TRIM6 promotes glioma malignant progression by enhancing FOXO3A ubiquitination and degradation.

PURPOSE: TRIM6, an E3 ubiquitin ligase with tripartite motif, directly targets protein substrates for degradation through ubiquitination. Studies have shown that TRIM6 plays a significant role in tumor development in various human malignancies. Thus, the aim of this study was to investigate the importance of TRIM6 and its associated mechanism in promoting the progression of glioma. METHODS: The expression of TRIM6 and its prognostic value in glioma patients were collected from the TCGA and CGGA databases. The effects of TRIM6 on glioma were investigated in vitro by CCK8, colony formation, wound healing, and transwell assays. Co-IP and western blot analysis were used to detect the interaction between TRIM6 and FOXO3A. The effects of TRIM6 were verified in vivo in subcutaneously xenograft models, and tumor size, and immunohistochemical changes were observed. RESULTS: Our analysis of TRIM6 expression in glioma tissues revealed a high level of expression, and the heightened expression of TRIM6 showed a positive correlation with the unfavorable prognosis among glioma/GBM patients. Through loss-of-function and gain-of-function experiments, we observed a profound impact on the proliferation, invasion, and migration abilities of glioma cells both in vitro and in vivo upon deletion of TRIM6. Conversely, the overexpression of TRIM6 intensified the malignant characteristics of glioma. Additionally, our findings revealed a significant interaction between TRIM6 and FOXO3A, wherein TRIM6 contributed to the destabilization of FOXO3A protein by promoting its ubiquitination and subsequent degradation. Experiments conducted in the rescue study affirmed that the promotion of glioma cell proliferation, invasion, and migration is facilitated by TRIM6 through the suppression of FOXO3A protein levels. CONCLUSIONS: These observations imply that the TRIM6-FOXO3A axis could potentially serve as an innovative focus for intervening in glioma.

Association of hemorrhage-to-treatment time with outcomes in patients with brainstem cavernous malformations: a nationwide cohort study.

BACKGROUND: Brainstem cavernous malformations (BSCMs) often present with haemorrhage, but the optimal timing for microsurgical intervention remains unclear. This study aims to explore how intervention timing relates to neurological outcomes in haemorrhagic BSCM patients undergoing microsurgery, offering insights for clinical decisions. METHODS: A total of 293 consecutive patients diagnosed with BSCMs, who underwent microsurgery were identified between March 2011 and January 2023 at two comprehensive centres in China, with a postoperative follow-up duration exceeding 6 months. Utilizing logistic regression models with restricted cubic splines, distinct time groups were identified. Subsequently, matching weight analysis compared these groups in terms of outcomes, new haemorrhage rates, cranial nerve deficits, and perioperative complications. The primary outcome was an unfavourable outcome, which was defined as a mRS score greater than 2 at the latest follow-up. RESULTS: Among the 293 patients, 48.5% were female, median age was (39.9±14.3) years, and median haemorrhage-to-treatment time was 42 days. Patients were categorized into acute (≤21 days), subacute (22-42 days), and delay (>42 days) intervention groups. After matching, 186 patients were analyzed. Adjusted analysis showed lower unfavourable outcome rates for acute [adjusted odds ratio (OR), 0.73; 95% CI, 0.65-0.82; P<0.001] and subacute (adjusted OR, 0.83; 95% CI, 0.72-0.95; P=0.007) groups compared to the delay group. Subacute intervention led to fewer cranial nerve deficits (adjusted OR, 0.76; 95% CI, 0.66-0.88, P<0.001). New haemorrhage incidence didn't significantly differ among groups. CONCLUSIONS: For haemorrhagic BSCMs patients, delayed microsurgical intervention that exceeded 42 days after a prior haemorrhage were associated with an increased risk of unfavourable neurological outcomes.

Molecular genetic features and clinical manifestations in Chinese familial cerebral cavernous malformation: from a novel KRIT1/CCM1 mutation (c.1119dupT) to an overall view.

Cerebral cavernous malformations (CCMs) are common vascular anomaly diseases in the central nervous system associated with seizures, cerebral microbleeds, or asymptomatic mostly. CCMs can be classified as sporadic or familial, with familial cerebral cavernous malformations (fCCMs) being the autosomal dominant manner with incomplete penetrance. Germline mutations of KRIT1, CCM2, and PDCD10 are associated with the pathogenesis of fCCMs. Till now, little is known about the fCCMs mutation spectrum in the Han Chinese population. In this study, we enrolled a large, aggregated family, 11/26 of the family members were diagnosed with CCMs by pathological or neuroradiological examination, with a high percentage (5/9) of focal spinal cord involvement. Genomic DNA sequencing verified a novel duplication mutation (c.1119dupT, p.L374Sfs*9) in exon 9 of the Krev interaction trapped 1 (KRIT1) gene. The mutation causes a frameshift and is predicted to generate a truncated KRIT1/CCM1 protein of 381 amino acids. All our findings confirm that c.1119dupT mutation of KRIT1 is associated with fCCMs, which enriched the CCM genes' mutational spectrum in the Chinese population and will be beneficial for deep insight into the pathogenesis of Chinese fCCMs. Additionally, with a retrospective study, we analyzed the molecular genetic features of Chinese fCCMs, most of the Chinese fCCMs variants are in the KRIT1 gene, and all these variants result in the functional deletion or insufficiency of the C-terminal FERM domain of the KRIT1 protein.

Crosstalk between microglia and neural stem cells influences the relapse of glioblastoma in GBM immunological microenvironment.

Interactions between immunocytes and Neural Stem Cells (NSCs) in glioblastoma multiforme still remains unclear. Here, microglial cells and NSCs in peri-tumoral tissue were analyzed via single-cell whole-transcriptome sequencing. Results showed that two clusters of putative NSCs (the EGFR+BCAN+ cell cluster, and the FABPT+H19+ cell cluster) exhibited immune-related functions. Two clusters of putative microglia (the XIST+PDK4+ and APOC1+CCL3+ cell clusters) exhibited the function of glial cell activation. The results of ligand receptor network analysis disclosed significant interactions between the APOC1+CCL3+ microglia and the NSCs. Correlation analysis on the overall survival (OS) and relapse-free survival (RFS) with 102 potential molecular targets in the TCGA database showed that a much larger number of molecules were correlated with RFS than with OS (34.31% vs. 8.82%), nine of them were validated in clinical specimens. In conclusion, crosstalk between APOC1+CCL3+ microglia and multiple molecule-labeled NSCs distal to the tumor core play certain roles on the recurrence of GBM.

METTL3 knockdown promotes temozolomide sensitivity of glioma stem cells via decreasing MGMT and APNG mRNA stability.

Chemo-resistance hinders the therapeutic efficacy of temozolomide (TMZ) in treating glioblastoma multiforme (GBM). Recurrence of GBM even after combination of maximal tumor resection, concurrent radio-chemotherapy, and systemic TMZ applocation is inevitable and attributed to the high therapeutic resistance of glioma stem cells (GSCs), which can survive, evolve, and initiate tumor tissue remodeling, the underlying mechanisms of GSCs chemo-resistance, have not been fully elucidated up-to-now. Emerging evidence showed that METTL3-mediated N6-methyladenosine (m6A) modification contributed to the self-renew and radio-resistance in GSCs, however, its role on maintenance of TMZ resistance of GSCs has not been clarified and need further investigations. We found that the cell viability and half-maximal inhibitory concentration (IC50) of GSCs against TMZ significantly decreased after GSCs underwent serum-induced differentiation to adherent growth of tumor cells. Besides, METTL3 expression and total m6A modification declined dramatically in consistence with GSCs differentiation. Knockdown of METTL3 weakened self-renew, proliferation and TMZ IC50 of GSCs, whereas enhanced TMZ induced γH2AX level, indicating upregulation of double-strand DNA damage. We also found that mRNA stability of two critical DNA repair genes (MGMT and APNG) was regulated by METTL3-mediated m6A modification. In conclusion, we speculated that METTL3-mediated m6A modification of MGMT and APNG mRNAs played crucial roles on suppression of TMZ sensitivity of GSCs, which suggest a potential new therapeutic target of METTL3 against GBM.

HOTAIRM1 Maintained the Malignant Phenotype of tMSCs Transformed by GSCs via E2F7 by Binding to FUS.

Objective: Mesenchymal stromal/stem cells (MSCs) are an important part of the glioma microenvironment and are involved in the malignant progression of glioma. In our previous study, we showed that MSCs can be induced to a malignant phenotype (tMSCs) by glioma stem cells (GSCs) in the microenvironment. However, the potential mechanism by which tMSCs maintain their malignant phenotype after malignant transformation has not been fully clarified. Methods: The expression of HOTAIRM1, FUS, and E2F7 was detected by qRT-PCR. Clone formation, EdU, and Transwell assay were used to explore the role of HOTAIRM1, FUS, and E2F7 on the proliferation, migration, and invasion of tMSCs. Bioinformatics analysis and RNA immunoprecipitation were used to explore the relation among HOTAIRM1, FUS, and E2F7. Results: HOTAIRM1 was upregulated in tMSCs compared with MSCs. Loss- and gain-of-function assays showed that HOTAIRM1 promoted the proliferation, migration, and invasion of tMSCs. qRT-PCR and functional assays revealed that E2F7 might be the downstream target of HOTAIRM1. A further study of the mechanism showed that HOTAIRM1 could bind to FUS, an RNA-binding protein (RBP), and thus regulate E2F7, which could promote the malignant phenotype of tMSCs. Conclusion: Our study revealed that the HOTAIRM1/FUS/E2F7 axis is involved in the malignant progression of tMSCs transformed by GSCs in the glioma microenvironment and may function as a novel target for glioma therapy.

Molecular characteristics of single patient-derived glioma stem-like cells from primary and recurrent glioblastoma.

Glioblastoma has high recurrence, while the sensitivity of recurrent glioblastoma to chemotherapy is lower than that of primary glioblastoma. Moreover, there is no standardized treatment for recurrent glioblastoma. Unfortunately, the biological mechanism of recurrent glioblastoma is still unclear, and there are few related studies. We compared the phenotypes of clinical glioblastoma specimens, in-vitro cultured glioma stem-like cells (GSCs) and patient-derived xenograft tumor (PDX) models to explore the molecular genetic characteristics of primary and recurrent glioblastoma from the same patient. In vitro, SU5-2, GSCs derived from recurrent glioblastoma specimens, had stronger proliferative activity and self-renewal ability. Meanwhile, SU5-2 was more resistant to temozolomide and invasive than SU5-1, which derived from primary glioblastoma specimens. Further analysis of the expression of costimulatory molecules showed that the expression of B7-H1, B7-H2 and B7-H3 of SU5-2 were upregulated. In vivo, Kaplan-Meier survival curve analysis showed that the median survival of the recurrent PDX group was worse. The results of gene detection in vitro, PDX model and clinical samples were consistent. Our results showed that the GSCs based on glioblastoma specimens and the PDX models could replicate the main molecular genetic characteristics of original tumors, which provided a reliable experimental platform for both tumor translation kinds of research and screening of molecular therapeutic targets.

The Circ_0001367/miR-545-3p/LUZP1 Axis Regulates Cell Proliferation, Migration and Invasion in Glioma Cells.

Glioma is the most common primary intracranial malignant tumour in adults. It has a high incidence and poses a serious threat to human health. Circular RNA is a hotspot of cancer research. In this study, we aimed to explore the role of circ_0001367 in gliomagenesis and the underlying mechanism. First, qRT-PCR was conducted, which showed that circ_0001367 level was downregulated in glioma tissues and cells. Next, gain-of-function and loss-of-function assays were performed, which indicated that circ_0001367 inhibited the proliferation, migration and invasion of glioma cells. Subsequent bioinformatics analysis, dual-luciferase reporter assays, RNA immunoprecipitation assays and cell function assays demonstrated that circ_0001367 inhibited the proliferation, migration and invasion of glioma cells by absorbing miR-545-3p and thereby regulating the expression of leucine zipper protein (LUZP1). Finally, an in vivo experiment was conducted, which demonstrated that circ_0001367 inhibited glioma growth in vivo by modulating miR-545-3p and LUZP1. Taken together, the results of this study demonstrate that the circ_0001367/miR-545-3p/LUZP1 axis may be a novel target for glioma therapy.

FGF14-AS2 accelerates tumorigenesis in glioma by forming a feedback loop with miR-320a/E2F1 axis.

Glioma is the most common primary tumour in the central nervous system in adults, and at present, there is no effective treatment to cure this malignancy. Long noncoding RNAs (lncRNAs) are closely related to tumour progression and have attracted increasing attention in tumour research. However, the role of lncRNA FGF14-AS2 in glioma tumorigenesis has not been determined. In the present study, we found that FGF14-AS2 expression was significantly elevated in glioma tissues and was associated with poor survival in glioma patients. Silencing FGF14-AS2 inhibited the proliferation, migration and invasion ability of glioma cells. In vivo assay showed that silencing FGF14-AS2 led to inhibition of tumour growth. In addition, FGF14-AS2 was observed to promote glioma progression via the miR-320a/E2F1 axis. Moreover, E2F1 could bind to the promoter region of FGF14-AS2, thereby enhancing FGF14-AS2 expression. In conclusion, FGF14-AS2 could accelerate tumorigenesis of glioma by forming a feedback loop with the miR-320a/E2F1 axis which suggested that FGF14-AS2 could serve as a therapeutic target for glioma.

METTL3 Promotes the Resistance of Glioma to Temozolomide via Increasing MGMT and ANPG in a m6A Dependent Manner.

Acquired chemoresistance is a major limiting factor in the clinical treatment of glioblastoma (GBM). However, the mechanism by which GBM acquires therapeutic resistance remains unclear. Here, we aimed to investigate whether METTL3-mediated N6-methyladenosine (m6A) modification contributes to the temozolomide (TMZ) resistance in GBM. We demonstrated that METTL3 METTL3-mediated m6A modification were significantly elevated in TMZ-resistant GBM cells. Functionally, METTL3 overexpression impaired the TMZ-sensitivity of GBM cells. In contrast, METTL3 silencing or DAA-mediated total methylation inhibition improved the sensitivity of TMZ-resistant GBM cells to TMZ in vitro and in vivo. Furthermore, we found that two critical DNA repair genes (MGMT and APNG) were m6A-modified by METTL3, whereas inhibited by METTL3 silencing or DAA-mediated total methylation inhibition, which is crucial for METTL3-improved TMZ resistance in GBM cells. Collectively, METTL3 acts as a critical promoter of TMZ resistance in glioma and extends the current understanding of m6A related signaling, thereby providing new insights into the field of glioma treatment.

Circ_0001367 inhibits glioma proliferation, migration and invasion by sponging miR-431 and thus regulating NRXN3.

Many studies have reported that circular RNAs play a vital role in the malignant progression of human cancers. However, the role and underlying mechanism of circRNAs in the development of gliomas have not been fully clarified. In this study, we found that circ_0001367 was downregulated in glioma tissues and showed a close correlation with glioma patient survival. Functional assays demonstrated that upregulation of circ_0001367 could suppress the proliferation, migration and invasion of glioma cells in vitro and inhibit glioma growth in vivo. Furthermore, bioinformatics analysis, luciferase reporter assay and RNA immunoprecipitation assay indicated that circ_0001367 can serve as a sponge for miR-431 and that miR-431 acts as an oncogene by regulating neurexin 3 (NRXN3). In addition, rescue experiments verified that circ_0001367 could regulate both the expression and function of NRXN3 in a miR-431-dependent manner. In conclusion, circ_0001367 functions as an suppressor in glioma by targeting the miR-431/NRXN3 axis and may be a promising therapeutic target against gliomas.

HOTAIRM1 Promotes Malignant Progression of Transformed Fibroblasts in Glioma Stem-Like Cells Remodeled Microenvironment via Regulating miR-133b-3p/TGFß Axis.

Recent studies have reported that cancer associated fibroblasts (CAFs) and glioma stem-like cells (GSCs) played active roles in glioma progression in tumor microenvironment (TME). Long non-coding RNAs (lncRNAs) have been found to be closely associated with glioma development in recent years, however, their molecular regulatory mechanisms on CAFs in GSCs remodeled TME kept largely unelucidated. Our study found that GSCs could induce malignant transformation of fibroblasts (t-FBs) based on dual-color fluorescence tracing orthotopic model. Associated with poor prognosis, Lnc HOXA transcript antisense RNA, myeloid-specific 1 (HOTAIRM1) was highly expressed in high-grade gliomas and t-FBs. Depleting HOTAIRM1 inhibited the proliferation, invasion, migration, and even tumorigenicity of t-FB. Conversely, overexpression of HOTAIRM1 promoted malignancy phenotype of t-FB. Mechanistically, HOTAIRM1 directly bound with miR-133b-3p, and negatively regulated the latter. MiR-133b-3p partly decreased the promotion effect of HOTAIRM1 on t-FBs. Furthermore, transforming growth factor-ß (TGFß) was verified to be a direct target of miR-133b-3p. HOTAIRM1 can modulate TGFß via competing with miR-133b-3p. Collectively, HOTAIRM1/miR-133b-3p/TGFß axis was involved in modulating t-FBs malignancy in TME remodeled by GSCs, which had the potential to serve as a target against gliomas.

Nicardipine sensitizes temozolomide by inhibiting autophagy and promoting cell apoptosis in glioma stem cells.

Glioblastoma multiforme (GBM) is the most invasive malignant central nervous system tumor with poor prognosis. Nicardipine, a dihydropyridine calcium channel antagonist, has been used as an adjuvant to enhance sensitivity to chemotherapeutic drugs. However, whether glioma stem cells (GSCs) can be sensitized to chemotherapy via combined treatment with temozolomide (TMZ) and nicardipine is unclear. In this study, surgical specimen derived GSCs SU4 and SU5 were applied to explore the sensitization effect of nicardipine on temozolomide against GSCs, and further explore the relevant molecular mechanisms. Our results showed that nicardipine can enhance the toxic effect of temozolomide against GSCs, promote apoptosis of GSCs, and inhibit autophagy of GSCs. The relevant mechanisms were related to activation of mTOR, and selective inhibition of mTOR by rapamycin could weaken the sensitization of nicardipine to temozolomide, which suggest that nicardipine can be applied as an adjuvant to inhibit autophagy in GSCs, and enhance apoptosis-promoting effect of temozolomide in GSCs as well. Nicardipine can inhibit autophagy by activating expression of mTOR, thus play tumor inhibition roles both in vitro and in vivo. Repurposing of nicardipine can help to improving therapeutic effect of TMZ against GBM, which deserves further clinical investigations.

MiR-146b-5p suppresses the malignancy of GSC/MSC fusion cells by targeting SMARCA5.

Recent studies have confirmed that both cancer-associated bone marrow mesenchymal stem cells (BM-MSCs, MSCs) and glioma stem-like cells (GSCs) contribute to malignant progression of gliomas through their mutual interactions within the tumor microenvironment. However, the exact ways and relevant mechanisms involved in the actions of GSCs and MSCs within the glioma microenvironment are not fully understood. Using a dual-color fluorescence tracing model, our studies revealed that GSCs are able to spontaneously fuse with MSCs, yielding GSC/MSC fusion cells, which exhibited markedly enhanced proliferation and invasiveness. MiR-146b-5p was downregulated in the GSC/MSC fusion cells, and its overexpression suppressed proliferation, migration and invasion by the fusion cells. SMARCA5, which is highly expressed in high-grade gliomas, was a direct downstream target of miR-146b-5p in the GSC/MSC fusion cells. miR-146b-5p inhibited SMARCA5 expression and inactivated a TGF-ß pathway, thereby decreasing GSC/MSC fusion cell proliferation, migration and invasion. Collectively, these findings demonstrate that miR-146b-5p suppresses the malignant phenotype of GSC/MSC fusion cells in the glioma microenvironment by targeting a SMARCA5-regulated TGF-ß pathway.

Downregulation of miRNA-146a-5p promotes malignant transformation of mesenchymal stromal/stem cells by glioma stem-like cells.

Mesenchymal stromal/stem cells (MSCs) are promising carriers in cell-based therapies against central nervous system diseases, and have been evaluated in various clinical trials in recent years. However, bone marrow-derived MSCs (BMSCs) are reportedly involved in tumorigenesis initiated by glioma stem-like cells (GSCs). We therefore established three different orthotopic models of GSC-MSC interactions in vivo using dual-color fluorescence tracing. Cell sorting and micropipetting techniques were used to obtain highly proliferative MSC monoclones from each model, and these cells were identified as transformed MSC lines 1, 2 and 3. Nineteen miRNAs were upregulated and 24 miRNAs were downregulated in all three transformed MSC lines compared to normal BMSCs. Reduced miR-146a-5p expression in the transformed MSCs was associated with their proliferation, malignant transformation and overexpression of heterogeneous nuclear ribonucleoprotein D. These findings suggest that downregulation of miR-146a-5p leads to overexpression of its target gene, heterogeneous nuclear ribonucleoprotein D, thereby promoting malignant transformation of MSCs during interactions with GSCs. Given the risk that MSCs will undergo malignant transformation in the glioma microenvironment, targeted glioma therapies employing MSCs as therapeutic carriers should be considered cautiously.

3-Bromopyruvate inhibits the malignant phenotype of malignantly transformed macrophages and dendritic cells induced by glioma stem cells in the glioma microenvironment via miR-449a/MCT1.

Bromopyruvate (3-BrPA) is a glycolysis inhibitor that has been reported to have a strong anti-tumour effect in many human tumours. Several studies have reported that 3-BrPA could inhibit glioma progression; however, its role on the interstitial cells in the glioma microenvironment has not been investigated. In previous studies, we found that in the glioma microenvironment, glioma stem cells can induce the malignant transformation of macrophages and dendritic cells. In this study, we focused on the effects of 3-BrPA on malignantly transformed macrophages and dendritic cells. First, we found that 3-BrPA inhibited the proliferation of malignantly transformed macrophages and dendritic cells in a dose-dependent and time-dependent manner. Further study indicated that 3-BrPA significantly decreased extracellular lactate and inhibited the clone formation, migration and invasion of malignantly transformed macrophages and dendritic cells. Using an online database and a series of experiments, we demonstrated that 3-BrPA inhibits the malignant progression of malignantly transformed macrophages and dendritic cells via the miR-449a/MCT1 axis. These findings built experimental basis for new approach against glioma.