Fig. 3

MEK inhibition increases tumor immunogenicity but reduces T-cell effector functions. Co-culture studies undertaken with AT3ova tumor cells and CD8⁺ OT-I T cells; 12 h pre-treatment followed by co-culture, or 24 h co-culture with trametinib treatment. a FACS analysis of MHC-I expression of AT3ova tumor cells normalized to non-treated tumors. b IFNγ production from OT-I T cells. c–e Mice (n = 3 per group) bearing AT3ova tumors were treated with vehicle (PEG 400/solutol) or trametinib (1 mg/kg/daily), and tumors were harvested on day 2, 4, 6, and 9 post treatment. Changes in c TIL frequency (CD8⁺, CD4⁺ FOXP3⁻, CD4⁺ FOXP3⁺) as a proportion of CD45⁺ live cells, d cytokine production by T cells, and e proliferation of T cells measured by Ki67 expression were determined ex vivo by FACS analysis. Values were normalized to vehicle controls at each time point and data are expressed as fold change for the number of positive cells. Data are presented as mean ± SEM, and is a representative of three independent repeats. P-values represent unpaired t-tests at each time point and post hoc Fisher’s LSD tests. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001