CircFOXO3 promotes glioblastoma progression by acting as a competing endogenous RNA for NFAT5
Shuai Zhang1, Keman Liao2, Zengli Miao1
1Department of Neurosurgery, the Affiliated Wuxi No. 2 People's Hospital of Nanjing Medical University, Wuxi, China.
Background:
Circular RNAs (circRNAs), a newly discovered type of endogenous noncoding RNA, have been proposed to mediate the progression of diverse types of tumors. Systematic studies of circRNAs have just begun, and the physiological roles of circRNAs remain largely unknown. Here, we focused on elucidating the potential role and molecular mechanism of circular forkhead box O3 (circFOXO3) in glioblastoma (GBM) progression.
Methods:
First, we analyzed circFOXO3 alterations in GBM and noncancerous tissues through real-time quantitative reverse transcription PCR (qRT-PCR). Next, we used loss- and gain-of-function approaches to evaluate the effect of circFOXO3 on GBM cell proliferation and invasion. Mechanistically, fluorescent in situ hybridization, RNA pull-down, dual luciferase reporter, and RNA immunoprecipitation assays were performed to confirm the interaction between circFOXO3 and miR-138-5p/miR-432-5p in GBM. An animal model was used to verify the in vitro experimental findings.
Results:
CircFOXO3 expression was significantly higher in GBM tissues than in noncancerous tissues. GBM cell proliferation and invasion were reduced by circFOXO3 knockdown and enhanced by circFOXO3 overexpression. Further biochemical analysis showed that circFOXO3 exerted its pro-tumorigenic activity by acting as a competing endogenous RNA (ceRNA) to increase expression of nuclear factor of activated T cells 5 (NFAT5) via sponging both miR-138-5p and miR-432-5p. Notably, tumor inhibition by circFOXO3 downregulation could be reversed by miR-138-5p/miR-432-5p inhibitors in GBM cells. Moreover, GBM cells with lower circFOXO3 expression developed less aggressive tumors in vivo.
Conclusions:
Our data demonstrate that circFOXO3 can exert regulatory functions in GBM and that ceRNA-mediated microRNA sequestration might be a potential strategy for GBM therapy.
Insights
Circular Forkhead Box O3 (circFOXO3) promotes glioblastoma growth by sponging microRNAs. Inhibiting circFOXO3 may offer a novel therapeutic strategy for glioblastoma, a type of brain tumor.
Area of Science:
- Oncology
- Molecular Biology
- RNA Biology
Background:
- Circular RNAs (circRNAs) are novel noncoding RNAs implicated in tumor progression.
- The specific roles and mechanisms of circRNAs, including circFOXO3, in glioblastoma (GBM) remain largely unexplored.
- This study investigates the function and molecular pathways of circFOXO3 in GBM.
Purpose of the Study:
- To elucidate the role of circular forkhead box O3 (circFOXO3) in glioblastoma (GBM) progression.
- To investigate the molecular mechanism by which circFOXO3 influences GBM.
- To assess the therapeutic potential of targeting circFOXO3 in GBM.
Main Methods:
- Quantitative reverse transcription PCR (qRT-PCR) to analyze circFOXO3 expression in GBM and noncancerous tissues.
- In vitro loss- and gain-of-function assays to assess the impact of circFOXO3 on GBM cell proliferation and invasion.
- Molecular assays including FISH, RNA pull-down, luciferase reporter, and RNA immunoprecipitation to confirm interactions between circFOXO3, miR-138-5p, miR-432-5p, and NFAT5.
- In vivo animal models to validate experimental findings.
Main Results:
- CircFOXO3 expression is significantly elevated in GBM tissues compared to noncancerous tissues.
- Knockdown of circFOXO3 inhibits GBM cell proliferation and invasion, while overexpression enhances these processes.
- CircFOXO3 acts as a competing endogenous RNA (ceRNA), sponging miR-138-5p and miR-432-5p to upregulate nuclear factor of activated T cells 5 (NFAT5) expression.
- Downregulation of circFOXO3 suppressed tumor growth in vivo, and this effect was reversible by inhibiting miR-138-5p/miR-432-5p.
Conclusions:
- CircFOXO3 plays a significant regulatory role in glioblastoma progression.
- The ceRNA mechanism involving circFOXO3, microRNAs, and NFAT5 is a key driver of GBM.
- Targeting circFOXO3 through ceRNA-mediated microRNA sequestration presents a promising therapeutic strategy for GBM.
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