X-rays modulate extracellular matrix in vivo

Area of Science:

• Angiogenesis research
• Radiation biology
• Extracellular matrix dynamics

Background:

• Angiogenesis, the formation of new blood vessels, is crucial for tumor growth and metastasis.
• X-rays are known to affect cellular processes, but their precise impact on angiogenesis and the tumor microenvironment requires further elucidation.

Purpose of the Study:

• To investigate the antiangiogenic effects of X-rays in the chicken embryo chorioallantoic membrane (CAM) model.
• To analyze the modulation of extracellular matrix (ECM) proteins and gene expression following irradiation.
• To determine the influence of X-ray-induced changes on tumor cell-stimulated angiogenesis.

Main Methods:

• Irradiation of the chicken embryo chorioallantoic membrane (CAM) model.
• Assessment of cell apoptosis at early time points post-irradiation.
• Quantification of ECM protein and mRNA levels (fibronectin, laminin, collagen type I, integrin alpha(v)beta3, MMP-2, collagen type IV).
• Implantation of C6 glioma tumor cells onto irradiated and non-irradiated CAMs to evaluate angiogenesis.

Main Results:

• X-rays induced early apoptosis of CAM cells within 1-6 hours.
• Decreased protein and gene expression of fibronectin, laminin, collagen type I, and MMP-2 at 6 hours post-irradiation.
• Collagen type IV levels remained unaffected, while integrin alpha(v)beta3 mRNA was stable up to 24 hours.
• Reversal of decreased expression and significant increase in gene expression observed at 48 hours.
• Irradiated CAMs showed enhanced angiogenesis when C6 glioma cells were implanted.

Conclusions:

• X-rays exert an initial inhibitory effect on angiogenesis through apoptosis and ECM modulation.
• The observed changes in ECM composition and gene expression are transient, with a subsequent rebound effect.
• X-ray-induced alterations in the CAM microenvironment can paradoxically promote tumor cell-driven angiogenesis, highlighting a complex interplay.