In- vivo tracking, histopathological analyses and leukemic stem cell markers assessment of imatinib-resistant leukemic cells in atimic mice

Chronic Myeloid Leukemia is a hematopoietic clonal stem cell disease that occurs as a result of respirocal translocation between the long arms of chromosomes 9 and 22. The fusion protein resulting from this translocation exhibits a continuous tyrosine kinase activity that allows expansion of the leukemic lines. Imatinib, one of the targeted tyrosine kinase inhibitors, inhibits the enzymatic activity of this fusion protein, but in the long term patients develop secondary resistance to this molecule. The aim of our project is to investigate the behavioral differences between imatinib-resistant K562-Ir cells and ancestral cells that in live system by inoculation the ancestral and imatinib-resistant cells subcutaneously into athymic mice in order to evaluate cell behavior and tumor formation capacity. In vitro stable transduction assays were performed to mark the imatinib-resistant and ancestral cells with a lentivirus that containing the luciferase gene and the green fluorescent protein gene. These two marked populations were inoculated subcutaneously to Balb-c / Nude mice in the presence or absence of imatinib. Bioluminescence measurements were taken and compared in IVIS imaging by using luciferase assay with specific intervals throughout the experiment. As a result, we concluded that in the stable transfection of imatinib-resistant cells with lentivirus, during experimental procedures puromycine resistant subpopulations have emerged, and they exhibit different behaviors compared to ancestral cells in vivo atimic nude mice rather than localized in tissue. Keywords; chronic myeloid leukemia, imatinib, drug resistance, leukemic stem cell, tumorogenesis