K-562 Extracellular Vesicles Partially Protect Intact Cells from Oxidative Stress and Provide Limited Resistance to Imatinib.

Chronic myeloid leukemia (CML) results from the formation of the BCR-ABL1 chimeric protein which serves as a target for clinically used tyrosine kinase inhibitors (TKIs), such as imatinib mesylate (IM). Although very efficient, the development of resistance to TKIs remains a critical issue for a subset of patients. In our study we aimed to identify one aspect of IM resistance in K-562 cells, a cell line used as a model for CML. Secreted from all cell types, extracellular vesicles (EVs) are nanoparticles that function as mediators of cell-cell communication. Upon engulfment by other cells they may modulate their phenotype. IM is linked to changes in oxidative metabolism in K-562 cells. Our study explored the putative involvement of EVs secreted from K-562 cells in providing protection from oxidative stress and resistance to IM in these cells. The results of our study showed that the protection from oxidative stress provided by previously exposed K-562 cell, derived EVs is only partial. Similarly, these EVs provided intact K-562 cells with some resistance to IM treatment. These results may suggest that resistance to IM may develop and expand to other cells by EVs that are secreted from already resistant cells, similar to a horizontal transfer of resistance provided by plasmids in bacteria.