Glutamate Dehydrogenase 1-Catalytic Glutaminolysis Feedback Activates EGFR/PI3K/AKT Pathway and Reprograms Glioblastoma Metabolism

Neurology Life Sciences Biochemistry Oncology Medicine
glutaminolysis EGFR/PI3K/AKT pathway glioblastoma metabolic reprogramming glutamate dehydrogenase 1

Academic Background

Glioblastoma (GBM) is one of the most aggressive and heterogeneous central nervous system tumors, with an extremely poor prognosis. Despite the emergence of novel therapies such as anti-angiogenic treatments and immunotherapy in recent years, the survival period of GBM patients remains very limited. GBM cells exhibit unique metabolic characteristics, particularly in the utilization of glucose and glutamine. While glucose metabolism in GBM has been extensively studied, the role of glutamine metabolism has received relatively less attention. Glutamine is not only an essential nutrient for cancer cell growth but also participates in nucleic acid and fatty acid synthesis. However, the role of glutamine metabolism in GBM signal transduction and metabolic reprogramming remains unclear.

This study aims to explore the novel mechanisms of glutamine metabolism in GBM, particularly how glutamate dehydrogenase 1 (GDH1)-catalyzed glutaminolysis feedback activates the epidermal growth factor receptor (EGFR)/phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway and reprograms GBM metabolism.

Source of the Paper

This paper was co-authored by Rui Yang, Guanghui Zhang, Zhen Meng, and others, affiliated with the School of Medicine at Liaocheng University, Henan University of Chinese Medicine, and the Institute of Precision Medicine at Jining Medical University, among other institutions. The paper was published in March 2025 in the journal Neuro-Oncology, titled “Glutamate Dehydrogenase 1-Catalytic Glutaminolysis Feedback Activates EGFR/PI3K/Akt Pathway and Reprograms Glioblastoma Metabolism.”

Research Process and Results

1. The Critical Role of GDH1-Mediated Glutaminolysis in GBM Growth

Research Process:
To evaluate the critical role of glutamine metabolism in GBM cell growth, researchers knocked down GDH1 expression using short hairpin RNA (shRNA). Subsequently, the survival rates of GBM cells were measured under both low glucose (LG) and high glucose (HG) conditions. Additionally, researchers supplemented methyl-α-ketoglutarate (Methyl-α-KG) to verify the importance of GDH1 catalytic activity. Finally, stable cell lines expressing GDH1 wild-type (GDH1 WT) and GDH1 R496S mutant (lacking dehydrogenase activity) were constructed, and the impact of GDH1 on tumor growth was validated in a mouse intracranial tumor model.

Results:
GDH1 knockdown significantly inhibited the survival rate of GBM cells under LG conditions but did not significantly affect cell survival under HG conditions in the short term. However, prolonged GDH1 knockdown significantly suppressed cell proliferation under HG conditions. Supplementation with Methyl-α-KG partially restored the survival rate of GDH1 knockdown cells. In the mouse intracranial tumor model, GDH1 knockdown significantly inhibited tumor growth, while GDH1 WT expression restored tumor growth, and the GDH1 R496S mutant had no such effect. These results indicate that GDH1-mediated glutaminolysis plays a critical role in GBM growth, even under HG conditions.

2. GDH1-Mediated Glutaminolysis Feedback Activates the EGFR/Akt/mTOR Signaling Pathway

Research Process:
To investigate the role of GDH1 in signal transduction, researchers analyzed the gene expression profiles of GDH1 knockdown cells through RNA sequencing (RNA-seq). Subsequently, the phosphorylation levels of Akt, mTOR, and p70S6K in GDH1 knockdown and overexpression cells were measured via Western blot. Additionally, the activation of the EGFR/Akt/mTOR signaling pathway in GDH1 knockdown cells under EGF stimulation was examined.

Results:
RNA-seq results showed that 623 genes were significantly altered in GDH1 knockdown cells, with 224 genes related to signal transduction, particularly the PI3K/Akt pathway. Western blot results revealed that GDH1 knockdown significantly reduced the phosphorylation levels of Akt, mTOR, and p70S6K, while GDH1 overexpression increased the phosphorylation levels of these proteins. Under EGF stimulation, the phosphorylation levels of Akt, mTOR, and p70S6K were significantly reduced in GDH1 knockdown cells, while the phosphorylation levels of EGFR and MEK1 were unaffected. These results suggest that GDH1-mediated glutaminolysis is a critical amplifier of the EGFR-activated PI3K/Akt/mTOR signaling pathway.

3. GDH1 Activates the Akt/mTOR Pathway by Regulating Histone Demethylation

Research Process:
To further explore the role of GDH1-catalyzed glutaminolysis in the Akt/mTOR signaling pathway, researchers examined changes in histone methylation levels in GDH1 knockdown cells. Subsequently, chromatin immunoprecipitation (ChIP) was used to detect the levels of histone H3K27 trimethylation (H3K27me3) at the PDPK1 promoter region in GDH1 knockdown cells. Additionally, the role of α-KG in histone demethylation was validated by supplementing Methyl-α-KG.

Results:
GDH1 knockdown significantly increased H3K27me3 levels and reduced PDPK1 expression. ChIP results showed that GDH1 knockdown significantly increased H3K27me3 levels at the PDPK1 promoter region. Supplementation with Methyl-α-KG restored the phosphorylation levels of Akt, mTOR, and p70S6K in GDH1 knockdown cells. These results indicate that GDH1 activates the Akt/mTOR pathway by regulating histone demethylation.

4. The Critical Role of KDM6A in GDH1-Mediated Signal Transduction and Metabolic Reprogramming

Research Process:
To validate the role of KDM6A (an α-KG-dependent histone demethylase) in GDH1-mediated signal transduction, researchers knocked down KDM6A expression using shRNA and measured the expression levels of PDPK1 and HK2 in GDH1-overexpressing cells. Additionally, ChIP was used to detect H3K27me3 levels at the PDPK1 and HK2 promoter regions in KDM6A knockdown cells.

Results:
KDM6A knockdown significantly increased H3K27me3 levels and reduced the expression of PDPK1 and HK2. ChIP results showed that KDM6A knockdown significantly increased H3K27me3 levels at the PDPK1 and HK2 promoter regions. These results suggest that KDM6A is a key factor in GDH1-mediated signal transduction and metabolic reprogramming.

Conclusions and Significance

This study demonstrates that GDH1-catalyzed glutaminolysis feedback activates the EGFR/PI3K/Akt signaling pathway through KDM6A-dependent histone demethylation and reprograms GBM metabolism. This discovery reveals a novel interaction between metabolism, epigenetic transcriptional machinery, and signal transduction, providing a new mechanistic explanation for GBM progression. Furthermore, this study offers potential new therapeutic targets for GBM, particularly inhibitors of GDH1 and KDM6A, which may become effective strategies for future GBM treatment.

Research Highlights

  1. Revelation of a New Mechanism: For the first time, it was revealed that GDH1-catalyzed glutaminolysis feedback activates the EGFR/PI3K/Akt signaling pathway through KDM6A-dependent histone demethylation.
  2. Interaction Between Metabolism and Signal Transduction: The complex interplay between metabolic reprogramming and signal transduction was elucidated, providing a new perspective for GBM metabolism research.
  3. Potential Therapeutic Targets: Inhibitors of GDH1 and KDM6A may become effective strategies for future GBM treatment, with significant clinical application value.

The innovation and importance of this study lie not only in its revelation of new mechanisms in GBM metabolism but also in providing new insights for future therapeutic strategies.