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Circular RNAs (circRNAs) have emerged as critical regulators in cancer progression. This study aimed to investigate the role of circ₀003266 in bladder cancer (BCa) and elucidate its underlying molecular mechanisms. The expression levels of circ₀003266, miR-503-5p, and SMAD7 in BCa tissues and cell lines were determined using bioinformatics analysis, clinical data, and quantitative real-time PCR (qPCR). Cellular phenotypes were evaluated through proliferation, migration, and apoptosis assays. RNA pull-down and luciferase reporter assays were conducted to validate the molecular interactions among circ₀003266, miR-503-5p, and SMAD7. The involvement of the TGF-β signaling pathway was assessed by Western blotting and co-immunoprecipitation (Co-IP) analysis. Circ₀003266 expression was significantly downregulated in BCa tissues and cell lines, and its low expression was clinically correlated with larger tumor size and advanced disease stage, including poor differentiation and higher TNM classification. Upregulation of circ₀003266 inhibited BCa cell proliferation and migration while promoting apoptosis. Mechanistic analyses revealed that miR-503-5p is a direct target of circ₀003266, and that circ₀003266-mediated regulation of miR-503-5p subsequently modulates SMAD7 expression. SMAD7, a well-established inhibitor of the TGF-β pathway, was shown to mediate the tumor-suppressive effects of circ₀003266. In vivo experiments confirmed that overexpression of circ₀003266 attenuated tumor growth and suppressed TGF-β signaling activity. Our findings demonstrate that circ₀003266 exerts tumor-suppressive functions in BCa by modulating the miR-503-5p/SMAD7/TGF-β axis, highlighting its potential as a novel therapeutic target for bladder cancer intervention.

Abstract Background Esophageal cancer (EC) is the ninth most common cancer globally. Circular RNAs (circRNAs), including hsa_(c)irc₀036722, are important in various cancers, but their specific role in EC remains unclear. Therefore, this study investigates the roles of hsa_(c)irc₀036722 in EC. Methods We analyzed circRNAs sequencing from Gene Expression Omnibus (GEO). On the other hand, analyzed miRNAs and mRNAs sequencing related to EC from The Cancer Genome Atlas (TCGA). Then, the hsa_(c)irc₀036722/hsa-mir-503-5p/PDCD4 axis was identified using online tools for detecting circRNA-associated miRNAs and target mRNAs. Gene expression levels in 20 EC tissue pairs were assessed using RT-qPCR, while PDCD4 protein expression was evaluated by Western blot. A receiver operating characteristic (ROC) analysis was performed to evaluate their diagnostic potential. Results RT-qPCR results demonstrated decreased expression of hsa_(c)irc₀036722 and PDCD4, alongside increased hsa-miR-503-5p expression in EC tissues. A reduction in PDCD4 protein expression was also noted. Correlations showed that hsa_(c)irc₀036722 and PDCD4 expressions were positively correlated, while hsa_(c)irc₀036722 and hsa-miR-503-5p were negatively correlated. In addition, a significant negative correlation was observed between hsa-miR-503-5p and PDCD4 expression. Elevated levels of hsa-miR-503-5p were detected in early stages of EC. The ROC curve reflected a significant area under the curve for the axis genes. Conclusion This study identified a novel regulatory axis, hsa_(c)irc₀036722/hsa-mir-503-5p/PDCD4, for regulating EC, which may be a potential target for treating patients with this cancer.

Background Metastasis is the main cause of mortality in cervical cancer (CC). Circular RNAs (circRNAs) have been demonstrated to play a crucial role in carcinoma biology. However, the expression and function of circRNAs in cervical cancer metastasis are still unclear. Methods In the present study, we identified a circRNA with an N6-methyladenosine (m6A) modification, circCCDC134, whose expression was increased in CC tissues by circRNA-Seq and qPCR. CircCCDC134 upregulation in CC was fine-tuned by ALKBH5-mediated m6A modification, which enhanced its stability in a YTHDF2-dependent manner. The functional experiments illustrated that circCCDC134 enhanced tumour proliferation and metastasis in vitro and in vivo. For the comprehensive identification of RNA-binding proteins, circRNA pull-down and mass spectrometry (ChIRP-MS), chromatin immunoprecipitation-seq (Chip-seq), RNA binding protein immunoprecipitation (RIP) and luciferase reporter assays were used to perform mechanistic investigations. Results The results revealed that circCCDC134 recruited p65 in the nucleus and acted as a miR-503-5p sponge to regulate the expression of MYB in the cytoplasm, ultimately stimulating HIF1A transcription and facilitating CC growth and metastasis. Conclusion: These findings indicate that circCCDC134 is an important therapeutic target and provide new regulatory model insights for exploring the carcinogenic mechanism of circCCDC134 in CC.

Ovarian cancer (OC) is a common female disease with a poor prognosis. But the possible mechanism of OC tumor progression remains an active area of research. This study is intended to explore the effect of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) on proliferation and apoptosis of OC and its mechanism. MALAT1 and miR-503-5p expressions in human OC cell lines and normal human ovarian epithelial (HOSE) cell line were measured using qRT-PCR. OC cell line SKOV3 is divided into 4 groups: pcDNA3.1 group, pcDNA3.1-MALAT1 group, si-NC group, and si-MALAT1 group. MTT assay and 5-ethynyl-2'-deoxyuridine (EdU) assay were applied for the detection of cell proliferation. Relationship of MALAT1 with miR-503-5p was verified using luciferase assay and RNA pull-down. The luciferase activity in cells was normalized to RNA concentrations determined by Bradford assays. MALAT1 expression in OC cells was elevated compared with HOSE cells. MTT assay and EdU assay supported that si-MALAT1 could inhibit cell proliferation in OC cells. Treatment of si-MALAT1 results in increased cell apoptosis rate in both SKOV3 cells and OVCAR3 cells. The expression of lncRNA-MALAT1 was negatively associated with the expression of miR-503-5p in OC cells, while luciferase assay and RNA pull-down together supported the direct binding of MALAT1 with miR-503-5p. Knockdown of MALAT1 was able to inhibit the activation of JAK2/STAT3 signal pathway, and MALAT1 overexpression was accompanied by activation of these factors. lncRNA-MALAT1 can negatively target miR-503-5p expression to further promote proliferation and depress apoptosis of OC cells through the JAK2-STAT3 pathway.

Circular RNAs (circRNAs) feature prominently in tumor progression. However, the biological function and molecular mechanism of circ₀003266 in colorectal cancer (CRC) require further investigation. Circ₀003266 expression in 46 pairs CRC tissues / adjacent tissues, and CRC cell lines was detected by quantitative real-time polymerase chain reaction (qRT-PCR); after circ₀003266 was overexpressed or knocked down in CRC cells, cell proliferation, apoptosis, migration, and invasion were evaluated by the cell counting kit-8 (CCK-8), flow cytometry, and Transwell assays, respectively; the interaction among circ₀003266, miR-503-5p, and programmed cell death 4 (PDCD4) was confirmed using bioinformatics analysis and dual-luciferase reporter assay; PDCD4 protein expression in CRC cells was quantified using Western blot. Circ₀003266 was significantly lowly expressed in CRC tissues and cell lines. Circ₀003266 overexpression markedly repressed CRC cell proliferation, migration, and invasion, and accelerated the cell apoptosis, but its overexpression promoted the malignant phenotypes of CRC cells. PDCD4 was a direct target of miR-503-5p and circ₀003266 promoted PDCD4 expression by competitively sponging miR-503-5p. Circ₀003266 suppresses the CRC progression via sponging miR-503-5p and regulating PDCD4 expressions, which suggests that circ₀003266 may serve as a novel target for the treatment of CRC.

Diabetic peripheral neuropathy (DPN) is a common complication of type 2 diabetes mellitus (T2DM) that causes peripheral and autonomic nervous system dysfunction. Dysregulation of miRNAs plays a crucial role in DPN development. However, the role of miR-503-5p in DPN remains unknown. Herein, T2DM mice (db/db) were used as a DPN model in vivo, and astrocytes isolated from db/db mice were induced with high glucose levels as a DPN model in vitro. MiR-503-5p expression was analyzed using qRT-PCR. GFAP, MCP-1, and SEPT9 protein levels were analyzed using western blotting and immunofluorescence. Luciferase assays were performed to investigate the interaction between miR-503-5p and SEPT9. We found that miR-503-5p expression decreased in the spinal cord of DPN model mice and astrocytes treated with high glucose (HG). The db/db mice displayed higher body weight and blood glucose, lower mechanical withdrawal threshold and thermal withdrawal latency, and higher GFAP and MCP-1 protein levels than db/m mice. However, tail vein injection of agomiR-503-5p remarkably reversed these parameters, whereas antigomiR-503-5p enhanced them. HG markedly facilitated GFAP and MCP-1 protein expression in astrocytes, whereas miR-503-5p mimic or inhibitor transfection markedly blocked or elevated GFAP and MCP-1 protein expression, respectively, in astrocytes with HG. SEPT9 was a target of miR-503-5p. In addition, SEPT9 protein levels were found to be elevated in db/db mice and astrocytes treated with HG. Treatment with agomiR-503-5p and miR-503-5p mimic was able to reduce SEPT9 protein levels, whereas treatment with antigomiR-503-5p and miR-503-5p inhibitor led to inhibition of the protein. Furthermore, SEPT9 overexpression suppressed the depressing effect of miR-503-5p overexpression in astrocytes subjected to HG doses. In conclusion, miR-503-5p was found to alleviate peripheral neuropathy-induced neuropathic pain in T2DM mice by regulating SEPT9 expression.

Background Ovarian cancer (OC) is a female malignant tumor with a high fatality rate. Long non-coding RNAs (lncRNAs) are deeply involved in OC progression. The aim of this study is to explore the specific mechanism of lncRNA prostate androgen-regulated transcript 1 (PART1) in OC. Methods Quantitative real time PCR was utilized to determine the expression levels of PART1, microRNA (miR)-503-5p and forkhead-box k1 (FOXK1) in OC tissues and/or cells. The cell viability, migration, and invasion in OC were evaluated by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-h-tetrazolium bromide assay, wound healing assay and transwell invasion assay, respectively. Flow cytometry was used to analyze the cell apoptosis. The xenograft tumor was conducted in nude mice to verify the effect of PART1 knockdown on OC in vivo. The target relationships among PART1, miR-503-5p and FOXK1 were predicted by StarBase, and verified by luciferase reporter assay. The level of FOXK1 was assessed by western blot. Results Increased expression of PART1 and FOXK1 was observed in OC tissues or cells, whereas miR-503-5p was downregulated. PART1 silencing or miR-503-5p overexpression repressed the cell viability, migration and invasion, and protomed apoptosis. Meanwhile, miR-503-5p was a target of PART1, and FOXK1 was a direct target gene of miR-503-5p. Both downregulation of miR-503-5p and upregulation of FOXK1 partly relieved the suppressive effects of PART1 knockdown on the oncogenicity of OC in vitro. Conclusion Decreased PART1 represses the cell viability, migration and invasion of OC via regulating the miR-503-5p/FOXK1 axis, which provided an underlying target for treating OC.

Ovarian cancer (OC) is a female malignant tumor with a high fatality rate. Long non-coding RNAs (lncRNAs) are deeply involved in OC progression. The aim of this study is to explore the specific mechanism of lncRNA prostate androgen-regulated transcript 1 (PART1) in OC. Quantitative real time PCR was utilized to determine the expression levels of PART1, microRNA (miR)-503-5p and forkhead-box k1 (FOXK1) in OC tissues and/or cells. The cell viability, migration, and invasion in OC were evaluated by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-h-tetrazolium bromide assay, wound healing assay and transwell invasion assay, respectively. Flow cytometry was used to analyze the cell apoptosis. The xenograft tumor was conducted in nude mice to verify the effect of PART1 knockdown on OC in vivo. The target relationships among PART1, miR-503-5p and FOXK1 were predicted by StarBase, and verified by luciferase reporter assay. The level of FOXK1 was assessed by western blot. Increased expression of PART1 and FOXK1 was observed in OC tissues or cells, whereas miR-503-5p was downregulated. PART1 silencing or miR-503-5p overexpression repressed the cell viability, migration and invasion, and protomed apoptosis. Meanwhile, miR-503-5p was a target of PART1, and FOXK1 was a direct target gene of miR-503-5p. Both downregulation of miR-503-5p and upregulation of FOXK1 partly relieved the suppressive effects of PART1 knockdown on the oncogenicity of OC in vitro. Decreased PART1 represses the cell viability, migration and invasion of OC via regulating the miR-503-5p/FOXK1 axis, which provided an underlying target for treating OC.

Diabetes mellitus is a major cause of blindness and chronic ulcers in the working‐age population worldwide. Wound healing is deeply dependent on neovascularization to restore blood flow. Former research has found that differentially expressed circular RNAs (circRNAs) are associated with hyperglycaemia‐induced endothelial cell damage, and hypoxia‐pretreated adipose‐derived stem cells (ADSCs)‐extracellular vesicle (HEV) transplants have a more therapeutic effect to enhance wound healing in diabetic mice by delivery circRNA. The current investigation employed high‐throughput sequencing to identify circRNAs that are abnormally expressed between EV and HEV. The regulatory mechanism and predicted targets of one differentially expressed circRNA, circ‐IGF1R, were investigated utilizing bioinformatics analyses, luciferase reporter assays, angiogenic differentiation assays, flow cytometric apoptosis analysis and RT‐qPCR. Circ‐IGF1R expression increased in HEV, and downregulation of circ‐IGF1R suppressed and reversed the promotion effect of HEV on angiogenesis in ulcerated tissue. Bioinformatics analyses and luciferase reporter assays confirmed that miR‐503‐5p was the downstream target of circ‐IGF1R, and inhibiting miR‐503‐5p restored the promotion effect of HEV on angiogenesis after circ‐IGF1R silence. The study also found that miR‐503‐5p can interact with 3'‐UTR of both HK2 and VEGFA. Overexpression of HK2 or VEGFA restored the promotion effect of HExo on angiogenesis after circ‐IGF1R silence. Overexpression miR‐503‐5p or silence HK2/VEGFA reversed the protective effect of circ‐IGF1R to MLMECs angiogenic differentiation. Overexpression of circ‐IGF1R increased the protective effect of HEV on the promotion of wound healing in mice with diabetes. Circ‐IGF1R promotes HIF‐1α expression through miR‐503‐5p sponging. Our data demonstrate that circ‐IGF1R overexpression EVs from ADSCs suppress high glucose‐induced endothelial cell damage by regulating miR‐503‐5p/HK2/VEGFA axis.

Postmenopausal osteoporosis (PMOP) is a prevalent metabolic disorder characterized by pathogenic mechanisms associated with the dysfunction of osteoclasts (OC) and osteoblasts (OB). Icaritin (ICT) is a flavonoid derived from icariin and epimedium, which is a natural product, and has demonstrated promising anti-osteoporosis properties. Nevertheless, the targets and mechanisms of ICT in osteoclast differentiation and PMOP remain unclear. we developed a bilateral ovariectomy-induced osteoporosis model in animals and receptor activator of nuclear factor kappa-B ligand (RANKL) induced RAW264.7 to differentiate into osteoclasts with or without MPP dihydrochloride (MPP) and antagomir-503-5p. Micro-CT, tartrate-resistant acid phosphatase (TRAP) staining, enzyme-linked immunosorbent assay (ELISA), Western blot and qRT-PCR were used to detect bone resorption function, bone metabolism parameters, osteoclast differentiation rate and the expression of related genes, as well as the expression of ESR1, miR-503 and RANK. Molecular docking, cell thermal shift assay (CETSA) and drug affinity responsive target stability (DARTs) experiments were used to confirmed that ESR1 is the direct target of ICT, and binding site of ICT with ESR1. ICT significantly inhibited OC differentiation and the expression of related genes ( , , and ), reduced bone loss, and improved osteoporosis and bone trabecular structure, and inhibited the levels of TRAP and RANKL in the serum and increase the level of osteoprotegerin (OPG). ICT significantly enhanced the expression of ESR1, ESR2 and miR-503, while inhibiting RANK expression, and ESR1 is the direct target of ICT, and Asparagine at 455 is the direct binding site of ICT with ESR1. Moreover, blocking ESR1 significantly reduced the regulatory effect of ICT on OC differentiation and related gens expression by MPP, especially the expression of miR-503 and RANK, as well as weakened the regulatory effect of ICT on inhibiting bone loss. Antagomir-503-5p significantly reduced the regulatory effect of ICT on OC differentiation, as well as the expression of genes related to OC differentiation. Taken together, our study confirmed that ESR1 is the direct target of ICT, and Asparagine at 455 is the direct binding site of ICT, and ICT inhibits OC differentiation and reduces bone loss by targeting ESR1 to upregulate miR503 level and weaken miR503/RANK pathway.