Figure 5. Exosomal PD-L1 Suppresses Tumor Progression in Syngeneic Colorectal Cancer Model.
(A) Western for PD-L1 in WT and Rab27a null MC38 100k g extracellular fraction.
(B) Flow cytometry for surface PD-L1 on MC38 cells.
(C) Cell counts over time for Rab27a null versus WT MC38 cells. n = 3. Error bars represent SD.
(D) Cell counts over time for Pd-l1 null versus WT MC38 cells. n = 3. Error bars represent SD.
(E) Tumor growth over time following subcutaneous injection of 1 × 106 WT, Rab27a null, or Pd-l1 null MC38 cells into immunocompetent B6 mice. n = 5 for each genotype. Error bars represent SEM. MC38 WT versus MC38 Rab27a null, p < 0.05. MC38 WT versus MC38 Pd-l1 null, p < 0.05. MC38 WT versus MC38 Pd-l1 null; Rab27a null, p < 0.05 (two-way ANOVA test).
(F) Mouse survival curve following injection of cells like in (D). n = 10 for each genotype. MC38 WT versus MC38 Rab27a null, p < 0.001. MC38 WT versus MC38 Pd-l1 null, p < 0.001. MC38 WT versus MC38 Pd-l1 null; Rab27a null, p < 0.001 (log rank test).
(G) Survival curve for mice injected with WT, Rab27a null, or Pd-l1 null MC38 cells followed by treatment with either anti-PD-L1 or isotype control antibody. n = 5 for each condition. MC38 WT isotype versus MC38 WT anti-PD-L1, p < 0.01. MC38 Rab27a isotype versus MC38 Rab27a anti-PD-L1, p < 0.05. MC38 Pd-l1 isotype versus MC38 Rab27a anti-PD-L1, ns. (log rank test).
See also Figure S7.