Knockdown of dual-specificity phosphatase 3 drives differentiation and polarization of myeloid leukemia cells into macrophages with reduced proliferative and DNA repair fitness.

Dual-specificity phosphatase 3 (DUSP3) regulates key cellular processes, including the cell cycle, proliferation, and differentiation. Recently, we demonstrated its crucial role in maintaining genomic stability by interacting with and dephosphorylating nucleophosmin (NPM), thereby modulating nuclear p53 activity under genotoxic stress. Given the frequent mutations in both p53 and NPM in acute myeloid leukemia (AML), this study aimed to investigate the impact of DUSP3 knockdown in two p53-deficient AML cell lines and explore potential correlations with NPM expression. THP-1 cells exhibited higher basal levels of DUSP3 and NPM compared to HL-60 cells, while DUSP3 knockdown reduced NPM expression in HL-60 cells. Upon phorbol 12-myristate 13-acetate (PMA)-induced differentiation into macrophage-like cells, only HL-60 cells displayed decreased levels of both DUSP3 and NPM. DUSP3 knockdown enhanced differentiation in THP-1 and HL-60 cells and promoted non-classical M2 macrophage polarization following additional PMA exposure, as indicated by increased expression of CD11b and CD206. Bioinformatics analysis revealed significant correlations between DUSP3 and NPM gene expression, AML patient survival, and the maturation stage of myeloid cells. Furthermore, DUSP3 knockdown in undifferentiated HL-60 cells impaired proliferation and compromised genomic stability under genotoxic stress induced by doxorubicin. These findings suggest that DUSP3 plays a regulatory role in the differentiation, polarization, and proliferation of myeloid cells. Through the modulation of NPM expression and activity, DUSP3 may contribute to a deeper understanding of leukemia pathophysiology and mechanisms of chemotherapy resistance.