Dithiocarbamates trigger differentiation and induction of CD11c gene through AP-1 in the myeloid lineage

It has recently been shown that the alteration of the cell-redox status affects the transcription factor expression and activity. Dithiocarbamates (DTCs) are potent antioxidant agents that can switch the expression of genes dependent on the activation of the transcription factors AP-1 and NF kappa B. In this study, we show that these agents triggered the expression of genes involved in myeloid differentiation of the promonocytic U-937 cell line. DTCs promoted differentiation-associated changes that included the surface up-regulation of beta 2-integrins (CD11a-c/CD18), cell growth arrest concomitant with transferrin receptor (CD71) down-modulation, induction of the nonspecific esterase enzyme, and a rapid drop in the mRNA levels of c-myc. A further analysis, focused on the molecular mechanisms leading to the activation of CD11c expression, revealed that the pyrrolidine derivative of DTC (PDTC) increased CD11c mRNA levels and augmented its gene promoter activity. Transfection experiments with reporter constructs harboring different promoter regions of CD11c gene, indicated the presence of a functional DTC-responsive region located between positions -160 and +40 of the promoter. Gel retardation assays revealed that the PDTC-induced DNA-protein complexes were restricted to members of the Fos and Jun families that bound to an AP-1 site located at position -60 from the transcription start site. A role for this site was confirmed by in vitro mutagenesis experiments that indicated the functional importance of this site for the CD11c gene transcriptional activation in response to PDTC. The effect of DTCs on myeloid cell differentiation supports a possible role for these agents in the therapy of some bone marrow-derived malignancies.