Figure 5.

RNA Silencing of E2F1 Sensitizes Prostate Cancer Cells to ICAM-1 Mediated Anti-tumor Responses. A. E2F1 knockdown increases cytotoxicity through ICAM-1. DU145/sh-Con and DU145/sh-E2F1 cells were transiently transfected with duplex siRNA of ICAM-1. The DU145 derived cells were used as the target cells and the CIK cells as the effector cells. Both of them at various ratios of effector cells to target cells were mixed and cytotoxicity was measured by ⁵¹Cr release. The results are shown as the mean ± SD of triplicate measurements. B. The expression of membrane ICAM-1 in the indicated cells was measured by FACS with ICAM-1 specific antibody. C. The expression of IL-1β, TNF-α, IL-6 and IL-8 in DU145/sh-Con and DU145/sh-E2F1 cells were measured by real-time PCR. The data presents the fold-induction of the levels of each tested cytokine in DU145/sh-E2F1 cells over DU145/sh-Con cell, and represent the mean ± SD of triplicate measurements. D. E2F1 knockdown inhibits tumor xenografts growth in vivo, DU145 cells were stably transfected with the control vectors or shRNA expressing plasmids targeting E2F1 or ICAM-1 respectively and injected subcutaneously into nude mice. Tumor volumes were measured and estimated by the formula: length (mm) X width (mm) X height (mm)/2. The results are shown as the mean value ± SD of at least five tumors in each group. E and F. E2F1 knockdown increases ICAM-1-mediated leucocytes infiltration. The infiltrating leucocytes to DU145-derived tumors in nude mice were stained by H&E and indicated by arrows. The expression of E2F1 and ICAM-1 in these DU145-derived tumors was monitored by immunohistochemistry analysis, H&E staining (D) and Western blot (E).