Fig. 1. Local p53 activation in the EL4 TME promotes systemic antitumor immunity and tumor regression.
A. 1 X 106 EL4 tumor cells were injected s.c. in the right flank of WT mice. When tumors reached 100 – 300 mm3, they were treated i.t. with 100 μl of 20 μM nutlin-3a or PBS twice, usually on day 6 and day 8. Tumor size was measured every day. When tumor diameters exceeded 15 mm, tumor bearing mice were euthanized. Nutlin-3a treated mice that experienced complete tumor elimination were re-challenged with1 X 106 EL4 cells on day 20. Tumor growth was assessed every other day till day 40. Individual EL4 tumor growth in WT mice treated with either PBS (left) or nutlin-3a (center and right) was plotted (n = 17–20). B. EL4 tumor growth in Rag1null and WT mice that were established s.c. and treated i.t. with 100 μl of 20 μM nutlin-3a or PBS (n = 5). C & D. 2 X 105 EL4 tumor cells were injected s.c. in both the right and left flanks of WT mice. When tumors reached 100 – 300 mm3, usually in 10 days, tumors only in the right flank received i.t. treatment of 100 μl of 20 μM nutlin-3a or PBS twice, one day apart. C. Tumors in both flanks were measured every day. The size of tumor at the side of treatment (top panel) and side contralateral to the treatment (right panel) was plotted. (n = 5). D. The percentages of tumor infiltrating (TILeus) CD8 T cells (left panel) and IFN-γ producing CD8 cells (right panel) were determined via flow cytometry. (n =5). The experiments were repeated at least 2–3 times with similar results. Data are presented as mean ± SEM of 5 – 20 mice. B and C. *** p < 0.001, two-way ANOVA; D. ** p < 0.01, *** p < 0.001, two-sided Student’s t-test.