Figure 5

MYB overexpression in MCF-7 cells prevents differentiation-inducing agent-induced differentiation and growth arrest. (a) MCF-7 cells were stably transduced with empty pMYS-IRES-GFP vector, or vectors encoding HA-tagged WT-or truncated, activated CT3-MYB. Western blotting with anti-MYB Ab and anti-HA Ab confirmed the expression of exogenous, HA-tagged MYB proteins. Note that the anti-MYB antibody used does not detect CT3-MYB. The Western blot was also probed for BCL2 expression (see text); a ß-tubulin loading control is also shown. (b) MYB overexpression blocks lipid accumulation associated with differentiation. Cells were treated with 0.5 mM or 1 mM sodium butyrate (NaBu) for 72 hours, stained with Nile Red and analyzed by flow cytometry. (c) Proliferation of MCF-7 cells overexpressing WT or CT3-MYB. MCF-7 cells overexpressing the WT or CT3-MYB, and controls, were grown in normal medium over seven days. (d) Proliferation of MCF-7 cells overexpressing the WT or CT3-MYB grown in medium containing 1 mM NaBu over seven days. In (c) and (d) cells were counted on days one, three, five, and seven. Standard deviation is represented by error bars (n = 3).