Journal of the National Cancer Institute Advance Access originally published online on January 8, 2008
JNCI Journal of the National Cancer Institute 2008 100(2):109-120; doi:10.1093/jnci/djm279
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
© The Author 2008. Published by Oxford University Press.
ARTICLES |
Therapeutic Targeting of Neuropilin-2 on Colorectal Carcinoma Cells Implanted in the Murine Liver
Affiliations of authors: Departments of Cancer Biology (LX, RJS, FF, TA, CDL, AKS, LME), Gynecologic Oncology (YGL, LSM, AKS), Experimental Therapeutics (GLB), Qualitative Sciences (XW), and Surgical Oncology (MJG, GVB, NAD, ADY, SL, LME), The University of Texas M. D. Anderson Cancer Center, Houston, TX
Correspondence to: Lee M. Ellis, MD, Department of Surgical Oncology, Unit 444, The University of Texas M. D. Anderson Cancer Center, PO Box 301402, Houston, TX 77230-1402 (e-mail: lellis{at}mdanderson.org).
Background: Neuropilin-2 (NRP2) is a high-affinity kinase-deficient receptor for vascular endothelial growth factor (VEGF) and semaphorin 3F. We investigated its function in human colorectal cancers.
Methods: Immunohistochemistry and immunoblotting were used to assess NRP2 expression levels in colorectal tumors and colorectal cancer cell lines, respectively. HCT-116 colorectal cancer cells stably transfected with short hairpin RNA (shRNAs) against NRP2 or control shRNAs were assayed for proliferation by the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and for activation of the VEGFR1 pathway by immunoblotting. Soft agar assays, Annexin V staining, and Boyden chamber assays were used to examine anchorage-independent growth, apoptosis in response to hypoxia, and cell migration/invasion, respectively, in HCT-116 transfectants. Tumor growth and metastasis were analyzed in mice (groups of 10) injected with shRNA-expressing HCT-116 cells. The effect of in vivo targeting of NRP2 by small interfering RNA (siRNA) on the growth of hepatic colorectal tumors derived from luciferase-expressing HCT-116 cells was assessed by measuring changes in bioluminescence and final tumor volumes. All statistical tests were two-sided.
Results: NRP2 expression was substantially higher in tumors than in adjacent mucosa. HCT-116 transfectants with reduced NRP2 levels had reduced VEGFR1 signaling, but proliferation was unchanged. Anchorage-independent growth, survival under hypoxic conditions, and motility/invasiveness were also reduced. In vivo, HCT-116 transfectants with reduced NRP2 demonstrated decreased tumor growth, fewer metastases, and increased apoptosis compared with control cells. Hepatic colorectal tumors in mice treated with NRP2 siRNAs were statistically significantly smaller than those in mice treated with control siRNAs (at 28 days after implantation, mean control siRNAs = 420 mm3, mean NRP2 siRNAs = 36 mm3, NRP2 vs control: difference = 385 mm3, 95% confidence interval = 174 mm3 to 595 mm3, P = .005).
Conclusion: NRP2 on colorectal carcinoma cells is important for tumor growth and is a potential therapeutic target in human cancers where it is expressed.
| CONTEXT AND CAVEATS Prior knowledge The neuropilins, a class of nonkinase cell surface receptors that bind VEGF and class III semaphorins, appear to enhance the activity of VEGF tyrosine kinase receptors in response to VEGF. The neuropilins are not normally expressed in nonvascular adult tissues but neuropilin-1 is present on some tumor cells, and inhibitors of neuropilin-1 have been shown to be effective in reducing tumor growth. Study design Expression of neuropilin-2 (NRP2) was examined in colorectal tumors and cell lines. HCT-116 colorectal cancer cells stably transfected with short hairpin RNAs to NRP2 were used to assess the role of NRP2 in cell proliferation, anchorage-independent growth, apoptosis, migration, invasion, and tumorigenesis. Liposomes carrying small interfering RNAs (siRNAs) to NRP2 were used to treat hepatic tumors derived from HCT-116 cells implanted in mice. Contribution NRP2 was expressed on tumors but not normal tissue. Blocking NRP2 function reduced anchorage-independent growth, cell survival under hypoxic conditions, cell migration, invasiveness, and tumorigenicity. Finally, therapeutic targeting of NRP2 was validated by its efficacy in treating tumor xenografts in mice. Implications NRP2 appears to be a promising target, possibly in combination with anti-VEGF therapies, for the treatment of human cancers. Limitations Only HCT-116 human colorectal carcinoma cells were used for most functional assays in the study. Whether the siRNAs used inhibit VEGF-dependent or -independent activities of NRP2 remains unclear.
|
The sponsors had no role in the study design, data collection and analysis, interpretation of the results, the preparation of the manuscript, or the decision to submit the manuscript for publication.
Manuscript received May 15, 2007; revised October 25, 2007; accepted November 21, 2007.
Editorial about this Article
Related Article in JNCI
CiteULike 
Connotea 
Del.icio.us What's this?
J Natl Cancer Inst 2008 100: 81-83.
J Natl Cancer Inst 2008 100: 79.
This article has been cited by other articles:
|
|
 |
|
  Z. Tong, A. B. Kunnumakkara, H. Wang, Y. Matsuo, P. Diagaradjane, K. B. Harikumar, V. Ramachandran, B. Sung, A. Chakraborty, R. S. Bresalier, et al. Neutrophil Gelatinase-Associated Lipocalin: A Novel Suppressor of Invasion and Angiogenesis in Pancreatic Cancer Cancer Res., August 1, 2008; 68(15): 6100 - 6108. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Narazaki, M. Segarra, and G. Tosato Neuropilin-2: A New Molecular Target for Antiangiogenic and Antitumor Strategies J Natl Cancer Inst, January 16, 2008; 100(2): 81 - 83. [Full Text] [PDF]
|
|