Fig. 1.

Combined depletion of ITGB4 and E-/P-selectin cooperatively reduces human prostate cancer xenograft tumor formation. Mean fold up- or down-regulation of integrin subunit gene expression comparing highly metastatic PC-3 vs. weakly metastatic DU-145 human prostate cancer cells (n = 3) and validation of differential ITGB4 protein levels in vitro and in situ. Arrowheads indicate ITGB4⁺ tumor cells at the xenograft tumor margin (A). shRNA-mediated knockdown of ITGB4 in PC-3 cells (B) and s. c. xeno-transplantation of shControl vs. shITGB4 cells into E-/P-selectin wildtype vs. knockout Pfp^−/−/Rag2^−/− mice resulting in four experimental groups: shControl/WT (blue), shITGB4/WT (orange), shControl/KO (grey), shITGB4/KO (green) as illustrated (C). Survival of mice after s. c. injection of tumor cells (endpoint: s. c. xenograft tumor of ~ 1.5 cm³, D). Tumor weights (E) and percentage of ITGB4⁺ primary tumor cells (F) at necropsy. Human cell loads in blood and lung samples at necropsy (s. c. xenograft experiment) (G). Black lines in scatter plots represent mean values. Red dotted lines in (G) indicate the detection limit of the respective Alu-PCR experiment. All statistical comparisons indicated by asterisks were calculated vs. shControl/WT. *p < 0.05; **p < 0.01; ***p < 0.001