Cytoplasmic Shotgun Proteomic Points to Key Proteins and Pathways in Temozolomide-Resistant Glioblastoma Multiforme
Milan Teraiya1, Oleg Krokhin1,2, Vincent C Chen3
1Chemistry Department, University of Manitoba, Winnipeg, Manitoba R3T3C7, Canada.
Abstract:
Temozolomide (TMZ) is the first line of chemotherapy to treat primary brain tumors of the type glioblastoma multiforme (GBM). TMZ resistance (TMZR) is one of the main barriers to successful treatment and is a principal factor in relapse, resulting in a poor median survival of 15 months. The present paper focuses on proteomic analyses of cytosolic fractions from TMZ-resistant (TMZR) LN-18 cells. The experimental workflow includes an easy, cost-effective, and reproducible method to isolate subcellular fraction of cytosolic (CYTO) proteins, mitochondria, and plasma membrane proteins for proteomic studies. For this study, enriched cytoplasmic fractions were analyzed in replicates by nanoflow liquid chromatography tandem high-resolution mass spectrometry (nLC-MS/MS), and proteins identified were quantified using a label-free approach (LFQ). Statistical analysis of control (CTRL) and temozolomide-resistant (TMZR) proteomes revealed proteins that appear to be differentially controlled in the cytoplasm. The functions of these proteins are discussed as well as their roles in other cancers and TMZ resistance in GBM. Key proteins are also described through biological processes related to gene ontology (GO), molecular functions, and cellular components. For protein-protein interactions (PPI), network and pathway involvement analyses have been performed, highlighting the roles of key proteins in the TMZ resistance phenotypes. This study provides a detailed insight into methods of subcellular fractionation for proteomic analysis of TMZ-resistant GBM cells and the potential to apply this approach to future large-scale studies. Several key proteins, protein-protein interactions (PPI), and pathways have been identified, underlying the TMZ resistance phenotype and highlighting the proteins' biological functions.
Insights
Temozolomide resistance in glioblastoma multiforme (GBM) is a major challenge. This study identifies key proteins and pathways in resistant GBM cells, offering insights into therapeutic strategies for brain tumors.
Area of Science:
- Proteomics
- Oncology
- Biochemistry
Background:
- Temozolomide (TMZ) is a primary chemotherapy for glioblastoma multiforme (GBM).
- Temozolomide resistance (TMZR) significantly limits treatment efficacy and survival in GBM patients.
- Understanding the molecular mechanisms of TMZR is crucial for developing improved therapies.
Purpose of the Study:
- To investigate the proteomic differences in cytosolic fractions of TMZ-resistant (TMZR) LN-18 GBM cells compared to control cells.
- To identify key proteins, pathways, and protein-protein interactions (PPI) associated with TMZR.
- To establish a reproducible method for subcellular fractionation and proteomic analysis of resistant GBM cells.
Main Methods:
- Isolation of cytosolic, mitochondrial, and plasma membrane protein fractions.
- Proteomic analysis using nanoflow liquid chromatography tandem high-resolution mass spectrometry (nLC-MS/MS).
- Label-free quantification (LFQ) for protein identification and statistical analysis of differentially expressed proteins.
Main Results:
- Identification of differentially regulated proteins in the cytoplasm of TMZR LN-18 cells.
- Functional analysis (Gene Ontology) of identified proteins, highlighting roles in biological processes, molecular functions, and cellular components.
- Network and pathway analyses revealed key proteins and PPIs underlying the TMZR phenotype.
Conclusions:
- The study provides a detailed proteomic insight into TMZR in GBM cells.
- Identified proteins and pathways offer potential targets for overcoming TMZ resistance.
- The developed subcellular fractionation method is applicable to future large-scale proteomic studies in cancer research.
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