A comparative study of apoptosis and proliferation in germinoma and glioblastoma

Intracranial germinoma has a relatively good prognosis when treated with ra diotherapy and chemotherapy, whereas glioblastoma has a poor prognosis irre spective of these treatments. Cell proliferation and cell death are opposin g processes in tumor growth, with tumor progression reflecting the balance between proliferating and apoptotic cells. We investigated cell proliferati on and cell death using MIB-1 staining and nick-end labeling in 13 germinom as in comparison with 11 glioblastomas, Expression of BAX and Bcl-2, which regulate apoptosis, were studied by immunohistochemistry. Although germinom as showed strong MIB-1 immunostaining similar to that seen in glioblastomas , germinomas included significantly more apoptotic cells. The ratio of apop totic ratio to MIB-1 labeling index for germinomas was 72.9 +/- 36.9 (mean +/- SD), a higher, statistically significant ratio as compared with gliobla stomas (14.5 +/- 11.2; P < 0.01). Furthermore, germinomas showed greater ex pression of BAX than did glioblastomas, while the expression of Bcl-2 was w eak in both tumor types. A comparison of these apoptotic-related proteins s howed that immunoreactivity for BAX was relatively higher in germinomas tha n in glioblastomas (P < 0.01), corresponding well to numerous apoptotic cel ls identified in germinoma tissues. These findings may account for the prog nostic difference between germinoma and glioblastoma in the face of a simil ar proliferation potential according to MIB-1 immunostaining. The balance b etween cell proliferation and death should be considered when predicting ou tcomes in patients with intracranial tumors.