Fig. 4: MYC expression and transcriptional activity in patient samples in function of ESR1.

a MYC expression levels (Y-axis) in a data set of 146 IBC and 252 nIBC tissue samples classified according to the ER status, calculated by stratifying ESR1 mRNA levels into low, moderate, and high categories. Data are represented in notched boxplot format and color-coding according to the legend shown underneath the plot. P values resulting from the pairwise comparison of the MYC expression distributions between the different tumor sample categories are indicated. b Scatter plot comparing ESR1 and MYC expression, represented in the X- and Y-axis respectively, in nIBC (left) and IBC (right) patient series. For each series, a trend line is plotted and the resulting Spearman correlation coefficients are shown in the top left corner. c Heatmap representing the result of a generalized linear regression analysis evaluating MYC expression levels (i.e., top row) and MYC transcriptional activation calculated using the gene sets published by Muhar et al., Gatza et al. and Bild et al. (i.e., bottom 3 rows) in function of the tumor phenotype (i.e., IBC vs. nIBC) and interactions thereof with different strata of ER expression. For each of the resulting categories, shown along the X-axis (i.e., nIBC—ER Moderate, nIBC—ER High, IBC—ER Low, IBC—ER Moderate, and IBC—ER High), regression coefficients representing the change in MYC expression or MYC transcriptional activity in that category relative to nIBC samples with low ER expression, are color-coded as shown in the legend. The heatmap for example shows that MYC expression (i.e., top row) in nIBC samples with high ER levels (i.e., 2nd column) decreases significantly (i.e., blue color) as compared to nIBC samples with low ER expression, whereas relative to the same category the MYC expression in IBC samples with high ER levels increases significantly. P values evaluating the significance of the changes are indicated in each cell.