Fig. 7

Silencing of SIRT2 increases long-term Lapatinib cytotoxicity in NPC cells. a NPC cells were transfected with siNSC and siSIRT2 smartpools. After 24 h both siNSC and siSIRT2-transfected cells were treated with DMSO or 5 μM Lapatinib for another 24 h. Forty-eight h after transfection, cells were harvested and SIRT2 protein knockdown was confirmed by western blot analysis. Protein levels were determined by using ImageJ and the protein levels relative to β-tubulin are shown below protein bands as ratios to the 0 h Lapatinib controls. b Forty-eight h after transfection, 1000 cells were seeded per well, into 6-well plates and then treated with the Lapatinib concentrations of 0, 0.01, 0.05, 0.1, 1 and 5 μM for 72 h and colony formation observed for 15 days. At the end of this time period, cells were fixed with 4% paraformaldehyde and stained with crystal violet. The stain was solubilised with 33% acetic acid and absorbance at 592 nm were obtained. Graphs were generated to show the effect of silencing SIRT2 on Lapatinib sensitivity. c Best fit-curves were generated to determine the effect of SIRT2 knock down on the IC₅₀ of Lapatinib in 5-8F and 6-10B cells. Numerical data represent the average ± SEM of three different experiments (**** P < 0.0001)