The Effects of irridation on glioblastoma cell lines: a potential tool to study the mechanism of tumor resistance

Glioblastoma Multiforme (GBM) is one of the most devastating brain cancers. Here, we sequentially irradiated rat and human GBM cell lines to examine cell injury and cell death in pre‐ and post‐irradiated cells. We have used TUNEL, flow cytometry, western blotting and immunocytochemistry methods to study the effects of radiation on cell death and cell cycle and to exam various proteins expression in post‐irradiated radio‐resistant cells. The results showed that radiation induces apoptotic cell death, and the mortality rate on post‐irradiated GBM cells and their vimentin expression have a negative correlation. Interestingly, vimentin not only expressed in the cytoplasm(s) of post‐irradiated cells but also formed aggregates on the nuclei. Post‐irradiated cells also formed three‐dimensional cell clusters and expressed desmin and myogenin. The radiation affected the expression of p53, Cdk‐2, and Cdk‐4. Correlation analysis of p53 and Cdk‐2 proteins expression on day 3 after 4 Gy radiation suggested that their expression may regulate through p21 in the cell cycle. Control cells and post‐irradiated cells do not express E‐cadherin but have different protein expression patterns for fibronectin and vimentin. This indicates that EMT may occur in these post‐irradiated cell lines. This may indicate that EMT occurs in this post‐irradiated cell lines.