Chronic myelogenous leukemia cells convert to myofibroblasts in vitro: Effect of vascular endothelial growth factor on development of the microenvironment

To elucidate the biological characteristics of chronic myelogenous leukemia (CML) cells, we observed morphological and functional changes of CML cells during primary long-term culture, in which their morphology changed to that of myofibroblasts with similar molecular characteristics to the parental CML cells including BCR–ABL fusion gene, and produced cytokines such as granulocyte colony-stimulating factor, interleukin-6, and vascular endothelial growth factor (VEGF)-A. When cultured on the CML-derived myofibroblasts, parental non-adherent CML cells significantly proliferated. When anti-VEGF-A-neutralizing antibody was added to the cultures, non-adherent CML cell proliferation was significantly inhibited. These observations indicate that CML cells can convert their morphology and function to adherent myofibroblasts, and produce a significant amount of cytokine to give a growth-promotion activity to CML cells.