Requirement for sphingosine 1–phosphate receptor-1 in tumor angiogenesis demonstrated by in vivo RNA interference
Sung-Suk Chae, … , Henry Furneaux, Timothy Hla
Sung-Suk Chae, … , Henry Furneaux, Timothy Hla
Published October 15, 2004
Citation Information: J Clin Invest. 2004;114(8):1082-1089. https://doi.org/10.1172/JCI22716.
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Article Vascular biology

Requirement for sphingosine 1–phosphate receptor-1 in tumor angiogenesis demonstrated by in vivo RNA interference

Abstract

Angiogenesis, or new blood vessel formation, is critical for the growth and spread of tumors. Multiple phases of this process, namely, migration, proliferation, morphogenesis, and vascular stabilization, are needed for optimal tumor growth beyond a diffusion-limited size. The sphingosine 1–phosphate (S1P) receptor-1 (S1P1) is required for stabilization of nascent blood vessels during embryonic development. Here we show that S1P1 expression is strongly induced in tumor vessels. We developed a multiplex RNA interference technique to downregulate S1P1 in mice. The small interfering RNA (siRNA) for S1P1 specifically silenced the cognate transcript in endothelial cells and inhibited endothelial cell migration in vitro and the growth of neovessels into subcutaneous implants of Matrigel in vivo. Local injection of S1P1 siRNA, but not a negative control siRNA, into established tumors inhibited the expression of S1P1 polypeptide on neovessels while concomitantly suppressing vascular stabilization and angiogenesis, which resulted in dramatic suppression of tumor growth in vivo. These data suggest that S1P1 is a critical component of the tumor angiogenic response and argue for the utility of siRNA technology in antiangiogenic therapeutics.

Authors

Sung-Suk Chae, Ji-Hye Paik, Henry Furneaux, Timothy Hla

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Figure 4

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Inhibition of tumor growth and angiogenesis by S1P1 siRNA. (A) Lewis lun...
Inhibition of tumor growth and angiogenesis by S1P1 siRNA. (A) Lewis lung carcinoma cells were implanted subcutaneously and allowed to establish as growing tumors, and various siRNA-liposome complexes were injected into the tumor every 3 days (where indicated by arrows) as described. Tumor volume was measured and plotted at various times following treatment with synthetic or multiplex siRNA for S1P1 (synthetic siS1P1, squares; multiplex siS1P1, circles) or liposome alone (triangles). The inset shows the tumor volume at 32 days for additional controls. Data represent mean ± SE of an experiment that was repeated twice. The right panel shows an independent experiment repeated with the inclusion of another control siRNA (multiplex β-gal siRNA, diamonds). n = 4; *P < 0.05; **P < 0.1. (B) Intratumoral microvessel density was quantified from multiple fields as described after CD31 staining. #P < 0.0003. (C) Morphology of tumor vessels is shown from a representative field. Note that vessel morphology and density are altered by S1P1, but not control, siRNA. Scale bar: 20 μm.