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Topoisomerase II alpha (topo II alpha) is a key enzyme in DNA replication and a target for many anti-cancer drugs. High levels are associated with sensitivity to topoisomerase II inhibitors. Because its chromosome location is similar to erbB2 (17q21-22), which is frequently amplified in breast cancer, co-amplification of these genes was assessed. In 117 primary breast cancers, 25 were amplified for erbB2. Three of these cases showed co-amplification of topo II alpha. Topo II beta was not amplified. Four human breast cancer cell lines were assessed for erbB2 and topo II alpha co-amplification. They were also analysed for sensitivity to the topoisomerase inhibitors m-AMSA and mitoxantrone. The most sensitive cell line was SKBr3, which was the only one with erbB2 amplification. Topo II alpha was co-amplified to a similar extent as in tumours. This suggests that patients whose tumours show topo II alpha amplification should be assessed specifically for therapy with topoisomerase inhibitors.


Journal article



Publication Date





933 - 938


Adult, Aged, Amsacrine, Breast Neoplasms, DNA Topoisomerases, Type II, DNA, Neoplasm, ErbB Receptors, Gene Amplification, Humans, In Vitro Techniques, Lymphatic Metastasis, Middle Aged, Mitoxantrone, Oncogenes, Proto-Oncogene Proteins, Receptor, ErbB-2, Receptors, Estrogen, Tumor Cells, Cultured