Using the Suppression of Cytoplasmic Iron-Sulfur Cluster Assembly to Restore PTEN and Inhibit Glioma Stem Cells

Background

Glioblastoma (GBM) is one of the most lethal primary brain tumors. Glioma stem cells (GSCs) not only initiate and sustain the malignant phenotype but also enhance treatment resistance. Although PTEN frequently mutates in glioblastoma, its function and regulatory mechanisms in PTEN-intact GSCs remain unclear. This study aims to explore the role of PTEN in PTEN-intact GSCs and its potential clinical significance.

Paper Source

The authors of this paper include Jianxing Yin, Xin Ge, Fangshu Ding, and other researchers from institutions such as Nanjing Medical University. The study’s findings were published on March 20, 2024, in the journal Science Translational Medicine.

Research Process

Research Steps

This study utilized multiple procedures, including cell culture, protein immunoprecipitation, mass spectrometry analysis, radioactive labeling, and animal model experiments.

Cell Culture

Cells involved in the study included PTEN-intact and PTEN-null GSCs, as well as differentiated glioma cells (DGCs) induced by fetal bovine serum. By culturing and processing these cells, researchers could compare the function and expression of PTEN under different cell states.

Protein Immunoprecipitation and Mass Spectrometry

The authors used immunoprecipitation and mass spectrometry analysis to investigate the interaction between PTEN and MMS19 and the modifications of PTEN in different states. These techniques helped them identify the succination modification of the C211 site of PTEN in GSCs and its impact on PTEN function.

Radioactive Labeling Experiment

To study the role of iron-sulfur cluster (Fe-S Cluster) assembly in GSCs, researchers labeled cells with radioactive 55Fe and quantified the content of 55Fe in specific Fe-S proteins through scintillation counting.

Animal Model Experiment

In animal experiments, GSCs expressing luciferase were injected into the brains of nude mice to study the effects of PTEN and succination modification on tumor growth and treatment response.

Special Methods and Algorithms

Special methods used in the study included stable isotope labeling by mass spectrometry, radioactive labeling experiments, immunoprecipitation techniques, and animal experiments. These methods enabled the authors to reveal PTEN modifications in GSCs and their impact on GSC maintenance and tumor treatment response.

Data Analysis Algorithms

Various statistical analysis and comparison methods, such as nonlinear regression analysis and survival analysis (Kaplan-Meier survival curves), were employed in the analysis of experimental data, ensuring the reliability and reproducibility of the research results.

Major Research Findings

Result 1: Role of PTEN Succination in GSC Maintenance

Mass spectrometry and immunoprecipitation experiments showed that the C211 site of PTEN underwent succination modification (PTEN C211SC) in GSCs. This modification significantly enhanced the self-renewal and proliferation abilities of GSCs by interrupting the interaction between PTEN and MMS19, thereby activating the CIA mechanism.

Result 2: Direct Interaction Between PTEN and MMS19

PTEN directly interacted with MMS19, competitively blocking MMS19 from binding with CIA-related proteins (CIAO1 and CIAO2B) and inhibiting the CIA mechanism. The study also found that the interaction between the C2 domain of PTEN and the α45 and α46 domains of MMS19 was particularly critical.

Result 3: Succination Modification Eliminates PTEN Inhibition of the CIA Mechanism

Reducing PTEN C211 succination could restore PTEN’s inhibition of the CIA mechanism, thereby affecting the function of Fe-S proteins. The study demonstrated that decreasing PTEN succination could reduce 55Fe assembly in CIA mechanical target proteins.

Result 4: Fumarate Promotes PTEN Succination Through Purine Synthesis Pathway

The study found that fumarate, produced in the purine synthesis pathway, was present at high concentrations in GSCs and could catalyze PTEN C211 succination through adenylosuccinate lyase (ADSL).

Result 5: Inhibiting PTEN C211 Succination Enhances Treatment Effect

Expressing the PTEN C211S mutant or treating with N-acetylcysteine (NAC) could inhibit PTEN succination, thereby increasing GSC sensitivity to temozolomide (TMZ) and irradiation (IR) and significantly prolonging the survival time of tumor-bearing mice.

Conclusions

This study revealed the function and clinical significance of PTEN in PTEN-intact GSCs. Intervening in PTEN succination could effectively inhibit GSC maintenance and enhance GBM responsiveness to TMZ and IR. This finding provides an immediately feasible strategy for GBM combination therapy, especially by repurposing NAC, an FDA-approved prescription drug.

Study Significance

This study holds significant scientific and application value. The results not only deepen the understanding of PTEN regulation in GSCs but also propose a new therapeutic strategy targeting GSCs, potentially improving clinical outcomes for GBM patients. This research provides a theoretical foundation and experimental support for the development of novel anti-glioblastoma treatments in the future.

Study Highlights

The main highlights of this study include: 1. New Discovery: First reveal of the critical role of PTEN C211 succination in GSC maintenance. 2. Mechanism Elucidation: Detailed explanation of the interaction between PTEN and MMS19 and its regulation of the CIA mechanism. 3. Clinical Application: Proposal of the practical feasibility of inhibiting PTEN succination with NAC to improve GBM treatment efficacy. 4. Experimental Methods: Comprehensive use of advanced experimental techniques and data analysis methods to ensure the reliability and accuracy of the research results.

Through these highlights, the study offers new perspectives and methods for basic glioblastoma research and clinical treatment.