Fig. 7: Combination treatment with αPD1 and trametinib reduced mammary tumor progression and increased the effector T-cell population.

Representative tumor images (a), and tumor weight plots (b) at day 22 from FVB mice implanted with HP5712 cells at 1×10⁶ cells per mammary fat pad, and treatment with PBS, PD1, trametinib (Tra), and PD1+Tra (n = 8 mice/group). c The plot of tumor volume in the processes of treatment in (a, b). d The plot of relative spleen weight from the same cohort of mice in a, b. Quantifications of PMN-MDSCs and M-MDSCs (e), CD4+ and CD8 + T cells (f) in CD45+ immune cell populations from the same cohorts of mice in a, b by CyTOF analysis at D12 (n = 3 mice/group). Quantifications of PMN-MDSCs and M-MDSCs (g), CD4+ and CD8 + T cells (h) in CD45+ immune cell populations from the same cohorts of mice in a, b by CyTOF analysis at D22 (n = 3 mice/group). i, j Tumor images from the HP Ctr mice, HP mice treated with αPD1 and Tra, and HP mice treated with αPD1 and Tra with depletion of T cell using CD8 antibody (i). The plot of tumor weight (j) in the same cohort of mice in (i) (n = 8 mice in each group). The protein levels of Smyd3 and Shcbp1 in tumors initiated with HP5712 cells and treatment with PBS, αPD1, Tra, and αPD1+Tra in FVB mice at D12 (k) and D22 (l) as shown by Western blots. The protein levels of pMek, pErk, Kras, and Grb2 in tumors initiated with HP5712 cells and treatment with PBS, αPD1, Tra, and αPD1+Tra in FVB mice at D12 (m) and D22 (n) as shown by Western blots. Expressions of Smyd3 (o) and Shcbp1 (p) in G600 cells with the treatment of E2, Tra, and E2 together with Tra at 1 hour, 2 hours, 4 hours, and 24 hours as determined by qPCR.