Ginsenoside Rg5 inhibits glioblastoma by activating ferroptosis via NR3C1/HSPB1/NCOA4.

BACKGROUND: The utilization of Chinese medicine as an adjunctive therapy for cancer has recently gained significant attention. Ferroptosis, a newly regulated cell death process depending on the ferrous ions, has been proved to be participated in glioma stem cells inactivation. PURPOSE: We aim to study whether ginsenoside Rg5 exerted inhibitory effects on crucial aspects of glioma stem cells, including cell viability, tumor initiation, invasion, self-renewal ability, neurosphere formation, and stemness. METHODS: Through comprehensive sequencing analysis, we identified a compelling association between ginsenoside Rg5 and the ferroptosis pathway, which was further validated through subsequent experiments demonstrating its ability to activate this pathway. RESULTS: To elucidate the precise molecular targets affected by ginsenoside Rg5 in gliomas, we conducted an intersection analysis between differentially expressed genes obtained from sequencing and a database-predicted list of transcription factors and potential targets of ginsenoside Rg5. This rigorous approach led us to unequivocally confirm NR3C1 (Nuclear Receptor Subfamily 3 Group C Member 1) as a direct target of ginsenoside Rg5, a finding consistently supported by subsequent experimental investigations. Moreover, we uncovered NR3C1's capacity to transcriptionally regulate ferroptosis -related genes HSPB1 and NCOA4. Strikingly, ginsenoside Rg5 induced notable alterations in the expression levels of both HSPB1 (Heat Shock Protein Family B Member 1) and NCOA4 (Nuclear Receptor Coactivator 4). Finally, our intracranial xenograft assays served to reaffirm the inhibitory effect of ginsenoside Rg5 on the malignant progression of glioblastoma. CONCLUSION: These collective findings strongly suggest that ginsenoside Rg5 hampers glioblastoma progression by activating ferroptosis through NR3C1, which subsequently modulates HSPB1 and NCOA4. Importantly, this novel therapeutic direction holds promise for advancing the treatment of glioblastoma.

CircGNB1 facilitates the malignant phenotype of GSCs by regulating miR-515-5p/miR-582-3p-XPR1 axis.

Glioma is the most common and aggressive primary malignant brain tumor. Circular RNAs (circRNAs) and RNA-binding proteins (RBPs) have been verified to mediate diverse biological behaviors in various human cancers. Therefore, the aim of this study was to explore a novel circRNA termed circGNB1 and elucidate relative molecular mechanism in functional phenotypes, which might be a potential prognostic biomarker and therapeutic approach for glioma. CircGNB1 was upregulated in glioma and closely associated with the low poor prognosis. Functional assays demonstrated that circGNB1 overexpression promoted glioma stem cells (GSCs) viability proliferation, invasion, and neurosphere formation. Mechanistically, circGNB1 upregulated the expression of oncogene XPR1 via sponging miR-515-5p and miR-582-3p. The following experiments proved XPR1 could promote the malignant phenotype of GSCs via upregulating IL6 expression and activating JAK2/STAT3 signaling. Moreover, the RNA binding protein IGF2BP3 could bind to and maintain the stability of circGNB1, thus promoting the effects of circGNB1 on GSCs. Our study reveals that circGNB1 plays a crucial role in promoting tumorigenesis and malignant progression in glioma, which provides a promising cancer biomarker.

The U2AF65/circNCAPG/RREB1 feedback loop promotes malignant phenotypes of glioma stem cells through activating the TGF-ß pathway.

Glioma is the most aggressive and common malignant neoplasms in human brain tumors. Numerous studies have showed that glioma stem cells (GSCs)drive the malignant progression of gliomas. Recent studies have revealed that circRNAs can maintain stemness and promote malignant progression of glioma stem cells. We used bioinformatics analysis to identify circRNAs and potential RNA-binding proteins (RBPs) in glioma. qRT-PCR, western blotting, RNA FISH, RNA pull-down, RNA immunoprecipitation assay, ChIP, immunohistochemistry, and immunofluorescence methods were used to quantified the expression of circNCAPG, U2AF65, RREB1 and TGF-ß1, and the underlying mechanisms between them. MTS, EDU, neurosphere formation, limiting dilution neurosphere formation and transwell assays examined the proliferation and invasive capability of GSCs, respectively. We identified a novel circRNA named circNCAPG was overexpressed and indicated the poor prognosis in glioma patients. Upregulating circNCAPG promoted the malignant progression of GSCs. RNA binding protein U2AF65 could stabilize circNCAPG by direct binding. Mechanically, circNCAPG interacted with and stabilized RREB1, as well as stimulated RREB1 nuclear translocation to activate TGF-ß1 signaling pathway. Furthermore, RREB1 transcriptionally upregulated U2AF65 expression to improve the stability of circNCAPG in GSCs, which established a feedback loop involving U2AF65, circNCAPG and RREB1. Since circRNA is more stable than mRNA and can execute its function continuously, targeting circNCAPG in glioma may be a novel promising therapeutic.

UPF1/circRPPH1/ATF3 feedback loop promotes the malignant phenotype and stemness of GSCs.

Glioblastoma multiforme (GBM) is the most lethal type of craniocerebral gliomas. Glioma stem cells (GSCs) are fundamental reasons for the malignancy and recurrence of GBM. Revealing the critical mechanism within GSCs' self-renewal ability is essential. Our study found a novel circular RNA (circRPPH1) that was up-regulated in GSCs and correlated with poor survival. The effect of circRPPH1 on the malignant phenotype and self-renewal of GSCs was detected in vitro and in vivo. Mechanistically, UPF1 can bind to circRPPH1 and maintain its stability. Therefore, more existing circRPPH1 can interact with transcription factor ATF3 to further transcribe UPF1 and Nestin expression. It formed a feedback loop to keep a stable stream for stemness biomarker Nestin to strengthen tumorigenesis of GSCs continually. Besides, ATF3 can activate the TGF-ß signaling to drive GSCs for tumorigenesis. Knocking down the expression of circRPPH1 significantly inhibited the proliferation and clonogenicity of GSCs both in vitro and in vivo. The overexpression of circRPPH1 enhanced the self-renewal of GSCs. Our findings suggest that UPF1/circRPPH1/ATF3 maintains the potential self-renewal of GSCs through interacting with RNA-binding protein and activating the TGF-ß signal pathway. Breaking the feedback loop against self-renewing GSCs may represent a novel therapeutic target in GBM treatment.