Oct-4 +/Tenascin C + neuroblastoma cells serve as progenitors of tumor-derived endothelial cells

Abstract

Neuroblastoma (NB)-associated endothelial microvessels (EMs) may be lined by tumor-derived endothelial cells (TECs), that are genetically unstable and chemoresistant. Here we have addressed the identification of TEC progenitors in NB by focusing on Octamer-binding transcription factor 4 (Oct-4) as a putative marker. Oct-4 + cells were detected in primary NB samples (n = 23), metastatic bone marrow aspirates (n = 10), NB cell lines (n = 4), and orthotopic tumors (n = 10) formed by the HTLA-230 NB cell line in immunodeficient mice. Most Oct-4 + cells showed a perivascular distribution, with 5% of them homing in perinecrotic areas. All Oct-4 + cells were tumor-derived since they shared amplification of MYCN oncogene with malignant cells. Perivascular Oct-4 + cells expressed stem cell-related, neural progenitor-related and NB-related markers, including surface Tenascin C (TNC), that was absent from perinecrotic Oct-4 + cells and bulk tumor cells. TNC + but not TNC HTLA-230 cells differentiated in vitro into endothelial-like cells expressing vascular-endothelial-cadherin, prostate-specific membrane antigen and CD31 upon culture in medium containing vascular endothelial growth factor (VEGF). TNC + + but not TNC HTLA-230 cells formed neurospheres when cultured in serum-free medium. Both cell fractions were tumorigenic, but only tumors formed by TNC + cells contained EMs lined by TECs. In conclusion, we have identified in NB tumors two putative niches containing Oct-4 + tumor cells. Oct-4 + /TNC +perivascular NB cells displayed a high degree of plasticity and served as progenitors of TECs. Therapeutic targeting of Oct4 + /TNC + progenitors may counteract the contribution of NB-derived ECs to tumor relapse and chemoresistance. © 2011 IBCB, SIBS, CAS All rights reserved.