FACTORS SUPPORTING SURVIVAL IN MULTIDRUG RESISTANT LYMPHOBLAST CELL LINE IM-9/ER
In this work we have analyzed the influence of some epigenetic factors, such as serum starvation, increased extracellular calcium concentration and presence of the solubilysed extracellular matrix protein fibronectin, on the level of resistance to apoptosis in cells of IM-9 lymphoblast line and its subline IM-9/ER established at Laboratory for Leukemia Pathophysiology of Hematology and Blood Transfusion Institute, Minsk, Belarus. It is shown that IM-9/ER cells are more resistant to serum starvation than parental IM-9 cells. Increase of calcium led to the enhanced apoptotic resistance in cells of both sublines. Addition of fibronectin to the culture medium caused tyrosine phosphorylation of focal adhesion kinase pp125FAK, and did not influence the level of cellular drug-resistance. Finally, the capability of IM-9/ER cells to increased short-term adhesion on immobilized fibronectin was revealed.Our data suggest that some factors, which act in vivo, can promote selective survival and progression of malignant clone by increasing of its resistance to apoptosis. These factors must thus be taken into account in clinics while the resistance level and prognosis of lymphoproliferative disorder are assessed in in vitro experiments.
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