Granulocyte-Macrophage Colony-Stimulating Factor, Phorbol Ester, and Sodium Butyrate Induce the CDl lc Integrin Gene Promoter Activity During Myeloid Cell Differentiation

To analyze the activity of the CDllc promoter during myeloid differentiation without the limitations of transient expression systems, we have stably transfected the myeloid U937 cell line with the pCDllC36l-Luc plasmid, in which the expression of the firefly luciferase cDNA is driven by the CDllc promoter region -361/+43, previously shown to confer myeloid specificity to reporter genes. The stable transfectants (U937-C361) retained the a b i l i t o differentiate in response to phorbol-ester (PMA), sodium butyrate (SB), granulocyte-macrophage colony-stimulating factor (GMCSF), and other differentiating agents. U9374361 differentiation correlated with increased cellular luciferase levels, showing the inducibility of the CD1 l e promoter during myeloid differentiation and establishing the U937-C361 cells as a suitable system for studying the myeloid differentiationinducing capacity of cytokines, growth factors, and other biological response modifiers. Unexpectedly, the inducibility of the CDllc gene promoter showed distinct kinetics and