers and therapeutic targets for hepatocellular carcinoma

One of the most prevalent pathological types of Primary Liver Cancer (PLC) is the Hepatocellular Carcinoma (HCC) poses a global health issue. The high recurrence and metastasis rate of HCC, coupled with a low 5-year survival rate, result in a bleak prognosis. Exosomes, small extracellular vesicles released by various cells, contain diverse non-coding RNA molecules, including circular RNAs (circRNAs), which play a significant role in intercellular communication and can impact HCC progression. Studies have revealed the potential clinical applications of exosomal circRNAs as biomarkers and therapeutic targets for HCC. These circRNAs can be transferred via exosomes to nearby non-cancerous cells, thereby regulating HCC progression and influencing malignant phenotypes, such as cell proliferation, invasion, metastasis, and drug resistance. This review provides a comprehensive overview of the identified exosomal circRNAs, highlighting their potential as non-invasive biomarkers for HCC, and suggesting new perspectives for HCC diagnosis and treatment. The circRNA from exosomal organelles promotes metastasis and immune scape because of their unique chirality which is different from the Biomolecular Homochirality.

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.

Circulating RNA ZFR promotes hepatocellular carcinoma cell proliferation and epithelial-mesenchymal transition process through miR-624-3p/WEE1 axis

BACKGROUND

Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, is the fourth leading cause of cancer-related deaths worldwide. Previous evidence shows that the expression of circulating RNA ZFR (circZFR) is upregulated in HCC tissues. However, the molecular mechanism of circZFR in HCC is unclear.

METHODS

Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was employed to detect the expression of circZFR, microRNA-624-3p (miR-624-3p) and WEE1 in HCC tissues and cells. RNase R assay and actinomycin D treatment assay were used to analyze the characteristics of circZFR. For functional analysis, the capacities of colony formation, cell proliferation, cell apoptosis, migration and invasion were assessed by colony formation assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry assay and transwell assay. Western blot was used to examine the protein levels of WEE1 and epithelial-mesenchymal transition (EMT)-related proteins. The interactions between miR-624-3p and circZFR or WEE1 were validated by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Xenograft models were established to determine the role of circZFR in vivo.

RESULTS

circZFR and WEE1 were upregulated, while miR-624-3p expression was reduced in HCC tissues and cells. circZFR could sponge miR-624-3p, and WEE1 was a downstream gene of miR-624-3p. Knockdown of circZFR significantly reduced the malignant behaviors of HCC and that co-transfection with miR-624-3p inhibitor restored this change. Overexpression of WEE1 abolished the inhibitory effect of miR-624-3p mimic on HCC cells. Mechanistically, circZFR acted as a competitive endogenous RNA (ceRNA) to regulate WEE1 expression by targeting miR-624-3p. Furthermore, in vivo studies have illustrated that circZFR knockdown inhibited tumor growth.

CONCLUSIONS

circZFR knockdown reduced HCC cell proliferation, migration and invasion and promoted apoptosis by regulating the miR-624-3p/WEE1 axis, suggesting that the circZFR/miR-624-3p/WEE1 axis might be a potential target for HCC treatment.

CircPOFUT1 fosters colorectal cancer metastasis and chemoresistance via decoying miR-653-5p/E2F7/WDR66 axis and stabilizing BMI1

CircRNAs are implicated in colorectal cancer (CRC) development and progression. Protein O-fucosyltransferase 1 (POFUT1) plays an oncogenic role via activating Notch1 signaling in CRC. However, the roles of circPOFUT1, which is originated from POFUT1, have not been investigated. Our study showed circPOFUT1 was highly expressed in CRC tissues and cells. CircPOFUT1 enhanced the proliferation, migration and invasion of CRC cells, and promoted tumor growth and liver metastasis in vivo. It also reinforced stemness and chemoresistance of CRC cells. Mechanistically, circPOFUT1 regulated the function of E2F7 via sponging miR-653-5p, thereby transcriptionally inducing WDR66 expression and further promoting metastasis in CRC. On the other hand, circPOFUT1 promoted stemness and chemoresistance of CRC cells via stabilizing BMI1 in an IGF2BP1-dependent manner. In conclusion, circPOFUT1 fosters CRC metastasis and chemoresistance via decoying miR-653-5p/E2F7/WDR66 axis and stabilizing BMI1.

Identification of peanut skin components for treating hepatocellular carcinoma via network pharmacology and in vitro experiments

Peanut skin (PS) contains various flavonoids and phenols that have antitumor and antioxidant effects. However, no research has been conducted on PS and hepatocellular carcinoma (HCC). Therefore, this study sought to explore the potential mechanism of PS in treating HCC. PS was searched for in the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform and SYMMAP databases. HCC targets were searched for in five major databases. Protein-protein interaction network, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes analyses were performed. Molecular docking and molecular dynamics simulation were used for verification. Furthermore, in vitro experiments were used to verify the regulation of PS on human HCC (HepG2) cells. Ten ingredients and 95 common targets were identified for PS and HCC, respectively. The key targets of ingredients mainly relate to pathways such as hepatitis B, lipid and atherosclerosis, advanced glycation end products (AGEs)-AGE receptors (RAGEs) signaling pathway in diabetic complications, interleukin-17 (IL-17) signaling pathway, mitogen activated kinase-like protein (MAPK) signaling pathway, the PI3K-Akt signaling pathway. In addition, the molecular docking and molecular dynamics simulation analysis indicated the ingredients had strong binding ability with the targets. Moreover, in vitro experiments confirmed that luteolin can promote the apoptosis of HepG2 cells by controlling the expression of phosphorylated protein-tyrosine kinase (p-AKT). This study provides preliminary evidence that PS produces a marked effect in regulating multiple signaling pathways in HCC through multiple ingredients acting on multiple core genes, including AKT serine/threonine kinase 1 (AKT1), MYC, caspase 3 (CASP3), estrogen receptor 1 (ESR1), epidermal growth factor receptor (EGFR), jun proto-oncogene(JUN), and provides the basis for follow-up research to verify the mechanism of action of PS in treating HCC.

Exosomes from hepatitis B virus-infected hepatocytes activate hepatic stellate cells and aggravate liver fibrosis through the miR-506-3p/Nur77 pathway

Cumulative evidence indicates the important role of Nur77 in organ fibrogenesis. However, the role of Nur77 in hepatitis B virus (HBV)-related liver fibrosis (LF) remains unclear. Cells were transfected with the microRNA mimic miRNA-506-3p or inhibitor, and pcDNA3.1-Nur77 or Nur77 guide RNA. Exosomes were isolated from HBV-infected HepG2-sodium taurocholate cotransporting polypeptide cells. The levels of miR-506-3p, Nur77, and LF-related genes and proteins were detected by quantitative polymerase chain reaction (qPCR) and western blot analysis, respectively. The pathology of the liver from HBV-infected patients was examined using hematoxylin-eosin and Masson's staining. The expression of Nur77 in liver tissue was determined by immunohistochemistry, and the LF score was assessed using the METAVIR system. The relationship between miR-506-3p/Nur77 and LF score was analyzed by correlation analysis. HBV infection downregulated miR-506-3p expression and upregulated Nur77 levels in hepatocytes. Exosomes from HBV-infected hepatocytes also displayed decreased gene expression of miR-506-3p and increased expressions of Nur77- and LF-related genes in stellate cells compared with exosomes from hepatocytes with mock infection. These changes were reversed by Nur77 guide RNA. Nur77 expression in liver tissue was strongly correlated with LF, whereas serum miR-506-3p was strongly negatively correlated with LF. Exosomes from HBV-infected hepatocytes activate stellate cells and aggravate LF through the miR-506-3p/Nur77 pathway. These exosomes may be the basis of a promising therapeutic strategy.

A spotlight on the interplay between Wnt/β-catenin signaling and circular RNAs in hepatocellular carcinoma progression

Hepatocellular carcinoma (HCC) is one of the deadliest cancers due to multifocal development and distant metastasis resulting from late diagnosis. Consequently, new approaches to HCC diagnosis and treatment are required to reduce mortality rates. A large body of evidence suggests that non-coding RNAs (ncRNAs) are important in cancer initiation and progression. Cancer cells release many of these ncRNAs into the blood or urine, enabling their use as a diagnostic tool. Circular RNAs (CircRNAs) are as a members of the ncRNAs that regulate cancer cell expansion, migration, metastasis, and chemoresistance through different mechanisms such as the Wnt/β-catenin Signaling pathway. The Wnt/β-catenin pathway plays prominent roles in several biological processes including organogenesis, stem cell regeneration, and cell survival. Aberrant signaling of both pathways mentioned above could affect the progression and metastasis of many cancers, including HCC. Based on several studies investigated in the current review, circRNAs have an effect on HCC formation and progression by sponging miRNAs and RNA-binding proteins (RBPs) and regulating the Wnt/β-catenin signaling pathway. Therefore, circRNAs/miRNAs or RBPs/Wnt/β-catenin signaling pathway could be considered promising prognostic and therapeutic targets in HCC.

Circ_RBM23 knockdown suppresses chemoresistance, proliferation, migration and invasion of sorafenib-resistant HCC cells through miR-338-3p/RAB1B axis

BACKGROUND

Circular RNA RNA-binding motif protein 23 (circ_RBM23; ID: hsa_circ_0000524) is a novel regulator in hepatocellular carcinoma (HCC). Herein, we planned to investigate its role in sorafenib resistance in HCC.

METHOD

Levels of circ_RBM23, microRNA (miR)-338-3p, Ras-related GTPase-trafficking protein (RAB1B), Snail and E-cadherin were detected by real-time quantitative PCR and western blotting. Sorafenib resistant (SR) HCC cells (Huh7/SR and SK-HEP-1/SR) were established by acquisition of sorafenib resistance, and cell functions were measured by MTT assay, Edu assay, colony formation assay, apoptosis assay, transwell assay, and in vivo xenograft formation assay. Crosslink between miR-338-3p and circ_RBM23 or RAB1B was confirmed by bioinformatics analysis and dual-luciferase reporter assay.

RESULTS

Circ_RBM23 upregulation was discovered in the tissues of SR patients and SR cells, which was accompanied with miR-338-3p downregulation and RAB1B upregulation. The 50% inhibitory concentration (IC₅₀) of sorafenib in SR cells was greatly suppressed by interfering circ_RBM23 or reinforcing miR-338-3p, allied with this was the inhibition of EdU-positive cell rate, colony formation and migration/invasion abilities under sorafenib treatment, as well as the enhancement of apoptotic rate. Moreover, circ_RBM23 inhibition delayed tumor growth of Huh7/SR cells under sorfanib treatment in vivo.

CONCLUSION

Circ_RBM23 promoted chemoresistance, malignant proliferation, migration and invasion of SR HCC cells by modulating miR-338-3p/RAB1B axis.

Exosomal miR-628-5p from M1 polarized macrophages hinders m6A modification of circFUT8 to suppress hepatocellular carcinoma progression

BACKGROUND

Hepatocellular carcinoma (HCC) is the most common type of liver cancer. CircFUT8 has been shown to be upregulated in cancers, but its function in HCC remains unclear. Tumor-associated macrophages (TAMs) are one of the main components of the tumor microenvironment (TME), and M1 macrophages function as tumor suppressors in cancers. Exosomes exert an important role in the TME, and circRNAs can be modified by m6A. We investigated the function of circFUT8 in HCC and its interaction with exosomes, M1 macrophages, and m6A.

METHODS

CircFUT8 expression was detected in HCC cells, and its effects on HCC cell growth were verified through functional assays. Mechanism assays including RNA pull down, RNA-binding protein immunoprecipitation (RIP), and luciferase reporter assays were undertaken to verify how circFUT8 may interact with miR-628-5p, and how these molecules may modulate HCC cell malignancy via interacting with exosomes and macrophages.

RESULTS

CircFUT8 was upregulated in HCC cells and it accelerated HCC cell growth. Exosomes derived from M1 macrophages transferred miR-628-5p to HCC cells to inhibit human methyltransferase-like 14 (METTL14) expression. METTL14 promoted circFUT8 m6A modification and facilitated its nuclear export to the cytoplasm, where M1 macrophages regulated the circFUT8/miR-552-3p/CHMP4B pathway, thereby suppressing HCC progression.

CONCLUSION

M1 macrophages-derived exosomal miR-628-5p inhibited the m6A modification of circFUT8, inhibiting HCC development.

Identification and validation of core genes as promising diagnostic signature in hepatocellular carcinoma based on integrated bioinformatics approach

The primary objective of this investigation was to determine the hub genes of hepatocellular carcinoma (HCC) through an in silico approach. In the current context of the increased incidence of liver cancers, this approach could be a useful prognostic biomarker and HCC prevention target. This study aimed to examine hub genes for immune cell infiltration and their good prognostic characteristics for HCC research. Human genes selected from databases (Gene Cards and DisGeNET) were used to identify the HCC markers. Further, classification of the hub genes from communicating genes was performed using data derived from the targets' protein-protein interaction (PPI) platform. The expression as well as survival studies of all these selected genes were validated by utilizing databases such as GEPIA2, HPA, and immune cell infiltration. Based on the studies, five hub genes (TP53, ESR1, AKT1, CASP3, and JUN) were identified, which have been linked to HCC. They may be an important prognostic biomarker and preventative target of HCC. In silico analysis revealed that out of five hub genes, the TP53 and ESR1 hub genes potentially act as key targets for HCC prevention and treatment.

Circular RNA Controls Tumor Occurrence and Development via Cell Cycle Regulation

Circular RNAs (circRNAs) participate in the occurrence and development of various diseases through different mechanisms, such as by acting as a microRNA (miRNA) sponge, interacting with RNA-binding proteins, and regulating gene transcription and protein translation. For example, the abnormal expression of specific circRNAs in tumor cells can alter key regulatory factors and the cell cycle network, resulting in cell cycle disorders and the development and metastasis of tumors. Here, we summarize the mechanisms involved in the circRNA-mediated processes that lead to uncontrolled cell cycle and tumor cell proliferation. Extensive studies investigating the abnormal expression of circRNAs in different cancer types have been conducted. The unique characteristics of circRNAs and their ability to regulate the cell cycle through diverse mechanisms is extremely valuable in tumor diagnosis, treatment, and prognosis. Our review may assist in further understanding the circRNA-mediated regulation of the cell cycle in tumors and provide insights for research on circRNA-based therapeutic strategies and biological diagnosis for cancer.

Long Noncoding RNAs and Circular RNAs Regulate AKT and Its Effectors to Control Cell Functions of Cancer Cells

AKT serine-threonine kinase (AKT) and its effectors are essential for maintaining cell proliferation, apoptosis, autophagy, endoplasmic reticulum (ER) stress, mitochondrial morphogenesis (fission/fusion), ferroptosis, necroptosis, DNA damage response (damage and repair), senescence, and migration of cancer cells. Several lncRNAs and circRNAs also regulate the expression of these functions by numerous pathways. However, the impact on cell functions by lncRNAs and circRNAs regulating AKT and its effectors is poorly understood. This review provides comprehensive information about the relationship of lncRNAs and circRNAs with AKT on the cell functions of cancer cells. the roles of several lncRNAs and circRNAs acting on AKT effectors, such as FOXO, mTORC1/2, S6K1/2, 4EBP1, SREBP, and HIF are explored. To further validate the relationship between AKT, AKT effectors, lncRNAs, and circRNAs, more predicted AKT- and AKT effector-targeting lncRNAs and circRNAs were retrieved from the LncTarD and circBase databases. Consistently, using an in-depth literature survey, these AKT- and AKT effector-targeting database lncRNAs and circRNAs were related to cell functions. Therefore, some lncRNAs and circRNAs can regulate several cell functions through modulating AKT and AKT effectors. This review provides insights into a comprehensive network of AKT and AKT effectors connecting to lncRNAs and circRNAs in the regulation of cancer cell functions.

Investigation of Anti-Liver Cancer Activity of the Herbal Drug FDY003 Using Network Pharmacology

Globally, liver cancer (LC) is the sixth-most frequently occurring and the second-most fatal malignancy, responsible for 0.83 million deaths annually. Although the application of herbal drugs in cancer therapies has increased, their anti-LC activity and relevant mechanisms have not been fully studied from a systems perspective. To address these issues, we conducted a system-perspective network pharmacological investigation into the activity and mechanisms underlying the action of the herbal drug. FDY003 reduced the viability of human LC treatment. FDY003 reduced the viability of human LC cells and elevated their chemosensitivity. There were a total of 16 potential bioactive chemical components in FDY003 and they had 91 corresponding targets responsible for the pathological processes in LC. These FDY003 targets were functionally involved in regulating the survival, proliferation, apoptosis, and cell cycle of LC cells. Additionally, we found that FDY003 may target key signaling cascades connected to diverse LC pathological mechanisms, namely, PI3K-Akt, focal adhesion, IL-17, FoxO, MAPK, and TNF pathways. Overall, this study contributed to integrative mechanistic insights into the anti-LC potential of FDY003.

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.

Prognostic and clinicopathologic significance of circZFR in multiple human cancers

Background

Abnormally expressed in diverse cancers, circZFR has been correlated with clinical outcomes of cancer patients. Aim of this meta-analysis was to elucidate the prognostic role of circZFR in multiple human malignancies.

Methods

Literature retrieval was conducted by systematically searching on Pubmed, Web of Science, and the Cochrane Library up to December 2nd, 2021. Hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were pooled to evaluate the association between circZFR expression and overall survival (OS). The reliability of the pooled results was assessed through sensitivity analysis and the publication bias was measured by Begg’s and Egger’s test.

Results

A total of seventeen studies comprising 1098 Chinese patients were enrolled in this meta-analysis. Results demonstrated that high circZFR expression was correlated with an unfavorable OS (HR = 2.14, 95% CI 1.74, 2.64). High circZFR expression predicted larger tumor size (OR = 2.79, 95% CI 1.52, 5.12), advanced clinical stage (OR = 3.38, 95% CI 1.49, 7.65), tendentiousness of lymph node metastasis (LNM) (OR = 3.08, 95% CI 2.01, 4.71), and malignant grade (OR = 3.18, 95% CI 1.09, 9.30), but not related to age, gender, and distant metastasis (DM).

Conclusions

High circZFR expression was associated with unfavorable OS and clinicopathologic parameters including tumor size, clinical stage, LNM, and histology grade, implicating a promising prognostic factor in cancers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-022-02733-9.

The function and regulation network mechanism of circRNA in liver diseases

Circular RNA (circRNA), a new type of endogenous non-coding RNA, is abundantly present in eukaryotic cells, and characterized as stable high conservation and tissue specific expression. It has been generated increasing attention because of their close association with the progress of diseases. The liver is the vital organ of humans, while it is prone to acute and chronic diseases due to the influence of multiple pathogenic factors. Moreover, hepatocellular carcinoma (HCC) is the one of most common cancer and the leading cause of cancer death worldwide. Overwhelming evidences indicate that some circRNAs are differentially expressed in liver diseases, such as, HCC, chronic hepatitis B, hepatic steatosis and hepatoblastoma tissues, etc. Additionally, these circRNAs are related to proliferation, invasion, migration, angiogenesis, apoptosis, and metastasis of cell in liver diseases and act as oncogenic agents or suppressors, and linked to clinical manifestations. In this review, we briefly summarize the biogenesis, characterization and biological functions, recent detection and identification technologies of circRNA, and regulation network mechanism of circRNA in liver diseases, and discuss their potential values as biomarkers or therapeutic targets for liver diseases, especially on HCC.

Cancer-associated fibroblast exosomes promote chemoresistance to cisplatin in hepatocellular carcinoma through circZFR targeting signal transducers and activators of transcription (STAT3)/ nuclear factor -kappa B (NF-κB) pathway

Chemoresistance in hepatocellular carcinoma (HCC) has been found to be influenced by exosomal transport of circRNAs. However, the role of circZFR in HCC chemoresistance still remains unclear. In the present study, circZFR was highly expressed in cisplatin (DDP)-resistant HCC cell lines and could regulate DDP resistance of the HCC cells. Also, circZFR was highly expressed in cancer-associated fibroblast (CAFs) and the exosome of CAFs. In addition, supplementation of CAFs in culture medium could promote DDP resistance of HCC cells. In vivo tumor xenograft experiments showed that knockdown of circZFR inhibited tumor growth and weakened DDP resistance, while CAFs-derived exosomes incubation increased the expression of circZFR, inhibited the STAT3/NF-κB pathway, promoted tumor growth, and enhanced DDP resistance. In general, CAFs-derived exosomes deliver circZFR to HCC cells, inhibit the STAT3/NF-κB pathway, and promote HCC development and chemoresistance. The results provided a new sight for the prevention and treatment of chemoresistance in HCC.

An Update on the Roles of circRNA-ZFR in Human Malignant Tumors

CircRNAs (circular RNAs) are single-stranded RNAs that form covalently closed loops and function as important regulatory elements of the genome through multiple mechanisms. Increasing evidence had indicated that circRNAs, which might serve as either oncogenes or tumor suppressors, played vital roles in the pathophysiology of human diseases, especially in tumorigenesis and progression. CircRNA-ZFR (circular RNA zinc finger RNA binding protein) is a circular RNA that had attracted much attention in recent years. It has been found that circRNA-ZFR was abnormally expressed in a variety of malignant tumors, and its dysregulated expression was closely related to tumor stage, cancer metastasis and patients’ prognosis. Recent studies had shown that aberrantly expressed circRNA-ZFR could regulate the malignant biological behaviors of tumors through various mechanisms; further exploration of circRNA-ZFR expression in tumors and its regulation on malignant biological behaviors such as tumor proliferation, invasion and drug resistance will provide new ideas for clinical tumors diagnosis and treatment.

Cholesterol modified DP7 and pantothenic acid induce dendritic cell homing to enhance the efficacy of dendritic cell vaccines

Dendritic cell (DC)-based cancer vaccines have so far achieved good therapeutic effects in animal experiments and early clinical trials for certain malignant tumors. However, the overall objective response rate in clinical trials rarely exceeds 15%. The poor efficiency of DC migration to lymph nodes (LNs) (< 5%) is one of the main factors limiting the effectiveness of DC vaccines. Therefore, increasing the efficiency of DC migration is expected to further enhance the efficacy of DC vaccines. Here, we used DP7-C (cholesterol modified VQWRIRVAVIRK), which can promote DC migration, as a medium. Through multiomics sequencing and biological experiments, we found that it is the metabolite pantothenic acid (PA) that improves the migration and effectiveness of DC vaccines. We clarified that both DP7-C and PA regulate DC migration by regulating the chemokine receptor CXCR2 and inhibiting miR-142a-3p to affect the NF-κB signaling pathway. This study will lay the foundation for the subsequent use of DP7-C as a universal substance to promote DC migration, further enhance the antitumor effect of DC vaccines, and solve the bottleneck problem of the low migration efficiency and unsatisfactory clinical response rate of DC vaccines.

Circular RNA circZFR Promotes Hepatocellular Carcinoma Progression by Regulating miR-375/HMGA2 Axis

BACKGROUND

Mounting evidence indicates that circular RNAs (circRNAs) have vital roles in human diseases, especially in cancers.

AIMS

The aim of this study was to explore the biological functions and underlying mechanism of circRNA zinc finger RNA binding (circZFR) in hepatocellular carcinoma (HCC).

METHODS

The expression levels of circZFR, microRNA-375 (miR-375) and high mobility group A2 (HMGA2) were detected by qRT-PCR or western blot assay. Glycolytic metabolism was examined via the measurement of extracellular acidification rate, oxygen consumption rate, glucose uptake, lactate production, and ATP level. MTT assay and flow cytometry were used to assess cell proliferation and cell apoptosis, respectively. The interaction between miR-375 and circZFR or HMGA2 was verified by dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays. The mice xenograft model was established to investigate the role of circZFR in vivo.

RESULTS

CircZFR and HMGA2 were upregulated while miR-375 was downregulated in HCC tissues and cells. CircZFR silence inhibited HCC progression by inhibiting cell proliferation, glycolysis and tumor growth and promoting apoptosis. MiR-375 was a direct target of circZFR and its knockdown reversed the inhibitory effect of circZFR silence on the progression of HCC cells. Moreover, HMGA2 was a downstream target of miR-375, and miR-375 suppressed proliferation and glycolysis and induced apoptosis by targeting HMGA2 in HCC cells. Besides, circZFR acted as a molecular sponge of miR-375 to regulate HMGA2 expression.

CONCLUSION

Knockdown of circZFR suppressed the progression of HCC by upregulating miR-375 and downregulating HMGA2, providing new insight into the pathogenesis of HCC.

Phospho-Smad3L promotes progression of hepatocellular carcinoma through decreasing miR-140-5p level and stimulating epithelial-mesenchymal transition

BACKGROUND

The transforming growth factor β (TGF-β) activates JNK, phosphorylates Smad3 to linker-phosphorylated Smad3 (pSmad3L), resulting in liver tumorigenesis. However, the effect of pSmad3L on hepatocellular carcinoma (HCC) prognosis is obscure.

AIM

To detect the effect of pSmad3L on HCC prognosis and investigate the mechanism.

METHODS

The expressions of pSmad3L, E-cadherin, vimentin and MicroRNA-140-5p (miR-140-5p) were detected by using immunohistochemistry, immunofluorescence and in situ hybridization. Next, the relationships of pSmad3L and HCC patients' prognoses, pSmad3L and EMT markers, pSmad3L and miR-140-5p were analyzed using Spearman's rank correlation test. JNK/pSmad3L specific inhibitor SP600125 or Smad3 mutant plasmid was used to suppress JNK/pSmad3L pathway, and QPCR assay was performed to investigate the effect of pSmad3L on miR-140-5p level. The proliferation and invasion of hepatoma cells were observed using colony formation assay and transwell assay.

RESULTS

We demonstrated that patient with high level of pSmad3L predicted poor prognosis. Next, we verified that pSmad3L promoted EMT of hepatoma cells in vivo and in vitro. In order to investigate the mechanism, we verified a negative correlation between pSmad3L and miR-140-5p, which was an EMT inhibitor, in the liver tissues of HCC patient and diethylnitrosamine (DEN)-induced rat HCC model. We further used SP600125 or pSmad3L mutant plasmid to decrease pSmad3L level of hepatoma cells, and inhibition of pSmad3L increased miR-140-5p level and suppressed EMT of hepatoma cells.

CONCLUSIONS

JNK/pSmad3L pathway induces EMT by inhibiting miR-140-5p in HCC progression.

miR-511-5p Suppresses Cell Migration, Invasion and Epithelial-Mesenchymal Transition Through Targeting PAK2 in Gastric Cancer

As a malignant tumor, gastric cancer (GC) is closely related with gastric mucosa and has a high mortality in the world. Since microRNA (miRNA) has become more and more important in tumor research, we intend to find out the functional role and mechanism of miR-511-5p in GC. Firstly, miR-511-5p level was examined in human GC cell lines and tissues, and its effect on cell migration and invasion of BGC-823 or HGC-27 cells was tested by migration assay and transwell assay. Then, we confirmed the association between miR-511-5p and p21 activated kinase 2 (PAK2) by the luciferase reporter assay, and further assessed their role in cell migration and invasion. Moreover, we verified the function of miR-511-5p and PAK2 in epithelial-mesenchymal transition (EMT). In our study, miR-511-5p was downregulated in GC cell lines and tissues, and inversely associated with PAK2. Luciferase reporter assay confirmed that miR-511-5p could bind to PAK2. MiR-511-5p mimics significantly upregulated E-cadherin and downregulated N-cadherin, Vimentin and Snail, and consequently inhibited cell migration and invasion. However, reintroduction of PAK2 reversed the inhibitory function of miR-511-5p on BGC-823 and HGC-27 cells. Our research suggested that tumor-suppressive function of miR-511-5p in GC was inhibited by PAK2, and miR-511-5p/PAK2 axis may serve as a new strategy in GC management.

CircUBAP2 Promotes MMP9-Mediated Oncogenic Effect via Sponging miR-194-3p in Hepatocellular Carcinoma

BACKGROUND

The physiological regulatory functions of circRNAs have become a topic of intensive research in recent years. Increasing evidence supports a significant role of circRNAs during cancer initiation and progression, including hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

A bioinformatics analysis from three independent Gene Expression Omnibus (GEO) databases was performed to profile and screen the dysregulated circRNAs in HCC. RT-qPCR was used to examine the expression level of circUBAP2 in HCC and adjacent non-tumor tissues. Then, proliferation assays (CCK8 and colony formation) and migration assays (transwell and wound healing) were performed to examine effect of circUBAP2 in vitro. Immunoprecipitation, RNA pulldown, FISH, and dual-luciferase reporter assay was conducted to explore the circUBAP2-related mechanism for regulating HCC progression. Moreover, a mouse xenograft model and a mouse lung metastasis model confirmed the effect of circUBAP2 in vivo.

RESULTS

In this study, we found a novel circRNA: circUBAP2, which was identified by bioinformatics analysis. Among 91 HCC patients, circUBAP2 was significantly upregulated in HCC tissues, and negatively correlated with aggressive clinical characteristics and prognosis. Functional assays demonstrated that circUBAP2 promoted cell proliferation, colony formation, migration, and invasion in vitro. Moreover, circUBAP2 enhanced tumor growth and pulmonary metastasis in vivo. Mechanistically, circUBAP2 acts as a competing endogenous RNA (ceRNA) for miR-194-3p, a tumor suppressor in HCC. We confirmed that MMP9 was direct target for miR-194-3p, which was regulated by circUBAP2.

CONCLUSION

CircUBAP2 plays a significant role in promoting HCC via the miR-194-3p/MMP9 pathway and could serve as a promising prognostic biomarker and novel therapeutic target for 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.

NSL2CD: identifying potential circRNA-disease associations based on network embedding and subspace learning

Many studies have evidenced that circular RNAs (circRNAs) are important regulators in various pathological processes and play vital roles in many human diseases, which could serve as promising biomarkers for disease diagnosis, treatment and prognosis. However, the functions of most of circRNAs remain to be unraveled, and it is time-consuming and costly to uncover those relationships between circRNAs and diseases by conventional experimental methods. Thus, identifying candidate circRNAs for human diseases offers new opportunities to understand the functional properties of circRNAs and the pathogenesis of diseases. In this study, we propose a novel network embedding-based adaptive subspace learning method (NSL2CD) for predicting potential circRNA-disease associations and discovering those disease-related circRNA candidates. The proposed method first calculates disease similarities and circRNA similarities by fully utilizing different data sources and learns low-dimensional node representations with network embedding methods. Then, we adopt an adaptive subspace learning model to discover potential associations between circRNAs and diseases. Meanwhile, an integrated weighted graph regularization term is imposed to preserve local geometric structures of data spaces, and L1,2-norm constraint is also incorporated into the model to realize the smoothness and sparsity of projection matrices. The experiment results show that NSL2CD achieves comparable performance under different evaluation metrics, and case studies further confirm its ability to discover potential candidate circRNAs for human diseases.

Circ-ZFR Promotes Progression of Bladder Cancer by Upregulating WNT5A Via Sponging miR-545 and miR-1270

Background

Bladder cancer is one of the most common cancers all over the world. CircZFR is a circular RNA and has been implicated in tumor generation and invasion. However, the exact role of circZFR in the development of bladder cancer (BCa) remains unknown. This study aimed to investigate the function of circZFR in BCa, and further to probe into the association between circ-ZFR, miR-545/miR-1270 and WNT5A.

Methods

The expression of circZFR in BCa was quantified by qRT-PCR and was positively correlated with the prognosis of BCa patients. Next, the stable knockdown of circZFR BCa cell lines was established and the resulting capacities of proliferation, migration and invasion were measured. The association of circZFR with miR-1270/miR-545 was predicted by circinteractome prediction, and was confirmed by luciferase assay as well as RNA pull down assay. Furthermore, miRNA inhibitors, WNT5A overexpression and Pearson correlation analysis were used to examine the relationship between circZFR, miR-1270/miR-545 and WNT5A.

Results

The expression of CircZFR was up-regulated both in BCa tissues and in BCa cell lines, and was positively correlated with patient survival rates. Blocking of circZFR's expression by RNA inhibitors suppressed the proliferation, migration and invasion of BCa cells both in vitro and in vivo. On the other hand, overexpression of target miRNA supported that circZFR directly interact with miR-545 and miR-1270. Moreover, we demonstrated that circZFR promotes the progression of BCa by upregulating WNT5A's expression via sponging miR-545 and miR-1270.

Conclusions

CircZFR promotes the proliferation, migration and invasion of BCa cells by upregulating WNT5A signaling pathway via sponging miR-545 and miR-1270. These results provide new insights into the molecular mechanism of circZFR in BCa progression, and more important, a novel target for BCa clinical treatment.

Tip of the Iceberg: Roles of CircRNAs in Cancer Glycolysis

Warburg effect reflects that tumor cells tend to generate energy by aerobic glycolysis rather than oxidative phosphorylation (OXPHOS), thus promoting the development of malignant tumors. As a kind of non-coding RNA, circular RNA (circRNA) is characterized by a closed ring structure and emerges as a regulator of cancer metabolism. Mounting studies revealed that circRNA can regulate the cancer metabolism process through affecting the expression of glycolysis relevant enzymes, transcription factors (TFs), and signaling pathways. In this review, we comprehensively analyzed and concluded the mechanism of circRNA regulating glycolysis, hoping to deepen the cognition of the cancer metabolic regulatory network and to reap huge fruits in targeted cancer treatment.

Comprehensive Analysis of Correlations in the Expression of miRNA Genes and Immune Checkpoint Genes in Bladder Cancer Cells

Personalised medicine is the future and hope for many patients, including those with cancers. Early detection, as well as rapid, well-selected treatment, are key factors leading to a good prognosis. MicroRNA mediated gene regulation is a promising area of development for new diagnostic and therapeutic methods, crucial for better prospects for patients. Bladder cancer is a frequent neoplasm, with high lethality and lacking modern, advanced therapeutic modalities, such as immunotherapy. MicroRNAs are involved in bladder cancer pathogenesis, proliferation, control and response to treatment, which we summarise in this perspective in response to lack of recent review publications in this field. We further performed a correlation-based analysis of microRNA and gene expression data in bladder cancer (BLCA) TCGA dataset. We identified 27 microRNAs hits with opposite expression profiles to genes involved in immune response in bladder cancer, and 24 microRNAs hits with similar expression profiles. We discuss previous studies linking the functions of these microRNAs to bladder cancer and assess if they are good candidates for personalised medicine therapeutics and diagnostics. The discussed functions include regulation of gene expression, interplay with transcription factors, response to treatment, apoptosis, cell proliferation and angiogenesis, initiation and development of cancer, genome instability and tumour-associated inflammatory reaction.

Long non-coding RNA 01559 mediates the malignant phenotypes of hepatocellular carcinoma cells through targeting miR-511

BACKGROUND

Long non-coding RNA 01559 (LINC01559) has been found to be associated with the tumorigenesis of malignant tumors. However, the expression pattern and the potential molecular mechanism of LINC01559 in hepatocellular carcinoma (HCC) progression remain unclear.

METHODS

Expression profile and clinical data of patients with HCC were retrieved from The Cancer Genome Atlas database. The quantitative real-time PCR (qRT-PCR) and western blot assays were used to detect the mRNA and protein levels of indicated molecules. Loss-of-function of LINC01559 and microRNA-511 (miR-511) assays were implemented to validate their roles in regulating proliferation, invasion and migration of HCC HepG2 and Huh7 cells. Bioinformatics and luciferase reporter assays were used to determine the possible interactions between LINC01559, miR-511 and solute carrier family 38 member 1 (SLC38A1).

RESULTS

LINC01559 was highly expressed, and related to poor prognosis in HCC patients. LINC01559-knockdown restrained the proliferation and growth of HepG2 and Huh7 cells. Furthermore, LINC01559 can function as a sponge for miR-511, which was downregulated in HCC patients. Downregulation of miR-511 significantly increased the cell viability, invasive and migratory capacities, and could abolish the suppressive effect of LINC01559-knockdown on these HCC cells. Moreover, SLC38A1 was a target of miR-511 and upregulated in HCC. Knockdown of LINC01559 significantly reduced while miR-511 inhibitor notably elevated the mRNA and protein levels of SLC38A1, which were abrogated by downregulation of LINC01559 and miR-511 simultaneously.

CONCLUSIONS

LINC01559 functioned as a competitive endogenous RNA mediating the malignant phenotypes of HCC cells via sponging miR-511, and may be a considerable therapeutic bio-target in HCC.

CircMAP3K11 Contributes to Proliferation, Apoptosis and Migration of Human Periodontal Ligament Stem Cells in Inflammatory Microenvironment by Regulating TLR4 via miR-511 Sponging

Growing number of studies regarding the role of circRNAs in the development of various diseases have emerged in recent years, but the role of circRNAs in periodontitis pathogenesis remains obscure. Human periodontal ligament stem cells (hPDLSCs) play a critical role in periodontal remodeling, regeneration and repair processes, and their regenerative capacity could be prohibited in local periodontal inflammatory microenvironment. Herein, we sought to uncover the molecular mechanisms of periodontitis pathogenesis by investigating the role of circMAP3K11 (hsa_circ_002284) for regenerative capacity of hPDLSCs under an inflammatory condition. The hPDLSCs isolated from periodontitis patients were used as a cell model of inflammatory microenvironment to study the effect of the circMAP3K11/miR-511-3p/TLR4 axis on the proliferation, apoptosis and migration of hPDLSCs under inflammatory conditions. Compared to the periodontal tissues from normal subjects, those from periodontitis patients exhibited higher expression levels of circMAP3K11 and TLR4, and lower expression level of miR-511-3p. Both the expressions of circMAP3K11 and TLR4 were negatively correlated with the expressions of miR-511-3p in periodontitis. In vitro studies demonstrated that circMAP3K11 is capable of enhancing hPDLSCs proliferation and migration, and reducing the apoptosis of hPDLSCs. We also found that circMAP3K11 could up-regulate the expression of transcription factors that are closely related to periodontal regeneration (Runx2, OSX, ATF4, and BSP). RT-PCR and western blot showed that the inhibitory role of miR-511-3p on TLR4 expression could be reversed by circMAP3K11, which was in line with the results of bioinformatics tools and luciferase reporter assay. Meanwhile, both in vitro and in vivo studies indicated that circMAP3K11 could reverse the effects of miR-511-3p in periodontitis, which further confirmed that circMAP3K11 functioned as a ‘sponge’ of miR-511-3p to positively regulate the expression of TLR4. Taken together, our study preliminarily uncovered a circMAP3K11/miR-511-3p/TLR4 axis that regulates the function of hPDLSCs in periodontitis, providing novel insight and scientific base in the treatment of periodontal tissue regeneration based on stem cells.

The Roles of circRNAs in Liver Cancer Immunity

Circular RNAs (circRNAs) are stable covalently closed non-coding RNAs (ncRNAs). Many studies indicate that circRNAs are involved in the pathological and physiological processes of liver cancer. However, the functions of circRNAs in liver cancer immunity are less known. In this review, we summarized the functions of circRNAs in liver cancer, including proliferative, metastasis and apoptosis, liver cancer stemness, cell cycle, immune evasion, glycolysis, angiogenesis, drug resistance/sensitizer, and senescence. Immune escape is considered to be one of the hallmarks of cancer development, and circRNA participates in the immune escape of liver cancer cells by regulating natural killer (NK) cell function. CircRNAs may provide new ideas for immunotherapy in liver cancer.

The circular RNA circZFR phosphorylates Rb promoting cervical cancer progression by regulating the SSBP1/CDK2/cyclin E1 complex

Background

As a novel type of non-coding RNA, circular RNAs (circRNAs) play a critical role in the initiation and development of various diseases, including cancer. However, the exact function of circRNAs in human cervical cancer remains largely unknown.

Methods

We identified the circRNA signature of upregulated circRNAs between cervical cancer and paired adjacent normal tissues. Using two different cohorts and GEO database, a total of six upregulated circRNAs were identified with a fold change > 2, and P < 0.05. Among these six circRNAs, hsa_circ_0072088 (circZFR) was the only exonic circRNA significantly overexpressed in cervical cancer. Functional experiments were performed to investigate the biological function of circZFR. CircRNA pull-down, circRNA immunoprecipitation (circRIP) and Co-immunoprecipitation (Co-IP) assays were executed to investigate the molecular mechanism underlying the function of circZFR.

Results

Functionally, circZFR knockdown represses the proliferation, invasion, and tumor growth. Furthermore, circRNA pull-down experiments combined with mass spectrometry unveil the interactions of circZFR with Single-Stranded DNA Binding Protein 1 (SSBP1). Mechanistically, circZFR bound with SSBP1, thereby promoting the assembly of CDK2/cyclin E1 complexes. The activation of CDK2/cyclin E1 complexes induced p-Rb phosphorylation, thus releasing activated E2F1 leading to cell cycle progression and cell proliferation.

Conclusion

Our findings provide the first evidence that circZFR is a novel onco-circRNA and might be a potential biomarker and therapeutic target for cervical cancer patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01849-2.

Circular RNAs in Human Cancer

Circular RNAs (circRNAs) are a class of endogenous single-stranded covalently closed RNAs, primarily produced from pre-mRNAs via non-canonical back-splicing. circRNAs are highly conserved, stable, and expressed in tissue- and development-specific pattern. circRNAs play essential roles in physiological process as well as cancer biology. By the advances of deep sequencing and bioinformatics, the number of circRNAs have increased explosively. circRNAs function as miRNA/protein sponge, protein scaffold, protein recruitment, enhancer of protein function, as well as templates for translation involved in the regulation of transcription/splicing, translation, protein degradation, and pri-miRNA processing in human cancers and contributed to the pathogenesis of cancer. Numerous circRNAs may function in diverse manners. In this review, we survey the current understanding of circRNA functions in human cancer including miRNA sponge, circRNA-protein interaction, and circRNA-encoded protein, and summarize available databases for circRNA annotation and functional prediction.

iCDA-CMG: identifying circRNA-disease associations by federating multi-similarity fusion and collective matrix completion

Circular RNAs (circRNAs) are a special class of non-coding RNAs with covalently closed-loop structures. Studies prove that circRNAs perform critical roles in various biological processes, and the aberrant expression of circRNAs is closely related to tumorigenesis. Therefore, identifying potential circRNA-disease associations is beneficial to understand the pathogenesis of complex diseases at the circRNA level and helps biomedical researchers and practitioners to discover diagnostic biomarkers accurately. However, it is tremendously laborious and time-consuming to discover disease-related circRNAs with conventional biological experiments. In this study, we develop an integrative framework, called iCDA-CMG, to predict potential associations between circRNAs and diseases. By incorporating multi-source prior knowledge, including known circRNA-disease associations, disease similarities and circRNA similarities, we adopt a collective matrix completion-based graph learning model to prioritize the most promising disease-related circRNAs for guiding laborious clinical trials. The results show that iCDA-CMG outperforms other state-of-the-art models in terms of cross-validation and independent prediction. Moreover, the case studies for several representative cancers suggest the effectiveness of iCDA-CMG in screening circRNA candidates for human diseases, which will contribute to elucidating the pathogenesis mechanisms and unveiling new opportunities for disease diagnosis and targeted therapy.

Circular RNAs in gastrointestinal cancer: Current knowledge, biomarkers and targeted therapy (Review)

Circular RNAs (circRNAs) are a type of endogenous non‑coding RNAs that are connected at the 3' and 5' ends by exon or intron cyclization, which forms a covalently closed loop. They are stable, well conserved, exhibit specific expression in mammalian cells and can function as microRNA (miRNA or miR) sponges to regulate the target genes of miRNAs, which influences biological processes. Such as tumor proliferation, invasion, metastasis, apoptosis and tumor stage. circRNAs represent promising candidates for clinical diagnosis and treatment. In the present review, the biogenesis, classification and functions of circRNAs in tumors are briefly summarized and discussed. In addition, the participation of circRNAs in signal transduction pathways regulating gastrointestinal cancer cellular functions is highlighted.

Construction of a circRNA-miRNA-mRNA Network Related to Macrophage Infiltration in Hepatocellular Carcinoma

Immune cells in the tumor microenvironment play a crucial role in regulating tumor progression. The circular RNA (circRNA) regulatory network involved in immune cell infiltration in hepatocellular carcinoma (HCC) remains largely unknown. In this study, the “estimate the proportion of immune and cancer cells” (EPIC) application is used to evaluate the fractions of immune cells, cancer-associated fibroblasts, and endothelial cells in HCC from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Patients with a high macrophage fraction have better overall survival, and macrophage fraction is an independent prognostic factor for HCC. Next, the common differentially expressed mRNAs (DEmRNAs), miRNAs (DEmiRNAs), and circRNAs (DEcircRNAs) between paired tumor and non-tumor tissues are screened out from the TCGA and/or GEO databases. Through spearman correlation analysis, the macrophage-related DEmRNAs are identified to construct a circRNA-miRNA-mRNA regulatory network, which includes 6 DEcircRNAs, 7 DEmiRNAs, and 45 DEmRNAs. Functional enrichment analysis reveals that these DEmRNAs are mainly involved in immune-related processes. Furthermore, six hub DEmRNAs are identified to establish a hub circRNA regulatory network. Among the DEmRNAs in the network, PRC1 is identified as the most influential node. PRC1 high expression is correlated with poor prognosis and low macrophage infiltration in HCC. Taken together, we identify a certain circRNA regulatory network related to macrophage infiltration and provide novel insight into the mechanism of study and therapeutic targets for HCC.

Novel potential tumor biomarkers: Circular RNAs and exosomal circular RNAs in gastrointestinal malignancies

BACKGROUND

Circular RNAs (circRNAs) are structural ubiquitous RNA molecules. Accumulating evidences have elucidated that circRNAs play essential roles in the pathogenesis of diseases including cancers. Exosomal circRNAs are those circRNAs stably existing in exosomes and having high clinical values as novel potential diagnostic biomarkers of many diseases. Gastrointestinal (GI) malignancies, including pancreatic cancer, colorectal cancer, hepatocellular carcinoma (HCC), and gastric cancer, are leading causes of mortality worldwide and a major global health burden. However, no ideal tumor biomarkers of screening early GI cancers are currently available.

METHODS

We collected data through Web of Science. The search terms used were as follows: circular RNA, circRNA, exosomes, exosomal circRNAs, biomarkers, gastrointestinal malignancies, pancreatic cancer, hepatocellular carcinoma, HCC, gastric cancer, colorectal cancer, physiological functions, biogenesis, molecular mechanism. Only articles published in English were included.

RESULTS

We found that several circRNAs and exosomal circRNAs have been used as potential biomarkers to screen GI cancers including pancreatic cancer (hsa_circ_0001649, circ_0007534, circ_0030235, circRHOT1, circZMYM2, circ-LDLRAD3, chr14:101402109-101464448C, chr4:52729603-52780244C, circ-IARS, and circ-PDE8A), HCC (circSETD3, circADAMTS13, hsa_circ_0007874, hsa_circ_104135, circFBLIM1, cSMARCA5, circRNA-100338, and circPTGR1), colorectal cancer (hsa_circ_0001178, hsa_circ_0000826, hsa_circ_0004771, circDDX17, circITGA7, and circHIPK3), and gastric cancer (hsa_circ_0074362, circNRIP1, circAKT3, circ-DONSON, circPSMC3, circ-KIAA1244, circPVRL3, circPVT1, hsa_circ_0000096, ciRS-133, hsa_circ_0001017, and hsa_circ_0061276).

CONCLUSION

CircRNAs and exosomal circRNAs have the potential high clinical diagnostic values for GI malignancies.

MiR-511 mimic transfection inhibits the proliferation, invasion of osteosarcoma cells and reduces metastatic osteosarcoma tumor burden in nude mice via targeting MAPK1

Osteosarcoma, a highly aggressive cancer, can rapidly metastasize to distant organs such as lung, liver, brain. Despite much progress in the therapeutic regime has been made, the prognosis of osteosarcoma remains poor. In present study, microRNA-511 (miR-511) is lowly expressed in osteosarcoma cells, including MG63, U-2 OS, Saos-2 cells, while mitogen activated protein kinase1 (MAPK1) is highly expressed in osteosarcoma cells. Interestingly, MAPK1 might be a target of miR-511. We found that overexpression of miR-511 by miR-511 mimic transfection may result to low expression of MAPK1. Further study showed that miR-511 mimic inhibits the development of osteosarcoma MG63 cell, including proliferation and invasion. Moreover, miR-511 mimic transfection reduces metastatic osteosarcoma tumor burden in nude mice. These activities are mediated by targeting MAPK1. Our study provides a new sight for the molecular pathogenesis of osteosarcoma.

Circ_0072083 interference enhances growth-inhibiting effects of cisplatin in non-small-cell lung cancer cells via miR-545-3p/CBLL1 axis

Background

Non-small-cell lung cancer (NSCLC) is one of the common cancers in the world. Circular RNA 0072083 (circ_0072083, circZFR) has been reported to be associated with the progression of NSCLC. In this study, we intended to explore the role and the potential mechanism of circ_0072083 in NSCLC.

Methods

Quantitative real time polymerase chain reaction (qRT-PCR) was performed to detect the expression of circ_0072083, its matching linear RNA (zinc finger RNA binding protein (ZFR)) and microRNA-545-3p (miR-545-3p) in NSCLC cells. The ability of colony formation in NSCLC cells was detected by colony formation assay. The apoptosis and cell cycle were measured by flow cytometry. The metastasis was determined by transwell migration and invasion assays. The protein expression of E-cadherin, N-cadherin, Vimentin and Cbl proto-oncogene like 1 (CBLL1) was examined by western blot assay. The interaction between miR-545-3p and circ_0072083 or CBLL1 was predicted by starBase or Targetscan software. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were applied to validate these interactions. Nude mice bearing tumors were used to confirm the role of circ_0072083 and cisplatin (DDP) in vivo.

Results

The level of circ_0072083 was higher in NSCLC tissues and cells relative to that in adjacent non-tumor tissues and normal lung cells. The transfection of si-circ_0072083 inhibited colony formation, cell cycle and metastasis while promoted the apoptosis of NSCLC cells stimulated by DDP. MiR-545-3p was a direct functional target of circ_0072083 in NSCLC cells. CBLL1 could bind to miR-545-3p in NSCLC cells. Circ_0072083 promoted the progression of NSCLC induced by DDP through sponging miR-545-3p and enhancing the enrichment of CBLL1 in vivo and in vitro.

Conclusion

Circ_0072083 depletion contributed to DDP-triggered inhibition of NSCLC tumor through miR-545-3p/CBLL1 axis.

MicroRNAs in Animal Models of HCC

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality. Molecular heterogeneity and absence of biomarkers for patient allocation to the best therapeutic option contribute to poor prognosis of advanced stages. Aberrant microRNA (miRNA) expression is associated with HCC development and progression and influences drug resistance. Therefore, miRNAs have been assayed as putative biomarkers and therapeutic targets. miRNA-based therapeutic approaches demonstrated safety profiles and antitumor efficacy in HCC animal models; nevertheless, caution should be used when transferring preclinical findings to the clinics, due to possible molecular inconsistency between animal models and the heterogeneous pattern of the human disease. In this context, models with defined genetic and molecular backgrounds might help to identify novel therapeutic options for specific HCC subgroups. In this review, we describe rodent models of HCC, emphasizing their representativeness with the human pathology and their usefulness as preclinical tools for assessing miRNA-based therapeutic strategies.