NG2 proteoglycan promotes tumor vascularization via integrin-dependent effects on pericyte function.
The NG2 proteoglycan stimulates the proliferation and migration of various immature cell types, including pericytes. However, the role of NG2 in mediating pericyte/endothelial cell interaction has been less clear. In this study, we show that pericyte-specific NG2 ablation causes several structural deficits in blood vessels in intracranial B16F10 melanomas, including decreased pericyte ensheathment of endothelial cells, diminished formation of endothelial junctions, and reduced assembly of the vascular basal lamina. These deficits result in decreased tumor vessel patency, increased vessel leakiness, and increased intratumoral hypoxia. NG2-dependent mechanisms of pericyte interaction with endothelial cells are further explored in pericyte/endothelial cell co-cultures. siRNA-mediated NG2 knockdown in pericytes leads to reduced formation of pericyte/endothelial networks, reduced formation of ZO-1 positive endothelial cell junctions, and increased permeability of endothelial cell monolayers. We also show that NG2 knockdown results in loss of β1 integrin activation in endothelial cells, revealing a mechanism for NG2-dependent cross talk between pericytes and endothelial cells.
Tumor Microenvironment and Metastasis Program, Sanford-Burnham Medical Research Institute, Cancer Center, 10901 North Torrey Pines Road, La Jolla, CA, 92037, USA, weonkyoo.you@hanwha.com.
Weon-Kyoo
WK
You
Fusanori
F
Yotsumoto
Kenji
K
Sakimura
Ralf H
RH
Adams
William B
WB
Stallcup
D000818:Animals; D000941:Antigens / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D055785:Gene Knockdown Techniques; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism / Q000473:pathology; D006801:Humans; D019012:Integrin beta1 / Q000235:genetics / Q000378:metabolism*; D016023:Integrins; D007365:Intercellular Junctions / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008545:Melanoma / Q000098:blood supply* / Q000235:genetics / Q000378:metabolism* / Q000401:mortality; D051379:Mice; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D020286:Pericytes / Q000378:metabolism* / Q000473:pathology; D011509:Proteoglycans / Q000235:genetics / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein / Q000235:genetics / Q000378:metabolism; D000099216:Chondroitin Sulfate Proteoglycan 4
D000941:Antigens; D019012:Integrin beta1; D016023:Integrins; D009363:Neoplasm Proteins; D011509:Proteoglycans; D062826:Zonula Occludens-1 Protein; D000099216:Chondroitin Sulfate Proteoglycan 4; C569042:TJP1 protein, human; C569043:Tjp1 protein, mouse