Figure 6. Tumor-stromal interaction accelerates PDAC progression in a Cxcr2-dependent manner in vivo.
(A) Growth of subcutaneous tumor allograft. K399 PDAC cells (3 × 106) or a mixture of 1.5 × 106 PDAC cells and 1.5 × 106 K643f fibroblasts were subcutaneously injected into nude mice. The mixture showed faster tumor growth. n = 8/group. (B) H&E staining of subcutaneous tumors. Scale bar: 200 μm (insets, 100 μm). (C) Growth of subcutaneous mixed-cell tumor allograft with or without CXCR2 antagonist. A mixture of 1.5 × 106 K399 PDAC cells and 1.5 × 106 K643f fibroblasts was subcutaneously injected into nude mice, and 1 week later, 30 mg/kg repertaxin or PBS was injected subcutaneously 5 days/week. Inhibition of Cxcr2 slowed tumor growth. n = 7/group. Tumor volume of day 1 was assigned as 1, and relative volume is shown. (D) Growth of subcutaneous mixed-cell tumor allograft with or without Cxcr2 knockdown. A mixture of Cxcr2 wild-type PDAC cells (K399) and Cxcr2-knockdown fibroblasts (K643f) (1.0 × 106 each) (group C) or a mixture of Cxcr2-knockdown K399 and Cxcr2 wild-type K643f (1.0 × 106 each) (group D) was subcutaneously injected into nude mice. n = 12/group. Cxcr2 knockdown in fibroblasts slowed tumor growth. The tumor volume was calculated by the following equation: volume = 0.5 × L × W2. *P < 0.05; **P < 0.01; ***P < 0.001.