RESUMEN
BACKGROUND: Topoisomerase II (topo II) is a major target of anthracyclines and epipodophyllotoxins for anticancer treatment. The expression of topo II is low in drug resistant cell lines. High levels of glutathione S-transferase (GST)pi have been associated with emergence of cell lines resistant to alkylating agents or adriamycin. METHODS: By immunostaining with paraffin embedded bone marrow tissues, the expression of topo II alpha and GSTpi was investigated in 51 patients with acute myeloid leukemia (AML), and the relation of topo II alpha and GSTpi expression to treatment response in 29 patients with AML following induction chemotherapy was also evaluated. RESULTS: Topo II positive cells varied from less than 1% to 60% of leukemic cells and 20 (39.2%) were negative for topo II (positive cells<10%). Treatment response following chemotherapy was not related to topo II. 26 (51.0%) were positive for GSTpi. GSTpi expression was related to treatment resistance of the patients following chemotherapy. In the patients who showed both topo II alpha negative and GSTpi positive, the frequency of treatment resistance following chemotherapy was high. CONCLUSIONS: This study suggests that immunostaining of topo II alpha and GSTpi with the bone marrow paraffin sections of AML patients can be useful to predict the treatment response following chemotherapy and that further study including more patients with prospective study may substantiate topo II alpha and GSTpi as multidrug resistant markers.