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Blood, 15 August 2007, Vol. 110, No. 4, pp. 1238-1250. Prepublished online as a Blood First Edition Paper on April 9, 2007; DOI 10.1182/blood-2006-02-003772.
NEOPLASIA VEGFR-1 (FLT-1), ß1 integrin, and hERG K+ channel for a macromolecular signaling complex in acute myeloid leukemia: role in cell migration and clinical outcome1 Department of Experimental Pathology and Oncology, University of Firenze, Firenze; 2 Department of Internal Medicine, University of Torino; 3 Azienda Ospedaliero Universitaria (A.O.U.). Hematology, Policlinico di Careggi, Firenze; 4 Azienda Ospedaliero Universitaria Careggi, Department of Laboratory Medicine, Firenze; 5 Department of Biotechnology and Biosciences, University of Milano Bicocca, Milano; and 6 Department of Public Health, Firenze, Italy Leukemia cell motility and transendothelial migration into extramedullary sites are regulated by angiogenic factors and are considered unfavorable prognostic factors in acute leukemias. We have studied cross talk among (1) the vascular endothelial growth factor receptor-1, FLT-1; (2) the human eag-related gene 1 (hERG1) K+ channels; and (3) integrin receptors in acute myeloid leukemia (AML) cells. FLT-1, hERG1, and the ß1 integrin were found to form a macromolecular signaling complex. The latter mostly recruited the hERG1B isoform of hERG1 channels, and its assembly was necessary for FLT-1 signaling activation and AML cell migration. Both effects were inhibited when hERG1 channels were specifically blocked. A FLT-1/hERG1/ß1 complex was also observed in primary AML blasts, obtained from a population of human patients. The co-expression of FLT-1 and hERG1 conferred a pro-migratory phenotype to AML blasts. Such a phenotype was also observed in vivo. The hERG1-positive blasts were more efficient in invading the peripheral circulation and the extramedullary sites after engraftment into immunodeficient mice. Moreover, hERG1 expression in leukemia patients correlated with a higher probability of relapse and shorter survival periods. We conclude that in AML, hERG1 channels mediate the FLT-1–dependent cell migration and invasion, and hence confer a greater malignancy.
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