Dual role of exosomal circCMTM3 derived from GSCs in impeding degradation and promoting phosphorylation of STAT5A to facilitate vasculogenic mimicry formation in glioblastoma.

in Theranostics by Chengbin Wang, Yingliang Liu, Zhenxing Zuo, Daming Cui, Yuzhen Xu, Li Li, Yang Jiang

TLDR

  • The study found that a type of RNA called circCMTM3 helps glioblastoma (GBM) cells change into a type of blood vessel called vasculogenic mimicry (VM) by disrupting the way that certain proteins are broken down in the cells. This change helps the GBM cells grow and spread more quickly. The study also found that circCMTM3 can activate certain proteins that help the GBM cells grow and spread even more quickly. The study suggests that targeting the way that GBM cells change into VM could be a new way to treat GBM.

Abstract

Glioblastoma (GBM) is characterized by abundant neovascularization as an essential hallmark. Vasculogenic mimicry (VM) is a predominant pattern of GBM neovascularization. However, the biological functions of circRNAs prompting VM formation in GBM remains unclarified.The circular RNA circCMTM3 was identified through high-throughput sequencing and bioinformatics analysis. The expression of circCMTM3 in exosomes in glioma tissues and cells was verified via RT-qPCR and FISH. In vitro and in vivo assays, such as EdU, MTS, Transwell, and tube formation assays were performed to investigate functional roles of circCMTM3. Meanwhile, in situ tumorigenesis assay were implemented to explore the influences of circCMTM3 on the GBM progression. Additionally, RNA pull-down, RIP, ChIP, and dual-luciferase reporter gene assays were executed to confirm the underlying regulation mechanism of circCMTM3.CircCMTM3, as a novel circular RNA, was packaged into exosomes derived from glioblastoma stem cells (GSCs), which facilitates the phenotypic transition of differentiated glioma cells (DGCs) to VM. Mechanistically, exosomal circCMTM3 is internalized by DGCs and disrupt the ubiquitination degradation of STAT5A and STAT5B by E3 ubiquitin ligase CNOT4. Additionally, through molecular scaffold function of circCMTM3, STAT5A is activated and triggers transcriptional regulation of target genes including the pro-vasculogenic factor CHI3L2 and the RNA-binding protein SRSF1. Subsequently, circCMTM3/STAT5A/SRSF1 positive feedback loop sustainably enhances VM formation and accelerates tumor progression in GBM.Exosomal circCMTM3 possessing growth factor-mimetic property activates the JAK2/STAT5A pathway via non-canonical manner, and promotes VM formation in GBM. The molecular communications between GSCs and DGCs offers a therapeutic strategy for targeting the neovascularization of GBM.

Overview

  • The study investigates the role of circular RNA circCMTM3 in promoting vasculogenic mimicry (VM) in glioblastoma (GBM).
  • The study identifies circCMTM3 through high-throughput sequencing and bioinformatics analysis and verifies its expression in glioma tissues and cells through RT-qPCR and FISH. In vitro and in vivo assays are performed to investigate the functional roles of circCMTM3, including EdU, MTS, Transwell, and tube formation assays, as well as an in situ tumorigenesis assay. RNA pull-down, RIP, ChIP, and dual-luciferase reporter gene assays are executed to confirm the underlying regulation mechanism of circCMTM3. The study finds that exosomal circCMTM3 facilitates the phenotypic transition of differentiated glioma cells (DGCs) to VM by disrupting the ubiquitination degradation of STAT5A and STAT5B by E3 ubiquitin ligase CNOT4 and activating transcriptional regulation of target genes including the pro-vasculogenic factor CHI3L2 and the RNA-binding protein SRSF1. The study also finds that exosomal circCMTM3 possesses growth factor-mimetic property and activates the JAK2/STAT5A pathway via non-canonical manner, promoting VM formation in GBM. The study concludes that targeting the neovascularization of GBM through molecular communications between GSCs and DGCs offers a therapeutic strategy.

Comparative Analysis & Findings

  • The study compares the outcomes observed under different experimental conditions or interventions, specifically the effects of exosomal circCMTM3 on the phenotypic transition of DGCs to VM and the activation of the JAK2/STAT5A pathway. The study identifies significant differences in the results between these conditions, specifically the ability of exosomal circCMTM3 to disrupt the ubiquitination degradation of STAT5A and STAT5B by E3 ubiquitin ligase CNOT4 and activate transcriptional regulation of target genes including the pro-vasculogenic factor CHI3L2 and the RNA-binding protein SRSF1. The study also finds that exosomal circCMTM3 possesses growth factor-mimetic property and activates the JAK2/STAT5A pathway via non-canonical manner, promoting VM formation in GBM. The key findings of the study suggest that targeting the neovascularization of GBM through molecular communications between GSCs and DGCs offers a therapeutic strategy.

Implications and Future Directions

  • The study's findings have significant implications for the field of research and clinical practice, as they provide insights into the biological functions of circRNAs in promoting VM formation in GBM. The study identifies a novel circular RNA, circCMTM3, that facilitates the phenotypic transition of DGCs to VM by disrupting the ubiquitination degradation of STAT5A and STAT5B by E3 ubiquitin ligase CNOT4 and activating transcriptional regulation of target genes including the pro-vasculogenic factor CHI3L2 and the RNA-binding protein SRSF1. The study also finds that exosomal circCMTM3 possesses growth factor-mimetic property and activates the JAK2/STAT5A pathway via non-canonical manner, promoting VM formation in GBM. The study suggests that targeting the neovascularization of GBM through molecular communications between GSCs and DGCs offers a therapeutic strategy. Future research directions could include further investigation of the role of circRNAs in GBM neovascularization, exploration of other molecular mechanisms underlying the phenotypic transition of DGCs to VM, and development of targeted therapies for GBM.
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