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. 2013 Jul 9;8(7):e68973. doi: 10.1371/journal.pone.0068973

Figure 1. The HDAC inhibitor PCI-24781 potentiates tamoxifen by inducing mitochondrial-mediated apoptosis.

Figure 1

(A) MCF-7 cells were treated with increasing concentrations of PCI-24781 and with or without 10 µM OH-tamoxifen for 72 hours and assayed for viability. The dotted line indicates maximal achievable serum levels in patients [26]. MCF-7 cells were treated with vehicle (V), 0.1 µM PCI-24781 (P), 10 µM OH-tamoxifen (T), or the combination (PT) for 72 h. Cells were evaluated by western blotting for expression of apoptotic BH3 family member proteins, cytoplasmic cytochrome C, and PARP cleavage (C) and by microscopy for TUNEL staining (B). (D) The indicated cell lines were treated with vehicle (V), 0.1 µM PCI-24781 (P), 10 µM OH-tamoxifen (T), or the combination (PT) for 72 hours assayed for viability. Vehicle and combination treated cells were further evaluated by western blot for PARP cleavage. For (A), (B), and (D) the average from three independent experiments is presented, with the error bars indicating the standard error of the mean. An (*) indicates a significant difference compared to vehicle treatment (P-value < 0.05), while an (#) indicates an insignificant difference (P-value > 0.05).