scholarly journals Circular RNA circCSPP1 knockdown attenuates doxorubicin resistance and suppresses tumor progression of colorectal cancer via miR-944/FZD7 axis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Lanlan Xi ◽  
Quanlin Liu ◽  
Wei Zhang ◽  
Linshan Luo ◽  
Jingfeng Song ◽  
...  

Abstract Background Circular RNAs (circRNAs) have been reported to play vital roles in colorectal cancer (CRC). However, only a few circRNAs have been experimentally validated and functionally described. In this research, we aimed to reveal the functional mechanism of circCSPP1 in CRC. Methods 36 DOX sensitive and 36 resistant CRC cases participated in this study. The expression of circCSPP1, miR-944 and FZD7 were detected by quantitative real time polymerase chain reaction (qRT-PCR) and the protein levels of FZD7, MRP1, P-gp and LRP were detected by western blot. Cell proliferation, migration, invasion, and apoptosis were assessed by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay, transwell assay, or flow cytometry analysis, respectively. The interaction between miR-944 and circCSPP1 or frizzled-7 (FZD7) was predicted by Starbase 3.0 and verified by the dual luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull down assay. Xenograft tumor assay was performed to examine the effect of circCSPP1 on tumor growth in vivo. Results The expression of circCSPP1 and FZD7 was upregulated while miR-944 expression was downregulated in doxorubicin (DOX)-resistant CRC tissues and cells. CircCSPP1 knockdown significantly downregulated enhanced doxorubicin sensitivity, suppressed proliferation, migration, invasion, and induced apoptosis in DOX-resistant CRC cells. Interestingly, we found that circCSPP1 directly downregulated miR-944 expression and miR-944 decreased FZD7 level through targeting to 3′ untranslated region (UTR) of FZD7. Furthermore, circCSPP1 mediated DOX-resistant CRC cell progression and doxorubicin sensitivity by regulating miR-944/FZD7 axis. Besides, circCSPP1 downregulation dramatically repressed CRC tumor growth in vivo. Conclusion Our data indicated that circCSPP1 knockdown inhibited DOX-resistant CRC cell growth and enhanced doxorubicin sensitivity by miR-944/FZD7 axis, providing a potential target for CRC therapy.

2020 ◽  
Vol 29 (4) ◽  
pp. 531-542
Author(s):  
Xiaowen He ◽  
Jun Ma ◽  
Mingming Zhang ◽  
Jianhua Cui ◽  
Hao Yang

Colorectal cancer (CRC) remains one of the most commonly diagnosed malignancies worldwide. Circular RNAs (circRNAs) are being found to play crucial roles in human cancer, including CRC. The purpose of this study was to explore the function and mechanism of circ_0007031 on CRC progression and 5-fluorouracil (5-FU) resistance. The levels of circ_0007031, ATP-binding cassette subfamily C member 5 (ABCC5) and miR-133b were assessed by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. Cell survival and proliferation were detected by the 3-(4,5-dimethylthiazol-2yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Cell colony formation was evaluated using a standard colony formation assay. Transwell assays were performed to determine cell migration and invasion. Targeted correlations among circ_0007031, miR-133b and ABCC5 were verified by dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pulldown assays. Animal experiments were performed to observe the role of circ_0007031 in vivo. Our data indicated that circ_0007031 up-regulation was associated with CRC resistance to 5-FU. Circ_0007031 knockdown repressed CRC cell proliferation, migration and invasion and enhanced 5-FU sensitivity. Circ_0007031 directly interacted with miR-133b. Moreover, circ_0007031 knockdown regulated CRC cell progression and 5-FU sensitivity by miR-133b. ABCC5 was a direct target of miR-133b, and circ_0007031 mediated ABCC5 expression via acting as a miR-133b sponge. Furthermore, miR-133b overexpression regulated CRC cell progression and sensitivity to 5-FU by down-regulating ABCC5. Additionally, circ_0007031 knockdown suppressed tumor growth in vivo. Our current work had led to the identification of circ_0007031 knockdown that repressed CRC cell malignant progression and enhanced 5-FU sensitivity via regulating ABCC5 expression by sponging miR-133b.


2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Jiaqi Wang ◽  
Yi Zhang ◽  
Hu Song ◽  
Hang Yin ◽  
Tao Jiang ◽  
...  

Abstract Background Noncoding RNAs such as circular RNAs (circRNAs) are abundant in the human body and influence the occurrence and development of various diseases. However, the biological functions of circRNAs in colorectal cancer (CRC) are largely unknown. Methods RT-qPCR was used to detect the expression of circRNAs and mRNA in CRC cells and tissues. Fluorescence in situ hybridization (FISH) was used to analyze the location of circSPARC. Function-based experiments were performed using circSPARC knockdown and overexpression cell lines in vitro and in vivo, including CCK8, colony formation, transwell and metastasis models. Mechanistically, luciferase reporter assay, western blots, RNA immunoprecipitation (RIP), Chromatin isolation by RNA purification (ChIRP) and immunohistochemical stainings were performed. Results CircSPARC was upregulated in both the tissues and plasma of CRC patients. High expression of circSPARC was associated with advanced TNM stage, lymph node metastases, and poor survival. Silencing circSPARC inhibited CRC cell migration and proliferation in vitro and vivo. Mechanistically, circSPARC sponged miR-485-3p to upregulate JAK2 expression and ultimately contribute to the accumulation of phosphorylated (p)-STAT3. Besides, circSPARC recruited FUS, which facilitated the nuclear translocation of p-STAT3. Conclusions These findings suggest that circSPARC might serve as a potential diagnostic and prognostic biomarker and a therapeutic target for CRC treatment by regulating JAK2/STAT3 pathway.


2021 ◽  
Vol 28 (1) ◽  
Author(s):  
Yan Zhang ◽  
Sheng Zheng ◽  
Nansheng Liao ◽  
Huifeng Huang ◽  
Wenxiao Chen ◽  
...  

Abstract Background Circular RNAs (circRNA) have been shown to be involved in the pathogenesis of colorectal cancer (CRC). CircCTNNA1 was found to be one of the upregulated circRNAs in CRC. However, there are few studies on circCTNNA1, so it is necessary to carry out further studies. Methods The expression of circCTNNA1, microRNA (miR)-363-3p, and chemokine C-X-C motif ligand 5 (CXCL5) was detected by quantitative real-time PCR (qRT-PCR). The protein levels of CXCL5 and metastasis markers were measured using western blot (WB) analysis. Cell proliferation, apoptosis, cell cycle, migration, and invasion were determined by cell counting kit 8 (CCK8) assay, colony formation assay, flow cytometry, and transwell assay. The relationship between miR-363-3p and circCTNNA1 or CXCL5 was evaluated via dual-luciferase reporter assay and RNA immunoprecipitation assay. Animal study was performed to explore the function of circCTNNA1 on CRC tumorigenesis. Results CircCTNNA1 and CXCL5 were highly expressed in CRC. Knockdown of circCTNNA1 could inhibit the proliferation, cell cycle, metastasis, and promote the apoptosis of CRC cells. MiR-363-3p could be sponged by circCTNNA1, and the inhibition effect of circCTNNA1 silencing on CRC progression could be reversed by miR-363-3p inhibitor. Moreover, miR-363-3p could interact with CXCL5, and CXCL5 overexpression also could reverse the suppressive effect of miR-363-3p on CRC progression. Downregulation of circCTNNA1 also could hinder the tumor growth of CRC in vivo. Conclusion CircCTNNA1 enhanced CRC progression via regulating the miR-363-3p/CXCL5 axis.


2020 ◽  
Author(s):  
Gaowu Hu ◽  
Wei Peng ◽  
Yongqing Cao

Abstract Background: Currently, more and more circular RNAs (circRNAs) have been identified to exert their functions in tumor progression, including colorectal cancer (CRC). However, the role of circSEC24A (circ_0003528) in CRC remains unknown.Methods: Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to determine the levels of circSEC24A, SEC24A and microRNA-488-3p (miR-488-3p). The characterization of circSEC24A was investigated by Actinomycin D and RNase R digestion assays. 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay was used to assess cell proliferation. Flow cytometry analysis was adopted for cell apoptosis and cell cycle process. Transwell assay was employed to evaluate cell migration and invasion. Western blot assay was performed to determine protein levels. Dual-luciferase reporter assay was utilized to explore the relationship between miR-488-3p and circSEC24A or transmembrane protein 106B (TMEM106B). Murine xenograft model was constructed to explore the effect of circSEC24A in vivo .Results: CircSEC24A level was increased in CRC tissues and cells. CircSEC24A deficiency impeded cell proliferation, cell cycle process, migration and invasion and induced apoptosis in CRC cells in vitro and blocked tumorigenesis in vivo . MiR-488-3p was a target of circSEC24A and miR-488-3p was downregulated in CRC tissues and cells. The inhibitory effect of circSEC24A silencing on CRC cell progression was restored by miR-488-3p inhibition. Moreover, TMEM106B could be negatively regulated by miR-488-3p via acting as a downstream gene of miR-488-3p. MiR-488-3p overexpression decelerated CRC cell progression by targeting TMEM106B.Conclusion: CircSEC24A facilitated CRC progression by regulating miR-488-3p/TMEM106B axis, which might provide a promising treatment approach for CRC.


2021 ◽  
Author(s):  
Penghui Xu ◽  
Xing Zhang ◽  
Jiacheng Cao ◽  
Jing Yang ◽  
Zetian Chen ◽  
...  

Abstract Background: Gastric cancer (GC) ranks third in motality among all cancers worldwide. Circular RNAs (circRNAs) play essential roles in the malignant progression and metastasis of gastric cancer. As a transcription factor, FOXP2 is involved in the progression of many tumours. However, the regulation and association between circRNAs and FOXP2 remain to be discovered. Methods: RNA sequencing was used to explore differential circRNA expression profile in gastric cancer and quantitative real-time PCR (qRT-PCR) were used to detect circST3GAL6 expression. The cellular location of circST3GAL6 was determined by fluorescence in situ hybridization (FISH). Functional experiments in circST3GAL6 knockdown and overexpression cell lines were performed in vitro and in vivo. The correlation between circST3GAL6 and miR-300 was confirmed by the RNA pull-down assay, dual-luciferase reporter assay and fluorescence in situ hybridization (FISH). The effects of circST3GAL6 on autophagy were detected by confocal microscopy and transmission electron microscopy (TEM). The mechanism of the circST3GAL6/miR-300/FOXP2 axis was verified by western blotting. The transcriptional regulation of Met by FOXP2 was proven by ChIP and luciferase reporter assays.Results: CircST3GAL6 was significantly depressed in GC tissues and cells. circST3GAL6 overexpression inhibited the proliferation, invasion and metastasis of GC cells in vitro and in vivo. Importantly, circST3GAL6 overexpression induced apoptosis and promote autophagy in GC cells. Furthermore, we found that circST3GAL6 sponged miR-300 and subsequently regulated FOXP2. We further revealed that FOXP2 suppressed the activation of the Met/AKT/mTOR axis, a classic pathway that regulates autophagy-mediated proliferation and migration.Conclusion: Our findings revealed that circST3GAL6 functions as a tumour suppressor through the miR-300/FOXP2 axis in GC, regulates apoptosis and autophagy through FOXP2-mediated transcriptional inhibition of the MET axis and may be a biomarker for GC treatment.


2020 ◽  
Author(s):  
Dianqi Hou ◽  
Zhenlin Wang ◽  
Haimeng Li ◽  
Juan Liu ◽  
Yaohua Liu ◽  
...  

Abstract background: Glioblastoma Multiform (GBM) is the primary malignancy with the highest incidence and worst prognosis in the adult CNS. Circular RNAs (circRNAs) are a novel and widely diverse class of endogenous non-coding RNAs that can promote or inhibit gliomagenesis. Our study aimed to explore the role of circASPM in GBM and its molecular mechanism.Methods: Levels of circASPM, miR-130b-3p and E2F1 were determined by quantitative real-time PCR (qRT-PCR) or western blotting assay. MTS, Edu, neurospheres formation and extreme limiting dilution assays were used to detect the tumorigenesis and proliferation of GSCs in vitro. The interactions between miR-130b-3p and circASPM or E2F1 was demonstrated via qPCR, western blotting, dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Xenograft experiments was used to analyze tumor growth in vivo.Results: CircASPM was overexpressed in GBM and could promote the tumorigenesis and proliferation of GSCs both in vitro and in vivo. Mechanistically, circASPM up-regulated the expression of E2F1 in GSCs via miR-130b-3p sponging. We furtherly demonstrated that circAPSM could promote the GSCs proliferation via E2F1 up-regulating. Therefore, our study identified a novel circRNA and its possible mechanism in the development and tumorigenesis of GBM.Conclusions: CircASPM can promote GBM progression via regulating miR-130b-3p/E2F1 axis, suggesting that circAPSM could provide an effective biomarker for GBM diagnosis and prognostic evaluation and possibly being used for molecular targeted therapy.


2020 ◽  
Author(s):  
Yanbo Wang ◽  
Fenghai Ren ◽  
Dawei Sun ◽  
Jing Liu ◽  
BenKun Liu ◽  
...  

Abstract BackgroundCircular RNAs (circRNAs) are widely expressed noncoding RNAs, and plays a key role in the biological function of competitive endogenous RNA (ceRNA) network in various human diseases, especially in cancer. However, the regulatory roles of circRNAs in lung adenocarcinoma (LUAD) remains largely unknown. MethodsThe expression profiles of circRNAs in LUAD tissues and adjacent non-tumor tissues were analyzed by Agilent Arraystar Human CircRNA microarray. The level and prognostic values of circKEAP1 in tissues and cancer cell lines were determined by quantitative real-time PCR. Then, the effects of circKEAP1 on tumor growth were investigated by functional experiments in vitro and in vivo. Mechanistically, dual luciferase reporter assay, RNA pull-down and RNA immunoprecipitation experiments were performed to confirm the interaction between circKEAP1 and miR-141-3p in LUAD.ResultsWe found circKEAP1 was significantly downregulated in LUAD tissues, and repressed tumor growth both in vitro and in vivo. Mechanistically, circKEAP1 competitively binds to miR-141-3p and relive miR-141-3p repression for its target gene KEAP1, which activated the KEAP1/NRF2 signal pathway, and finally suppress the cell proliferation.ConclusionsOur findings suggest that circKEAP1 inhibits LUAD progression through circKEAP1/miR-141-3p/KEAP1 axis and it may serve as a new target for treatment of LUAD patients.


2020 ◽  
Author(s):  
Wei-Zhong Sheng ◽  
Tian-Geng Dong ◽  
Bo Zhang ◽  
Yu-Da Gong ◽  
Wei-Dong Gao

Abstract Background: Circular RNA (circRNA) is a novel noncoding RNA (ncRNA) that assumes critical roles in tumor occurrence and progression. circRNA functions in many tumors as a kind of microRNA (mRNA) “sponge.” The present study sought to investigate the part played by circRNA in colorectal cancer (CRC) progression and to elucidate the relevant action mechanism(s). Methods: We detected lower hsa_circ_0077837 (circEPB41L2) expression in CRC by data analysis based on previous studies. We demonstrated the antitumor part of circEPB41L2 in CRC cells via a group of biological experiments. We subsequently took advantage of pull-down and dual-luciferase reporter assays to recognize circEPB41L2 downstream microRNA 21 (miR-21). Western blotting was conducted to confirm that the circEPB41L2–miR-21–phosphatase and tensin homolog (Pten)/AKT axis is responsible for CRC tumor growth suppression. The antitumor part of circEPB41L2 in vivo was eventually demonstrated by HCT116 xenograft model. Results: We found that circEPB41L2 overexpression inhibited the proliferation of CRC cells. Further, the miR-21 phenocopy suppressed circNRIP1 overexpression, while its overexpression also inhibited the cancer suppressive function of circEPB41L2. circEPB41L2 was confirmed to be able to inhibit tumor growth by enhancing Pten expression. Finally, the antitumor part of circEPB41L2 was confirmed. Conclusions: We demonstrated that circEPB41L2 sponges miR-21 to increase the Pten expression level and consequently serve as a cancer suppressor in CRC.


2021 ◽  
Vol 12 (1) ◽  
pp. 260-272
Author(s):  
Yun Shao ◽  
Zhengxiang Yang ◽  
Weifeng Miao ◽  
Xiangrong Yu ◽  
Yiping Wu ◽  
...  

Abstract Background Circular RNA (circRNA) plays an essential role in tumor progression, including glioma. circ_0030018 is a newly discovered circRNA that is highly expressed in glioma. However, its role and mechanism in glioma need to be further elucidated. Methods The expression of circ_0030018, microRNA (miR)-194-5p, and tripartite motif containing 44 (TRIM44) was examined using quantitative real-time PCR. Cell proliferation, migration, invasion, and apoptosis were determined using MTT assay, colony formation assay, transwell assay, and flow cytometry. Moreover, dual-luciferase reporter assay and RNA pull-down assay were used to verify the interactions among circ_0030018, miR-194-5p, and TRIM44. The protein expression of TRIM44 was assessed by western blot analysis. Animal experiments were conducted to explore the role of circ_0030018 in glioma tumor growth in vivo. Results circ_0030018 was overexpressed in glioma tissues and cells, and its silencing could inhibit glioma cell proliferation, migration, invasion, and accelerate apoptosis. miR-194-5p could be sponged by circ_0030018, and its overexpression could hinder the progression of glioma cells. Further experiments revealed that miR-194-5p inhibitor reversed the negative regulation of circ_0030018 knockdown on glioma cell progression. In addition, TRIM44 was a target of miR-194-5p, and its downregulation could repress glioma cell progression. Overexpressed TRIM44 reversed the inhibition effect of miR-194-5p on glioma cell progression. Animal experiments suggested that circ_0030018 knockdown could reduce glioma tumor growth through regulating miR-194-5p and TRIM44. Conclusion Our 8data showed that circ_0030018 enhanced glioma progression by sponging miR-194-5p to regulate TRIM44, indicating that circ_0030018 might be a potential treatment target for glioma.


Author(s):  
Yutian Wei ◽  
Chenfei Lu ◽  
Peng Zhou ◽  
Lin Zhao ◽  
Xiao Lyu ◽  
...  

Abstract Background Acquired chemoresistance is a major challenge in the clinical treatment of glioblastoma (GBM). Circular RNAs have been verified to play a role in tumor chemoresistance. However, the underlying mechanisms remain unclear. The aim of this study was to elucidate the potential role and molecular mechanism of circular (circ)RNA ADP-ribosylation factor GTPase activating proteins with Src homology 3 domain, ankyrin repeat and Pleckstrin homology domain 1 (circASAP1) in temozolomide (TMZ) resistance of GBM. Methods We analyzed circRNA alterations in recurrent GBM tissues relative to primary GBM through RNA sequencing. Real-time quantitative reverse transcription PCR verified the expression of circASAP1 in tissues and cells. Knockdown and overexpressed plasmids were used to evaluate the effect of circASAP1 on GBM cell proliferation and TMZ-induced apoptosis. Mechanistically, fluorescent in situ hybridization, dual-luciferase reporter, and RNA immunoprecipitation assays were performed to confirm the regulatory network of circASAP1/miR-502-5p/neuroblastoma Ras (NRAS). An intracranial tumor model was used to verify our findings in vivo. Results CircASAP1 expression was significantly upregulated in recurrent GBM tissues and TMZ-resistant cell lines. CircASAP1 overexpression enhanced GBM cell proliferation and TMZ resistance, which could be reduced by circASAP1 knockdown. Further experiments revealed that circASAP1 increased the expression of NRAS via sponging miR-502-5p. Moreover, circASAP1 depletion effectively restored the sensitivity of TMZ-resistant xenografts to TMZ treatment in vivo. Conclusions Our data demonstrate that circASAP1 exerts regulatory functions in GBM and that competing endogenous (ce)RNA-mediated microRNA sequestration might be a potential therapeutic strategy for GBM treatment.


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