Dual Specificity Phosphatase 3 knockdown drives myeloid leukemia cells to differentiate into macrophages and polarize

The dual-specificity phosphatase 3 (DUSP3) has been implicated in the maintenance of genomic stability, cell cycle, proliferation, and differentiation. Recently we reported an important role of the interaction between DUSP3 and nucleophosmin (NPM) proteins on the regulation of the p53 actions to maintain genomic stability. Since both p53 and NPM often have mutations related to a diverse set of leukemia, this work aimed to evaluate the roles of DUSP3 in the differentiation of two acute myeloid leukemia cell lines not expressing the p53 protein, and the potential correlations with NPM expression. The results demonstrated higher levels of DUSP3 in THP-1 cells compared to HL-60 cells under basal conditions. After PMA-induced differentiation into macrophages, only HL-60 cells presented a dramatic decrease in DUSP3 and NPM proteins expression. The permanent DUSP3 knockdown in THP-1 and HL-60 cells contributed to their differentiation and non-classical polarization after PMA exposure, since the CD14, MHCII, and CD163 markers were decreased whereas the CD11b and CD206 markers were increased. Bioinformatics analyses identified that the negative regulation of the npm1 and dusp3 genes correlates with the reduced survival of patients with acute myeloid leukemia (AML) and the strong positive correlation existing between the expression of these two genes is progressively lost according to the degree of maturation of the myeloid cells. These results suggest DUSP3 plays regulatory roles of differentiation and polarization of myeloid cells, and its association with NPM expression levels may allow a better understanding of mechanisms involved in leukemia and treatment resistance.