Figure 5.

Inhibition of S1P1 expression and vascular stabilization in siRNA-injected tumor xenografts. Tumor xenografts were injected with multiplex siRNAs for β-gal (A–C and G) or S1P1 (D–F and H) as described. Tissue sections were harvested at 15 days and stained for S1P1 (red, A and D) and CD31 (green, B and E). Overlays are shown in C and F. siRNA for S1P1 potently suppressed the expression of S1P1 in endothelial cells (arrowheads). Arrows indicate S1P1 positivity in necrotic areas of the tumor. (G and H) Some sections were costained with anti–α-SMA and anti–CD31, and then α-SMA and CD31 were detected with secondary antibodies conjugated with alexa 568 (red, α-SMA) and alexa 488 (green, CD31) as described. Images were acquired using a confocal microscope. Note that α-SMA–positive cell association with angiogenic vessels were reduced after treatment with siRNA for S1P1.