CircLMTK2 acts as a tumor suppressor in prostate cancer via regulating the expression of microRNA-183

circITGA7 Acts as a miR-370-3p Sponge to Suppress the Proliferation of Prostate Cancer

Prostate cancer (PCa) refers to one of the most common tumors in male's genitourinary system. Emerging research has confirmed that circRNAs play an important role in the occurrence and development of tumors. However, the correlation between circular RNA circITGA7 and PCa still remains unclear. Here, the role of circITGA7 in PCa was explored and the underlying mechanism was investigated as well. The circRNA expression profiles in PCa and the paracancerous tissues were established by high-throughput sequencing. The expression levels of circITGA7 in PCa tissues and cells were detected by qRT-PCR. Cell Counting Kit-8, colony formation, EdU, and flow cytometry assays were used to detect the effects of circITGA7 on PCa cell proliferation. To further explore the underlying mechanisms, bioinformatics analysis on downstream target genes was carried out. RNA immunoprecipitation and dual-luciferase reporter assays were used to verify the direct relationship between miR-370-3p and circITGA7 or P21CIP1. The present results demonstrated that circITGA7 was downregulated in PCa tissues and cells. Gain- or loss-of-function assays showed that circITGA7 inhibited the proliferation of PCa cells in vivo and in vitro. Mechanically, circITGA7 served as a sponge for miR-370-3p, and miR-370-3p could target P21CIP1 in PCa cells. The inhibition of cell proliferation induced by circITGA7 could be reversed by transfecting miR-370-3p mimic. Collectively, our data indicated that circITGA7 played an important role in inhibiting tumor proliferation in PCa and might be a potential therapeutic target.

Circ_0004104 Accelerates the Progression of Gastric Cancer by Regulating the miR-539-3p/RNF2 Axis

BACKGROUND

Circular RNA (circRNA) has been shown to be closely associated with cancer progression, including gastric cancer (GC). However, the function of circ_0004104 in GC progression has not been clarified.

AIMS

The purpose of this study was to explore the role of circ_0004104 in GC progression.

METHODS

The expression levels of circ_0004104, miR-539-3p, and ring finger protein 2 (RNF2) were assessed using quantitative real-time polymerase chain reaction. Cell proliferation was measured by 3-(4,5-dimethyl-2 thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay, and cell migration and invasion were detected using transwell assay. The levels of glutamine, glutamate, and α-ketoglutarate were determined to evaluate the glutaminolysis of cells, and the protein levels of glutaminolysis-related markers and RNF2 were detected using western blot analysis. Furthermore, Dual-Luciferase Reporter Assay was employed to assess the interaction between miR-539-3p and circ_0004104 or RNF2. Animal experiments were carried out to evaluate the effect of circ_0004104 silencing on GC tumor growth in vivo.

RESULTS

Circ_0004104 was upregulated in GC, and its knockdown repressed the proliferation, metastasis, and glutaminolysis of GC cells in vitro and reduced GC tumor growth in vivo. Furthermore, we discovered that circ_0004104 could sponge miR-539-3p and miR-539-3p could target RNF2. The rescue experiments suggested that miR-539-3p inhibitor could reverse the suppressive effect of circ_0004104 silencing on GC progression, and RNF2 overexpression also reversed the inhibition effect of miR-539-3p mimic on GC progression.

CONCLUSION

Circ_0004104 accelerated GC progression via regulating the miR-539-3p/RNF2 axis, indicating that circ_0004104 might be a potential therapeutic target for GC.

Advancement and properties of circular RNAs in prostate cancer: An emerging and compelling frontier for discovering

Prostate cancer (PC) is the most common carcinoma among men worldwide which results in 26% of leading causes of cancer-related death. However, the ideal and effective molecular marker remains elusive. CircRNA, initially observed in plant-infected viruses and Sendai virus in 1979, is generated from pre-mRNA back-splicing and comes in to play by adequate expression. The differential expression in prostate tissues compared with the control reveals the promising capacity in modulating processes including carcinogenesis and metastasis. However, the biological mechanisms of regulatory network in PC needs to systemically concluded. In this review, we enlightened the comprehensive studies on the definite mechanisms of circRNAs affecting tumor progression and metastasis. What's more, we validated the potential clinical application of circRNAs serving as diagnostic and prognostic biomarker. The discussion and analysis in circRNAs will broaden our knowledge of the pathogenesis of PC and further optimize the current therapies against different condition.

Role of microRNAs in the development, prognosis and therapeutic response of patients with prostate cancer

Prostate cancer is the most common cancer in males in several regions. One of the major challenges in diagnosis and treatment of this cancer is how to identify men who harbor an increased risk of having clinically significant prostate cancer and how to assess response to therapy. Biomarkers, like microRNAs (miRNAs) are one of the new diagnostic/therapeutic tools for clinicians. Finding men at high risk of significant cancer is essential as they will mostly benefit from earlier diagnosis and treatment. At the same time, it is important to reduce the number of unnecessary invasive biopsies in men without (clinically significant) cancer and miRNAs have especial application in this regard. MiRNAs can regulate expression of several genes. Up to 30 percent of protein coding genes are regulated by miRNAs. Based on this critical regulatory role, miRNAs impact cell differentiation, growth and apoptosis. Several studies have reported aberrant expression of miRNAs in different cancers including prostate cancer. miRNAs are regarded as biomarkers in this kind of cancer. Moreover, expression profiles of miRNAs can predict therapeutic response to a number of drugs such docetaxel and some natural agents such as isoflavone. Functional studies have shown that miRNAs regulate a number of critical targets such as Wnt/β-catenin, PI3K/AKT, cyclin dependent kinases, VEGF and JAK/ STAT. Therefore, several aspects of prostate cancer development are influenced by miRNAs. Finally, circulating miRNAs are promising tools for assessment of prostate cancer course and prognosis. In the current review, we summarize the results of studies which reported abnormal expression of miRNAs in prostate cancer and their role as biomarkers or therapeutic targets.