Fig. 5
Impact of clinically relevant CHK1 inhibitors in inducing ERα degradation and preventing proliferation in MCF-7 and Y537S cells. A Sensitivity scores of ERα-negative (black) and ERα-positive (red) breast cancer cell lines to AZD7762 (AZD), prexasertib (Prexa), MK8776 (MK), PF-477736 (PF), Ly-2603618 (Ly), PD-407824 (PD), CHIR-124 (CHIR), and SB-218078 (SB). A’ Sensitivity scores of ERα-negative (black) and ERα-positive (red) breast cancer cell lines to 4OH-Tamoxifen (Tam), VE822 (VE), and KU60019 (KU). * (p < 0.05), ** (p < 0.01) and **** (p < 0.001) indicate significant differences to drugs among ERα-negative or ERα-positive breast cancer cell lines. The graphs have been generated by downloading the experimental data from the Broad Institute through the DepMap portal https://depmap.org/portal. Each dot of the plot in (A and A’) represents the value of the indicated parameter in a single breast cancer cell line. Crude data are given in supplementary table 1. Western blot (B) and relative densitometric analyses (B’) of ERα expression levels in MCF-7 (yellow) and Y537S (red) cells treated for 24 h with the indicated doses of prexasertib (Prexa). The loading control was done by evaluating vinculin expression in the same filter. Significant differences with respect to control (0) were obtained by unpaired two-tailed Student’s t-test. Data show the mean ± the standard deviations, **** p < 0.0001. The number of replicates is given as solid dots in the bar graph. C Growth curve analyses in MCF-7 (yellow) and Y537S (red) cells were performed as indicated in the material and method section for 5 days with different doses of prexasertib (Prexa). The graph shows only one concentration for each cell line and the normalized cell index (i.e., cell number), which is detected with the xCelligence DP device and calculated at each time point with respect to the control sample. Each sample was measured in a quadruplicate. For details, please see the material and methods section. D The inhibitor concentration 50 (IC50) was calculated for each cell line at 5 days after initial treatment