Fig. 2: Inhibition of CDK8/19 and other epigenetic modifiers prevents resistance to ERK/MAPK inhibition.

a Scatter plots comparing gene expression changes in SW1573 cells (left) and SW620 cells (right) treated with SCH772984 (1 µM) compared to DMSO (1:1000) for either one week (early) or eight weeks (stable resistance), each performed in triplicate. Each dot represents a single gene, with colored dots representing statistically significant (p < 10⁻³) gene expression changes at the indicated time points, with statistical significance determined by Wald test using the Benjamini and Hochberg method to correct for multiple hypothesis testing. b Venn diagram depicting differentially expressed genes (p < 10⁻³) in MIA PaCa-2, SW1573, and SW620 cells treated with SCH772984 (1 µM) relative to DMSO (1:1000) for eight weeks (stable resistance). c Reverse volcano plot depicting gene set enrichment analysis gene sets from the MsigDB Biologic Process Ontology based on the gene expression data from Fig. 2b; Venn diagram depicting enriched gene sets with an FDR < 0.1 (insert). d Schematic representation of the transcriptional modifier pharmacologic screen (left). The heatmap (right) demonstrates the ratio of cell doublings of MIA PaCa-2 cells co-treated with the indicated epigenetic modifier and MAPK inhibitor compared to that MAPK inhibitor alone for three weeks, with each row representing a single biologic replicate. The doubling ratio is plotted, which is calculated as the number of doublings per experimental condition compared to control condition. e Crystal violet staining of 21-day colony growth in MIA PaCa-2 cells treated with the indicated drug combinations, performed in triplicate. f Immunoblot of MIA PaCa-2 cells with indicated genetic modifications (top); the doubling ratio of those same populations treated with Senexin A (1 µM) relative to DMSO (1:1000) for two weeks, either alone (basal growth) or in the presence of SCH772984 (1 µM) (bottom), each condition performed in triplicate. g Eight-point growth inhibition assay of MIA PaCa-2 cells (left), SW620 cells (middle), and SW1573 cells (right) treated with increasing concentrations of SCH772984 in the background of Senexin A (1 µM) or DMSO (1:1000) for four days (top), each condition performed in triplicate; TTP assay of those same cell lines and drug conditions for eight weeks of treatment, each condition performed in triplicate. Error bars represent standard deviations.