Down-regulation Of Circ Research Articles

Inhibiting circ_0000673 blocks the progression of colorectal cancer through downregulating CPSF6 via targeting miR-548b-3p.

Colorectal cancer (CRC) is one of the most common cancers, and its progression is regulated by several factors, including circular RNA (circRNA). The objective of this study was to determine the role, or roles, of circ_0000673 in CRC. We used quantitative real-time polymerase chain reaction (qPCR) to detect the expression of circ_0000673, miR-548b-3p and cleavage and polyadenylation specific factor 6 (CPSF6) in DLD-1 and RKO cells. Cell Counting Kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU) assays were used to determine circ_0000673 roles in proliferation. Wound healing and transwell assays were used to detect cell migration and invasion abilities. Expression of CPSF6 protein and stem cell-associated proteins were examined using western blot. The putative relationship between miR-548b-3p and circ_0000673 or CPSF6 was verified with dual-luciferase reporter assay. The role of circ_0000673 in CRC was also investigated in a tumor xenograft assay in nude mice. Circ_0000673 expression was increased in CRC tissues and cancer cells. Silencing circ_0000673 reduced tumor cell proliferation, migration and invasion, while also decreasing cell stemness. MiR-548b-3p was found to be a target of circ_0000673, while CPSF6 was a downstream target of miR-548b-3p. The tumor-regulatory effects of si-circ_0000673, anti-miR-548b-3p and oe-CPSF6 were partially reversed by anti-miR-548b-3p, si-CPSF6 and si-circ_0000673, respectively, in rescue assays. Downregulation of circ_0000673 reduced solid tumor growth in vivo. Circ_0000673 inhibition reduced CPSF6 expression by targeting miR-548b-3p, thereby blocking proliferation, migration and invasion of CRC tumor cells.

Circ_0008315 promotes tumorigenesis and cisplatin resistance and acts as a nanotherapeutic target in gastric cancer

IntroductionCisplatin-based chemotherapy is one of the fundamental therapeutic modalities for gastric cancer (GC). Chemoresistance to cisplatin is a great clinical challenge, and its underlying mechanisms remain poorly understood. Circular RNAs (circRNAs) are involved in the pathophysiology of multiple human malignancies.MethodsHigh-throughput sequencing was performed to determine the differentially expressed profile of circRNA in GC tissues and cisplatin-resistant GC cells. Quantitative real-time polymerase chain reaction and Fluorescence in situ hybridization was utilized to confirm the dysregulation of circ_0008315 in GC tissues. To evaluate the prognostic significance of circ_0008315 in GC, we used Kaplan-Meier plot. The self-renewal ability of drug-resistant GC cell was verified through tumor sphere formation assay. GC organoids were constructed to simulate the tumor microenvironment and verified the function of circ_0008315 in cisplatin resistance of gastric cancer. In vivo evaluation was conducted using patient-derived xenograft models. Dual-luciferase reporter gene, RNA immunoprecipitation and miRNA pull-down assays were employed to investigate the molecular mechanisms of circ_0008315 in GC.ResultsWe revealed that a novel circRNA hsa_circ_0008315 was upregulated in GC and cisplatin-resistant GC cells. Elevated circ_0008315 was also observed in cisplatin-resistant GC organoid model. High circ_0008315 expression predicted unfavorable survival outcome in GC patients. Downregulation of circ_0008315 expression inhibited proliferation, mobility, and epithelial-mesenchymal transition of GC cells in vitro and in vivo. Reducing circ_0008315 expression in cisplatin-resistant GC organoid model reversed cisplatin resistance. Mechanistically, circ_0008315 modulated the stem cell properties of GC through the miR-3666/CPEB4 signaling pathway, thereby promoting cisplatin resistance and GC malignant progression. Furthermore, we developed PLGA-PEG nanoparticles targeting circ_0008315, and the nanoparticles could effectively inhibit GC proliferation and cisplatin resistance.ConclusionCirc_0008315 exacerbates GC progression and cisplatin resistance, and can be used as a prognostic predictor. Circ_0008315 may function as a promising nanotherapeutic target for GC treatment.Graphical

METTL3 -mediated m6A modification of circ_0000620 regulates cisplatin sensitivity and apoptosis in lung adenocarcinoma via the MiR-216b-5p/KRAS axis

Circular RNAs (circRNAs) are stable non-coding RNAs characterized by the absence of the conventional 5' cap and 3' polyadenylated tail structure. Its involvement in various aspects of cancers underscores its significance in oncology. Elevated expression of circ_0000620 was observed in both lung adenocarcinoma (LUAD) tissues and cell lines. In vitro, experiments demonstrated that the downregulation of circ_0000620 increased cisplatin sensitivity and promoted cell apoptosis while suppressing malignant characteristics such as cell migration and proliferation. Further investigation into the mechanism underlying the increased expression of circ_0000620 revealed that Methyltransferase 3, N6-Adenosine-Methyltransferase Complex Catalytic Subunit (METTL3) mediates the m6A methylation modification of circ_0000620, thereby promoting its stability and expression. Furthermore, circ_0000620 modulates the miR-216b-5p/KRAS axis to influence apoptosis and cisplatin sensitivity in both A549 and H1299 cell lines. These findings were corroborated by in vivo nude mouse experiments, which showed that knockdown of circ_0000620 inhibited tumor growth and proliferation. In summary, METTL3 plays a role in regulating the stability of circ_0000620 expression, and circ_0000620 exerts its effects on LUAD apoptosis and cisplatin sensitivity through the miR-216b-5p/KRAS signaling pathway.

Circ_0000069 promotes the development of hepatocellular carcinoma by regulating CCL25

BackgroundHepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths globally, influenced by aberrant circRNA expression. Investigating circRNA-miRNA-mRNA interactions can unveil underlying mechanisms of HCC and identify potential therapeutic targets.MethodsIn this study, we conducted differential analyses of mRNAs, miRNAs, and circRNAs, and established their relationships using various databases such as miRanda, miRDB, and miTarBase. Additionally, functional enrichment and immune infiltration analyses were performed to evaluate the roles of key genes. We also conducted qPCR assays and western blotting (WB) to examine the expression levels of circRNA, CCL25, and MAP2K1 in both HCC cells and clinical samples. Furthermore, we utilized overexpression and knockdown techniques for circ_0000069 and conducted wound healing, transwell invasion assays, and a tumorigenesis experiment to assess the migratory and invasive abilities of HCC cells.ResultsOur findings revealed significant differential expression of 612 upregulated genes and 1173 downregulated genes in HCC samples compared to normal liver tissue. Additionally, 429 upregulated circRNAs and 453 downregulated circRNAs were identified. Significantly, circ_0000069 exhibited upregulation in HCC tissues and cell lines. The overexpression of circ_0000069 notably increased the invasion and migration capacity of Huh7 cells, whereas the downregulation of circ_0000069 reduced this capability in HepG2 cells. Furthermore, this effect was counteracted by CCL25 silencing or overexpression, separately. Animal studies further confirmed that the overexpression of hsa_circ_0000069 facilitated tumor growth in xenografted nude mice, while the inhibition of CCL25 attenuated this effect.ConclusionCirc_0000069 appears to promote HCC progression by regulating CCL25, suggesting that both circ_0000069 and CCL25 can serve as potential therapeutic targets.

Knockdown of circ_0044226 promotes endoplasmic reticulum stress-mediated autophagy and apoptosis in hepatic stellate cells via miR-4677-3p/SEC61G axis.

Downregulation of circ_0044226 has been demonstrated to reduce pulmonary fibrosis, but the role of circ_0044226 in liver fibrosis remains to be explored. In this work, we found that circ_0044226 expression was upregulated during liver fibrosis. Knockdown of circ_0044226 inhibited proliferation, promoted autophagy and apoptosis of hepatic stellate cell LX-2. Bioinformatic analysis and dual luciferase reporter assays confirmed the interaction between circ_0044226, miR-4677-3p and SEC61G. Mechanistically, knockdown of circ_0044226 suppressed SEC61G expression by releasing miR-4677-3p, thereby enhancing endoplasmic reticulum stress. Overexpression of SEC61G or endoplasmic reticulum stress inhibitor 4-phenylbutiric acid partially reversed the effect of knockdown circ_0044226 on LX-2 cell function. In vivo experiments showed that inhibition of circ_0044226 attenuated CCL4-induced liver fibrosis in mice. These imply that circ_0044226 may be a potential target for the treatment of liver fibrosis.

Circ_0007351 Exerts an Oncogenic Role In Colorectal Cancer Depending on the Modulation of the miR-5195-3p/GPRC5A Cascade.

Circular RNAs (circRNAs) exert critical functions in colorectal cancer development. In this work, we wanted to elucidate the functional role and regulatory mechanism of circ_0007351 in colorectal cancer. For quantification of circ_0007351, microRNA (miR)-5195-3p and G Protein-coupled receptor class C group 5 member A (GPRC5A), a qRT-PCR, immunoblotting or immunohistochemistry assay was performed. Effects of circ_0007351/miR-5195-3p/GPRC5A cascade were evaluated by determining cell viability, proliferation, colony formation, motility, and invasion. Relationships among variables were assessed by dual-luciferase reporter assay. Animal studies were performed to evaluate circ_0007351's function in the growth of xenograft tumors. Circ_0007351 was markedly up-regulated in colorectal cancer tissues and cells. Down-regulation of circ_0007351 hindered cell growth, migration and invasiveness. Also, circ_0007351 depletion exerted a suppressive function in colorectal cell xenograft growth in vivo. Mechanistically, circ_0007351 sponged miR-5195-3p to sequester miR-5195-3p. Reduction of available miR-5195-3p neutralized the effects of circ_0007351 down-regulation on cell phenotypes. MiR-5195-3p directly targeted and inhibited GPRC5A. Circ_0007351 regulated GPRC5A expression by sponging miR-5195-3p. Moreover, the effects of circ_0007351 down-regulation on cell functional phenotypes were due to in part the reduction of GPRC5A expression. Our findings show that circ_0007351 down-regulation impedes proliferation, motility, and invasiveness in colorectal cancer cells at least in part via the regulation of the miR-5195-3p/GPRC5A cascade, highlighting that circ_0007351 inhibition may have a potential therapeutic value for colorectal cancer.

Exosomal circ_0000722 derived from periodontal ligament stem cells undergoing osteogenic differentiation promotes osteoclastogenesis

Periodontal ligament stem cells (PDLSCs), which are considered promising stem cells for regeneration of periodontal bony tissue, can also manipulate alveolar bone remodeling by exosomes. In this study, we investigated interactions between PDLSCs under osteogenic differentiation and osteoclast precursors. The results showed that conditioned medium from PDLSCs under 5d osteogenic induction promoted osteoclastogenesis of RAW264.7 cells. The exosomes extracted from those conditioned media showed similar effects on osteoclastogenesis. Furthermore, exosomes from PDLSCs under 5d of osteogenic induction showed significantly high expression of circ_0000722, compared with exosomes from PDLSCs before osteogenic induction. Downregulation of circ_0000722 significantly attenuated the effect of PDLSC-derived exosomes on the osteoclastogenesis of RAW264.7 cells. Our findings suggested that exosomal circ_0000722 derived from periodontal ligament stem cells undergoing osteogenic differentiation might promote osteoclastogenesis by upregulating TRAF6 expression and activating downstream NF-κB and AKT signaling pathways.

Hsa_circ_0046534 accelerates esophageal squamous cell carcinoma proliferation and metastasis via regulating MMP2 expression by sponging miR-339-5p

Esophageal cancer is one of the most malignant gastrointestinal malignancies. Esophageal squamous cell carcinoma (ESCC) is the most common type of esophageal cancer in China. In recent years, with developments in basic medicine, it has been demonstrated that the abnormal expression of circular RNA (circRNA) plays an important role in the progression and prognosis of ESCC. This study explored the role and downstream molecular mechanisms of circ_0046534 in ESCC. We identified circ_0046534, which was found to be highly expressed in ESCC tissues and cells. Moreover, the downregulation of circ_0046534 inhibited the proliferation, migration and invasion of ESCC cells and the growth and metastasis of ESCC tumours in vivo. Dual-luciferase reporter assays showed that circ_0046534 sponged miR-339-5p and inhibited the expression of miR-339-5p. Furthermore, MMP2 was identified to be a direct target of miR-339-5p through bioinformatics analysis. In addition, the knockdown of circ_0046534 inhibited the expression of the downstream target gene matrix metalloproteinase 2 (MMP2) by releasing the adsorption of miR-339-5p. Taken together, this study demonstrated that silencing circ_0046534 inhibited the growth and metastasis of ESCC through the miR-339-5p/MMP2 pathway. Circ_0046534 is expected to serve as a new biomarker and target for ESCC and provide a new direction for its diagnosis and treatment.

Circ_0068481 Affects the Human Pulmonary Artery Smooth Muscle Cells' Progression by miR-361-3p/KLF5 Axis.

Uncontrolled proliferation of pulmonary artery smooth muscle cells (PASMCs) contributes to the pathogenesis of pulmonary arterial hypertension (PAH). In this work, we defined the precise part of circ_0068481 in PASMC proliferation and migration induced by hypoxia. We hypothesized that circ_0068481 enhanced hypoxia-induced PASMC proliferation, invasion, and migration through the microRNA (miR)-361-3p/Krüppel-like factor 5 (KLF5) pathway. Human PASMCs (hPASMCs) were exposed to hypoxic (3% O2) conditions. Circ_0068481, miR-361-3p, and KLF5 levels were gauged by qRT-PCR and western blot. Cell viability, proliferation, invasion, and migration were detected by XTT, EdU incorporation, transwell, and wound-healing assays, respectively. Dual-luciferase reporter, RNA immunoprecipitation, and RNA pull-down assays were performed to confirm the direct relationship between miR-361-3p and circ_0068481 or KLF5. Circ_0068481 expression was increased in the serum of PAH patients and hypoxia-induced hPASMCs. Downregulation of circ_0068481 attenuated hypoxia-induced promotion in hPASMC proliferation, invasion, and migration. Circ_0068481 directly targeted miR-361-3p, and miR-361-3p downregulation reversed the inhibitory effects of circ_0068481 silencing on hypoxia-induced hPASMC proliferation, invasion, and migration. KLF5 was a direct miR-361-3p target, and miR-361-3p upregulation mitigated hypoxia-induced hPASMC proliferation, invasion, and migration by inhibiting KLF5 expression. Moreover, circ_0068481-induced KLF5 expression by binding to miR-361-3p in hypoxic hPASMCs. Circ_0068481 knockdown ameliorated hypoxia-induced hPASMC proliferation, invasion, and migration at least in part through the miR-361-3p/KLF5 axis.

Downregulation of Circ_0071589 Suppresses Cisplatin Resistance in Colorectal Cancer by Regulating the MiR-526b-3p/KLF12 Axis [Retraction

[This retracts the article DOI: 10.2147/CMAR.S294880.].

Circular RNA circ_0101675 Promotes NSCLC Cell Proliferation, Migration, Invasion, Angiogenesis and Immune Evasion by Sponging miR-607/PDL1 Axis.

Non-small cell lung cancer (NSCLC) is one of the most common and fatal cancers in the world. Circular RNA (circRNA) can broadly participate in the initiation and progression of the NSCLC. However, the regulatory mechanisms of circRNA in NSCLC remain poorly understood. In present study, we aimed to explore the potential role of circ_0101675 in the progression of NSCLC.Quantitative real-time polymerase chain reaction was performed to examine the expression of circ_0101675, microRNA-607 (miR-607) and programmed cell death receptor ligand 1 (PDL1) in NSCLC tissues and cells. Cell count kit 8 assay, colony formation assay, wound healing assay, transwell assay, tube formation assay and flow cytometry were applied to examine NSCLC cell proliferation, migration, invasion, angiogenesis and apoptosis. NSCLC cells were co-cultured with peripheral blood mononuclear cells to assess immune response. The protein levels of PDL1 and proteins related to apoptosis were detected by western blotting. Dual-luciferase reporter assay and RNA immunoprecipitation assay were conducted to verify the direct target site between miR-607 and circ_0101675 or PDL1. The experiments in vivo were employed to explore the effects of circ_0101675 on tumor growth in NSCLC.Circ_0101675 and PDL1 were high-expressed, while miR-607 was low-expressed in NSCLC cells and cancer tissues. The suppression of circ_0101675 suppressed growth, migration, invasion, angiogenesis and immune escape in NSCLC cells. Mechanistically, we found that high level of circ_0101675 could upregulate PDL1 expression via sponging miR-607. Moreover, the down-regulation of circ_0101675 inhibited the growth of NSCLC tumors in vivo by enhancing miR-607 expression to decrease PDL1 expression.Taken together, our results suggested that circ_0101675 might promote the proliferation, migration, invasion, and immune evasion abilities of NSCLC through miR-607/PDL1 axis.

Circular RNA circ_0058123 Targets the miR-939-5p/RAC1 Pathway to Promote the Development of Colorectal Cancer.

Circular RNA (circRNA) can be used as a potential target for cancer treatment. However, the biological function and potential molecular mechanism of circ_0058123 in the development of colorectal cancer (CRC) are still unclear. The expression levels of circ_0058123, microRNA-939-5p (miR-939-5p) and Rac family small GTPase 1 (RAC1) were measured by quantitative real-time polymerase chain reaction or western blot assay. 5-Ethynyl-2'-deoxyuridine (EdU) incorporation assay, transwell assay, tube formation assay and flow cytometry apoptosis assay were conducted to assess CRC cell functions. In addition, protein expression was measured with western blot assay. Dual-luciferase reporter assays and RNA immunoprecipitation assay were conducted to confirm the relationships between miR-939-5p and circ_0058123, and miR-939-5p and RAC1. In vivo CRC tumor growth experiment also were carried out to determine circ_0058123-mediatede effects on tumor formation. Our data showed that circ_0058123 and RAC1 expression were increased, but miR-939-5p was decreased in both of CRC tissues and cell lines. Circ_0058123 depletion repressed CRC cell proliferation, migration, invasion and tube formation but promoted cell apoptosis. Down-regulation of circ_0058123 could significantly suppress the CRC progression, while the addition of miR-939-5p inhibitor could reverse this effect. Circ_0058123 directly targeted miR-939-5p, and RAC1 was a target of miR-939-5p. Furthermore, RAC1 overexpression could rescue the effect of miR-939-5p on CRC development. Lastly, silence of circ_0058123 inhibited CRC tumor growth in vivo. In conclusion, circ_0058123 could promote CRC progression through regulating the miR-939-5p/RAC1 axis and may be a valuable biomarker for early diagnosis and prognosis of CRC.

Downregulation of circ_0035292 Alleviates LPS-Induced WI-38 Cell Injury via Targeting miR-494-3p/TLR4 Pathway in Infantile Pneumonia.

Circular RNAs (circRNAs) have been confirmed to mediate infantile pneumonia development. In this, we investigated the role and new mechanism of circ_0035292 regulating infantile pneumonia progression. Lipopolysaccharide (LPS)-treated WI-38 cells were used to mimic infantile pneumonia cell injury models. Quantitative real-time PCR was used to measure circ_0035292, microRNA (miR)-494-3p and toll-like receptor 4 (TLR4). Cell proliferation and apoptosis were assessed by MTT assay, EdU assay, and flow cytometry. Protein expression was tested using western blot analysis. Inflammation and oxidative stress were evaluated by measuring IL-6, IL-1β, MDA and SOD levels using ELISA assay and corresponding kits. RNA interaction was confirmed by dual-luciferase reporter assay and RIP assay. Circ_0035292 had elevated expression in infantile pneumonia patients and LPS-induced WI-38 cells. Silenced circ_0035292 could enhance WI-38 cell proliferation, while suppress apoptosis, inflammation and oxidative stress under LPS treatment. Mechanically, circ_0035292 targeted miR-494-3p to positively regulate TLR4. The rescue experiments indicated that miR-494-3p inhibitor abolished the function of circ_0035292 knockdown, and TLR4 overexpression reversed the inhibitory effect of miR-494-3p on LPS-induced WI-38 cell injury. Circ_0035292 might be a potential target for infantile pneumonia treatment, which knockdown could relieve LPS-induced cell injury via the regulation of miR-494-3p/TLR4 axis.

Downregulation of circ_0119412 expression inhibits malignant progression of breast cancer by targeting the miR-1205/GALNT6 pathway in vivo and in vitro

IntroductionAberrant circular RNA (circRNA) expression is associated with development of breast cancer. In this study, we aimed to assess the anti-proliferative effect of <i>circ_0119412</i> knockdown on breast cancer cells.Material and methodsTumor and adjacent normal tissues were collected from 35 patients with invasive breast cancer (mean age: 56 years; mean tumor size: 2 cm; 46% patients with TNM I and II stages). The levels of <i>circ_0119412</i>, microRNA (<i>miR</i>)-1205, and N-acetylgalactosaminyltransferase 6 (<i>GALNT6</i>) were determined using reverse transcription-quantitative polymerase chain reaction. Cell proliferation and invasion were assessed using cell counting kit-8 and transwell assays, respectively. Cell apoptosis was assessed using flow cytometry. Moreover, the targeting relationships of <i>miR-1205</i> with <i>circ_0119412</i> and <i>GALNT6</i> were determined using dual-luciferase reporter and RNA immunoprecipitation assays. Furthermore, tumor growth was observed in an animal model in vivo.ResultsWe found that <i>circ_0119412</i> expression levels were upregulated in breast cancer tumor specimens and cell lines. Downregulation of <i>circ _0119412</i> inhibited the invasion and proliferation, while enhancing the apoptosis of breast cancer cells. Furthermore, <i>circ_0119412</i> knockdown suppressed tumor growth in vivo. Notably, <i>miR-1205</i> was identified as a downstream target of <i>circ_0119412</i>. Downregulation of <i>circ_0119412</i> suppressed the aggressive behavior of breast cancer cells by targeting <i>miR-1205</i>. Moreover, <i>GALNT6</i> was the downstream target of <i>miR-1205</i>. Inhibition of <i>miR-1205</i> aggravated the malignant behavior of breast cancer cells by increasing <i>GALNT6</i> expression.ConclusionsOur findings suggest that the downregulation of <i>circ_0119412</i> inhibits breast cancer progression, at least in part, by targeting the <i>miR-1205/GALNT6</i> pathway.

A novel CircRNA Circ_0001722 regulates proliferation and invasion of osteosarcoma cells through targeting miR-204-5p/RUNX2 axis

BackgroundOsteosarcoma (OS) is the most prevalent primary fatal bone neoplasm in adolescents and children owing to limited therapeutic methods. Circular RNAs (circRNAs) are identified as vital regulators in a variety of cancers. However, the roles of circRNAs in OS are still unclear.MethodsFirstly, we evaluate the differentially expressed circRNAs in 3 paired OS and corresponding adjacent nontumor tissue samples by circRNA microarray assay, finding a novel circRNA, circ_001722, significantly upregulated in OS tissues and cells. The circular structure of candidate circRNA was confirmed through Sanger sequencing, divergent primer PCR, and RNase R treatments. Proliferation of OS cells was evaluated in vitro and in vivo. The microRNA (miRNA) sponge mechanism of circRNAs was verified by dual-luciferase assay and RNA immunoprecipitation assay.ResultsA novel circRNA, circ_001722, is significantly upregulated in OS tissues and cells. Downregulation of circ_0001722 can suppress proliferation and invasion of human OS cells in vitro and in vivo. Computational algorithms predict miR-204-5p can bind with circ_0001722 and RUNX2 mRNA 3’UTR, which is verified by Dual-luciferase assay and RNA immunoprecipitation assay. Further functional experiments show that circ_0001722 competitively binds to miR-204-5p and prevents it to decrease the level of RUNX2, which upregulates proliferation and invasion of human OS cells.ConclusionCirc_001722 is a novel tumor promotor in OS, and promotes the progression of OS via miR-204-5p/RUNX2 axis.

Circ_0001387 regulates SKA2 to accelerate breast cancer progression through miR-136-5p.

Growing evidence has revealed the critical regulatory role for circular RNAs (circRNAs) in cancer. This study aimed to explore the function of circ_0001387 in breast cancer (BC). Circ_0001387, miR-136-5p, and spindle and kinetochore-associated protein 2 (SKA2) levels were analyzed by quantitative real-time polymerase chain reaction. Clone formation and 5-ethynyl-2'-deoxyuridine assays were used to analyze cell proliferation. Cell apoptosis and cell migration and invasion abilities were analyzed using flow cytometry or transwell assay. Mechanism assay was used to confirm the association between miR-136-5p and circ_0001387 or SKA2. The effect of circ_0001387 on tumor growth in vivo was analyzed by the xenograft mice model. Circ_0001387 and SKA2 were expressed at high levels, whereas miR-136-5p was lowly expressed in BC tissues and cells. Meanwhile, the downregulation of circ_0001387 restrained BC cell progression in vitro and in vivo. Circ_0001387 competitively bound to miR-136-5p to regulate BC cell malignant behaviors. SKA2 was targeted by miR-136-5p, and SKA2 reinstated the suppressive effect of miR-136-5p upregulation in BC cells. Our study indicated that circ_0001387 contributed to BC cell progression through miR-136-5p/SKA2 axis.

The regulation of circRNA_kif26b on alveolar epithelial cell senescence via miR-346-3p is involved in microplastics-induced lung injuries

Microplastics (MPs), the emerging environmental contaminants, can be inhaled and lead to lung injuries, including inflammation and fibrosis. Alveolar epithelial cell senescence is associated with several lung diseases, but its mechanism in MPs-induced lung injuries remains unknown. In this study, polystyrene microplastics (PS-MPs) in the form of microspheres with a particle size of 100 nm were used for a 35-day inhalation exposure in SPF-grade Sprague-Dawley (SD) rats. The plethysmograph showed lung dysfunction. The hematoxylin and eosin (H&E) staining revealed lung histological lesions with a significant accumulation of inflammatory cells. The β-galactosidase staining indicated increased senescent cells in lung tissues. The ELISA suggested increased senescence-associated secretory phenotype (SASP) in bronchoalveolar lavage fluid (BALF). Treatment of mouse alveolar epithelial cell line MLE12 with PS-MPs raised levels of senescence-related markers p21, p16, and p27 and SASP secretion. circ_kif26b, a ring-structured non-coding RNA (ncRNA), is homologous in human, rat, and mouse and was elevated in PS-MPs-exposed rat lung tissues as well as in PS-MPs-treated MLE12 cells. The luciferase reporter gene revealed that circ_kif26b was bound to miR-346-3p and co-regulated p21, a target gene of miR-346-3p. circ_kif26b knockdown or miR-346-3p overexpression attenuated PS-MPs-induced MLE12 cell senescence and secretion of the SASP cytokines IL-6 and IL-8. However, down-regulation of circ_kif26b and miR-346-3p reversed this depressive effect. Overall, circ_kif26b mediates alveolar epithelial cell senescence through miR-346-3p and participates in PS-MPs-induced lung inflammation. These findings provide new insights into the mechanisms of MPs inhalation toxicity and lay a mechanistic foundation for health risk assessment of MPs.

Inhibition of circ_0000231 suppresses oxidized low density lipoprotein-induced apoptosis, autophagy and inflammation in human umbilical vein endothelial cells by regulating miR-590-5p/PDCD4 axis.

Circular RNAs (circRNAs) are the emerging informative RNAs, involved in cardiovascular diseases including atherosclerosis (AS). Endothelial injury is the initial qualitative change of AS. Thus, the objective of this study was to confirm the dysregulation and mechanism of circ_0000231 in cell model of AS at early stage in human umbilical vein endothelial cells (HUVECs) induced by oxidized low-density lipoprotein (ox-LDL). The expression of circ_0000231, miR-590-5p and programmed cell death 4 (PDCD4) was detected using real-time quantitative PCR and western blot. Cell injury was measured with MTT, flow cytometry, caspase-3 activity assay and enzyme-linked immunosorbent assay (ELISA). The interaction among circ_0000231, miR-590-5p and PDCD4 was validated by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) and pull-down assays. Stress ox-LDL decreased cell viability, and increased apoptosis rate and caspase-3 activity in HUVECs in a dose- and time-dependent manner in concomitant with promotions of interleukin-6, interleukin-1β, tumor necrosis factor-α, LC3-II/I and Beclin-1 levels. Besides, circ_0000231 and PDCD4 expressions were upregulated, and miR-590-5p was downregulated in ox-LDL-stimulated HUVECs. Functionally, knockdown of circ_0000231 and overexpression of miR-590-5p could suppress ox-LDL-elicited above effects on apoptosis, autophagy and inflammatory response, accompanied with PDCD4 downregulation. Physically, miR-590-5p could directly interact with circ_0000231 and PDCD4. Downregulation of circ_0000231 suppresses HUVECs from ox-LDL-induced injury partially through regulating miR-590-5p/PDCD4 axis via competing endogenous RNA mechanism, showing a novel potential target for the pathology and treatment of endothelial injury in AS.

Downregulation of circ_0024028 inhibits IL-22-induced keratinocyte proliferation and migration by miR-486-3p/AKT3 axis.

Circular RNA (circRNA) has been confirmed to participate in psoriasis process, but the role of circ_0024028 in psoriasis development is still unclear. Interleukin 22 (IL-22)-induced keratinocytes (HaCaT) were used to construct psoriasis cell models in vitro. The expression of circ_0024028, microRNA (miR)-486-3p and AKT serine/threonine kinase 3 (AKT3) was analyzed by quantitative real-time PCR. Cell function was assessed by cell counting kit 8 assay, EdU assay, transwell assay, and wound healing assay. Protein expression was examined using western blot analysis. RNA interaction was confirmed by dual-luciferase reporter assay and RIP assay. Exosomes were isolated from cell culture medium using ultracentrifugation and examined by transmission electron microscopy and nanoparticle tracking analysis. Circ_0024028 was highly expressed in psoriasis lesions and IL-22-induced HaCaT cells, and its silencing could inhibit IL-22-induced HaCaT cell proliferation and migration. MiR-486-3p could be sponged by circ_0024028, and its inhibitor restored the functions of circ_0024028 knockdown on IL-22-induced HaCaT cell proliferation and migration. AKT3 was targeted by miR-486-3p, and its overexpression reversed the inhibitory effect of miR-486-3p on IL-22-induced HaCaT cell proliferation and migration. AKT3 expression was positively regulated by circ_0024028, and circ_0024028/miR-486-3p/AKT3 axis could regulate the activity of AKT/mTOR pathway. Additionally, exosomes mediated the transfer of circ_0024028 in cells. Circ_0024028 might be a potential target for psoriasis treatment, which knockdown repressed IL-22-induced keratinocytes proliferation and migration through miR-486-3p/AKT3 pathway.

Circular RNA circ_SKA3 enhances gastric cancer development by targeting miR-520h.

To explore the mechanisms of action of circ_SKA3 in gastric cancer (GC), which are still not fully understood. Subcellular localization assay was used to analyze the localization of circ_SKA3, and Actinomycin D assay was applied to confirm the stability of circ_SKA3. The levels of circ_SKA3, microRNA (miR)-520h, and cell division cycle 42 (CDC42) mRNA were gauged by quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of CDC42 and proliferating cell nuclear antigen (PCNA) were assessed by western blot. Cell proliferation, colony formation, cell cycle distribution, apoptosis, migration, and invasion were detected by 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT), 5-Ethynyl-2'-Deoxyuridine (EdU) incorporation, colony formation, flow cytometry, and transwell assays, respectively. Directed relationship between miR-520h and circ_SKA3 or CDC42 was verified by a dual-luciferase reporter assay. Mouse xenograft experiments were used to elucidate the impact of circ_SKA3 in vivo. Overexpression of circ_SKA3 was validated in GC tissues and cells. The down-regulation of circ_SKA3 suppressed proliferation, cell cycle progression, colony formation, migration, invasion, and promoted cell apoptosis in vitro, as well as weakening tumor growth in vivo. Circ_SKA3 directly bound to miR-520h, and circ_SKA3 regulated CDC42 expression through miR-520h. Circ_SKA3 exerted regulatory effects on GC cell behaviors by inhibiting miR-520h. Furthermore, CDC42 was a functional target of miR-520h in regulating GC cell behaviors. Our findings established a strong molecular mechanism, the miR-520h/CDC42 axis, at least in part, for the oncogenic role of circ_SKA3 in GC.