Single X-ray irradiation modulates proteoglycan expression in brain tissue: investigation using mouse model

Area of Science:

• Neuroscience
• Radiation Oncology
• Molecular Biology

Background:

• Proteoglycans (PGs) are crucial extracellular matrix components in brain tissue.
• The molecular impact of radiotherapy on PGs in brain tissue remains poorly understood.
• Understanding these effects is vital for glioblastoma treatment and managing recurrence.

Purpose of the Study:

• To investigate the short-term effects of X-ray irradiation on proteoglycan expression in normal mouse brain tissue.
• To analyze changes in PGs expression at 24, 48, and 72 hours post-irradiation.
• To compare the effects of synchrotron and clinical linear accelerator irradiation.

Main Methods:

• In vivo mouse model (CBL/6Bl mice) exposed to 7 Gy X-ray irradiation.
• Analysis of brain tissue morphology using Hematoxylin and Eosin (H&E) staining.
• Quantification of proteoglycan mRNA expression (syndecan-1, glypican-1, HSPG2/perlecan, versican, brevican, neurocan, NG2/CSPG4, CD44, decorin, biglycan) via RT-PCR.

Main Results:

• Single 7 Gy X-ray irradiation did not significantly alter brain tissue morphology (cortex and hippocampus).
• Expression of most PGs, including decorin and neurocan, remained unaffected.
• Significant downregulation (3-10 fold for brevican, 8-9 fold for NG2/CSPG4) was observed in both cerebral cortex and subcortex.

Conclusions:

• X-ray irradiation selectively downregulates brevican and NG2/CSPG4 expression in mouse brain tissue.
• These changes indicate an alteration of the extracellular matrix following radiotherapy.
• The observed PGs downregulation may contribute to a microenvironment conducive to glioblastoma relapse.