N6L Pseudopeptide Interferes with Nucleophosmin Protein-protein Interactions and Sensitizes Leukemic Cells to Chemotherapy

De Cola A, et al., 412:272-282, Cancer Letters, 2018

Nucleophosmin (NPM1) is a nucleolar phosphoprotein, which plays key structural and functional roles including centrosome duplication, rRNA biogenesis and maturation, DNA damage response and chaperone activity. In one third of acute myeloid leukemia (AML) patients, NPM1 is aberrantly localized in the cytoplasm. It is believed that this "wrong" cytoplasmic localization of NPM1 obstruct the tumor suppressive mechanisms. The anticancer molecule NucAnt 6L (N6L) is a synthetic pseudopeptide which has been shown to interact with NPM1. Investigated herein are the interaction of N6L with NPM1 and the antitumor effect of N6L on AML cell lines. The binding interaction between N6L and NPM1 was studied by using Surface Plasmon Resonance (SPR). A Pall ForteBio Pioneer instrument equipped with a Streptavidin-coated BioCap sensor chip was used to perform all SPR experiments. Biotinylated N6L was immobilized onto sensor chip surface. Both human full length NPM1 and its isolated N-terminal domain were injected in increasing concentrations. SPR data obtained were globally fitted using two-site and three-site binding models. Equilibrium dissociation constants (KD) were determined for all binding interactions between N6L and NPM1 constructs. Overall results of this study demonstrate that N6L interferes with NPM1 protein-protein interactions and sensitizes AML cells to chemotherapy, suggesting that N6L may have important implications for the development of AML therapies.

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