Frequency and Clinical Significance of P-Glycoprotein and Multidrug Resistance-Associated Protein-1 Expression in Leukemic Cells from Acute Myeloid Leukemia

BACKGROUND: Despite advances in the cure rate for acute myeloid leukemia, a considerable number of patients die from the disease due to multidrug resistance (MDR). Overexpression of the transporter proteins P-glycoprotein (Pgp) and multidrug resistance-associated protein (MRP) provide resistance to the treatment of these leukemias. OBJECTIVE: To analyze Gpp and MRP1 expression in patients with AML using flow cytometry (FC) and determine the correlation between expression and demographics and clinical and laboratory variables. METHODS: Bone marrow and peripheral blood samples from 346 patients diagnosed with AML were assessed for Pgp and MRP1 expression by FC. RESULTS: Pgp and MRP1 expression was found in 111 (32.1%) and 133 (38.4%) patients, respectively, with greater prevalence in older patients and lower in adolescents, in addition to a high incidence in patients with refractory, recurrent and secondary disease in comparison with cases of de novo AML. With respect to laboratory findings, we observed a statistically significant higher correlation between Pgp and MRP1 expression in AML CD34+ and FAB AML M7, M5A and M2 and lower in the M3 subtype, with no statistically significant correlation between the phenotype MDR and other laboratory data such as hemoglobin, leukocyte count, platelet count, and aberrant lymphoid antigen expression (CD2, CD7 and CD19) and clinical signs related to the disease. CONCLUSIONS: The results showed that detecting MDR phenotype by flow cytometry may be a molecular marker for the independent prognosis of patients diagnosed with AML.