Coordinated deregulation of cellular receptors, proangiogenic factors and intracellular pathways in acute myeloid leukaemia

Abstract

Different signaling routes seem to be simultaneously triggered in leukemia, with distinct and overlapping activities. To analyze if altered signals are coordinated and to evaluate their effect on this disease, we have investigated in acute myeloid leukemia samples (AML) the expression and activation status of procoagulant/proangiogenic tissue factor receptor (TF), angiogenic protein VEGF, its cell surface receptor, KDR, and two intracellular proteins involved in their regulation: extracellular regulated kinase (ERK1/2) and nuclear factor kappa-B (NFκB). Significantly higher mRNA and protein levels of VEGF, KDR, and TF were found in the AML samples versus controls. Enhanced ERK phosphorylation and NFκB activation in most AML samples were also found. In vitro MEK/ERK and NFκB-binding activity blockade suppressed the constitutive expression of TF, VEGF, and KDR. Anti-TF antibody treatment significantly suppressed VEGF and KDR expression as well as ERK activation, suggesting that TF expressed by AML cells may be both a regulatory target and a mediator of tumor-associated angiogenesis. Patients showing parallel activation of the studied proteins trended to exhibit higher incidence of fatal outcome. Our results show a coordinated deregulation of cellular receptors, proangiogenic factors, and intracellular pathways in leukemia cells, which may help to design mechanism-based combinations of single transduction-related therapies.