Comprehensive Profiling of the Cell Surface Proteome of Sy5Y Neuroblastoma Cells Yields a Subset of Proteins Associated with Tumor Differentiation

Neuroblastoma tumors are derived from the neural crest and exhibit substantial phenotypic heterogeneity and various degrees of differentiation and maturation. The identification of new cell surface markers in neuroblastoma has relevance to disease classification and therapy. As a means to categorize neuroblastomas based on cell surface protein expression, we have obtained a comprehensive profile of the cell surface proteome of the MYCN nonamplified SH-SY5Y neuroblastoma cell line. Biotinylated cell surface proteins were captured using an avidin affinity column, fractionated by reversed-phase chromatography and subjected to in-depth analysis by LC-MS/MS. An extensive list of proteins was established and a subset of surface membrane proteins was assessed by immunohistochemistry in a set of neuroblastoma tissue microarrays. Among identified proteins tested, NCAM and CD147 exhibited increased expression in poorly differentiated tumors (p < 0.01 and <0.03, respectively). CD147 expression was previously associated with aggressive carcinomas but has not been described in neuroblastoma. This comprehensive neuroblastoma cell surface profile has identified novel potential markers for neuroblastoma classification and novel potential targets for therapy.