Figure 6.

SOCS3 causes growth suppression and angiogenesis of NCI-H446 cells in vivo and HIF-1α is required in this process. (A) NCI-H446 cells were transfected with empty Ad5 vector, Ad5-SOCS3 or Ad5-SOCS3+HIF-1α. Subsequently, transfected cells (1×10⁷) of the three groups were subcutaneously injected into mice to form transplantation tumors. The growth curve shows that compared with that of the Ad5 group, the growth rate of Ad5-SOCS3 cells was decreased, particularly from 21 days after inoculation (Ad5-SOCS3 group vs. Ad5 group, ^*P<0.05; n=11). Compared with that of the Ad5-SOCS3 group, the growth rate in the Ad5-SOCS3+HIF-1α co-transfection group was increased, particularly from 18 days after inoculation (Ad5-SOCS3+HIF-1α group vs. Ad5-SOCS3 group, ^▲P<0.05, n=11). (B) Following sacrification of the mice 30 days after inoculation, tumor weight was significantly decreased in the Ad5-SOCS3 group (Ad5-SOCS3 group vs. Ad5 group, ^*P<0.05, n=11) as compared with that in the Ad5 group, but following co-transfection with HIF-1α, the tumor weight increased (Ad5-SOCS3+HIF-1α group vs. Ad5-SOCS3 group, ^▲P<0.05, n=11). (C) Representative microscopic images of CD34 antibody-stained tumor sections (magnification, ×10). The bar graph shows the mean neovascular densities ± standard deviation. Images of the entire area of each tumor were captured and analyzed. Results of immunohistochemical semiquantitative analysis showed that the number of CD34-positive areas was decreased following transfection with SOCS3 as compared with that in the empty vector-transfected group (^*P<0.05), while this effect was significantly reduced following co-transfection with HIF-1α (Ad5-SOCS3+HIF-1α group vs. Ad5-SOCS3 group, ^▲P<0.05). Ad5, tumor-specific replication-defective adenovirus type 5; SOCS3, suppressor of cytokine signaling, 3; HIF-1α, hypoxia-inducible factor-1α.