Influence of ST1346 on the steady-state levels of ATRA-modulated proteins and the secretion of the MCP-1 chemokine, TNF, and IL-1 proinflammatory cytokines.

NB4 cells were treated for 1 or 3 days, as indicated, with vehicle alone, ST1346 (10 μM), the indicated concentrations of ATRA, or the combination of the 2 compounds. (A) The level of expression of the indicated phenotypic markers was determined by flow cytometry using fluorescein-labeled monoclonal antibodies against ICAM-1 and integrin α4 or irrelevant isotype-matched antibodies (Neg). NB4 cells are more than 95% positive for the expression of the 2 integrins in all the experimental conditions considered. The results are expressed in mean cell-associated fluorescence. (B) The amounts of the indicated proteins were determined by Western blot analysis with the use of anti–cathepsin D, anti-Tyk2, anti-Mlh1, and antiactin polyclonal antibodies. (C) The amounts of MCP-1, TNF, and IL-1 secreted in the conditioned medium of NB4 cells treated as indicated were determined with the use of specific ELISA assays. Results are expressed as the means ± SD of 3 separate culture dishes and are representative of at least 3 independent experiments.