In vitro activity: In HCT116 colorectal carcinoma cell line, with intact or depleted p53 protein levels, SNS-314 Mesylate shows enhanced efficacy when administered sequentially with other standard chemotherapeutic agents and the most profound synergies are identified for agents that activate the spindle assembly checkpoint, e.g., docetaxel and vincristine. A recent study shows that SNS-314 Mesylate shows potent antiproliferative activity in HCT116 cells and inhibits soft agar colony formation.

Kinase Assay: Humanized mouse Aurora A (amino acids 107-403) is expressed in E. coli as described previously. For IC50 assays, compounds are titrated three-fold in DMSO and diluted 12.5-fold into assay buffer (10 mM Tris HCl pH 7.2, 10 mM MgCl2, 0.05% NaN3, 0.01% Tween-20, and 0.1% BSA). Compounds are then diluted 4-fold into assay buffer containing Aurora A and FAM-PKAtide at final concentrations of 2 nM and 50 nM, respectively. The kinase reaction is initiated by adding ATP in assay buffer at a final concentration of 10 mM and incubated at 21 °C for 25 minutes. As a positive control, DMSO is added instead of compound and as a negative control assay buffer is added instead of Aurora A. Both control reactions are conducted in triplicate. To detect phosphorylated PKAtide, the kinase reaction is combined with Progressive Binding Solution (1:400 Progressive Binding Reagent, 1 × Buffer A, Molecular Devices) in a 1:3 ratio. The mixture is incubated for 30 minutes at 21 °C and the plate is scanned on an Analyst AD with excitation at 485 nm and emission at 530 nm. The percent relative enzymatic activity is calculated by normalizing the mP value for each well to the average positive control. Relative enzymatic activity values are plotted as a function of the logarithm of compound concentration and IC50 values are generated in GraphPad Prism software using a sigmoidal dose-response curve-fit. IC50's are calculated as the concentration of compound at which enzymatic activity.

Cell Assay: Viability is measured using the CellTiter-Blue cell viability assay. Cells are treated as described above, although with a 5-day incubation period. Cytotoxicity is determined by measuring intracellular ATP using the CellTiter-Glo Luminescence Cell Viability Assay. Cells (HCT116 SCR and HCT116 p53 RNAi cells) are seeded in white 96-well tissue culture plates at a density of 1.5-2 × 103 cells/well, and a serial dilution of SNS-314 is dosed in combination with fixed concentrations of either docetaxel or vincristine for a total of 72 hours. Viability is determined as the ratio between the ATP in treated cells versus control cells. Apoptosis is measured using the caspase-Glo 3/7 system. Cells are plated in white 96-well plates as described above and treated first with SNS-314 for 24 hours, washed with 200 μL of 1× PBS, and fresh medium is added with the second agent for 24 hours.

Mol Cancer Ther. 2009 Apr;8(4):930-9; Cancer Chemother Pharmacol. 2010 Mar;65(4):707-17.