Correlation between Topo II alpha expression and chemosensitivity testing for Topo II-targeting drugs in gynaecological carcinomas.

Background: The purpose of this study was to investigate the correlation between topoisomerase IIa (Topo IIa) expression and the chemosensitivity to Topo II-targeting drugs in gynaecological carcinomas. Materials and Methods: We analysed the expression of Topo IIa, and then correlated this with the in vitro chemosensitivities of 43 gynaecological tumors using immunohistochemistry and a tetrazolium dye (MTT) assay. Results. There was a significant correlation between the Topo IIa index (the number of positive cells per 100 cells: %) and the tumor cell growth inhibition rate in culture (I.R.: %) for doxorubicin and etoposide (r=0.631, p<0.001 and r=0.645, p<0.001, respectively). The I.Rs for doxorubicin and etoposide in endometrial carcinomas were lower than those in ovarian carcinomas [38.2±22.8 vs 54.6±29.8, 37.3±19.8 vs 59.3±30.6](p<0.05, respectively). Furthermore, the number of high Topo IIa index (over 30% ) tumors in the ovarian carcinoma cases was higher than that in the endometrial carcinoma cases (63.1% vs 45.8%, p<0.05). Conclusions. Our data suggest that the Topo IIa index of a tumor is a reflection of its chemosensitivity to Topo II-targeting drugs. The use of this index may enable prediction of a clinical response to chemotherapy using Topo II-targeting drugs in gynaecological malignancies.