Production of VEGF165 by Ewing's sarcoma cells induces vasculogenesis and the incorporation of CD34+ stem cells into the expanding tumor vasculature.
The Ewing's sarcoma cell line TC71 overexpresses vascular endothelial growth factor isoform 165 (VEGF165), a potent proangiogenic molecule that induces endothelial cell proliferation, migration, and chemotaxis. CD34+ bone marrow stem cells can differentiate into endothelial and hematopoietic cells. We used a transplant model to determine whether CD34+ cells migrate from the bone marrow to Ewing's sarcoma tumors and participate in the neovascularization process that supports tumor growth. We also examined the role of VEGF165 in CD34+ cell migration. Human umbilical cord CD34+ cells were transplanted into sublethally irradiated severe combined immunodeficient mice. Seven days later, the mice were injected subcutaneously with TC71 tumor cells. Tumors were excised 2 weeks later and analyzed by immunohistochemistry. The tumor sections expressed both human VE-cadherin and mouse CD31, indicating involvement of donor-derived human cells in the tumor vessels. To determine the role of VEGF165 in the chemoattraction of CD34+ cells, we generated two VEGF165-deficient TC71 clones, a stable anti-sense VEGF165 cell line (Clone 17) and a VEGF165 siRNA-inhibited clone (TC/siVEGF(7-1)). The resulting VEGF165-deficient tumor cells had normal growth rates in vitro, but had delayed growth when implanted into mice. Immunohistochemical analysis revealed decreased infiltration of CD34+ cells into both VEGF165-deficient tumors. These data show that bone marrow stem cells contribute to the growing tumor vasculature in Ewing's sarcoma and that VEGF165 is critical for the migration of CD34+ cells from the bone marrow into the tumor.
Division of Pediatrics, University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA.
Tim H
TH
Lee
Marcela F
MF
Bolontrade
Laura L
LL
Worth
Hui
H
Guan
Lee M
LM
Ellis
Eugenie S
ES
Kleinerman
D000818:Animals; D018952:Antigens, CD34 / Q000378:metabolism*; D002465:Cell Movement; D003094:Collagen; D016373:DNA, Antisense / Q000235:genetics; D004338:Drug Combinations; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007797:Laminin; D051379:Mice; D009368:Neoplasm Transplantation; D011509:Proteoglycans; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012512:Sarcoma, Ewing / Q000098:blood supply* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics
D018952:Antigens, CD34; D016373:DNA, Antisense; D004338:Drug Combinations; D007797:Laminin; D011509:Proteoglycans; D011994:Recombinant Proteins; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C059485:matrigel; D003094:Collagen