Cell aggregation increases drug resistance of acute myeloid leukemia cells

One of the major causes of low efficiency of the therapy for acute myeloid leukemia is drug resistance of leukemic cells. Microenvironment plays a key role in formation of the phenotype of leukemic cell drug resistance. Investigation of the mechanisms of microenvironment-mediated drug resistance is important to identify novel pharmacological targets for the acute myeloid leukemia therapy. We studied the role of cell aggregation in the drug resistance of leukemic cells. We showed the increased resistance of acute myeloid leukemia cells THP-1 to bortezomib, doxorubicin and fludarabine in multicellular aggregates. In the multicellular aggregates of THP-1 with the higher drug resistance, cell proliferation activity did not change, while the intracellular level of anti-apoptotic protein Bcl-2 increased. Inhibition of the aggregation of THP-1 cells prevented drug resistance. This work demonstrates the involvement of cell aggregation in the formation of drug resistance phenotype in leukemic cells. © 2015, Pleiades Publishing, Ltd.