Figure 3.

β₁ integrin inhibition does not induce apoptosis in vivo. A, PC3 xenograft (100 mm³) bearing nude mice were injected with either AIIB2 or rat IgG (rtIgG) biweekly. Tumor growth was measured up to 20 days and is expressed as tumor volume in mm³. Data are the mean ± SEM of 6 animals per group. The differences in tumor volume in the range of 10 to 20 days after injection are statistically significant between the mice injected with AIIB2 versus mice injected with rtIgG (*p≤0.001). The graph shows kinetics of tumor growth. B, Subcutaneous tumors from mice described in panel (A) were dissected and fixed in 10% neutral buffered formalin. The fixed tissues were then embedded in paraffin. A section from female rat mammary gland, 3-5 days after rat pups weaning, was used as a positive control. Apoptosis was measured using Apoptag cell death detection kit from Chemicon. C, DU145 cells transiently transfected with three β₁ siRNAs (R1, R2 and R3) or control siRNA or oligofectamine (OLF) alone (left panel) or DU145 stable transfectants expressing β₁-shRNA or vector alone (right panel) were detached and processed for DNA fragmentation assay. DU145 cells treated with staurosporine (1 μM) were used as a positive control for apoptosis.