Production of VEGF165 by Ewing’s sarcoma cells induces vasculogenesis and theincorporation of CD341 stem cells into the expanding tumor vasculature

TIM H. LEE, MARCELA F. BOLONTRADE, LAURA L. WORTH, HUI GUAN, LEE M. ELLIS AND EUGENIE S. KLEINERMAN

INTERNATIONAL JOURNAL OF CANCER. JOURNAL INTERNATIONAL DU CANCER.

JOHN WILEY & SONS INC

Lugar: Hoboken, N.J.; Año: 2006 vol. 119 p. 839 - 846

0020-7136

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. CD341 bone marrow stem cells can differentiate into endothelial and hematopoietic cells. We used a transplant model to determine whether CD341 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 CD341 cell migration. Human umbilical cord CD341 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 CD341 cells, we generated two VEGF165-defi- cient TC71 clones, a stable anti-sense VEGF165 cell line (Clone 17) and a VEGF165 siRNA-inhibited clone (TC/siVEGF7-1). 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 CD341 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 CD341 cells from the bone marrow into the tumor.