Figure 2

Entinostat reduces the protein levels of endogenous, but not exogenous, erbB2 and erbB3 in human and mouse breast/mammary cancer cells. (a) MDA-MB-453 (MDA-453) and BT474 cells transiently transfected (TXN) with either control vector (Vector) or pDsRed-erbB3 (erbB3) were cultured in the presence or absence of entinostat for 24 h. Cells were collected and subjected to western blot analyses with specific antibody directed against erbB2, erbB3, or β-actin. (b) MDA-MB-435 (MDA-435) and 435.eB1 cells were treated with entinostat at the indicated concentrations for 24 h. Cells were collected and subjected to western blot analyses with specific antibody directed against erbB2, erbB3, or β-actin. (c) Mammary tumor cell lines 85815 and 85819 were plated onto 96-well plates. After 24 h incubation, cells were grown in either control medium, or the same medium containing indicated concentrations of entinostat for another 72 h. The percentages of surviving cells relative to controls, defined as 100% survival, were determined by reduction of MTS. Bars, S.D. The data are representative of three independent experiments. (d) The cells treated with entinostat (ent) at indicated concentrations for 24 h or with 2 μmol/l of entinostat (ent) for different time points were collected and subjected to western blot analyses with specific antibody directed against erbB2, erbB3, IGF-1R, or β-actin