Topoisomerase II alpha as a reliable proliferation marker in meningiomas

The value of DNA Topoisomerase IIalpha expression as a proliferation marker in meningiomas was investigated. The correlation to MIB-1 expression and tumor grade in 85 meningiomas (60 classical, 19 atypical and 6 anaplastic) was analysed by immunohistochemistry. MIB-1 labeling indices (LI) were 1.1% (+/- 0.85) for classical meningiomas, 1.9% (+/- 1.5) for atypical meningiomas and 5.6% (+/- 4.1) for anaplastic meningiomas, differences statistically significant (p = 0.03, < 0.0001, < 0.0001). Topoisomerase IIalpha LIs were 1.4% (+/- 1.2) for classical, 3.2% (+/- 2.4) for atypical and 9.7% (+/- 6.6) for anaplastic meningiomas, differences statistically significant (p = 0.003, < 0.0001, < 0.0001). Proliferation indices based on cells staining for MIB-1 and Topoisomerase IIalpha correlated highly with one another (r= 0.906, p <0.0001). Topoisomerase IIalpha exhibited a more distinct, less variable nuclear staining pattern compared to MIB-1 expression. DNA Topoisomerase IIalpha LI represents a reliable alternative to MIB-1 as a proliferation marker in human meningiomas, especially for computer assisted assessment, where a distinct uniform staining pattern is required.