Angiogenesis in different clinical phases of chronic myeloid leukemia

Abstract Angiogensis plays the crucial role in growth and dissemination of neoplastic diseases, both for solid tumors and hematopoietic malignancies. Development of the abundant neoplastic vasculature results from an imbalance between pro- and antiangiogenic regulatory mechanisms. The investigation was focused on expression of the main regulatory angiogeneic factors in different phases of chronic myeloid leukemia (CML) and on influence of leukemic cells on the human umbilical vein endothelial cells proliferation. The groups of 29 patients with CML and of 14 healthy controls were enrolled to the study. The expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor, interleukin-8, angiopoetin-1, platelet factor-4, extracellular matrix metalloproteinases (MMP) -2 and -9 as well as tissue inhibitors of metalloproteinases was determined in peripheral blood and bone marrow mononuclear cells with the use of quantitative real-time PCR method and additionally the concentration of VEGF with the flow cytofluorometry. We evaluated the phosphorylation of endothelial mitogen activated protein kinase in human umbilical vein endothelial cells after incubation in CML cells conditioned media, applying Western blot technique. We determined an influence of the leukemic cells on the endothelial cells proliferation with the colorimetric metabolic MTT test. We showed, that in peripheral blood and bone marrow mononuclear cells in CML patients most of the studied factors were increased at the time of CML diagnosis and became lower in remission. In newly diagnosed CML patients an expression of VEGF, MMP-2 and MMP-9 was particularly elevated. In remission, the levels of VEGF and metalloproteinases, specifically MMP-9, were decreased. If failed to achieve remission, the patients presented the elevated expression of most of the investigated angiogenic factors. In the acceleration or blast crisis phase angiopoetin, VEGF and MMP-2 levels were particularly high. We noticed the markedly enhanced human umbilical vein endothelium proliferation after an incubation in CML cells conditioned media, both in the test of mitogen activated protein kinase phosphorylation in endothelial cells and in the metabolic test for the proliferation intensity of endothelium. The differences of an angiogeneic potential found between clinical phases of CML, and the ability of leukemic cells to stimulate endothelial proliferation, point at the significance of neovascularisation in CML pathogenesis. Further studies are necessary to delineate the possibility of the use of angiogenic inhibitors in the treatment of this malignancy.