Arsenic enhances temsirolimus-induced growth inhibition of selective breast cancer cell lines.

<p>(A) MDA-MB-468, MCF-7, SkBr3, and T47D cell lines were exposed to vehicle control (Vh; 5.3 x 10^-6 N NaOH and 2.5 x 10^-5 % EtOH in PBS), 2 µM arsenic trioxide (ATO), 5 ng/ml temsirolimus, or the combination for 48 hours and relative cell number assessed by SRB assay. (B&C) Cell lines were exposed to vehicle control (Vh), 1 µM ATO, 5 ng/ml temsirolimus, or the combination for 48 hours and stained with propidium iodide and assessed by flow cytometry for cell cycle analyses (B) or percentage of cells with fragmented DNA (C). Annexin V staining was performed in SkBr3 cells and the apoptotic cells were determined as those staining positive for annexin V, but negative fot 7AAD. Statistical significance is denoted as follows: * = p<0.05, ** = p<0.01, and *** = p<0.001. Experiments were performed at least three times with technical triplicates.