Distinct radiochemotherapy protocols differentially influence cellular proliferation and expression of p53 and Bcl-2 in glioblastoma multiforme relapses in vivo

Several protocols for the adjuvant treatment of glioblastoma multiforme (GBM) are currently being evaluated. In this context, little is known about the influence of radiochemotherapy on apoptosis and the expression of apoptosis-related proteins in vivo. We have analyzed the incidence of apoptosis using in situ nick translation (ISNT) and expression of Ki-67 (MIB-1), p53 (DO-1 and DO-7), Bcl-2 and transglutaminase II (TGase II) by immunohistochemistry in 41 patients with GBM and their matched relapses. Sixteen patients received radiochemotherapy, 18 irradiation and 7 no treatment. Radiochemotherapy resulted in an increase in Bcl-2(+) cells (p = 0.013). Irradiation caused the reduction of MIB-1(+) (p = 0.0015), DO-7(+) (p = 0.0043) and the increase of Bcl-2(+) cells (p = 0.016). We calculated a positive correlation between high TGase II scores in patients preceding radiochemotherapy (p = 0.0186) and no treatment (p = 0.0158), low ISNT scores (p = 0.0018) and high DO-1 scores (p = 0.0233) in patients preceding irradiation and short time to progression. These data show that distinct postsurgical radiochemotherapy protocols differentially alter cellular proliferation and expression of p53 and Bcl-2 in GBM relapses. Furthermore, we show that ISNT, DO-1 and TGase II labeling scores are therapy-specific predictors of time to progression in GBM patients.