6663

SOX10

DOM|PCWH|WS2E|WS4|WS4C;SRY (sex determining region Y)-box 10;SOX10;SRY (sex determining region Y)-box 10

SRY-related HMG-box gene 10|dominant megacolon, mouse, human homolog of|transcription factor SOX-10

22q13.1

protein-coding

Pilocytic astrocytoma (PA) is the most common glioma of childhood. Despite theirrelatively high incidence, the molecular mechanisms responsible for tumorigenesis and growth of PA are poorly understood. Previous in vitro studies in our laboratory showed that despite the absence of ErbB1, PA was sensitive to ErbB1 tyrosine kinase inhibitor gefitinib. To identify alternative targets of gefitinib in PA, we studied other members of the ErbB receptor tyrosine kinase family thathave been identified in brain tumors. Using gene expression microarray and Western blot analyses, we found that ErbB3 is highly overexpressed in PA compared with other pediatric brain tumors (glioblastoma, ependymoma, medulloblastoma, atypical teratoid/rhabdoid tumor, and choroid plexus papilloma). Developmental biology studies have identified Sox10 as a regulator of ErbB3 expression during development of the neural crest. Investigation of Sox10 in PA revealed that it is highly overexpressed relative to other pediatric brain tumors, lending support to the theory that Sox10-regulated overexpression of ErbB3 may be driving growth inPA. Sox10-regulated ErbB3 overexpression is a novel insight into the biology of PA, suggests possible recapitulation of developmental pathways in tumorigenesis,and presents possible targets for therapeutic intervention that might be used for hypothalamic variants not amenable to surgical cure.

Radiation-induced glioblastomas (RIGs) represent a significant proportion of glioblastomas (GBMs) seen in children and young adults and manifest poor prognosis. Little is known about their underlying biology, although limited studies have suggested no unique histologic or cytogenetic characteristics to distinguish them from de novo GBMs. In this study, we confirmed that a series of5 RIGs showed no unique histologic or cytogenetic features compared with de novopediatric GBMs, prompting us to further investigate RIGs using gene expression microarray profiling and Western blot analysis. Despite the inability of histologic and molecular genetic studies to identify distinguishing features between RIGs and pediatric GBMs, gene microarrays suggested significant differences between these 2 tumor types, at least those occurring in pediatric patients. pediatric RIGs show greater homogeneity of gene expression than do de novo pediatric GBMs. Greater overlap was detected in gene expression patterns between RIGs and pilocytic astrocytomas than between RIGs and GBMs, medulloblastomas, ependymomas, atypical teratoid rhabdoid tumors, or rhabdomyosarcomas, suggesting a common precursor cell for RIG and pilocytic astrocytoma. Western blot analyses confirmed that ErbB3, Sox10, and platelet-derived growth factor receptor-alpha proteins were consistently expressed in RIGs but rarely in pediatric GBMs.