Combination therapy of an anticancer drug with the FNIII14 peptide of fibronectin effectively overcomes cell adhesion-mediated drug resistance of acute myelogenous leukemia.
We investigated whether FNIII14, a 22-mer peptide derived from fibronectin (FN) that potently impairs interaction of FN with β1-integrin, could overcome cell adhesion-mediated drug resistance (CAM-DR) induced by very late antigen (VLA)-4-to-FN interaction in acute myelogenous leukemia (AML). Two AML cell lines, U937 cells and HL-60 cells, and fresh leukemic cells from six AML patients with high α4-integrin expression exhibited CAM-DR to cytosine arabinoside (Ara C) through VLA-4-to-FN interaction, while fresh leukemic cells from two AML patients with low α4-integrin expression did not display CAM-DR to Ara C. FNIII14 impaired VLA-4-to-FN interaction and restored sensitivity to Ara C in the CAM-DR leukemic cells. In these CAM-DR leukemic cells, upregulation of Bcl-2, which was induced through the focal adhesion kinase/Akt signal pathway upon VLA-4-to-FN interaction, was inhibited by FNIII14 treatment. In a mouse model of minimal residual disease (MRD) in bone marrow, 100% survival was achieved by combining FNIII14 with Ara C, whereas Ara C alone prolonged survival only slightly. The myelosuppression induced by Ara C was not augmented by the combination of FNIII14 in mouse experiments. Thus, the combination of anticancer drugs and FNIII14 holds promise to eradicate MRD in bone marrow after chemotherapy.Leukemia (2008) 22, 353–360; doi:10.1038/sj.leu.2405017; published online 1 November 2007