Figure 3: IL-4 expression from cancer cells suppressed tumor grow and metastasis in a Rag2-/-; IL2Rγc-/- mouse orthotopic engraftment mode. A: EV-AC2M2 or IL4-AC2M2 cells were engrafted into the fourth mammary glands of Rag2-/- ; IL2Rγc-/- mice and tumor growth was assessed over a period of 19 days. Tumor growth rate of IL-4 expressing tumors (IL4-AC2M2) was significantly slower as compared to control tumors (EV-AC2M2) (P<0.001; n=6 for each group). B: Tumors were resected by recovery surgery on day 19 post-engraftment. On day 31 postengraftment, 12 days after tumor resection, mice were sacrificed and lungs were removed for biophotonic imaging of metastatic lesions. 100% (6 of 6) of the lungs harvested from control tumorbearing mice (EV-AC2M2) harbored detectable metastasis while none (0 of 6) of the lungs from IL-4 expressing tumor-bearing mice (IL4-AC2M2) displayed lung metastasis (P<0.0001; n=6 for each group; ND, not detectable). C: Tumors were resected on day 14 or day 19 post-engraftment for EV-AC2M2 and IL4-AC2M2, respectively, by recovery surgery when they had achieved a volume of ~500mm3. Twelve days after tumor resection mice were sacrificed and lungs were removed for biophotonic imaging of metastatic lesions. 100% (6 of 6) of the lungs harvested from control tumor-bearing mice (EV-AC2M2) harbored detectable metastasis while none (0 of 6) of the lungs from IL-4 expressing tumor-bearing mice (IL4-AC2M2) displayed lung metastasis (P<0.0001; n=6 for each group; ND, not detectable). Data shown are representative of four independent experiments.