Expression of DNA topoisomerase I, IIalpha, and IIbeta in human brain tumors.

We investigated the expression of DNA topoisomerase I (Topo I), IIalpha (Topo IIalpha), and IIbeta (Topo IIbeta) mRNA using reverse transcription-polymerase chain reaction (RT-PCR) assay in 31 human brain tumors, and examined the relationship between DNA topoisomerase mRNA expression and Topo IIalpha and MIB-1 positive index (PI) as a cell proliferation marker. Topo IIalpha mRNA was expressed in 11 of 31 cases, and Topo I and IIbeta were each expressed in 18 of 31 cases. A significant correlation was seen between the MIB-1 PI and Topo IIalpha PI (P < 0.001). The cases with overexpression of Topo IIalpha mRNA had significantly high MIB-1 and Topo IIalpha PI (P < 0.0001). There was no significant correlation between Topo I and IIbeta mRNA expression and MIB-1 PI. We concluded that it was useful as a cell proliferation marker to analyze the expression of Topo IIalpha mRNA using RT-PCR in human brain tumors.