Autophagy and lysosomal related protein expression patterns in human glioblastoma

Area of Science:

• Oncology
• Cell Biology
• Molecular Biology

Background:

• Glioblastoma exhibits resistance to apoptosis, with autophagy playing a key role in cell death under stress.
• Autophagy interfering agents are a potential therapeutic strategy for glioblastoma, particularly in combination with chemo-radiation.

Purpose of the Study:

• To investigate the expression patterns of autophagy-related proteins in glioblastoma patients treated with radiotherapy.
• To assess the autophagic response in glioblastoma cell lines under simulated intratumoral stress conditions.
• To explore the relationship between autophagy markers, lysosomal proteins, TFEB, and PTEN in glioblastoma.

Main Methods:

• Immunohistochemical analysis of autophagy proteins (LC3A, LC3B, p62, Beclin 1, ULK1, ULK2) and lysosomal markers (Cathepsin D, LAMP2a) in patient samples.
• Gene expression analysis and confocal microscopy in glioblastoma cell lines (T98, U87) under stress conditions (acidosis, 2DG).
• Correlation analysis between autophagy markers, TFEB, and PTEN expression.

Main Results:

• Glioblastomas showed variable cytoplasmic overexpression of autophagy proteins, with distinct LC3A and LC3B autophagosome patterns.
• Lysosomal markers and TFEB were frequently overexpressed and linked to PTEN, HIF1α, and autophagy proteins (LC3B, Beclin 1, p62).
• The stone-like structure (SLS) pattern of LC3 expression correlated with prognosis and was inducible under acidic and glucose-antagonist conditions.

Conclusions:

• Autophagic protein expression varies in glioblastoma, offering potential for stratification and targeted therapies.
• TFEB and lysosomal biogenesis are linked to glioblastoma progression and may represent therapeutic targets.
• Understanding the distinct roles of LC3A and LC3B and the prognostic significance of the SLS pattern is crucial for developing novel glioblastoma treatments.