Overexpression of NELFE contributes to gastric cancer progression via Wnt/β-catenin signaling-mediated activation of CSNK2B expression

Abstract Background Accumulating evidence has highlighted the importance of negative elongation factor complex member E (NELFE) in tumorigenesis. However, the relationship between NELFE and gastric cancer (GC) remains unclear. This study aimed to explore the expression pattern and specific function of NELFE in GC. Methods NELFE expression was evaluated by immunohistochemistry and qRT-PCR in GC tissues, respectively. Cell proliferation, migration and invasion were measured by CCK-8, colony formation, transwell assays, and nude mice model. Bioinformatics analysis was performed to search potential target genes of NELFE, and a Cignal Finder 10-Pathway Reporter Array was used to explore potential signaling pathways regulated by NELFE. Dual-luciferase reporter assays, qRT-PCR and western blotting were conducted to verify their regulatory relationship. The expression correlations among NELFE, β-catenin and CSNK2B were further explored by immunohistochemistry on consecutive resections. Results NELFE was significantly overexpressed in GC tissues both in protein and mRNA level and negatively correlated with the prognosis of GC patients. Gain- and loss-of-function experiments showed that NELFE potentiated GC cell proliferation and metastasis in vitro and in vivo. CSNK2B was identified as a downstream effector of NELFE. Wnt/β-catenin signaling may mediate the regulation of CSNK2B by NELFE. In addition, NELFE, β-catenin and CSNK2B were all remarkably upregulated in tumor tissues compared with adjacent normal tissues, and their expression levels in GC were positively correlated with each other. Conclusion Our findings reveal a new NELFE-Wnt/β-catenin-CSNK2B axis to promote GC progression and provide new candidate targets against this disease.

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LncRNA SNHG14 Promotes Progression of Ovarian Cancer by Regulating miR-206 Expression

Tobacco Regulatory Science ◽

10.18001/trs.7.5.1.174 ◽

2021 ◽

Vol 7 (5) ◽

pp. 3997-4004

Author(s):

Zhibo Zou ◽

Lin Peng

Keyword(s):

Ovarian Cancer ◽

Flow Cytometry ◽

Cell Proliferation ◽

Tumor Growth ◽

Cancer Progression ◽

Nude Mice ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Qrt Pcr ◽

Research Objects

Objective: This study aimed to probe into the effect of LncRNA SNHG14 on ovarian cancer progression by regulating miR-206.Methods: Fifty-seven ovarian cancer (OC) patients who were treated in our hospital from December 2017 to December 2019 were collected as the research objects. During the operation, OC tissues and paracancerous tissues of patients were collected, and the effect of SNHG14 on OC tumor growth in nude mice was detected, and SNHG14 inhibitor was transfected into OC cells. The relative expression of SNHG14 in tissues and cells was detected by qRT-PCR, cell proliferation was testedvia CCK8, migration and invasion were detected through Transwell, apoptosis was assessedvia flow cytometry, and the targeted relationship between SNHG14 and miR-206 was detected by dual luciferase reporter gene.Results: SNHG14 is highly expressed in OC tissues, cells and nude mice. Down-regulating it can inhibit the biological ability of OC cells and inhibit the growth of nude mice tumors. It can directly target miR-206 to regulate CCND1 expression and promote OC progression.Conclusion: LncRNA SNHG14 can act as miR-206 sponge to regulate CCND1 expression downstream of miR-206 and promote OC progression.

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Long noncoding RNA LBX2-AS1-modulated miR-4766-5p regulates gastric cancer development through targeting CXCL5

Cancer Cell International ◽

10.1186/s12935-020-01579-z ◽

2020 ◽

Vol 20 (1) ◽

Author(s):

LiPan Peng ◽

ZeZhong Chen ◽

GuangChuan Wang ◽

ShuBo Tian ◽

Shuai Kong ◽

...

Keyword(s):

Gastric Cancer ◽

Cell Proliferation ◽

Noncoding Rna ◽

Mrna Level ◽

Cell Counting ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Polymerase Chain ◽

Dual Luciferase Reporter Assay

Abstract Background Long noncoding RNAs (LncRNAs) have been reported to critically regulate gastric cancer (GC). Recently, it was reported that LBX2 antisense RNA 1 (LBX2-AS1) is abnormally expressed in GC. However, the role of LBX2-AS1 in the malignancy of GC is worth further discussion. Methods Quantitative real-time polymerase chain reaction (qRT-PCR) was used to determine the LBX2-AS1, miR-4766-5p and C-X-C motif chemokine (CXCL5) expression in GC tissues and cells. Dual-luciferase reporter assay was applied to examine the target relationship between LBX2-AS1 and miR-4766-5p or miR-4766-5p and CXCL5. Cell counting kit-8 (CCK-8) and Transwell assays were used to detect cell proliferation, migration and invasion rates. The protein expression of CXCL5 was confirmed using western blot. The RNA pull down experiment was used to verify the specificity of LBX2-AS1 and miR-4766-5p on BGC-823 and SGC-7901 cells. Results LBX2-AS1 was up-regulated in GC tissues and cells, and its knockdown suppressed proliferation, migration and invasion of GC cells. While, overexpression of LBX2-AS1 increased proliferation and increased CXCL5 mRNA level. CXCL5 improved cell proliferation, migration and invasion of GC cells. LBX2-AS1 could bind to miR-4766-5p to regulate CXCL5 expression. Overexpression of CXCL5 overturned those effects of miR-4766-5p in GC cells. RNA Pull down shown that BGC-823 and SGC-7901 cells, miR-4766-5p specifically binds to LBX2-AS1. Conclusions In short, this study demonstrated that LBX2-AS1 promoted proliferation, migration and invasion through up-regulation CXCL5 mediated by miR-4766-5p in GC. The LBX2-AS1/miR-4766-5p/CXCL5 regulatory axis provides a theoretical basis for the research on lncRNA-directed therapeutics in GC.

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The role of XBP-1-mediated unfolded protein response in colorectal cancer progression-a regulatory mechanism associated with lncRNA-miRNA-mRNA network

Cancer Cell International ◽

10.1186/s12935-021-02167-5 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Yong Wang ◽

Jingyu Zhang ◽

Shuang Zheng

Keyword(s):

Colorectal Cancer ◽

Cell Proliferation ◽

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Stress ◽

Cancer Progression ◽

Cell Apoptosis ◽

Regulatory Mechanism ◽

Luciferase Reporter ◽

Loss Of Function ◽

Mice Model

Abstract Background We aim to identify the expression and analyze the molecular action of dysregulated lncRNA-miRNA mediated by XBP-1 in colorectal cancer (CRC). Methods Here, we identified XBP-1-mediated dysregulated lncRNAs and miRNAs in CRC by bioinformatics analysis. The expression level of lncRNAs and miRNA was measured using quantitative real time PCR, and the expression of XBP-1, as well as apoptosis-related proteins, were detected by western blot. CCK-8 and TUNEL assays were performed to determine cell proliferation and apoptosis, respectively. Luciferase reporter assay was conducted to verify the binding relationship among lncRNA-miRNA-XBP-1. BALB/c nude mice were inoculated subcutaneously with HCT116 cells to establish tumor-bearing mice model. Histological analysis was carried out by HE staining and immunohistochemical staining. Results Six downregulated lncRNAs (SLFNL1-AS1, KCNQ1OT1, NEAT1, XIST, AC016876.2, AC026362.1), four dysregulated miRNAs (miR-500a-3p, miR-370-3p, miR-2467-3p, miR-512-3p) and upregulated XBP-1 were identified in CRC cell lines. Gain- and loss-of-function experiments showed that overexpression of KCNQ1OT1/XIST promoted cell proliferation and suppressed cell apoptosis. In addition, overexpression of KCNQ1OT1/XIST partly abolished the inhibitory effects of XBP-1u knockdown or tunicamycin, an activator of endoplasmic reticulum stress, on CRC cell viability loss and apoptosis. Furthermore, KCNQ1OT1/XIST aggravated tumor growth in vivo by regulating endoplasmic reticulum stress and cell apoptosis. Conclusions This study has constructed lncRNA-miRNA-mRNA networks based on XBP-1 in CRC, and disclosed the regulatory mechanism of action, providing a set of pivotal biomarkers for future molecular investigation and targeted treatment of CRC.

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Circ_0000144 functions as a miR-623 sponge to enhance gastric cancer progression via up-regulating GPRC5A

Bioscience Reports ◽

10.1042/bsr20201313 ◽

2020 ◽

Vol 40 (8) ◽

Author(s):

Lili Mi ◽

Lianhui Lei ◽

Xiaolei Yin ◽

Ning Li ◽

Jianfei Shi ◽

...

Keyword(s):

Gastric Cancer ◽

Cell Proliferation ◽

Tumor Growth ◽

Cancer Progression ◽

Colony Formation ◽

Human Cancer ◽

Luciferase Reporter ◽

Migration And Invasion ◽

The Impact

Abstract Background: Gastric cancer (GC) remains one of the most common malignancies worldwide. Increasing evidence has demonstrated that circRNAs serve as critical roles in human cancer, including GC. In the present study, we focused on the detailed function and mechanism of circ_0000144 on GC progression. Methods: The levels of circ_0000144, miR-623 and G-protein-coupled receptor, family C, group 5, member A (GPRC5A) were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Targeted relationships among circ_0000144, miR-623 and GPRC5A were confirmed using dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Cell proliferation, colony formation, apoptosis, migration and invasion were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), colony formation, flow cytometry and transwell assays. Measurement of glutamine and α-ketoglutarate (α-KG) levels was performed using a corresponding assay kit. GPRC5A protein expression was detected using Western blot. In vivo assays were used to explore the impact of circ_0000144 on tumor growth. Results: Our data indicated that circ_0000144 was up-regulated and miR-623 was down-regulated in GC tissues and cells. Circ_0000144 interacted with miR-623 through directly binding to miR-623. Moreover, the knockdown of circ_0000144 weakened GC cell proliferation, colony formation, migration, invasion and glutaminolysis and accelerated cell apoptosis by up-regulating miR-623. GPRC5A was a direct target of miR-623 and circ_0000144 protected against GPRC5A repression through sponging miR-623. Furthermore, miR-623-mediated regulation on GC cell progression was reversed by the stored expression of GPRC5A. Additionally, circ_0000144 depletion inhibited tumor growth in vivo. Conclusion: Our study indicated that circ-0000144 knockdown repressed GC progression at least partly by regulating GPRC5A expression via sponging miR-623, illumining a novel therapeutic target for GC treatment.

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Identification of a Key Competing Endogenous RNA Axis, “COL5A1/miR-137-3p/FSTL1”, Associated With Gastric Cancer Progression by Integrated Bioinformatics Analyses and Experimental Verification

10.21203/rs.3.rs-824329/v1 ◽

2021 ◽

Author(s):

Ming Yang ◽

Zhixing Lu ◽

Liang Li ◽

Min Ma ◽

Fei Long ◽

...

Keyword(s):

Gastric Cancer ◽

Cancer Progression ◽

Target Gene ◽

Target Genes ◽

Differentially Expressed ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Bioinformatics Analyses ◽

Immune Infiltration ◽

Differentially Expressed Mirnas

Abstract Background MicroRNAs (miRNAs) and their target genes have been shown to play an important role in gastric cancer (GC), but this role has not been fully clarified. Therefore, our goal was to find the key miRNA-mRNA regulatory network in GC by combining a variety of bioinformatics and experimental analyses. Methods Differentially expressed miRNAs (DEMs) and genes (DEGs) were screened from TCGA and GEO, respectively. Survival-related differentially expressed miRNAs (SRDEMs) were determined by Cox proportional hazards regression and lasso regression analyses. Differentially expressed target genes (DETGs) of SRDEMs were predicted by TargetScan and miRDB and overlapped with DEGs. We constructed a protein–protein interaction (PPI) network of DETGs and conducted weighted gene coexpression network analysis (WGCNA) to screen the hub genes. Then, qRT–PCR and western blotting were performed to detect the expression level, and a dual-luciferase reporter assay was conducted to verify the binding of miRNA and mRNAs. CCK-8, EdU, wound healing and Transwell assays were conducted to compare the proliferation, migration and invasion abilities of GC cells in the different groups. Results We identified 11 SRDEMs and 233 DETGs, from which we selected miR-137-3p and its target gene COL5A1 for further research because of their key roles in the results of the bioinformatics analyses. Then, we showed that miR-137-3p was significantly downregulated in GC and that overexpression of miR-137-3p suppressed the proliferation, invasion and migration of GC cells by targeting COL5A1. Furthermore, we found that COL5A1 could regulate the expression of FSTL1 and GC progression by sponging miR-137-3p. Finally, bioinformatics analyses showed that FSTL1 might promote GC progression by regulating the immune infiltration of GC. Conclusions miR-137-3p played a tumor-suppressive role in GC, and its target gene COL5A1 could competitively bind miR-137-3p to upregulate the expression of FSTL1, which affects immune infiltration.

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miR-491-3p is Downregulated in Retinoblastoma and Inhibit Tumor Cells Growth and Metastasis by Targeting SNN

Biochemical Genetics ◽

10.1007/s10528-020-10007-w ◽

2020 ◽

Author(s):

Yang Hu ◽

Ming Zhao ◽

Li Li ◽

Jie Ding ◽

Yu-Min Gui ◽

...

Keyword(s):

Cell Proliferation ◽

Cell Lines ◽

Target Genes ◽

Expression Profiles ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Mesenchymal Transition ◽

Qrt Pcr ◽

Gene Assay ◽

E Cadherin

Abstract Retinoblastoma (Rb) is the most common pediatric malignant tumor of the eyes. Previous studies demonstrated that miR-491-3p is downregulated in various cancers. However, its function in Rb remains unknown. A total of 15 pairs of primary Rb tissues and adjacent noncancerous tissues were collected. Quantitative real-time PCR (qRT-PCR) was used to investigate the expression profiles of miR-491-3p. qRT-PCR, western blotting and in situ immunocytochemistry were performed to investigate the expression profiles of epithelial–mesenchymal transition-related proteins (E-cadherin, Vimentin and N-cadherin) in Rb tissues and Rb cell lines as well as cell morphology. Cell proliferation was estimated by MTS and colony formation assays. Apoptosis was determined by FACS, cell migration and invasion were analyzed using transwell chambers. MiR-491-3p’s target genes were predicted using target gene prediction databases. The interplay between miR-491-3p and SNN was evaluated through dual luciferase reporter gene assay. MiR-491-3p was significantly downregulated in mixed collection of 15 pairs of Rb tissues and Rb cell lines. Overexpression of miR-491-3p enhanced apoptosis, and significantly suppressed proliferation, migration and invasion of Rb cells. In contrast, the present of miR-491-3p inhibitor showed reversed results which apoptosis decreased, while cell proliferation of ARPE-19 cells increased. In addition, miR-491-3p increased the expression of E-cadherin, and dramatically decreased the expression of Vimentin and N-cadherin in Rb tissues and Rb cell lines, noticeable changes in morphology, too, as cells became less cohesive and more adhering. We found out that SNN was the pairing target of miR-491-3p and result showed that miR-491-3p and SNN interacted with each other. We also found out that the effects of miR-491-3p were in Rb cells were almost entirely canceled out at the overexpression of SNN. Our findings collectively suggest that miR-491-3p is an important tumor suppressor in Rb, which inhibits tumor growth and metastasis in Rb. These implicate it may be explored as a new therapeutic target in Rb.

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miR-100-3p inhibits cell proliferation and induces apoptosis in human gastric cancer through targeting to BMPR2

Cancer Cell International ◽

10.1186/s12935-019-1060-2 ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 4

Author(s):

Chun-Wei Peng ◽

Ling-Xiao Yue ◽

Yuan-Qin Zhou ◽

Sai Tang ◽

Chen Kan ◽

...

Keyword(s):

Gastric Cancer ◽

Cell Proliferation ◽

Tumor Growth ◽

Cell Lines ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Human Gastric Cancer ◽

Over Expression ◽

Qrt Pcr

Abstract Background miR-100 has been reported to closely associate with gastric cancer (GC) initiation and progression. However, the underlying mechanism of miR-100-3p in GC is still largely unclear. In this study, we intend to study how miR-100-3p regulates GC malignancy. Methods The expression levels of miR-100-3p in vitro (GES-1 and GC cell lines) and in vivo (cancerous and normal gastric tissues) were examined by quantitative real-time PCR (qRT-PCR). MTT and PE/Annexin V analyses were responsible for measurement of the effects of miR-100-3p on GC cell proliferation and apoptosis. Transwell assay with or without matrigel was used to examine the capacity of migration and invasion in GC cells. The interaction of miR-100-3p with bone morphogenetic protein receptor 2 (BMPR2) was confirmed through transcriptomics analysis and luciferase reporter assay. qRT-PCR and Western blot analyses were applied to determine the expression of ERK/AKT and Bax/Bcl2/Caspase3, which were responsible for the dysfunction of miR-100-3p. Results miR-100-3p was down-regulated in GC cell lines and cancerous tissues, and was negatively correlated with BMPR2. Loss of miR-100-3p promoted tumor growth and BMPR2 expression. Consistently, the effects of miR-100-3p inhibition on GC cells were partially neutralized by knockdown of BMPR2. Over-expression of miR-100-3p simultaneously inhibited tumor growth and down-regulated BMPR2 expression. Consistently, over-expression of BMPR2 partially neutralized the effects of miR-100-3p over-expression. Further study demonstrated that BMPR2 mediated the effects downstream of miR-100-3p, which might indirectly regulate ERK/AKT and Bax/Bcl2/Caspase3 signaling pathways. Conclusion miR-100-3p acted as a tumor-suppressor miRNA that down-regulated BMPR2, which consequently inhibited the ERK/AKT signaling and activated Bax/Bcl2/Caspase3 signaling. This finding provided novel insights into GC and could contribute to identify a new diagnostic and therapeutic target.

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TEAD4 modulated LncRNA MNX1-AS1 contributes to gastric cancer progression partly through suppressing BTG2 and activating BCL2

Molecular Cancer ◽

10.1186/s12943-019-1104-1 ◽

2020 ◽

Vol 19 (1) ◽

Cited By ~ 12

Author(s):

You Shuai ◽

Zhonghua Ma ◽

Weitao Liu ◽

Tao Yu ◽

Changsheng Yan ◽

...

Keyword(s):

Gastric Cancer ◽

Cancer Progression ◽

Molecular Mechanisms ◽

Mechanistic Model ◽

Ectopic Expression ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Tissue Samples ◽

Reporter Assays

Abstract Background Gastric cancer (GC) is the third leading cause of cancer-related mortality globally. Long noncoding RNAs (lncRNAs) are dysregulated in obvious malignancies including GC and exploring the regulatory mechanisms underlying their expression is an attractive research area. However, these molecular mechanisms require further clarification, especially upstream mechanisms. Methods LncRNA MNX1-AS1 expression in GC tissue samples was investigated via microarray analysis and further determined in a cohort of GC tissues via quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays. Cell proliferation and flow cytometry assays were performed to confirm the roles of MNX1-AS1 in GC proliferation, cell cycle regulation, and apoptosis. The influence of MNX1-AS1 on GC cell migration and invasion was explored with Transwell assays. A xenograft tumour model was established to verify the effects of MNX1-AS1 on in vivo tumourigenesis. The TEAD4-involved upstream regulatory mechanism of MNX1-AS1 was explored through ChIP and luciferase reporter assays. The mechanistic model of MNX1-AS1 in regulating gene expression was further detected by subcellular fractionation, FISH, RIP, ChIP and luciferase reporter assays. Results It was found that MNX1-AS1 displayed obvious upregulation in GC tissue samples and cell lines, and ectopic expression of MNX1-AS1 predicted poor clinical outcomes for patients with GC. Overexpressed MNX1-AS1 expression promoted proliferation, migration and invasion of GC cells markedly, whereas decreased MNX1-AS1 expression elicited the opposite effects. Consistent with the in vitro results, MNX1-AS1 depletion effectively inhibited the growth of xenograft tumour in vivo. Mechanistically, TEAD4 directly bound the promoter region of MNX1-AS1 and stimulated the transcription of MNX1-AS1. Furthermore, MNX1-AS1 can sponge miR-6785-5p to upregulate the expression of BCL2 in GC cells. Meanwhile, MNX1-AS1 suppressed the transcription of BTG2 by recruiting polycomb repressive complex 2 to BTG2 promoter regions. Conclusions Our findings demonstrate that MNX1-AS1 may be able to serve as a prognostic indicator in GC patients and that TEAD4-activatd MNX1-AS1 can promote GC progression through EZH2/BTG2 and miR-6785-5p/BCL2 axes, implicating it as a novel and potent target for the treatment of GC.

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LINC01089 functions as a ceRNA for miR-152-3p to inhibit non‐small lung cancer progression through regulating PTEN

Cancer Cell International ◽

10.1186/s12935-021-01846-7 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Huixian Zhang ◽

Hao Zhang ◽

Xingya Li ◽

Siyuan Huang ◽

Qianqian Guo ◽

...

Keyword(s):

Lung Cancer ◽

Cancer Progression ◽

Expression Level ◽

Cell Counting ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Loss Of Function ◽

Protein Coding ◽

Tensin Homolog ◽

Pten Mrna

Abstract Background Long non-coding RNAs (lncRNAs) have been reported to exert crucial functions in regulating the progression of human cancers. However, the function and mechanism of long intergenic non-protein coding RNA 01089 (LINC01089) in non-small cell lung cancer (NSCLC) have not been revealed. Methods The expression level of LINC01089, microRNA (miRNA, miR)-152-3p and phosphatase and tensin homolog deleted onc hromosome ten (PTEN) mRNA was detected by quantitative real-time PCR (qRT-PCR). After gain-of-function and loss-of-function models were established with NSCLC cell lines, the proliferation, migration and invasion of NSCLC cells were detected by cell counting kit-8 (CCK-8) assay, scratch healing assay, Transwell assay, respectively. Dual luciferase reporter assay was employed to validate the binding relationship between miR-152-3p and LINC01089 or the 3’UTR of PTEN. Western blot was used to detect PTEN expression in NSCLC cells after LINC01089 and miR-152-3p were selectively modulated. Results LINC01089 was down-regulated in NSCLC tissues and cells. Functional experiments showed that knockdown of LINC01089 could promote the proliferation, migration and invasion of NSCLC cells, while over-expression of LINC01089 had the opposite effects. miR-152-3p was identified as a functional target for LIN01089, and miR-152-3p could reverse the function of LINC01089. Additionally, LINC01089 could up-regulate the expression level of PTEN via repressing miR-152-3p. Conclusions Down-regulation of LINC01089 promoted the progression of NSCLC through regulating miR-152-3p/PTEN axis.

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Circ_0003266 sponges miR-503-5p to suppress colorectal cancer progression via regulating PDCD4 expression

BMC Cancer ◽

10.1186/s12885-021-07997-0 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Caihong Wen ◽

Xiaoqing Feng ◽

Honggang Yuan ◽

Yong Gong ◽

Guangsheng Wang

Keyword(s):

Colorectal Cancer ◽

Cell Proliferation ◽

Cell Lines ◽

Cancer Progression ◽

Cell Counting ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Circular Rnas ◽

Pdcd4 Expression ◽

Novel Target

Abstract Background Circular RNAs (circRNAs) feature prominently in tumor progression. However, the biological function and molecular mechanism of circ_0003266 in colorectal cancer (CRC) require further investigation. Methods Circ_0003266 expression in 46 pairs CRC tissues / adjacent tissues, and CRC cell lines was detected by quantitative real-time polymerase chain reaction (qRT-PCR); after circ_0003266 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 circ_0003266, 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. Results Circ_0003266 was significantly lowly expressed in CRC tissues and cell lines. Circ_0003266 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 circ_0003266 promoted PDCD4 expression by competitively sponging miR-503-5p. Conclusion Circ_0003266 suppresses the CRC progression via sponging miR-503-5p and regulating PDCD4 expressions, which suggests that circ_0003266 may serve as a novel target for the treatment of CRC.

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