Expression of Angiogenic Factors in Invasive Retinoblastoma Tumors Is Associated With Increase in Tumor Cells Expressing Stem Cell Marker Sox2

Context.— Progression of retinoblastoma is associated with increased tumor angiogenesis. However, a clear relationship between the expression of angiogenic markers in specific regions of the tumor and tumor progression has not been established. This study investigates the association between angiogenic factors in retinoblastomas with choroidal and/or optic nerve invasion (high-risk/invasive retinoblastoma) and expression of Sox2, a stem cell marker. Objective.— To investigate the association between the expression of angiogenic factors and markers of tumor invasiveness, such as the stem cell marker Sox2, in retinoblastoma tissues. Design.— Immunohistochemistry was used to evaluate coexpression of the angiogenic growth factors vascular endothelial growth factor A (VEGF-A), VEGF receptor 2 (VEGFR-2), and endoglin (CD105); markers of glial differentiation (vimentin and glial fibrillary acidic protein); and a neural stem cell marker (Sox2). Expression was assessed in nonneoplastic and neoplastic ocular tissue...