BACKGROUND: Increasing evidence had proved that some circular RNA (circRNA) exerted critical roles in tumors progression by functioning as \"microRNAs (miRNAs) sponges\" to regulate their targeted genes.
METHODS: circFAM114A2 and miR-647 expression was measured in CRC tissues and cells by quantitative real-time polymerase chain reaction (qRT-PCR), and the prognostic value of circFAM114A2 evaluated by Kaplan-Meier survival curve. Subsequently, wounding healing and transwell assays were performed to assess cell proliferation, migration, and invasion. RNA pull-down and dual-luciferase reporter assays were used to confirm the interactions between circFAM114A2, miR-647, and DAB2IP.
RESULTS: CircFAM114A2 was notably downregulated in CRC tissues and cells, and low circFAM114A2 expression indicated the poor prognosis of CRC patients. Next, overexpression of circFAM114A2 suppressed CRC cells proliferation, migration, and invasion in vitro and impede CRC tumor growth in vivo. Mechanically, circFAM114A2 competitively bound to miR-647 and upregulated its target gene DAB2IP expression in CRC cells.
CONCLUSIONS: Our results indicated that circFAM114A2/miR-647/DAP2IP axis played an important role in CRC progression, suggesting that circFAM114A2 might be a novel therapeutic target in patients with CRC.

BACKGROUND: Ovarian cancer (OC) is one of the most common gynecological malignant cancers. Our previous work confirmed that circNFIX acted as an oncogene in OC, which could promote malignant proliferation, metastasis and angiogenesis. However, the role and mechanism of circNFIX in OC immune escape remain unclear.
METHODS: The RNA and protein levels were determined by qRT-PCR and western blot assays. The malignant phenotypes were tested by cell count kit-8, EdU staining, flow cytometry and transwell assays. The immune cytokines levels were measured by ELISA analysis. Molecular interactions were verified employing RNA immunoprecipitation, meRIP and dual luciferase methods. In vivo validation was performed by xenograft tumor and lung metastasis model. Hematoxylin & eosin and immunohistochemistry staining were used to observe the pathological changes.
RESULTS: The levels of circNFIX, PD-L1, and IL-6R were upregulated in OC tissues and cell lines, while miR-647 was downregulated. Functional assays showed that loss of circNFIX suppressed the growth, metastasis and immune escape of OC cells both in vitro and in vivo. On the molecular level, the m6A modification of circNFIX was elevated in OC cells, and its expression was positively correlated to m6A modification and depended on IGF2BP1 ∼ 3 recognition. Moreover, circNFIX acted as a competing endogenous RNA for miR-647 to upregulate IL-6R expression, thereby activating JAK/STAT3 signaling and elevating PD-L1 expression. Rescue assays revealed that co-silencing of miR-647 reversed the antitumor effects of circNFIX knockdown on cell proliferation, metastasis and immune escape of OC cells.
CONCLUSIONS: This study provided a comprehensive understanding of the molecular mechanism about circNFIX in OC, demonstrating m6A activated-circNFIX accelerated OC development and immune escape via regulating miR-647/IL-6R/PD-L1 pathway.

MicroRNAs are a large group of small, non-coding ssRNAs (miRNAs) that have an epigenetically pivotal role in gene expression and other biological processes in cells and can be regarded as capable biomarkers for the early detection and management of cancer. The aim of the present review article is to summarize the evidence for recognizing the molecular mechanism, target genes, and clinical significance of miR-647 in different cancers. Multiple studies have demonstrated that aberrant expression of miR-647 could be found in a variety of malignancies, such as bladder cancer, cervical cancer, colorectal cancer, gastric cancer, glioma, hepatocellular carcinoma, non-small cell lung cancer, ovarian cancer, and prostate cancer have reported, notably, increase or decrease in expression of miR-647 so that it can function as a tumorigenic (oncomiR) or tumor suppressor gene. MiR-647 is effective in the proliferation, migration, and invasion of cancer cells by playing a function in cell cycle pathways. MiR-647 can be a valuable potential biomarker for assessing the extent of cancer, prognosis, and response to therapy and shows great therapeutic efficacy in different solid tumors. Moreover, serum concentrations of miR-647 are directly effective in decreasing overall survival and disease progression. So, an efficient therapeutic target can be the effect on miR-647 expression by antitumor drugs.

OBJECTIVE: Circular RNAs (circRNAs) are important regulators in breast cancer progression. However, the underlying mechanism of circRNAs functions in breast cancer remain largely unclear.
METHODS: To investigate the circRNAs expression pattern in breast cancer, high-throughput circRNA microarray assay was used. The top up-regulated circRNA, circZFAND6, was submitted to further experiments, including cell counting kit-8 (CCK-8) assay, colony formation assay, transwell assay and mouse xenograft assay. To investigate the underlying mechanism of circZFAND6 function in breast cancer progression, luciferase reporter assay and RNA immunoprecipitation (RIP) assay were conducted.
RESULTS: We found a novel circRNA, circZFAND6, was up-regulated in breast cancer tissues and cell lines. Inhibition of circZFAND6 reduced proliferation and metastasis of breast cancer. Mechanically, circZFAND6 acted as a competing endogenous RNA (ceRNA) to sponge miR-647 and increase fatty acid synthase (FASN) expression. And eukaryotic translation initiation factor 4A3 (EIF4A3) was found to bind to circZFAND6 pre-mRNA transcript upstream region, leading to the high expression of circZFAND6 in breast cancer. Inhibition of EIF4A3 also suppressed proliferation and metastasis of breast cancer.
CONCLUSIONS: EIF4A3-induced circZFAND6 up-regulation promoted proliferation and metastasis of breast cancer through the miR-647/FASN axis. Our results uncovered a possible mechanism underlying breast cancer progression and might provide a breast cancer treatment target.

UNASSIGNED: The current study aimed to investigate the effect of circ_0000799 on the biological function of colorectal cancer (CRC) cells and its mechanism.
UNASSIGNED: First, quantitative reverse transcription polymerase chain reaction (qRT-PCR) was employed for detecting the expression of circ_0000799, miR-647, and miR-1243 in surgically resected specimens from hospitalized CRC patients, CRC-adjacent normal tissues (Normal group), human normal colon epithelial cells (FHC group), and CRC cell lines (HCT116, HT29, SW480, SW620). The cell proliferation, viability, and invasion were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), colony formation assay, transwell assay in HCT116 and SW480 cells with overexpression or inhibition of circ_0000799. The targeting relationship between circ_0000799 and miR-647 was verified by dual-luciferase reporter assay. The expression of epithelial-mesenchymal transition (EMT) proteins (E-cadherin, vimentin, and N-cadherin) was tested by western blot.
UNASSIGNED: The expression level of circ_0000799 was significantly increased in CRC tissues and cells. Overexpression of circ_0000799 significantly increased cell proliferation rate, viability, invasion, and the EMT process, whereas knockdown of circ_0000799 inhibited the biological performance of CRC cells. Bioinformatic analysis suggested that miR-647 was regulated by circ_0000799, and a dual-luciferase reporter assay further showed a targeting relationship between the two. In addition, circ_0000799 was negatively correlated with miR-647 expression in CRC.
UNASSIGNED: Our findings suggest that circ_0000799 promotes proliferation and invasion in CRC and EMT. These effects of circ_0000799 may be achieved by negatively regulating miR-62.

OBJECTIVE: Vascular smooth muscle cells are key participants in atherosclerosis. Circular RNA hsa_circ_0000345 (circ_0000345) and miR-647 are related to oxygenized low-density lipoprotein (ox-LDL)-induced arterial smooth muscle cell (ASMC) dysregulation. However, the relationship between circ_0000345 and miR-647 in ox-LDL-induced ASMC dysregulation is unclear.
METHODS: Relative levels of circ_0000345, miR-647, and PAP-associated domain containing 5 (PAPD5) mRNA in AS patient\'s serum and ox-LDL-induced ASMCs were detected via RT-qPCR. Gain-of-function experiments were utilized to analyze the effects of circ_0000345 upregulation on ox-LDL-induced cell proliferation, migration, invasion, and inflammatory response in ASMCs. The relationship between circ_0000345 or PAPD5 and miR-647 was validated by dual-luciferase reporter and RNA immunoprecipitation assays.
RESULTS: Circ_0000345 and PAPD5 were lowly expressed in AS patient\'s serum and ox-LDL-induced ASMCs, while miR-647 expression had an opposing trend. Mechanistically, circ_0000345 was verified as a miR-647 sponge, and miR-647 overexpression impaired the inhibitory effects of circ_0000345 upregulation on ox-LDL-induced ASMC proliferation, migration, invasion, and inflammatory response. Further experiments demonstrated that PAPD5 was a miR-647 target, and circ_0000345 adsorbed miR-647 to mediate PAPD5 expression. Also, PAPD5 inhibition relieved miR-647 silencing-mediated suppression on ox-LDL-induced ASMC proliferation, migration, invasion, and inflammatory response.
CONCLUSIONS: Circ_0000345 elevated PAPD5 expression via acting as a miR-647 sponge, resulting in alleviating ox-LDL-induced ASMC dysregulation. The study highlighted the critical role of circ_0000345 in AS.

LncRNA-Atherosclerotic plaque pathogenesis-associated transcript (APPAT) could be detected in circulating blood and has been demonstrated to correlate with the development of atherosclerosis in our previous work. It could be a potential noninvasive biomarker for earlier diagnoses of clinical cardiovascular disease. Moreover, the expression of miR-647 increased in ox-LDL-treated vascular smooth muscle cells and peripheral blood of patients with coronary heart disease. A negative correlation between APPAT and miR-647 was confirmed, and FGF5 was screened as molecular target of miR-647. However, it is largely unclear how APPAT, miR-647, and FGF5 interact and function in disease development. Here, we aim to explore the underlying molecular mechanism in this progression.
APPAT, miR-647, and FGF5 expression levels were detected by quantitative reverse transcription polymerase chain reaction; cell proliferation was detected by EdU incorporation assay; cell migration was detected by wound-healing assay; the molecular interaction of APPAT/FGF5 with miR-647 was verified by dual-luciferase reporter assay; the western blot was performed to determine the gene expression at protein levels; subcellular localizations of APPAT and miR-647 were observed by fluorescence in situ hybridization; cytosolic and nucleus fractionation assay was performed to further detect the distribution of miR-647.
APPAT and miR-647 have inverse effects on human aortic smooth muscle cells\' (HASMCs) proliferation and migration. APPAT negatively regulated the cell activity, whereas miR-647 did it in a positive way (p<0.05). Three pairs of molecular interplay were found: mutual negative regulation between APPAT and miR-647, APPAT downregulated FGF5, miR-647 regulation on FGF5 (p<0.05). Subcellular location assay confirmed the molecular interaction of APPAT and miR-647.
APPAT could suppress the migration and proliferation of ox-LDL-treated HASMCs via interacting with miR-647 and FGF5. We revealed a nontypical competing endogenous RNA mechanism of long noncoding RNA in the progression of atherosclerosis.

Hepatocellular carcinoma (HCC) is a kind of malignant tumor derived from hepatocytes and hepatobiliary cells, and its occurrence is prevalent worldwide. Although medical technology is developing rapidly, the therapeutic efficacy of HCC is still poor. Emerging evidence manifests that microRNAs (miRNAs) play a crucial role in various cancers and have been regarded as cancer suppressor gene. However, the regulatory mechanisms mediated by miR-647 involved in HCC remain unclear. Hence, to clarify the regulatory mechanisms mediated by miR-647 in HCC, we studied the independent effects of miR-647 and explored protein tyrosine phosphatase receptor type F (PTPRF) in the constructed HCC cell line (HCV-huh7.5). Thereafter, we used dual-luciferase gene reporting and Western blot to investigate the relationship between PTPRF and miR-647. Furthermore, we studied the mechanism of miR-647 on PTPRF in HCV-huh7.5. We found that miR-647 could not only promote the proliferation and invasion of HCV-huh7.5 cells but also facilitate cell migration, while PTPRF has the opposite effect. Besides, the results of cell function experiment implied that the overexpression of miR-647 or inhibition of PTPFRF remarkably influenced the Erk signaling pathway, which could regulate cell proliferation, migration, and invasion. In addition, the dual luciferase reporting identified PTPRF as a direct target of miR-647. We further demonstrated that miR-647 inhibitor or PTPRF knockdown administration boosted HCV-huh7.5 cell proliferation, migration, and invasion by targeting PTPRF.These findings provided clues for the mechanism of miR-647 in promoting the biology of HCV-huh7.5 cells by inhibiting the expression level of PTPRF.

UNASSIGNED: CircRNAs recently have shown critical roles in tumor biology. However, their roles in prostate cancer (PCa) remains largely unclear.
UNASSIGNED: CircRNA microarrays were performed in immortal prostate cell line RWPE1 and PCa cell lines as DU145, PC3, LNCaP, C4-2, and 22RV1. Combined with upregulated circRNAs in PCa tissues, circNOLC1 expression was validated in PCa cells and tissues via qRT-PCR and FISH. Sanger sequencing, actinomycin D, gDNA, and cDNA, RNase R assays were used to assess the circular characteristics of circNOLC1. CCK-8, colony formation, transwell migration assays, and mice xenograft models were conducted to evaluate the functions of PCa cells after circNOLC1 knockdown and overexpression. RNA pulldown, luciferase reporter assay, FISH (fluorescence in situ hybridization), and CHIP were utilized to illustrate the further mechanisms of circNOLC1.
UNASSIGNED: Our research indicated that circNOLC1 was overexpressed in PCa cells and tissues, and circNOLC1 was more stable than linear NOLC1 mRNA. CircNOLC1 promoted PCa cells proliferation and migration in vitro and vivo. Additionally, we found that circNOLC1 could upregulate PAQR4 expression by sponging miR-647, leading to the activation of PI3K/Akt pathway. Moreover, NF-kappaB was identified to bind to the NOLC1 promoter sites and upregulated both NOLC1 and circNOLC1 expression.
UNASSIGNED: CircNOLC1, elevated by transcription factor NF-kappaB, promotes PCa progression via a miR-647/PAQR4 axis, and circNOLC1 is a potential biomarker and target for PCa treatment.

Osteosarcoma (OS) is a serious bone malignancy commonly occurred in childhood and adolescence. Circular RNA (circRNA) is a novel endogenous RNA that may be considered as a new biomarker for diseases\' diagnosis or prognosis. This study explored the roles and mechanism of circ_0001649 in OS. The qRT-PCR was performed to test circ_0001649 expression in OS tissues and cells. Luciferase was used to confirm the binding of circ_0001649 with miR-338-5p, miR-647 and miR-942. OS cells were stably transfected with pEX-circ_0001649 or miRNAs mimic, CCK-8 kit, colony formation, apoptosis and western blot analysis were used to detect the roles of circ_0001649. Circ_0001649 was low-expressed in OS tissues and cell lines. Circ_0001649 overexpression suppressed U2OS and HOS cell viability and survival fraction, and induced apoptosis presented as the increasing levels of Apaf-1, cleaved-caspase-3 and cleaved-caspase-9. Further, circ_0001649 worked as a sponge to absorb miR-338-5p, miR-647 and miR-942 to suppress cell proliferation, induce apoptosis and inhibit STAT pathway. Circ_0001649 suppressed OS cell proliferation and STAT pathway and induced apoptosis through sponging miR-338-5p, miR-647 and miR-942.