CircRNAs: Emerging Bladder Cancer Biomarkers and Targets

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.

CircITGA7 regulates malignant phenotypes in bladder cancer cells via targeting miR-330-3p/KLF10 axis

Bladder cancer (BCa) is one of the common malignancies. Circular RNAs (circRNAs) play regulatory roles in cancer progression. CircITGA7 is a circRNA generated from several exons of ITGA7. The potential role of circITGA7 in BCa remains unknown and needs to be explored. Quantitative real time polymerase chain reaction (qRT-PCR) was used to assess circITGA7 and miR-330-3p expression in BCa tissues and cell lines. Kaplan-Meier analysis was used to evaluate the overall survival of these BCa patients. The biological function of circITGA7 was examined by overexpression of circITGA7 using CCK-8, EdU, wound-healing, and Transwell assays. Xenograft assay was performed to further validate the in vitro results. To explore the mechanism of circITGA7, luciferase reporter, RNA pull-down, fluorescence in situ hybridization (FISH) assays were employed to examine the binding interaction among circITGA7, miR-330-3p and kruppel-like factor 10 (KLF10). Western blot was used to study the protein levels of KLF10.CircITGA7 was downregulated in BCa tissues and cell lines and indicated longer overall survival. Moreover, circITGA7 restricted cell proliferation, migration and invasion of BCa through negatively regulating miR-330-3p. The in vivo model showed that circITGA7 influenced the tumor growth. Besides, the overexpression of miR-330-3p promoted cell progression by directly targeting KLF10. Mechanistically, circITGA7 inhibited BCa progression by activating KLF10 via targeting miR-330-3p.CircITGA7 alleviates BCa cell progression via circITGA7/hsa-miR-330-3p/KLF10 axis, which may provide novel therapeutic targets for BCa.

Dysregulation and antimetastatic function of circLRIG1 modulated by miR-214-3p/LRIG1 axis in bladder carcinoma

CircLRIG1, a newly discovered circRNA, has yet to have its potential function and biological processes reported. This study explored the role of circLRIG1 in the development and progression of bladder carcinoma and its potential molecular mechanisms. Techniques such as qRT-PCR, Western blot, various cellular assays, and in vivo models were used to investigate mRNA and protein levels, cell behavior, molecular interactions, and tumor growth. The results showed that both circLRIG1 and LRIG1 were significantly reduced in bladder carcinoma tissues and cell lines. Low circLRIG1 expression was associated with poor patient prognosis. Overexpressing circLRIG1 inhibited bladder carcinoma cell growth, migration, and invasion, promoted apoptosis, and decreased tumor growth and metastasis in vivo. Importantly, circLRIG1 was found to sponge miR-214-3p, enhancing LRIG1 expression, and its overexpression also modulated protein levels of E-cadherin, N-cadherin, Vimentin, and LRIG1. Similar effects were observed with LRIG1 overexpression. Notably, a positive correlation was found between circLRIG1 and LRIG1 expression in bladder carcinoma tissues. Additionally, the tumor-suppressing effect of circLRIG1 was reversed by overexpressing miR-214-3p or silencing LRIG1. The study concludes that circLRIG1 suppresses bladder carcinoma progression by enhancing LRIG1 expression via sponging miR-214-3p, providing a potential strategy for early diagnosis and treatment of bladder carcinoma.

Recent advances in the understanding of urothelial tumorigenesis

INTRODUCTION

Patients with non-muscle-invasive bladder tumor suffer from disease recurrence following transurethral surgery even with intravesical pharmacotherapy, while muscle-invasive disease is often deadly. It is therefore critical to elucidate the underlying molecular mechanisms responsible for not only bladder tumor progression but also its tumorigenesis. Indeed, various molecules and/or signaling pathways have been suggested to contribute to the pathogenesis of bladder cancer.

AREAS COVERED

We summarize the progress during the last few years on the initiation or development, but not progression, of urothelial cancer. The clinical implications of these available data, including prognostic significance and possible application for the prevention of the recurrence of non-muscle-invasive bladder tumors, are also discussed.

EXPERT OPINION

Bladder cancer is a heterogeneous group of neoplasms. The establishment of personalized therapeutic options based on the molecular profile in each case should thus be considered. On that account, further accumulation of data on urothelial tumorigenesis is warranted to identify promising targets for the prevention of postoperative tumor recurrence or tumor development in otherwise high-risk patients.

Cost-Effective Transcriptome-Wide Profiling of Circular RNAs by the Improved-tdMDA-NGS Method

Covalently closed circular RNAs are neoteric to the eukaryotic family of long non-coding RNAs emerging as a result of 5′–3′ backsplicing from exonic, intronic, or intergenic regions spanning the parental gene. Owing to their unique structure and stability, circular RNAs have a multitude of functional properties such as micro-RNA and protein sponges, direct and indirect modulators of gene expression, protein translation, and many unproven activities apart from being potential biomarkers. However, due to their low abundance, most of the global circular RNA identification is carried out by high-throughput NGS-based approaches requiring millions of sequencing reads. This lag in methodological advancements demands for newer, more refined, and efficient identification techniques. Here, we aim to show an improved version of our previously reported template-dependent multiple displacement amplification (tdMDA)-NGS method by superimposing the ribosomal depletion step and use of H minus reverse transcriptase and RNase H. Implication of tdMDA using highly replicative Phi29 DNA polymerase after minimizing the linear and ribosomal RNA content further intensifies its detection limit toward even the abysmally expressing circular RNA at a low NGS depth, thereby decreasing the cost of identifying a single circular RNA. A >11-fold and >6-fold increase in total circular RNA was identified from the improved-tdMDA-NGS method over the traditional method of circRNA sequencing using DCC and CIRI2 pipelines, respectively, from Oryza sativa subsp. Indica. Furthermore, the reliability of the improved-tdMDA-NGS method was also asserted in HeLa cell lines, showing a significant fold difference in comparison with the existing traditional method of circRNA sequencing. Among the identified circular RNAs, a significant percentage from both rice (∼58%) and HeLa cell lines (∼84%) is found to be matched with the previously reported circular RNAs, suggesting that the improved-tdMDA-NGS method can be adapted to detect and characterize the circular RNAs from different biological systems.

CircMYC promotes proliferation, migration, invasion and inhibits apoptosis of small cell lung cancer by targeting miR-145/ Matrix Metallopeptidase 2 axis

Circular RNAs (circRNAs) are involved in the carcinogenesis of lung cancer. Human MYC gene is highly expressed in melanoma, multiple myeloma, and nasopharyngeal carcinoma. We aimed to investigate the role of circMYC in small cell lung cancer (SCLC). The expression of cirMYC in SCLC tissues and cells were examined. Functional studies were performed to evaluate the roles of circMYC in SCLC cells. Luciferase reporter gene assay, RNA pull-down assay, and rescue experiments were performed to evaluate the regulatory relationship between circMYC and miR-145, and MiR-145 and MMP2 mRNA. We found that CirMYC was highly expressed in SCLC tissues and cells. Knockdown of circMYC could inhibit cell proliferation, migration, invasion, and induce apoptosis. CircMYC targeted miR-145 and miR-145 targeted MMP2 (Matrix Metallopeptidase 2) mRNA. Our data indicated that circMYC upregulates the expression of MMP-2 by inhibiting miR-145, which functions to promote the proliferation, migration, and invasion and inhibit the apoptosis of SCLC. These findings suggest that targeting circMYC/miR-145/MMP-2 could serve as a potential therapeutic strategy for SCLC treatment.

Emerging Biomarkers for Predicting Bladder Cancer Lymph Node Metastasis

Bladder cancer is one of the leading causes of cancer deaths worldwide. Early detection of lymph node metastasis of bladder cancer is essential to improve patients' prognosis and overall survival. Current diagnostic methods are limited, so there is an urgent need for new specific biomarkers. Non-coding RNA and m6A have recently been reported to be abnormally expressed in bladder cancer related to lymph node metastasis. In this review, we tried to summarize the latest knowledge about biomarkers, which predict lymph node metastasis in bladder cancer and their mechanisms. In particular, we paid attention to the impact of non-coding RNA on lymphatic metastasis of bladder cancer and its specific molecular mechanisms, as well as some prediction models based on imaging, pathology, and biomolecules, in an effort to find more accurate diagnostic methods for future clinical application.