Profiling Protein Post-Translational Modifications in Plasma-derived Extracellular Vesicles as Fingerprints for...

Area of Science:

• Proteomics
• Cancer Biology
• Biochemistry

Background:

• Breast cancer (BC) heterogeneity necessitates precise subtype differentiation for effective treatment.
• Plasma extracellular vesicles (EVs) are crucial for intercellular communication and immune regulation.
• Post-translational modifications (PTMs) on EV proteins offer insights into BC dynamics.

Purpose of the Study:

• To develop a non-invasive method for differentiating breast cancer subtypes using PTMs in plasma EVs.
• To identify novel protein modification-based biomarkers for BC diagnosis and prognosis.

Main Methods:

• Analysis of post-translationally modified proteins (phosphorylation, acetylation, glycosylation) in plasma EVs from 101 individuals.
• Utilized mass spectrometry for peptide characterization and bioinformatics for differential analysis.
• Employed machine learning and parallel reaction monitoring (PRM) for marker validation and subtype differentiation.

Main Results:

• Characterized over 28,000 non-modified peptides, 5,000 phosphopeptides, 680 acetyl peptides, and 1,300 glycopeptides.
• Identified significant overexpression of numerous modified peptides in Luminal A/B (LAB) BC and triple-negative (TN) BC subtypes.
• Discovered phosphorylated and glycosylated PD-L1 peptides as potential pan-BC markers and pinpointed specific modification sites for subtype differentiation.

Conclusions:

• This research presents a novel non-invasive approach for BC detection and subtype classification using EV PTMs.
• Identified potential diagnostic and prognostic biomarkers, including PD-L1 modifications, enhancing understanding of BC molecular landscape.
• Findings contribute to the development of personalized diagnostics and treatments for breast cancer.