Fig. 3

Modulation of CK1δ and CK1ε expression does not significantly influence melanoma cell viability and proliferation. a Inhibition of isoform specific CK1- activity via siRNA mediated knockdown of CK1α, CK1δ and CK1ε. SbCl2 (left diagram) and SKMEL19 (right diagram) cells were used and cell growth was monitored for 4 days using the MUH viability assay. Shown is the mean with SD of hexatuplicates. b Inhibition of CK1- activity via different small molecules (upper left and right plus lower left diagram) with predominant efficacy for CK1δ and CK1ε. Dose response curves using viability measurements (MUH assay) 72 h after treatment with the inhibitors are shown. Mean values with SD values of hexatuplicates are shown. The fourth diagram (lower right) shows dose response curves of melanoma cell lines treated with the allosteric CK1α activator pyrvinium at 72 h post start of treatment. c Effects of CK1 specific small molecules on 3D spheroid SKMel19 cultures. Spheroids were treated with the indicated concentrations of small molecules for CK1- inhibition or CK1α activation for 4 days. Live-dead staining with calcein-AM (1 μM) and propidium iodide (100 ng/ml) and size measurements are shown. Mean with SEM values of five spheroids are used. Multiple t-tests against vehicle controls were used for statistical analysis (* p < 0.05). d Effect of overexpression of the isoforms CK1α, CK1δ and CK1ε in SbCL2 and SKMEL19 melanoma cells. Isoforms were overexpressed as previously (Fig. 2b, c) and viability was assessed 72 h after overexpression of the respective CK1- isoforms by MUH assays. Shown are changes in viability after overexpression as mean values with SD of hexatuplicates are shown (*** p < 0.001)