Circular RNA circ-LDLRAD3 as a biomarker in diagnosis of pancreatic cancer

Advanced approaches of the use of circRNAs as a replacement for cancer therapy

Cancer is a broad name for a group of diseases in which abnormal cells grow out of control and are characterized by their complexity and recurrence. Although there has been progress in cancer therapy with the entry of precision medicine and immunotherapy, cancer incidence rates have increased globally. Non-coding RNAs in the form of circular RNAs (circRNAs) play crucial roles in the pathogenesis, clinical diagnosis, and therapy of different diseases, including cancer. According to recent studies, circRNAs appear to serve as accurate indicators and therapeutic targets for cancer treatment. However, circRNAs are promising candidates for cutting-edge cancer therapy because of their distinctive circular structure, stability, and wide range of capabilities; many challenges persist that decrease the applications of circRNA-based cancer therapeutics. Here, we explore the roles of circRNAs as a replacement for cancer therapy, highlight the main challenges facing circRNA-based cancer therapies, and discuss the key strategies to overcome these challenges to improve advanced innovative therapies based on circRNAs with long-term health effects.

Exploring the prognostic value of circular RNAs in pancreatic ductal adenocarcinoma using genome-wide expression profiling

BACKGROUND/OBJECTIVES

Median survival of pancreatic ductal adenocarcinoma (PDAC) is around eight months and new prognostic tools are needed. Circular RNAs (circRNAs) have gained interest in different types of cancer. However, only a few studies have evaluated their potential in PDAC. We aimed to identify the most differentially expressed circRNAs in PDAC compared to controls and to explore their potential as prognostic markers.

METHODS

Using frozen specimens with PDAC and controls, we performed RNA sequencing and identified 20,440 unique circRNAs. A custom code set of capture- and reporter probes for NanoString nCounter analysis was designed to target 152 circRNAs, based on abundancy, differential expression and a literature study. Expression of these 152 circRNAs was examined in 108 formalin-fixed and paraffin-embedded surgical PDAC specimens and controls. The spatial expression of one of the most promising candidates, ciRS-7 (hsa_circ_0001946), was evaluated by chromogenic in situ hybridization (CISH) using multi-punch tissue microarrays (TMAs) and digital imaging analysis.

RESULTS

Based on circRNA expression profiles, we identified different PDAC subclusters. The 30 most differentially expressed circRNAs showed log2 fold changes from -3.43 to 0.94, where circNRIP1 (hsa_circ_0004771), circMBOAT2 (hsa_circ_0007334) and circRUNX1 (hsa_circ_0002360) held significant prognostic value in multivariate analysis. CiRS-7 was absent in PDAC cells but highly expressed in the tumor microenvironment.

CONCLUSIONS

We identified several new circRNAs with biomarker potential in surgically treated PDAC, three of which showed an independent prognostic value. We also found that ciRS-7 is absent in cancer cells but abundant in tumor microenvironment and may hold potential as marker of activated stroma.

Imaging Techniques and Biochemical Biomarkers: New Insights into Diagnosis of Pancreatic Cancer

Pancreatic cancer (PaC) incidence is increasing, but our current screening and diagnostic strategies are not very effective. However, screening could be helpful in the case of PaC, as recent evidence shows that the disease progresses gradually. Unfortunately, there is no ideal screening method or program for detecting PaC in its early stages. Conventional imaging techniques, such as abdominal ultrasound, CT, MRI, and EUS, have not been successful in detecting early-stage PaC. On the other hand, biomarkers may be a more effective screening tool for PaC and have greater potential for further evaluation compared to imaging. Recent studies on biomarkers and artificial intelligence (AI)-enhanced imaging have shown promising results in the early diagnosis of PaC. In addition to proteins, non-coding RNAs are also being studied as potential biomarkers for PaC. This review consolidates the current literature on PaC screening modalities to provide an organized framework for future studies. While conventional imaging techniques have not been effective in detecting early-stage PaC, biomarkers and AI-enhanced imaging are promising avenues of research. Further studies on the use of biomarkers, particularly non-coding RNAs, in combination with imaging modalities may improve the accuracy of PaC screening and lead to earlier detection of this deadly disease.

The novel circ_0004674/miR-139-5p/ZBTB2 regulatory cascade inhibits the development of oral squamous cell carcinoma

BACKGROUND

Circular RNAs (circRNAs) are an intriguing family of RNA molecules due to their crucial roles in the pathogenesis of oral squamous cell carcinoma (OSCC). Here, we sought to define the action of human circ_0004674 in OSCC progression.

METHODS

The functional role of circ_0004674 was validated by determining its effect on cell growth, apoptosis, and tube formation ability of OSCC cells. For protein quantification, a western blot or immunohistochemistry method was applied. The interaction between miR-139-5p and circ_0004674 or zinc finger and BTB domain containing 2 (ZBTB2) was predicted by online algorithms, and their relationships were confirmed by dual-luciferase reporter and RIP assays. Xenograft models were established to uncover circ_0004674's role in tumor growth.

RESULTS

Circ_0004674 expression was upregulated in OSCC. Functionally, knocking down circ_0004674 led to suppressed OSCC cell progression in vitro and delayed tumor growth in vivo. Mechanistically, circ_0004674 post-transcriptionally controlled ZBTB2 expression by competitively pairing to miR-139-5p. Furthermore, the deficiency of miR-139-5p abated circ_0004674 silencing-mediated OSCC cell progression repression, and augmentation of ZBTB2 reversed the anticancer effect of miR-139-5p on OSCC.

CONCLUSION

Our findings uncover a novel regulatory cascade, the circ_0004674/miR-139-5p/ZBTB2 axis, with the ability to affect OSCC development in vitro and in vivo, providing a potential opportunity for development of OSCC therapy.

Circ_0004592: An auxiliary diagnostic biomarker for gastric cancer

BACKGROUND

Gastric cancer (GC) has a high mortality rate, and robust diagnostic biomarkers are currently lacking. However, the clinical relevance of circular RNAs (circRNAs) as GC biomarkers remains largely unexplored.

AIM

To evaluate the potential of novel circRNA circ_0004592 in the early screening and prognosis of GC.

METHODS

High-throughput sequencing of circRNAs was performed to screen for potential target molecules. Circ_0004592 expression was examined in GC tissues, cells, and plasma. Plasma samples were collected from healthy subjects’ patients, as well as from patients with benign lesions, precancerous lesions, and GC, whereafter the diagnostic accuracy of circ_0004592 was evaluated. The correlation between circ_0004592 levels in plasma and clinicopathological data of patients with GC was further analyzed.

RESULTS

Circ_0004592 was upregulated in both the tissue and plasma of patients with GC. Further, circ_0004592 expression was higher in patients with precancerous lesions than in healthy controls while being highest in patients with GC. In the same patient, the postoperative plasma level of circ_0004592 was lower than that in the preoperative period. Moreover, circ_0004592 level was significantly correlated with tumor differentiation, tumor depth, and lymph node metastasis. The area under the curve (AUC) of plasma circ_0004592 exhibited high sensitivity and specificity for differentiating patients with GC from healthy donors. Diagnosis based on circ_0004592, carcinoembryonic antigen, and cancer antigen 199 achieved a superior AUC and was highly sensitive.

CONCLUSION

Plasma circ_0004592 may represent a potential non-invasive auxiliary diagnostic biomarker for patients with GC.

Circ_0004592: An auxiliary diagnostic biomarker for gastric cancer

BACKGROUND

Gastric cancer (GC) has a high mortality rate, and robust diagnostic biomarkers are currently lacking. However, the clinical relevance of circular RNAs (circRNAs) as GC biomarkers remains largely unexplored.

AIM

To evaluate the potential of novel circRNA circ_0004592 in the early screening and prognosis of GC.

METHODS

High-throughput sequencing of circRNAs was performed to screen for potential target molecules. Circ_0004592 expression was examined in GC tissues, cells, and plasma. Plasma samples were collected from healthy subjects' patients, as well as from patients with benign lesions, precancerous lesions, and GC, whereafter the diagnostic accuracy of circ_0004592 was evaluated. The correlation between circ_0004592 levels in plasma and clinicopathological data of patients with GC was further analyzed.

RESULTS

Circ_0004592 was upregulated in both the tissue and plasma of patients with GC. Further, circ_0004592 expression was higher in patients with precancerous lesions than in healthy controls while being highest in patients with GC. In the same patient, the postoperative plasma level of circ_0004592 was lower than that in the preoperative period. Moreover, circ_0004592 level was significantly correlated with tumor differentiation, tumor depth, and lymph node metastasis. The area under the curve (AUC) of plasma circ_0004592 exhibited high sensitivity and specificity for differentiating patients with GC from healthy donors. Diagnosis based on circ_0004592, carcinoembryonic antigen, and cancer antigen 199 achieved a superior AUC and was highly sensitive.

CONCLUSION

Plasma circ_0004592 may represent a potential non-invasive auxiliary diagnostic biomarker for patients with GC.

Silencing circLDLRAD3 Inhibits Lung Cancer Progression by Regulating the miR-497-5p/PFKP Axis

PURPOSE

Lung cancer is one of the leading causes of death worldwide. Recent studies have shown that circular RNAs are dysregulated in a variety of cancers, but the mechanism in lung cancer is still indistinct. In our work, we explored the action mechanism of circLDLRAD3 in lung cancer.

METHODS

The abundance of circLDLRAD3, microRNA-497-5p (miR-497-5p) and platelet-type PFK (PFKP) was measured by real-time quantitative polymerase chain reaction (RT-qPCR) in lung cancer. Meanwhile, the level of PFKP was quantified by western blot. Cell counting kit-8 (CCK-8), 5-Ethynyl-2'-deoxyuridine (EdU) assay, transwell assay, wound healing assay, flow cytometry, western blot, immunohistochemical (IHC) assay and glycolysis metabolism analysis were performed for functional analyses. Furthermore, the interplay between miR-497-5p and circLDLRAD3 or FKPF was detected by the dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays. Eventually, the in vivo experiments were applied to measure the role of circLDLRAD3.

RESULT

The levels of circLDLRAD3 and PFKP were increased. Silencing circLDLRAD3 inhibited cell viability, proliferation, migration, invasion and glycolysis metabolism and promoted cell apoptosis in lung cancer cells. In mechanism, circLDLRAD3 regulated PFKP level as a miR-497-5p sponge. MiR-497-5p suppressed the progression of lung cancer by inhibiting PFKP. In addition, circLDLRAD3 knockdown also inhibited tumor growth in vivo.

CONCLUSION

CircLDLRAD3 promoted the development of lung cancer through increasing PFKP expression by regulating miR-497-5p, which also provided a potential targeted therapy for lung cancer treatment.

A Comprehensive Review of the Potential Role of Liquid Biopsy as a Diagnostic, Prognostic, and Predictive Biomarker in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma is one of the most lethal malignant diseases, with a mortality rate being close to incidence. Due to its heterogeneity and plasticity, as well as the lack of distinct symptoms in the early phases, it is very often diagnosed at an advanced stage, resulting in poor prognosis. Traditional tissue biopsies remain the gold standard for making a diagnosis, but have an obvious disadvantage in their inapplicability for frequent sampling. Blood-based biopsies represent a non-invasive method which potentially offers easy and repeated sampling, leading to the early detection and real-time monitoring of the disease and hopefully an accurate prognosis. Given the urgent need for a reliable biomarker that can estimate a patient's condition and response to an assigned treatment, blood-based biopsies are emerging as a potential new tool for improving patients' survival and surveillance. In this article, we discuss the current advances and challenges in using liquid biopsies for pancreatic cancer, focusing on circulating tumour DNA (ctDNA), extracellular vesicles (EVs), and circulating tumour cells (CTCs), and compare the performance and reliability of different biomarkers and combinations of biomarkers.

Hsa_circ_0000106 Acts as a Tumor Promoter in Pancreatic Cancer by Targeting the MiR-455-3p/HDAC4

Circular RNAs (circRNAs) frequently participate in pancreatic cancer (PC) progression. This study focuses on circ_0000106, a novel circRNA, and its potential function in PC development. Circ_00001106, miR-455-3p, and HDAC4 expression levels in PC were determined using qRT-PCR and immunoblotting. RNA immunoprecipitation and dual-luciferase reporter assays were performed to verify their binding interactions. Loss-of-function assays, including CCK-8, colony formation, and transwell assays, were used to estimate the proliferative and migratory properties of PC cells. A nude mouse model was constructed to assess the influence of circ_0000106 on tumor formation in vivo. A pronounced elevation of circ_0000106 and HDAC4 and a reduction of miR-455-3p in PC were observed. Circ_0000106 was prone to binding to miR-455-3p, and miR-455-3p further targeted HDAC4. Functionally, the proliferative and migratory properties of PC cells were dampened by the loss of circ_0000106 or HDAC4 and could be potentiated by miR-455-3p inhibition. Moreover, the knockdown of circ_0000106 delayed tumor growth in vivo. Additionally, the downregulation of miR-455-3p attenuated the repressive effects of circ_0000106 deficiency on PC cell migration and proliferation. Loss of HDAC4 exerted similar mitigative effects on miR-455-3p downregulation-stimulated PC cells. In conclusion, circ_0000106 promotes tumor migration and growth in PC by targeting the miR-455-3p/HDAC4 axis. These results suggest that the circ_0000106/miR-455-3p/HDAC4 network could be regarded as a latent target for PC treatment.

Going circular: history, present, and future of circRNAs in cancer

To date, thousands of highly abundant and conserved single-stranded RNA molecules shaped into ring structures (circRNAs) have been identified. CircRNAs are multifunctional molecules that have been shown to regulate gene expression transcriptionally and post-transcriptionally and exhibit distinct tissue- and development-specific expression patterns associated with a variety of normal and disease conditions, including cancer pathogenesis. Over the past years, due to their intrinsic stability and resistance to ribonucleases, particular attention has been drawn to their use as reliable diagnostic and prognostic biomarkers in cancer diagnosis, treatment, and prevention. However, there are some critical caveats to their utility in the clinic. Their circular shape limits their annotation and a complete functional elucidation is lacking. This makes their detection and biomedical application still challenging. Herein, we review the current knowledge of circRNA biogenesis and function, and of their involvement in tumorigenesis and potential utility in cancer-targeted therapy.

Expression status of circ-SMARCA5, circ-NOL10, circ-LDLRAD3, and circ-RHOT1 in patients with colorectal cancer

Colorectal cancer (CRC) poses a significant burden on both the healthcare systems as well as individuals. The high mortality rate of CRC may be attributed to its metastatic potential, heterogeneity, and delayed diagnosis. CircRNAs are an essential class of regulatory RNAs that play significant roles in cancers. This study aimed to detect the expression status of circ-SMARCA5, circ-NOL10, circ-LDLRAD3, and circ-RHOT1 in patients with CRC. This study included 50 CRC patients, 30 individuals with colorectal diseases (non-cancer), and 20 healthy volunteers. By using real-time PCR, the relative expression of circ-SMARCA5, circ-NOL10, circ-LDLRAD3, and circ-RHOT1 was determined in the collected blood samples. In addition, ECLIA was used to quantify carcinoembryonic antigen (CEA) level. All circRNAs expression and CEA levels were significantly up-regulated in cancer patients (CRC, colon, rectum) as compared to healthy controls, except circ-SMARCA5. Moreover, there was a significant up-regulation of circRNAs in most non-cancer patients (UC, polyp, piles). Insignificant upregulation was observed in circRNAs and CEA when comparing cancer with non-cancer patients. No correlations were found between the studied parameters and most clinicopathological characteristics of cancer and non-cancer patients. Circ-SMARCA5, circ-NOL10, circ-LDLRAD3, and circ-RHOT1 were differentially expressed in patients with CRC as well as in non-cancer patients. Circ-SMARCA5 and circ-NOL10 may act as tumor suppressors, while circ-LDLRAD3 and circ-RHOT1 may be oncogenes. Circ-SMARCA5, circ-NOL10, circ-LDLRAD3, and circ-RHOT1 could be promising markers for the early detection of CRC.

Diagnostic and prognostic role of circRNAs in pancreatic cancer: a meta-analysis

Background

Circular RNAs (circRNAs) are types of endogenous noncoding RNAs produced by selective splicing that are expressed highly specifically in various organisms and tissues and have numerous clinical implications in the regulation of cancer development and progression. Since circRNA is resistant to digestion by ribonucleases and has a long half-life, there is increasing evidence that circRNA can be used as an ideal candidate biomarker for the early diagnosis and prognosis of tumors. In this study, we aimed to reveal the diagnostic and prognostic value of circRNA in human pancreatic cancer (PC).

Methods

A systematic search for publications from inception to 22 July 2022 was conducted on Embase, PubMed, Web of Science (WOS), and the Cochrane Library databases. Available studies that correlated circRNA expression in tissue or serum with the clinicopathological, diagnostic, and prognostic values of PC patients were enrolled. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were used to evaluate clinical pathological characteristics. Area under the curve (AUC), sensitivity, and specificity were adopted to assess diagnostic value. Hazard ratios (HRs) were utilized to assess disease-free survival (DFS) and overall survival (OS).

Results

This meta-analysis enrolled 32 eligible studies, including six on diagnosis and 21 on prognosis, which accounted for 2,396 cases from 245 references. For clinical parameters, high expression of carcinogenic circRNA was significantly associated with degree of differentiation (OR = 1.85, 95% CI = 1.47-2.34), TNM stage (OR = 0.46, 95% CI = 0.35-0.62), lymph node metastasis (OR = 0.39, 95% CI = 0.32-0.48), and distant metastasis (OR = 0.26, 95% CI = 0.13-0.51). As for clinical diagnostic utility, circRNA could discriminate patients with pancreatic cancer from controls, with an AUC of 0.86 (95% CI: 0.82-0.88), a relatively high sensitivity of 84%, and a specificity of 80% in tissue. In terms of prognostic significance, carcinogenic circRNA was correlated with poor OS (HR = 2.00, 95% CI: 1.76-2.26) and DFS (HR = 1.96, 95% CI: 1.47-2.62).

Conclusion

In summary, this study demonstrated that circRNA may act as a significant diagnostic and prognostic biomarker for pancreatic cancer.

Intragenic β-synuclein rearrangements in malignancy

The synuclein family, consisting of α-, β-, and γ-synuclein, is primarily expressed in neurons. Mutations of α- and β-synuclein have been linked to Parkinson's disease and dementia with Lewy bodies, respectively. Recent studies have shown that synucleins are upregulated in various tumors, including breast, ovarian, meningioma, and melanoma, and high synuclein expression is associated with poor prognosis and drug resistance. We report a novel rearrangement of β-synuclein in a pediatric T-cell acute lymphoblastic leukemia (T-ALL) case, where β-synuclein (SNCB) is fused in-frame with ETS variant transcription factor 6 (ETV6), a gene frequently rearranged in acute leukemia including acute myeloid leukemia (AML), B-cell acute lymphoblastic leukemia (B-ALL), and T-ALL. An additional case of β-synuclein rearrangement was identified in a squamous cell carcinoma of the lung through analysis of the public TCGA database. Both rearrangements involve the C-terminal of β-synuclein. Since β-synuclein shares extensive amino acid similarities with α-synuclein and α-synuclein binds to 14-3-3, an important regulator of apoptosis, the rearranged β-synuclein may contribute to tumorigenesis by deregulating apoptosis. In addition, overexpression of synucleins has been shown to increase cell proliferation, suggesting that the rearranged β-synuclein may also deregulate the cell cycle.

Role of Biomarkers in Hepatocellular Carcinoma and Their Disease Progression

Hepatocellular carcinoma (HCC) is one of the third leading and common lethal cancers worldwide. Early detection of tumorigenesis of hepatocellular carcinoma is through ultrasonography, computerized tomography (CT) scans, and magnetic resonance imaging (MRI) scans; however, these methods are not up to the mark, so a search for an efficient biomarker for early diagnosis and treatment of hepatocarcinogenesis is important. Proteomic and genomic approaches aid to develop new promising biomarkers for the diagnosis of HCC at the early stages. These biomarkers not only help in prognosis but also provide better therapeutic intervention against HCC. Among the different biomarker candidates, liquid biopsy [including circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA)] has recently emerged as a noninvasive detection technique for the characterization of circulating cells, providing a strong basis and early diagnosis for the individualized treatment of patients. This review provides the current understanding of HCC biomarkers that predict the risk of HCC recurrence.

Circulating Cell-Free Nucleic Acids as Biomarkers for Diagnosis and Prognosis of Pancreatic Cancer

A lack of reliable early diagnostic tools represents a major challenge in the management of pancreatic cancer (PCa), as the disease is often only identified after it reaches an advanced stage. This highlights the urgent need to identify biomarkers that can be used for the early detection, staging, treatment monitoring, and prognosis of PCa. A novel approach called liquid biopsy has emerged in recent years, which is a less- or non-invasive procedure since it focuses on plasmatic biomarkers such as DNA and RNA. In the blood of patients with cancer, circulating tumor cells (CTCs) and cell-free nucleic acids (cfNAs) have been identified such as DNA, mRNA, and non-coding RNA (miRNA and lncRNA). The presence of these molecules encouraged researchers to investigate their potential as biomarkers. In this article, we focused on circulating cfNAs as plasmatic biomarkers of PCa and analyzed their advantages compared to traditional biopsy methods.

Hsa_circRNA_001859 regulates pancreatic cancer progression and epithelial-mesenchymal transition through the miR-21-5p/SLC38A2 pathway

OBJECTIVE: This study attempts to investigate whether hsa_circRNA_001859 (circ_001859) could regulate the proliferation and invasion of pancreatic cancer through the miR-21-5p/SLC38A2 pathway. METHODS: GSE79634 microarray was analyzed with R package. The expression of circ_001859 in pancreatic cancer tissues and cells was verified by qRT-PCR. After the overexpression of circ_001859, cell proliferation, cell migration and invasion were verified by colony formation and transwell assay. The targeting relationship between miR-21-5p and circ_001859 was predicted by TargetScan and was verified by dual luciferase reporter assay, RNA pull down and qRT-PCR. The effect of miR-21-5p on cell proliferation, migration and invasion were investigated by colony formation and transwell assay respectively. Similarly, the targeting relationship between miR-21-5p and SLC38A2 was predicted by TargetScan and was verified by dual luciferase reporter assay, western blot and qRT-PCR. The effect of SLC38A2 on cell proliferation was investigated by colony formation. RESULTS: Circ_001859 was lowly expressed in pancreatic cancer tissues and cells. In vitro assays showed that overexpression of circ_001859 could inhibit the proliferation, migration and invasion of pancreatic cancer. In addition, this effect was also confirmed in xenograft transplantation model. Circ_001859 could be bind to miR-21-5p and sponge its expression in pancreatic cancer cells. Overexpression of miR-21-5p enhanced the proliferation, migration and invasion ability of pancreatic cancer cells, while the inhibition of miR-21-5p expression suppressed these abilities. Moreover, miR-21-5p directly targeted at SLC38A2 and inhibited SLC38A2 expression levels while circ_001859 up-regulated SLC38A2 levels. SLC38A2 expression knockdown enhanced cell proliferation but SLC38A2 overexpression resulted in decreased proliferation, and effects of SLC38A2 could be rescued by miR-21-5p and circ_001859. In addition, both QRT-PCR and immunofluorescence confirmed that circ_001859 could regulate tumor epithelial-mesenchymal transition (EMT) through the miR-21-5p/SLC38A2 pathway. CONCLUSIONS: This study suggests that circ_001859 may inhibit the proliferation, invasion and EMT of pancreatic cancer through the miR-21-5p/SLC38A2 pathway.

Knockdown of circGOLPH3 inhibits cell progression and glycolysis by targeting miR-145-5p/lysine demethylase 2A (KDM2A) axis in oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is one of the most common head and neck malignancies. The aim of this study is to explore the role of circRNA Golgi phosphoprotein 3 (GOLPH3) (circGOLPH3) in OSCC.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot were performed to detect changes in the levels of circGOLPH3, microRNA-145-5p (miR-145-5p), and lysine demethylase 2A (KDM2A). The functions of circGOLPH3 were assessed using in vitro and in vivo assays. Dual-luciferase reporter assay detected the interaction of miR-145-5p with circGOLPH3 or KDM2A.

RESULTS

circGOLPH3 expression was upregulated in OSCC. circGOLPH3 downregulation inhibited cell growth, metastasis, and glycolysis in vitro, and in vivo experiments revealed that circGOLPH3 inhibited tumor growth. In addition, circGOLPH3 bound to miR-145-5p and competitively inhibited KDM2A expression, thereby regulating OSCC cell behaviors as well as glycolysis.

CONCLUSION

circGOLPH3 exerted pro-oncogenic effects through the miR-145-5p/KDM2A axis to regulate OSCC cell behaviors.

Circ_0018909 knockdown inhibits the development of pancreatic cancer via the miR‐545‐3p/FASN axis and reduces macrophage polarization to M2

Multiple circular RNAs (circRNAs) were proven to regulate the development of pancreatic cancer. However, the action of circ_0018909 in pancreatic cancer was still unclear. The expression of circ_0018909, microRNA-545-3p (miR-545-3p), and fatty acid synthase (FASN) was measured using quantitative reverse-transcriptase PCR (qRT-PCR). Cell growth, cell cycle arrest, apoptotic cells, metastasis, and epithelial to mesenchymal transition (EMT) were determined using EdU assay, flow cytometry, wound-healing assay, transwell invasion, and western blotting, respectively. The expression of the macrophage markers, including CD80, MCP-1, iNOS, and IL-6 (M1 markers), as well as CD206 and CD163 (M2 markers), was analyzed using qRT-PCR. Circ_0018909 knockdown dramatically depressed cell growth, migration, invasion, EMT, and elevated the number of apoptotic cells in pancreatic cancer cells, and repressed tumor growth in mice. Moreover, we proved that the absence of miR-545-3p rescued the action of circ_0018909 downregulation on cell growth, metastasis, apoptosis, and EMT in pancreatic cancer cells. MiR-545-3p bound to FASN and FASN overexpression hindered the impacts of miR-545-3p on the progression of pancreatic cancer. Besides this, our data demonstrated that circ_0018909 induced polarization from M0 macrophages to M2 macrophages. Circ_0018909 knockdown retarded the development of pancreatic cancer by modulating miR-545-3p to regulate FASN expression.

Prognostic, Diagnostic, and Clinicopathological Significance of Circular RNAs in Pancreatic Cancer: A Systematic Review and Meta-Analysis

Pancreatic cancer (PC) is a highly aggressive malignant tumor with a high mortality rate. It is urgent to find optimal molecular targets for the early diagnosis and treatment of PC. Here, we aimed to systematically analyze the prognostic, diagnostic, and clinicopathological significance of circular RNAs (circRNAs) in PC. Relevant studies were screened through PubMed, Web of Science, and other databases. The prognostic value of PC-associated circRNAs was assessed using the composite hazard ratio (HR), the diagnostic performance was assessed using the area under the summary receiver operator characteristic (SROC) curve (AUC), and the correlation with clinicopathological characteristics using the composite odds ratio (OR) was explored. In our study, 48 studies were included: 34 for prognosis, 11 for diagnosis, and 30 for correlation with clinicopathological characteristics. For prognosis, upregulated circRNAs were associated with poorer overall survival (OS) (HR = 2.02) and disease-free survival/progression-free survival (HR = 1.84) while downregulated circRNAs were associated with longer OS (HR = 0.55). Notably, the combination of circRNAs, including hsa_circ_0064288, hsa_circ_0000234, hsa_circ_0004680, hsa_circ_0071036, hsa_circ_0000677, and hsa_circ_0001460, was associated with worse OS (HR = 2.35). For diagnosis, the AUC was 0.83, and the pooled sensitivity and specificity were 0.79 and 0.73, respectively. For clinicopathologic characteristics, upregulated circRNAs were associated with poorer tumor differentiation, more nerve and vascular invasion, higher T stage, lymphatic metastasis, distant metastasis, advanced TNM stage, and higher preoperative CA19-9 level. In contrast, downregulated circRNAs were negatively associated with PC differentiation and lymphatic metastasis. Overall, our results showed that circRNAs are closely related to the prognosis and clinicopathological characteristics of PC patients and could be utilized for early diagnosis; thus, they are promising biomarkers for clinical application in PC.

Downregulation of hsa_circ_0000885 suppressed osteosarcoma metastasis and progression via regulating E2F3 expression and sponging miR-16-5p

Introduction

Accumulating evidence has shown that circular RNAs (circRNAs) have indispensable functions during tumor progression by regulating gene expression. A previous study found that upregulation of hsa_circ_0000885 indicated a poor clinical outcome of osteosarcoma (OS). However, the regulatory mechanism of this process is unclear.

Methods

This investigation aimed to elucidate how hsa_circ_0000885 regulated OSs. The study used RT-qPCR to investigate hsa_circ_0000885 expression in OS cells. We conducted luciferase reporter assays and analyses to confirm the hsa_circ_0000885 downstream target. We transfected OS cells using different vectors and used Transwell migration, colony formation, western blotting, Matrigel invasion, proliferation, in vivo tumorigenesis, and metastasis assays to identify the role of hsa_circ_0000885 in OS.

Results

The results showed that hsa_circ_0000885 expression altered OS cell lines, and that hsa_circ_0000885 downregulation suppressed OS cell proliferation and invasion using in vivo and in vitro experiments. Luciferase reporter assays verified that miR-16-5p and E2F3 were downstream targets of hsa_circ_0000885. E2F3 overexpression or miR-16-5p inhibition reversed OS cell invasion and proliferation after silencing hsa_circ_0000885. Furthermore, hsa_circ_0000885 affected cancer stem cell differentiation by regulating miR-16-5p/E2F3.

Conclusions

Overall, the results showed that hsa_circ_0000885 downregulation suppressed OS progression and metastasis via regulating E2F3 expression and sponging miR-16-5p.

Roles of circular RNAs in the pathogenesis and treatment of pancreatic cancer

Circular RNAs are single-stranded RNAs with a covalently closed structure formed by the process of back-splicing. Aberrant expression of circular RNAs contributes to the pathogenesis of a wide range of cancers. Pancreatic cancer is one of the most lethal cancers due to diagnostic difficulties and limited therapeutic options. Circular RNAs are emerging as novel diagnostic biomarkers and therapeutic targets for pancreatic cancer. Moreover, recent advances in the therapeutic application of engineered circular RNAs have provided a promising approach to overcoming pancreatic cancer. This review discusses the roles of circular RNAs in the pathogenesis of pancreatic cancer and in potential treatment applications and their usefulness as diagnostic biomarkers.

Circ_0058063 promotes progression of thyroid cancer by sponging miR-330-3p/SDC4 axis

Circular RNA takes a crucial part in carcinogenesis. Circ_0058063 has been found to act as an oncogene in esophageal cancer and bladder cancer, but its role in thyroid cancer (TC) is still under investigation. Therefore, we carried out a study to understand its role in TC and its association with miR-330-3p. The circ_0058063 and miR-330-3p in TC tissues and cells were quantified by quantitative reverse transcription PCR, and cell counting kit-8 and scratch adhesion test were conducted for evaluation of cell proliferation and migration. In addition, a dual luciferase reporter assay and RNA immunoprecipitation assay were conducted for interaction analysis between circ_0058063 and miR-330-3p. Circ_0058063 was upregulated in TC tissues and cells, but miR-330-3p expression showed an opposite trend. Both silencing circ_0058063 and upregulating miR-330-3p can suppress the proliferation and migration of TC cells, upregulate Bax, and downregulate Bcl-2. In addition, circ_0058063 is able to target miR-330-3p that is also able to target syndecan 4 (SDC4). circ_0058063 can act as a carcinogen in cases with TC via the miR-330-3p/SDC4 axis.

Emerging roles of long noncoding RNAs in chemoresistance of pancreatic cancer

Pancreatic cancer is one of the most common causes of cancer death in the world due to the lack of early symptoms, metastasis occurrence and chemoresistance. Therefore, early diagnosis by detection of biomarkers, blockade of metastasis, and overcoming chemoresistance are the effective strategies to improve the survival of pancreatic cancer patients. Accumulating evidence has revealed that long noncoding RNA (lncRNA) and circular RNAs (circRNAs) play essential roles in modulating chemosensitivity in pancreatic cancer. In this review article, we will summarize the role of lncRNAs in drug resistance of pancreatic cancer cells, including HOTTIP, HOTAIR, PVT1, linc-ROR, GAS5, UCA1, DYNC2H1-4, MEG3, TUG1, HOST2, HCP5, SLC7A11-AS1 and CASC2. We also highlight the function of circRNAs, such as circHIPK3 and circ_0000284, in regulation of drug sensitivity of pancreatic cancer cells. Moreover, we describe a number of compounds, including curcumin, genistein, resveratrol, quercetin, and salinomycin, which may modulate the expression of lncRNAs and enhance chemosensitivity in pancreatic cancers. Therefore, targeting specific lncRNAs and cicrRNAs could contribute to reverse chemoresistance of pancreatic cancer cells. We hope this review might stimulate the studies of lncRNAs and cicrRNAs, and develop the new therapeutic strategy via modulating these noncoding RNAs to promote chemosensitivity of pancreatic cancer cells.

Advances in biomarkers and techniques for pancreatic cancer diagnosis

Pancreatic cancer is the most lethal type of malignancy and is characterized by high invasiveness without severe symptoms. It is difficult to detect PC at an early stage because of the low diagnostic accuracy of existing routine methods, such as abdominal ultrasound, CT, MRI, and endoscopic ultrasound (EUS). Therefore, it is of value to develop new diagnostic techniques for early detection with high accuracy. In this review, we aim to highlight research progress on novel biomarkers, artificial intelligence, and nanomaterial applications on the diagnostic accuracy of pancreatic cancer.

Biological functions, mechanisms, and clinical significance of circular RNA in pancreatic cancer: a promising rising star

Pancreatic cancer (PC) is a highly malignant solid tumor with insidious onset and easy early metastasis. Despite tremendous efforts devoted to research in this field, the mechanisms underlying PC tumorigenesis and progression remain unclear. Additionally, robust biomarkers and satisfactory therapeutic strategies for clinical use in PC patients are still lacking. Circular RNAs (circRNAs) are a new type of non-coding RNA originating from precursor messenger RNAs, with a covalent continuous closed-loop structure, strong stability and high specificity. Accumulating evidence suggests that circRNAs may participate in PC development and progression. Abnormal expression of circRNAs in PC is considered a vital factor that affects tumor cell proliferation, migration, invasion, apoptosis, angiogenesis and drug resistance. In this review of relevant articles published in recent years, we describe the basic knowledge concerning circRNAs, including their classification, biogenesis, functions and research approaches. Moreover, the biological roles and clinical significance of circRNAs related to PC are discussed. Finally, we note the questions remaining from recent studies and anticipate that further investigations will address these gaps in knowledge in this field. In conclusion, we expect to provide insights into circRNAs as potential targets for specific PC diagnosis and treatment in the future.

Circular RNA circ_0004277 Inhibits Acute Myeloid Leukemia Progression Through MicroRNA-134-5p / Single stranded DNA binding protein 2

Circular RNAs (circRNAs) are crucial non-coding RNAs in the process of tumorigenesis. Nevertheless, the biological function of circ_0004277 in acute myeloid leukemia (AML) is blurred. Microarray data of circRNAs were utilized to evaluate circRNAs’ differential expression in AML. Quantitative real-time polymerase chain reaction (qRT-PCR) was executed to determine circ_0004277 and microRNA-134-5p (miR-134-5p) expression levels. The growth, migration and invasion of AML cells were tested by the cell counting kit-8 and Transwell experiment. Dual-luciferase reporter gene experiment, RNA immunoprecipitation (RIP) experiment and RNA pull-down experiment were executed to determine the targeting relationship between circ_0004277 and miR-134-5p. Western blot assay was used to detect single stranded DNA binding protein 2 (SSBP2) expression. We observed that circ_0004277 was down-regulated in AML, while miR-134-5p was up-regulated. Functionally, circ_0004277 overexpression or inhibition of miR-134-5p remarkably suppressed AML cell viability, migration and invasion. Furthermore, miR-134-5p served as a direct downstream target of circ_0004277 and SSBP2 was identified as a target of miR-134-5p. Compensation experiments showed that miR-134-5p mimics abolished the biological function of circ_0004277 on malignant phenotypes of AML cells. Collectively, circ_0004277 impedes AML development by adsorbing miR-134-5p and up-regulating SSBP2.

Circular RNAs and thyroid cancer: closed molecules, open possibilities

Thyroid neoplasms requiring differential diagnosis between thyroid cancer and benign tumors can be detected in more than half of the healthy population. A generally accepted method that allows assessing the risk of malignant potential and determining the indications for surgical treatment of thyroid tumor is a fine-needle aspiration biopsy followed by a cytological examination. Nevertheless, in patients with indeterminate categories of cytological conclusions according to Bethesda system, the positive predictive value of the cytology result is significantly lower than desired and often leads to unjustified surgical treatment. In this regard, the search for alternative diagnostic solutions continues. Circular RNAs are a group of non-coding RNAs distinguished by a closed structure formed by covalent bonding of the nucleotide chain ends. Recent studies allow us to conclude that many different circular RNAs are involved in processes mediating oncogenesis in the thyroid gland, and their altered expression in tissue, blood, and exosomes of plasma may be a characteristic sign of thyroid cancer and certain clinicopathological features of its course. The purpose of this review is to analyze the accumulated data on the association of various circular RNAs with thyroid cancer and to discuss possible ways to improve the diagnosis and treatment of the disease based on the assessment of the expression of these molecules.

Circ_0101802 Facilitates Colorectal Cancer Progression Depending on the Regulation of miR-665/DVL3 Signaling

Colorectal cancer (CRC) is a common malignancy in both men and women, and the prognosis of CRC patients is still unsatisfactory. We aimed to identify novel effective diagnostic and prognostic targets for CRC. The study design is listed as below: we first confirmed the linear correlation between the expression of disheveled 3 (DVL3) and circular RNA_0101802 (circ_0101802) in CRC tissues, and their functional correlation in CRC cells was verified by rescue assays. Subsequently, bioinformatics databases were used to search the common interacted microRNAs (miRNAs) of DVL3 and circ_0101802, and compensation experiments were conducted to verify the functional correlation between miR-665 and DVL3 in CRC cells. Finally, xenograft tumor model was established to confirm the role of circ_0101802/miR-665/DVL3 axis in tumor growth in vivo. The expression of DVL3 and circ_0101802 was elevated in CRC tissues and cell lines, and high levels of DVL3 and circ_0101802 were closely associated with short survival time of CRC patients. Circ_0101802 silencing restrained the proliferation, migration, and tube formation abilities and induced the apoptosis of CRC cells. Circ_0101802 silencing-induced anti-tumor effects in CRC cells were partly reversed by DVL3 overexpression. miR-665 was an intermediary molecule between circ_0101802 and DVL3, and circ_0101802 could positively regulate DVL3 protein expression by sponging miR-665 in CRC cells. DVL3 overexpression partly overturned miR-665 overexpression-mediated anti-tumor effects in CRC cells. Circ_0101802 knockdown significantly suppressed xenograft tumor growth in vivo. In conclusion, circ_0101802 contributed to CRC progression by targeting miR-665/DVL3 signaling.

Autophagy-associated circRNA circATG7 facilitates autophagy and promotes pancreatic cancer progression

Dysregulation of autophagy and circular RNAs (circRNAs) are involved in the pancreatic cancer (PC) progression. However, the regulatory network between circRNAs, autophagy, and PC progression remains unknown. Herein, we demonstrated that autophagy-associated circRNA circ-autophagy related 7 (circATG7) was elevated in PC tissues compared to adjacent tissues, and in PC cells treated with EBSS and hypoxia. circATG7 expression was positively associated with tumor diameter and lymph node invasion in patients with PC. circATG7 overexpression promoted PC cell proliferation, mobility, and autophagy in vitro, while circATG7 knockdown induced the opposite effects. ATG7 inhibition attenuated the effects of circATG7 on the biological functions of PC cells. CircATG7 is located in the cell cytoplasm and nucleus. Cytoplasmic circATG7 sponged miR-766-5p and decreased its expression, and increased the expression of ATG7, a target gene of miR-766-5p. Nuclear circATG7 acted as a scaffold to increase the interaction between the human antigen R protein and ATG7 mRNA and enhanced ATG mRNA stability. Furthermore, we demonstrated that circATG7 regulates PC cell proliferation and metastasis in vivo via ATG7-dependent autophagy. In conclusion, our results demonstrated that circATG7 accelerates PC progression via miR-766-5p/ATG7 and that HUR/ATG7 depends on autophagic flux. Thus, circATG7 may be a potential therapeutic target for PC.

SP1-Mediated Upregulation of circFAM126A Promotes Proliferation and Epithelial-Mesenchymal Transition of Oral Squamous Cell Carcinoma via Regulation of RAB41

Background

Accumulating evidence indicates that circular RNAs have major roles in the progression of human cancers. Nevertheless, the molecular mechanism and effects of circFAM126A in oral squamous cell carcinoma (OSCC) remain unclear.

Methods

Quantitative real-time PCR (qRT-PCR) was used to detect expression levels of circFAM126A in OSCC tumor tissues and cell lines; the effects of circFAM126A small hairpin RNA (shRNA) on the proliferation, migration, and invasion of OSCC cells were detected by MTT, colony formation, and transwell assays; xenograft mouse models were used to determine the effects of circFAM126A shRNA on the growth of OSCC tumors in vivo; the expression of miR-186 and RAB41 in OSCC tissues and cells was examined by qRT-PCR; the targeting relationship between circFAM126A and miR-186 was verified by dual-luciferase reporter and RNA pull-down assays; and the relationship between miR-186 and RAB41 was explored.

Results

The expression of circFAM126A was significantly upregulated in OSCC tissues and cells. The transcription factor SP1 transcriptionally activated circFAM126A. However, knockdown of circFAM126A markedly suppressed the proliferation, migration, and invasion of OSCC cells in vitro and inhibited tumor growth and distant metastasis in vivo. Moreover, circFAM126A increased the expression of RAB41 and promoted its mRNA stability via binding to miR-186 and RNA-binding protein FUS. Overexpression of RAB41 antagonized the effects of circFAM126A knockdown and induced an aggressive phenotype of OSCC cells.

Conclusion

SP1 transcriptionally activated circFAM126A modulated the growth, epithelial-mesenchymal transition (EMT) of OSCC cells via targeting the miR-186/FUS/RAB41 axis, suggesting that circFAM126A is a potential biomarker for the treatment of OSCC.

Hsa_circ_0050102 regulates the pancreatic cancer development via miR‐218‐5p/PPME1 axis

Background

Pancreatic cancer (PC) is a malignancy worldwide. Circular RNAs (circRNAs) affects the growth of PC, nonetheless the mechanism is blurry. Here, we reconnoitered the parts of hsa_circ_0050102 in PC.

Methods

Hsa_circ_0050102, microRNA‐218‐5p (miR‐218‐5p) and protein phosphatase methylesterase 1 (PPME1) abundances were indicated by quantitative RT‐PCR or Western blot. Moreover, the cell functions were uncovered. Additionally, the relation of miR‐218‐5p and hsa_circ_0050102 or PPME1 was identified by dual‐luciferase reporter assay. Ultimately, the mice teats were utilized to quantity the part of hsa_circ_0050102.

Results

Hsa_circ_0050102 and PPME1 contents were increased, and the miR‐218‐5p was dwindled in PC. Hsa_circ_0050102 lack subdued cell vitality, colony formation, cell migration and invasion, and angiogenesis, but endorsed cell apoptosis in PC cells. Furthermore, miR‐218‐5p was established to block the development of PC cells via PPME1. Hsa_circ_0050102 bound to miR‐218‐5p to adjust the content of PPME1.

Conclusion

Hsa_circ_0050102 expedited the expansion of PC through growing PPME1 abundance by adjusting miR‐218‐5p.

Hsa_circ_0074298 promotes pancreatic cancer progression and resistance to gemcitabine by sponging miR-519 to target SMOC

Objective: To investigate the expression of hsa_circ_0074298 (circular RNA) and the molecular mechanism that promotes tumor growth and enhances the chemoresistance of pancreatic cancer.

Methods: Real-time reverse transcription-PCR was used to detect hsa_circ_0074298 expression in pancreatic cancer. The intracellular localization of hsa_circ_0074298 was determined by RNA in situ hybridization. The CCK8 method, colony formation assay, Transwell assay, and flow cytometry were used to evaluate the effects of hsa_circ_0074298 on the proliferation, migration, invasion, cell cycle, apoptosis of pancreatic cancer cells. Bioinformatics analysis and dual luciferase assays were employed to detect the association of hsa_circ_0074298 and miR-519d and the binding of miR-519d to the target gene SMOC2. A subcutaneous xenograft model was established to observe the effect of hsa_circ_0074298 in vivo.

Results: The hsa_circ_0074298 was mainly localized in the cytoplasm. Hsa_circ_0074298 was highly expressed in pancreatic cancer tissues and cell lines. The expression of hsa_circ_0074298 was significantly correlated with pancreatic cancer tumor size, lymph node metastasis, and pathological grade. hsa_circ_0074298 could sponge miR-519, and miR-519d bound to SMOC2. Downregulation of hsa_circ_0074298 expression significantly inhibited cell proliferation, migration, invasion, colony forming ability and promoted cell cycle arrest, apoptosis and chemo-resistance of pancreatic cancer in vitro and vivo. However, the effects could be reversed by a miR-519d inhibitor or SMOC2 overexpression.

Conclusion: By sponging miR-519 and targeting SMOC2, hsa_circ_0074298 promotes the growth and metastasis of pancreatic cancer and increases the resistance of pancreatic cancer cells to gemcitabine.

circPUM1 Activates the PI3K/AKT Signaling Pathway by Sponging to Promote the Proliferation, Invasion and Glycolysis of Pancreatic Cancer

BACKGROUND

Our study seeks to obtain data to assess the impact of circPUM1 on pancreatic cancer (PC) and its mechanism.

METHODS

The expression of circPUM1 and miR-200c-3p in PC and normal tissues and PC cell lines was collected and detected, and subsequently dual-luciferase assay-based verification of the binding site of the two was carried out. After interfering with circPUM1 expression in MIAPaCa-2 and PANC-1 cells, cell proliferation, viability, apoptosis rate, invasion ability, glucose consumption, and lactate production were measured by MTT, colony formation, flow cytometry, Transwell assays, and glucose and lactate assay kits. Additionally, western blot was utilized for assessing PI3K/AKT signaling pathway-related proteins. From the results, highly expressed circPUM1 and miR-200c-3p in PC tissues and cells were proved.

RESULTS

Down-regulation of circPUM1 expression significantly inhibited cell proliferation, cell viability, invasion and glycolysis, while increasing the apoptosis rate. Down-regulated circPUM1 led to the inhibition of the PI3K/AKT signaling pathway activity in PC cells; while up-regulated circPUM1 increased its activity. Further experiments revealed that down-regulation of miR-200c-3p expression reversed the inhibitory effect of lowly expressed circPUM1 on PC cells.

CONCLUSION

In summary, circPUM1 activates PI3K/AKT signaling pathway by sponging miR-200c-3p and promotes PC progression.

The potential of using blood circular RNA as liquid biopsy biomarker for human diseases

Circular RNA (circRNA) is a novel class of single-stranded RNAs with a closed loop structure. The majority of circRNAs are formed by a back-splicing process in pre-mRNA splicing. Their expression is dynamically regulated and shows spatiotemporal patterns among cell types, tissues and developmental stages. CircRNAs have important biological functions in many physiological processes, and their aberrant expression is implicated in many human diseases. Due to their high stability, circRNAs are becoming promising biomarkers in many human diseases, such as cardiovascular diseases, autoimmune diseases and human cancers. In this review, we focus on the translational potential of using human blood circRNAs as liquid biopsy biomarkers for human diseases. We highlight their abundant expression, essential biological functions and significant correlations to human diseases in various components of peripheral blood, including whole blood, blood cells and extracellular vesicles. In addition, we summarize the current knowledge of blood circRNA biomarkers for disease diagnosis or prognosis.

Circ_0079558 promotes papillary thyroid cancer progression by binding to miR-26b-5p to activate MET/AKT signaling

Circular RNAs (circRNAs) are a group of non-coding RNAs featured by covalently closed circular structure. CircRNA_0079558 (circ_0079558) is derived from RAPGEF5 gene, and it has been found to be significantly up-regulated in papillary thyroid carcinoma (PTC). However, the role and working mechanism of circ_0079558 in PTC progression have never been illustrated. The levels of circ_0079558 and MET proto-oncogene, receptor tyrosine kinase (MET) were up-regulated in PTC tissues and cell lines, as evidenced by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot assay. The silencing of circ_0079558 or MET restrained cell proliferation, migration and invasion whereas triggered cell apoptosis in PTC cells, as verified by Cell Counting Kit-8 (CCK8) assay, plate colony formation assay, transwell invasion assay, wound healing assay and flow cytometry. Through using MET specific inhibitor PHA665752, we found that circ_0079558 overexpression enhanced the malignant behaviors of PTC cells through activating MET/AKT pathway. Through dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay, microRNA-26b-5p (miR-26b-5p) was identified to be the intermediary molecular between circ_0079558 and MET, and circ_0079558 knockdown reduced the expression of MET partly through elevating miR-26b-5p in PTC cells. The miR-198/FGFR1 pathway was identified as another signal axis downstream of circ_0079558, and the co-overexpression of FGFR1 and MET largely rescued the proliferation ability of circ_0079558-silenced PTC cells. Through xenograft tumor model, we found that circ_0079558 silencing restrained xenograft tumor growth in vivo. In conclusion, circ_0079558 facilitated the proliferation and motility whereas inhibited the apoptosis of PTC cells largely through mediating miR-26b-5p/MET/AKT signaling.

Circular RNA-Is the Circle Perfect?

Circular RNA (circRNA) is a distinct class of non-coding RNA produced, in principle, using a back-splicing mechanism, conserved during evolution, with increased stability and a tissue-dependent expression. Circular RNA represents a functional molecule with roles in the regulation of transcription and splicing, microRNA sponge, and the modulation of protein–protein interaction. CircRNAs are involved in essential processes of life such as apoptosis, cell cycle, and proliferation. Due to the regulatory role (upregulation/downregulation) in pathogenic mechanisms of some diseases (including cancer), its potential roles as a biomarker or therapeutic target in these diseases were studied. This review focuses on the importance of circular RNA in cancer.

The Value of Circulating Circular RNA in Cancer Diagnosis, Monitoring, Prognosis, and Guiding Treatment

Liquid biopsy includes non-invasive analysis of circulating tumor-derived substances. It is a novel, innovative cancer screening tool that overcomes the limitations of current invasive tissue examinations in precision oncology. Circular RNA (circRNA) is a recent, novel, and attractive liquid biomarker showing stability, abundance, and high specificity in various diseases, especially in human cancers. This review focused on the emerging potential of human circRNA in body fluids as the liquid biopsy biomarkers for cancers and the methods used to detect the circRNA expression and summarized the construction of circRNA biomarkers in body fluids for treating human cancers and their limitations before they become part of routine clinical medicine. Furthermore, the future opportunities and challenges of translating circRNAs in liquid biopsy into clinical practices were explored.

Circular RNA Paired-Related Homeobox 1 Promotes Gastric Carcinoma Cell Progression via Regulating MicroRNA-665/YWHAZ Axis

BACKGROUND

Gastric carcinoma (GC) is a ubiquitous malignant tumor worldwide. Circular RNA paired-related homeobox 1 (circ-PRRX1), one kind of non-coding RNAs, has been reported to act as a promoter in tumor growth. This study aims to explore the effects of circ-PRRX1 on proliferation, apoptosis, and metastasis in GC and the underlying regulatory mechanisms.

METHODS

The expression of circ-PRRX1, miR-665, and tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta (YWHAZ) mRNA was analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). Western blot was used to analyze YWHAZ protein expression. 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-Htetrazolium bromide (MTT), flow cytometry, and transwell assay were carried out to assess the viability, apoptosis, migration, and invasion in GC cells. The interaction between miR-665 and circ-PRRX1 or YWHAZ was predicted by StarBase v2.0 and identified by dual-luciferase reporter system. Xenograft mouse model was employed to determine the effects of circ-PRRX1 knockdown on GC growth in vivo.

RESULTS

Compared with normal tissues and cells, circ-PRRX1 and YWHAZ levels were upregulated, and miR-665 was downregulated in GC tissues and cells. Functionally, circ-PRRX1 knockdown inhibited the viability, migration, and invasion and promoted apoptosis in GC cells, whereas anti-miR-665 abolished these effects. Mechanistically, circ-PRRX1 was confirmed as a sponge of miR-665 to regulate YWHAZ expression. Xenograft mouse model suggested that circ-PRRX1 knockdown reduced GC cells growth in vivo.

CONCLUSION

Circ-PRRX1 knockdown suppressed GC development by targeting miR-665 to inhibit YWHAZ expression, and the potential molecular mechanism may provide a theoretical basis for GC therapy.

Circ-LDLRAD3 Enhances Cell Growth, Migration, and Invasion and Inhibits Apoptosis by Regulating MiR-224-5p/NRP2 Axis in Gastric Cancer

BACKGROUND

Emerging as a newly discovered type of noncoding RNAs, circular RNAs have been manifested as a crucial regulator in tumorigenesis of human malignancies, including gastric cancer (GC). Although circ-LDLRAD3 has been revealed as an oncogene in pancreatic cancer, the underlying role of circ-LDLRAD3 in GC remains poorly understood.

AIMS

Exploring the underlying function of circ-LDLRAD3 on GC progression.

METHODS

Circ-LDLRAD3 expression was detected through RT-qPCR. EdU, colony formation, TUNEL, and transwell assays were performed to analyze the function of circ-LDLRAD3 on GC progression. Luciferase reporter and RIP assays were applied to testify the interaction between circ-LDLRAD, miR-224-5p, and NRP2 in GC.

RESULTS

We detected preliminarily the expression of circ-LDLRAD3 and observed a markedly high expression of circ-LDLRAD3 in GC cells. Besides, circ-LDLRAD3 was featured with loop structure. Biological function assays testified that silenced circ-LDLRAD3 inhibited cell proliferation, migration, and invasion capacity but facilitated apoptosis of GC cells. Molecular mechanism assays uncovered that circ-LDLRAD3 combined with miR-224-5p in GC. Moreover, rescue assays delineated that inhibited expression of miR-224-5p could restore the inhibitive influence of circ-LDLRAD3 knockdown on the progression of GC. Moreover, neuropilin 2 (NRP2) was a downstream target of miR-224-5p. Additionally, circ-LDLRAD3 regulated NRP2 expression by sponging miR-224-5p in GC. Furthermore, circ-LDLRAD3 depletion-mediated effect on GC progression could be reversed by overexpressing NRP2.

CONCLUSIONS

Circ-LDLRAD3 facilitates GC progression by regulating miR-224-5p/NRP2 axis, providing new insights for the researches of GC treatment.

Magnetic detection of albuminuria using hematite nanorods synthesized via chemical hydrothermal method

Objectives

Albuminuria is a biomarker in the diagnosis of kidney disease which is due to the presence of high albumin in the urine and is one of the complications of diabetes. In recent years, the methods used to identify albuminuria have been expensive and time-consuming. Furthermore, another problem is the lack of accurate measurement of albuminuria. This problem leads to kidney isolation as well as a decrease in erythropoietin levels. Therefore, the main aim of our work is to design a magnetic nanobiosensor with better sensitivity to detect minimal levels of albuminuria.

Materials and Methods

In the present work, we synthesized Hematite Nano Rods (HNRs) using FeCl₃, NaOH and Cetyltrimethylammonium bromide (CTAB) precursors via the hydrothermal method. Then, HNRs were characterized using UV-vis spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometer (VSM) techniques.

Results

The obtained results from clinical performance of the HNR nanobiosensor show that the magnetization changes of HNR in interaction with the albumin biomarker can determine the presence or absence of protein in biological samples. The accuracy and repeatability of the HNR nanobiosensor from the value of the R2 coefficient in the standard equation is 0.9743.

Conclusion

We obtained the standard curve through interaction of the HNRs with albumin protein. The standard equation is obtained by plotting the magnetization curve of a non-interacting sample to interacting samples in terms of protein concentration. The Bland-Altman statistical graph prove that the HNR nanobiosensor is as reliable as experimental methods.

Plasma circRNAs as Biomarkers in Cancer

The incidence and mortality of cancer are increasing each year. At present, the sensitivity and specificity of the blood biomarkers that were used in clinical practice are low, which make the detection rate of cancer decrease. With advances in bioinformatics and technology, some non-coding RNA as biomarkers can be easily detected through some traditional and new technologies. Circular RNAs (circRNAs) are non-coding RNAs, that is, they do not encode proteins, and have important regulatory functions. CircRNAs can remain stable in bodily fluids, such as in saliva, blood, urine, and especially plasma. The difference in the expression of plasma circRNAs between cancer patients and normal people may suggest that plasma circRNAs may play an important role in the occurrence and development of cancer. In this review, we summarized the clinical effect of plasma circRNAs in several high-incidence cancers. CircRNAs may be effective biomarkers for tumour diagnosis, treatment selection and prognosis evaluation.

Mobius strip in pancreatic cancer: biogenesis, function and clinical significance of circular RNAs

Pancreatic cancer (PC) is a kind of common digestive system cancer with the worst prognosis for its insidious symptoms and high invasiveness. Circular RNAs (circRNAs) are endogenous non-coding RNAs with covalently closed circular structure, which are more stable and conservative than linear RNAs and process major functions of microRNA (miRNA) sponge, RNA binding protein (RBP) sponge and polypeptide translation template. Incremental researches have proved that circRNAs express aberrantly and play a vital role in various types of cancer. Hence, we reviewed the biogenesis, degradation, characteristics, and biological functions of circRNAs and summarized the roles circRNAs played in the proliferation, invasion, metastasis, chemoresistance and exosome-mediated intercellular communication of PC. We then summed up a workflow regarding circRNA research in cancer and relative specific databases and experimental methods. In the future, more efforts ought to be put into circRNAs research in PC, including basic research of discovering and testifying circRNAs centered ceRNA networks, and clinical research of exploiting exosomal or circulating circRNAs as a diagnostic biomarker, chemotherapy sensitivity predictor and prognostic predictor.

Advances of Tumorigenesis, Diagnosis at Early Stage, and Cellular Immunotherapy in Gastrointestinal Malignancies

Globally, in 2018, 4.8 million new patients have a diagnosis of gastrointestinal (GI) cancers, while 3.4 million people died of such disorders. GI malignancies are tightly relevant to 26% of the world-wide cancer incidence and occupies 35% of all cancer-associated deaths. In this article, we principally investigated molecular and cellular mechanisms of tumorigenesis in five major GI cancers occurring at esophagus, stomach, liver, pancreas, and colorectal region that illustrate high morbidity in Eastern and Western countries. Moreover, through this investigation, we not only emphasize importance of the tumor microenvironment in development and treatment of malignant tumors but also identify significance of M2PK, miRNAs, ctDNAs, circRNAs, and CTCs in early detection of GI cancers, as well as systematically evaluate contribution of personalized precision medicine including cellular immunotherapy, new antigen and vaccine therapy, and oncolytic virotherapy in treatment of GI cancers.

CircRNAs and their regulatory roles in cancers

Circular RNAs (circRNAs), a novel type of non-coding RNAs (ncRNAs), have a covalently closed circular structure resulting from pre-mRNA back splicing via spliceosome and ribozymes. They can be classified differently in accordance with different criteria. As circRNAs are abundant, conserved, and stable, they can be used as diagnostic markers in various diseases and targets to develop new therapies. There are various functions of circRNAs, including sponge for miR/proteins, role of scaffolds, templates for translation, and regulators of mRNA translation and stability. Without m7G cap and poly-A tail, circRNAs can still be degraded in several ways, including RNase L, Ago-dependent, and Ago-independent degradation. Increasing evidence indicates that circRNAs can be modified by N-6 methylation (m6A) in many aspects such as biogenesis, nuclear export, translation, and degradation. In addition, they have been proved to play a regulatory role in the progression of various cancers. Recently, methods of detecting circRNAs with high sensitivity and specificity have also been reported. This review presents a detailed overview of circRNAs regarding biogenesis, biomarker, functions, degradation, and dynamic modification as well as their regulatory roles in various cancers. It’s particularly summarized in detail in the biogenesis of circRNAs, regulation of circRNAs by m6A modification and mechanisms by which circRNAs affect tumor progression respectively. Moreover, existing circRNA detection methods and their characteristics are also mentioned.

Non-Coding RNAs in Pancreatic Cancer Diagnostics and Therapy: Focus on lncRNAs, circRNAs, and piRNAs

Simple Summary

Pancreatic cancer is the seventh leading cause of cancer related death worldwide. In the United States, pancreatic cancer remains the fourth leading cause of cancer related death. The lack of early diagnosis and effective therapy contributes to the high mortality of pancreatic cancer. Therefore, there is an urgent need to find novel and effective biomarkers for the diagnosis and treatment of pancreatic cancer. Long noncoding RNA, circular RNAs and piwi-interacting RNA are non-coding RNAs and could become new biomarkers for the diagnosis, prognosis, and treatment of pancreatic cancer. We summarize the new findings on the roles of these non-coding RNAs in pancreatic cancer diagnosis, prognosis and targeted therapy.

Abstract

Pancreatic cancer is an aggressive malignance with high mortality. The lack of early diagnosis and effective therapy contributes to the high mortality of this deadly disease. For a long time being, the alterations in coding RNAs have been considered as major targets for diagnosis and treatment of pancreatic cancer. However, with the advances in high-throughput next generation of sequencing more alterations in non-coding RNAs (ncRNAs) have been discovered in different cancers. Further mechanistic studies have demonstrated that ncRNAs such as long noncoding RNAs (lncRNA), circular RNAs (circRNA) and piwi-interacting RNA (piRNA) play vital roles in the regulation of tumorigenesis, tumor progression and prognosis. In recent years, increasing studies have focused on the roles of ncRNAs in the development and progression of pancreatic cancer. Novel findings have demonstrated that lncRNA, circRNA, and piRNA are critically involved in the regulation of gene expression and cellular signal transduction in pancreatic cancer. In this review, we summarize the current knowledge of roles of lncRNA, circRNA, and piRNA in the diagnosis and prognosis of pancreatic cancer, and molecular mechanisms underlying the regulation of these ncRNAs and related signaling in pancreatic cancer therapy. The information provided here will help to find new strategies for better treatment of pancreatic cancer.

Circ_0087862 promotes the progression of colorectal cancer by sponging miR-142-3p and up-regulating BACH1 expression

Circular RNAs (circRNAs) feature prominently in regulating the malignant biological behaviors of colorectal cancer (CRC), including cell viability, cell cycle progression, apoptosis, migration, invasion, and so on. This study is performed to probe into the biological function and molecular mechanism of circ_0087862 in CRC. The expression profile of GSE138589 was available from Gene Expression Omnibus (GEO), and the differentially expressed circRNAs were analyzed by GEO2R. The expression of circ_0087862, miR-142-3p, and BACH1 mRNA in CRC tissues and cells was measured by qRT-PCR. CCK-8 assay was employed to determine the proliferation of CRC cells. Scratch wound healing and transwell assays were used to examine the migration and invasion of CRC cells. The targeting relationships between circ_0087862 and miR-142-3p, and between miR-142-3p and BACH1 3'UTR were verified by dual-luciferase reporter gene assay and RIP assay. BACH1 protein expression was probed by western blot. Circ_0087862 was highly expressed in CRC tissues and cell lines. Knocking down circ_0087862 significantly restrained the multiplication, migration and invasion of CRC cells. miR-142-3p inhibition weakened the impact of circ_0087862 knockdown on CRC cells. Circ_0087862 regulated BACH1 expressions by targeting miR-142-3p. Circ_0087862 regulates BACH1 expressions through sponging miR-142-3p, and promotes the proliferation, migration, and invasion of CRC cells.