Fig. 5

MSS CRC cell lines are highly sensitive to STAT5/MEK inhibitors. a MSS BRAF(V600E), KRAS mutant and b MSI BRAF(V600E), KRAS mutant CRC cells were seeded at low confluence and treated with increasing concentrations (lower than IC50 values) of momelotinib, trametinib or in combination (comb) twice a week. Viability was assessed by a colony formation assay. Cells were fixed, stained, and photographed after 10 days of culture. For each cell line, in the low panel the percent of cell growth inhibition determined by treatment is shown. Results represent three separate experiments, each performed in triplicate. P-value by two-tailed Student’s (related to untreated vehicle control) are shown, P* < 0.05, **P < 0.01, ***P < 0.001, NS, non significant. c representative immunoblot of phosphorylated STAT5 and ERK1/2 compared to LY6G6D following treatment with momelotinib, trametinib or combination. Bottom right, quantification to β-actin. Low left, viability of HCT116 cell lines (KRAS mutant), and its derivative HKE-3 KRAS wild type (KRASWT) to momelotinib, trametinib or their combination assessed by colony formation assay. Low on the right, quantification of LY6G6D and FUT4 mRNA by RT-PCR analysis following drug treatments. ***P < 0.001 by Mann–Whitney U test. d Illustration of immune suppressive pathway mediated by LY6G6D and CD15, which could predict response to JAK- and MAPK-directed therapies in microsatellite stable CRC