The circular RNA circSPARC enhances the migration and proliferation of colorectal cancer by regulating the JAK/STAT pathway

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.

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

Cancer Cell International ◽

10.1186/s12935-021-01855-6 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Lanlan Xi ◽

Quanlin Liu ◽

Wei Zhang ◽

Linshan Luo ◽

Jingfeng Song ◽

...

Keyword(s):

Colorectal Cancer ◽

Tumor Growth ◽

Circular Rna ◽

Luciferase Reporter ◽

Circular Rnas ◽

Protein Levels ◽

Cell Progression ◽

Rna Immunoprecipitation ◽

Induced Apoptosis

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.

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Circular RNA circASPM Promotes the Progression of Glioblastoma by Acting as a Competing Endogenous RNA to Regulate miR-130b–3p/E2F1 Axis

10.21203/rs.3.rs-132678/v1 ◽

2020 ◽

Author(s):

Dianqi Hou ◽

Zhenlin Wang ◽

Haimeng Li ◽

Juan Liu ◽

Yaohua Liu ◽

...

Keyword(s):

Western Blotting ◽

Circular Rna ◽

Luciferase Reporter ◽

Circular Rnas ◽

Primary Malignancy ◽

Rna Immunoprecipitation ◽

Western Blotting Assay

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.

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The circular RNA circ-ERBIN promotes growth and metastasis of colorectal cancer by miR-125a-5p and miR-138-5p/4EBP-1 mediated cap-independent HIF-1α translation

Molecular Cancer ◽

10.1186/s12943-020-01272-9 ◽

2020 ◽

Vol 19 (1) ◽

Author(s):

Liang-Yan Chen ◽

Lian Wang ◽

Yue-Xiang Ren ◽

Zheng Pang ◽

Yao Liu ◽

...

Keyword(s):

Colorectal Cancer ◽

Protein Translation ◽

Circular Rna ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Luciferase Reporter ◽

Western Blots ◽

Eukaryotic Translation

Abstract Background Circular RNA (circRNAs) and hypoxia have been found to play the key roles in the pathogenesis and progression of cancer including colorectal cancer (CRC). However, the expressions and functions of the specific circRNAs in regulating hypoxia-involved CRC metastasis, and the circRNAs that are relevant to regulate HIF-1α levels in CRC remain elusive. Methods qRT-PCR 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 circ-ERBIN. Function-based experiments were performed using circ-ERBIN overexpression and knockdown cell lines in vitro and in vivo, including CCK8, colony formation, EdU assay, transwell, tumor growth and metastasis models. Mechanistically, luciferase reporter assay, western blots and immunohistochemical stainings were performed. Results Circ-Erbin was highly expressed in the CRC cells and Circ-Erbin overexpression facilitated the proliferation, migration and metastasis of CRC in vitro and in vivo. Notably, circ-Erbin overexpression significantly promoted angiogenesis by increasing the expression of hypoxia induced factor (HIF-1α) in CRC. Mechanistically, circ-Erbin accelerated a cap-independent protein translation of HIF-1α in CRC cells as the sponges of miR-125a-5p and miR-138-5p, which synergistically targeted eukaryotic translation initiation factor 4E binding protein 1(4EBP-1). Conclusions Our findings uncover a key mechanism for circ-Erbin mediated HIF-1α activation by miR-125a-5p-5p/miR-138-5p/4EBP-1 axis and circ-ERBIN is a potential target for CRC treatment.

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Exosome-Mediated Transfer of circ_0000338 Enhances 5-Fluorouracil Resistance in Colorectal Cancer through Regulating MicroRNA 217 (miR-217) and miR-485-3p

Molecular and Cellular Biology ◽

10.1128/mcb.00517-20 ◽

2021 ◽

Vol 41 (5) ◽

Author(s):

Kui Zhao ◽

Xiaohui Cheng ◽

Zhenyu Ye ◽

Yecheng Li ◽

Wei Peng ◽

...

Keyword(s):

Colorectal Cancer ◽

Circular Rna ◽

Cell Counting ◽

Luciferase Reporter ◽

Diagnostic Efficiency ◽

Transmission Electron ◽

Proliferation And Apoptosis ◽

Rna Immunoprecipitation

ABSTRACT Exosomes are microvesicles secreted by body cells for intercellular communication. The circular RNA circ_0000338 was found to be present in extracellular vesicles and improve the chemoresistance of colorectal cancer (CRC) cells. However, the role of exosomal circ_0000338 in 5-fluorouracil (5-FU) resistance in CRC is largely unknown. The levels of circ_0000338, microRNA 217 (miR-217), and miR-485-3p were detected using quantitative real-time PCR (qRT-PCR). The 50% inhibitory concentration (IC50) values of cells for 5-FU, cell proliferation, and apoptosis were evaluated using cell counting kit 8 (CCK-8), colony formation, flow cytometry, and Western blot assays. The interaction between miR-217 or miR-485-3p and circ_0000338 was confirmed by RNA immunoprecipitation (RIP), dual-luciferase reporter, and pulldown assays. Exosomes were isolated by ultracentrifugation and qualified by transmission electron microscopy (TEM), Nanosight tracking analysis (NTA), and Western blotting. Xenograft models were performed to analyze whether circ_0000338-loaded exosomes could increase resistance of CRC cells to 5-FU in vivo. The circ_0000338 level was elevated in 5-FU-resistant CRC tissues and cells, and circ_0000338 knockdown sensitized 5-FU-resistant CRC cells to 5-FU through enhancing apoptosis and decreasing proliferation in vitro. Mechanistically, circ_0000338 directly bound to miR-217 and miR-485-3p, and the inhibition of miR-217 or miR-485-3p reversed the effects of circ_0000338 knockdown on cell 5-FU resistance in CRC. Additionally, extracellular circ_0000338 could be incorporated into secreted exosomes and transmitted to 5-FU-sensitive cells. Treatment-sensitive cells with exosomes containing circ_0000338 reduced the 5-FU response in CRC both in vitro and in vivo. Besides that, the exosomal circ_0000338 concentration was higher in patients exhibiting resistance to 5-FU and showed good diagnostic efficiency in 5-FU-resistant CRC. The delivery of circ_0000338 via exosomes enhanced 5-FU resistance in CRC through negative regulation of miR-217 and miR-485-3p, indicating a promising diagnostic and therapeutic marker for 5-FU-based chemotherapy in CRC patients.

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Sevoflurane inhibits malignant progression of colorectal cancer via hsa_circ_0000231-mediated miR-622

Journal of Biological Research-Thessaloniki ◽

10.1186/s40709-021-00145-6 ◽

2021 ◽

Vol 28 (1) ◽

Author(s):

Jingpeng Wang ◽

Shuyuan Li ◽

Gaofeng Zhang ◽

Huihua Han

Keyword(s):

Colorectal Cancer ◽

Cell Proliferation ◽

Cell Apoptosis ◽

Volatile Anesthetic ◽

Tumor Formation ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Circular Rnas

Abstract Background Sevoflurane (Sev), a commonly used volatile anesthetic, has been reported to inhibit the process of colorectal cancer (CRC). Circular RNAs (circRNAs) are revealed to participate in the pathogenesis of CRC. This study aims to reveal the mechanism of hsa_circ_0000231 in Sev-mediated CRC progression. Methods The expression of hsa_circ_0000231 and microRNA-622 (miR-622) was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Protein level was determined by western blot analysis. Cell proliferation was investigated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), cell colony formation and DNA content quantitation assays. Cell apoptosis was detected by Annexin V-fluorescein isothiocyanate and propidium iodide double staining and caspase 3 activity assays. Cell migration and invasion were investigated by wound-healing and transwell invasion assays, respectively. The putative relationship between hsa_circ_0000231 and miR-622 was predicted by circular RNA Interactome online database, and identified by dual-luciferase reporter and RNA immunoprecipitation assays. The impacts of hsa_circ_0000231 on Sev-mediated tumor formation in vivo were presented by in vivo assay. Results Hsa_circ_0000231 expression was upregulated, while miR-622 was downregulated in CRC tissues and cells compared with control groups. Sev treatment decreased hsa_circ_0000231 expression, but increased miR-622 expression in CRC cells. Sev treatment suppressed cell proliferation, migration and invasion, and induced cell apoptosis. Hsa_circ_0000231 overexpression restored Sev-mediated CRC progression in vitro. Additionally, hsa_circ_0000231 acted as a sponge of miR-622, and miR-622 inhibitors reversed the impacts of hsa_circ_0000231 silencing on CRC process. Furthermore, Sev treatment inhibited tumor growth by regulating hsa_circ_0000231 in vivo. Conclusion Hsa_circ_0000231 attenuated Sev-aroused repression impacts on CRC development by sponging miR-622. This findings may provide an appropriate anesthetic protocol for CRC sufferers undergoing surgery.

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Circular RNA circFAT1(e2) Promotes Colorectal Cancer Tumorigenesis via the miR-30e-5p/ITGA6 Axis

Computational and Mathematical Methods in Medicine ◽

10.1155/2021/9980459 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Fei Pan ◽

Dongqing Zhang ◽

Na Li ◽

Mei Liu

Keyword(s):

Colorectal Cancer ◽

Circular Rna ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Circular Rnas ◽

Small Interfering Rnas ◽

Regulatory Relationship ◽

Downstream Target ◽

Normal Tissues

circRNAs (circular RNAs) are a family of noncoding RNAs and have diverse physiological and pathological functions. However, the functions and mechanisms of circRNAs in the development and progression of colorectal cancer (CRC) remain largely unknown. Here, we aimed to explore the functions and roles of circFAT1(e2) in CRC. qRT-PCR revealed that circFAT1(e2) in CRC tumor tissues was upregulated compared with that in adjacent normal tissues and was also upregulated in CRC cell lines. Small interfering RNAs (siRNAs) against circFAT1(e2) were used to decrease the expression of circFAT1(e2) in HCT116 and RKO cells in vitro. The roles of circFAT1(e2) in CRC cell metastasis and proliferation were then determined by transwell and CCK-8 assays. The results showed that circFAT1(e2) silencing markedly suppressed CRC growth. Moreover, we identified circFAT1(e2) as a promoter of CRC metastasis. Knockdown of circFAT1(e2) evidently reduced HCT116 and RKO cell migration and invasion. Furthermore, the regulatory relationship between circFAT1(e2) and its target miRNAs was verified by a luciferase reporter assay. We demonstrated that circFAT1(e2) could sponge miR-30e-5p, which regulated the expression level of integrin α6 (ITGA6), the downstream target gene of miR-30e-5p. Rescue assays demonstrated that knockdown of miR-30e-5p enhanced CRC proliferation and migration via ITGA6. Taken together, our results reveal the novel oncogenic roles of circFAT1(e2) in CRC through the miR-30e-5p/ITGA6 axis.

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Circ_0007031 enhances tumor progression and promotes 5-fluorouracil resistance in colorectal cancer through regulating miR-133b/ABCC5 axis

Cancer Biomarkers ◽

10.3233/cbm-200023 ◽

2020 ◽

Vol 29 (4) ◽

pp. 531-542

Author(s):

Xiaowen He ◽

Jun Ma ◽

Mingming Zhang ◽

Jianhua Cui ◽

Hao Yang

Keyword(s):

Colorectal Cancer ◽

Colony Formation ◽

Human Cancer ◽

Animal Experiments ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Circular Rnas ◽

Cell Progression ◽

Rna Immunoprecipitation

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.

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LncRNA LINC00342 contributes to the growth and metastasis of colorectal cancer via targeting miR-19a-3p/NPEPL1

10.21203/rs.3.rs-35112/v1 ◽

2020 ◽

Author(s):

Peng Shen ◽

Lili Qu ◽

Jingjing Wang ◽

Quchen Ding ◽

Chuanwen Zhou ◽

...

Keyword(s):

Colorectal Cancer ◽

Cell Proliferation ◽

Xenograft Model ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Protein Coding ◽

Mechanistic Investigation ◽

Rna Immunoprecipitation

Abstract Background Long intergenic non-protein coding RNA 342 (LINC00342) has been identified as a novel oncogene, however, the functional role of LINC00342 in colorectal cancer (CRC) remained unclear. Methods The expression of LINC00342 was detected by real-time PCR. Cell proliferation, migration and invasion and xenograft model were examined to analyze the biological functions of LINC00342 in vitro and in vivo. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to identify the target interactions between LINC00342, miR-19a-3p and aminopeptidase like 1 (NPEPL1). Results LINC00342 was highly expressed in CRC. Downregulation of LINC00342 inhibited cell proliferation and metastasis of CRC cells. Moreover, knocking down LINC00342 could weaken the tumor growth in vivo. Mechanistic investigation revealed that LINC00342 may sponge miR-19a-3p to regulate NPEPL1 expression. Further investigation indicated that the oncogenesis facilitated by LINC00342 was inhibited by NPEPL1 depletion.Conclusion LINC00342 promoted CRC progression by competitively binding miR-19a-3p with NPEPL1.

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hsa_circ_0000231 Promotes Colorectal Cancer Cell Growth Through Upregulation of CCND2 by IGF2BP3/miR-375 Dual Pathway

10.21203/rs.3.rs-47893/v1 ◽

2020 ◽

Author(s):

Wei Zhang ◽

Bo Wang ◽

Yang Yang ◽

Zhen Zhang ◽

Quan Wang ◽

...

Keyword(s):

Colorectal Cancer ◽

Cell Proliferation ◽

In Situ Hybridization ◽

Luciferase Reporter ◽

Circular Rnas ◽

Cancer Cell Growth ◽

Normal Tissues

Abstract Background circular RNAs (circRNAs) recently have been emerged as vital regulators for involvement of initiation and progression of diverse kinds of human cancers. This study aimed to investigate the role of circRNAs in colorectal cancer (CRC). Methods The expression profile of circRNAs in 5 pairs of CRC tissues and adjacent normal tissues were analyzed by Microarray. Quantitative real-time PCR and in situ hybridization and Base Scope Assay were used to determine the level and prognostic values of hsa_circ_0000231. Then, functional experiments in vitro and in vivo were performed to investigate the effects of hsa_circ_0000231 on cell proliferation. Mechanistically, fluorescent in situ hybridization, dual luciferase reporter assay, RNA pull-down and RNA immunoprecipitation experiments were performed to confirm the interaction between hsa_circ_0000231 and IGF2BP3 or has_miR-375. Results hsa_circ_0000231 was evidently up-regulated in CRC primary tissues, which was indicated to poor prognosis of CRC patients. The results demonstrated that hsa_circ_0000231 could promote CRC cell proliferation as well as tumorigenesis in vitro and in vivo. Mechanistic analysis showed that hsa_circ_0000231 might on the one hand act as a ceRNA (competing endogenous RNA) of miR-375 to regulate cyclin D2 (CCND2), and on the other hand bind to IGF2BP3 protein to protect CCND2 from being degraded. Conclusion Our findings suggest that hsa_circ_0000231 facilitated CRC progression by sponging miR-375 or binding to IGF2BP3 to modulate CCND2. This discovery implied that has_circ_0000231 may be a potential new diagnostic and therapeutic biomarker for CRC.

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Circular RNA MCTP2 inhibits cisplatin resistance in gastric cancer by miR-99a-5p-mediated induction of MTMR3 expression

Journal of Experimental & Clinical Cancer Research ◽

10.1186/s13046-020-01758-w ◽

2020 ◽

Vol 39 (1) ◽

Author(s):

Guangli Sun ◽

Zheng Li ◽

Zhongyuan He ◽

Weizhi Wang ◽

Sen Wang ◽

...

Keyword(s):

Gastric Cancer ◽

Xenograft Model ◽

Circular Rna ◽

Luciferase Reporter ◽

Circular Rnas ◽

Mouse Xenograft Model ◽

Mirna Sponges ◽

High Level

Abstract Background Cisplatin (CDDP) is the first-line chemotherapy for gastric cancer (GC). The poor prognosis of GC patients is partially due to the development of CDDP resistance. Circular RNAs (circRNAs) are a subclass of noncoding RNAs that function as microRNA (miRNA) sponges. The role of circRNAs in CDDP resistance in GC has not been evaluated. Methods RNA sequencing was used to identify the differentially expressed circRNAs between CDDP-resistant and CDDP-sensitive GC cells. qRT-PCR was used to detect the expression of circMCTP2 in GC tissues. The effects of circMCTP2 on CDDP resistance were investigated in vitro and in vivo. Pull-down assays and luciferase reporter assays were performed to confirm the interactions among circMCTP2, miR-99a-5p, and myotubularin-related protein 3 (MTMR3). The protein expression levels of MTMR3 were detected by western blotting. Autophagy was evaluated by confocal microscopy and transmission electron microscopy (TEM). Results CircMCTP2 was downregulated in CDDP-resistant GC cells and tissues compared to CDDP-sensitive GC cells and tissues. A high level of circMCTP2 was found to be a favorable factor for the prognosis of patients with GC. CircMCTP2 inhibited proliferation while promoting apoptosis of CDDP-resistant GC cells in response to CDDP treatment. CircMCTP2 was also found to reduce autophagy in CDDP-resistant GC cells. MiR-99a-5p was verified to be sponged by circMCTP2. Inhibition of miR-99a-5p could sensitize GC cells to CDDP. MTMR3 was confirmed to be a direct target of miR-99a-5p. Knockdown of MTMR3 reversed the effects of circMCTP2 on the proliferation, apoptosis and autophagy of CDDP-resistant GC cells. CircMCTP2 was also confirmed to inhibit CDDP resistance in vivo in a nude mouse xenograft model. Conclusions CircMCTP2 sensitizes GC to CDDP through the upregulation of MTMR3 by sponging miR-99a-5p. Overexpression of CircMCTP2 could be a new therapeutic strategy for counteracting CDDP resistance in GC.

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