Figure 6. STK40 is a pro-survival protein kinase in breast cancer cells.

MDA-MB-468 and HCC38 cells were transfected with control siRNA (black) or with one of three different siRNAs against STK40 (green: ^#3, ^#5, ^#6). (A) RT-qPCR analysis showing that transfection with these three STK40 siRNAs results in lower levels of STK40 RNA. The data shown are means ± SD from three independent experiments. (B) Cell viability was assessed in MTT (MDA-MB-468) or WST-1 (HCC38) assays, 144 hours after transfection. Results are presented as percent cell viability relative to cells treated with control siRNA (100%). The data shown are means ± SD from three independent experiments. (C) The cells were transfected and then cultured in six-well plates for 6-10 days, until colony formation. The number of colonies is presented as a percentage relative to that in cells treatment with the control siRNA (graphs). The data shown are means ± SD from three independent experiments. A representative image of one well is also shown for all conditions. The 2 images for ctrl siRNAs are the same than those shown in Figure 2C as the experiments were performed at the same time and therefore all the LRP5, LRP6 and STK40 siRNA shared the same control siRNAs. (D) Transfected MDA-MB-468 cells were embedded in agar medium. One month later, the colonies formed were stained with MTT, photographed and counted. The number of colonies is expressed as a percentage relative to that for cells treated with control siRNA (graph). The data are expressed as means ± SD from three independent experiments. A representative image of one well is shown for all conditions. (E) We analyzed the cleavage of PARP (c-PARP), caspase 3 (c-casp3), caspase 7 (c-casp7) and caspase 8 (c-casp8) by western blotting, 96 hours after transfection. One representative experiment of the three performed, all of which gave similar results, is shown. Actin was used as a loading control. ^*P<0.05, ^**P<0.01, ^***P<0.001 (i.e. a decrease relative to the control siRN A).