Rapamycin reduces expression of endogenous c-MYC and promotes terminal myeloid differentiation. (A) MPRO cells were treated with EtOH (vehicle control), 10−6 M AGN194204 (RXR), 80 nM rapamycin (rapa), or 10−6 M AGN194204 and 80 nM rapamycin in combination (RXR + rapa) for 48 hours. Protein lysates were analyzed for c-MYC expression by Western blotting. α-Tubulin was used as a loading control. (B) Quantitative real-time PCR was used to assay the abundance of myeloperoxidase (Mpo) and neutrophil-galactosidase-associated lipocalcin (Ngal) transcripts in MPRO cells treated as described in panel A. Results were corrected for β-2-microglobulin transcript abundance and represented as fold change relative to undifferentiated EtOH (vehicle control). Results are the mean plus or minus SEM of 3 independent experiments. (C) Representative morphology of MGG-stained MPRO cells treated with 10−6 M AGN194204 and EtOH (vehicle control) or 80 nM rapamycin. (D) Cells treated as in panel C were subject to FACS analysis for surface expression of CD11b. For panels B and D, results are the mean plus or minus SEM of 3 independent experiments. *P < .05, Student t test.
