796 Proteins and Protein Pattern Differences between Glioma Cell Lines and Glioblastoma Multiforme

Abstract

INTRODUCTION: Research into the pathogenesis, molecular signaling, and treatment of glioblastoma multiforme (GBM) has traditionally been conducted using cell lines derived from malignant gliomas. To identify proteins whose expression may be altered in cell culture, we compared protein expression patterns between solid primary GBMs and GBM cell lines. METHODS: Cultured human glioma cell lines U87, U118, U251, and A172 and tissue from selective microdissection of eight primary GBMs to obtain pure populations of tumor cells were studied using two-dimensional gel electrophoresis (2DGE) and differential expression software. Select protein targets expressed differentially between GBM tumors and GBM cell lines were sequenced using tandem mass spectrometry (MS/MS). RESULTS: Analysis of primary GBM (n = 8) and GBM cell lines revealed reproducibly similar and distinct proteomic patterns for each group, which distinguished tumors from the cell lines. Gels contained up to 500 proteins that were consistently identified in the pH 4 to 7 range. Comparison of proteins identified in the tumors and cell lines demonstrated approximately 160 proteins that were gained and 60 proteins that were lost on culture. Using normalized intensity patterns from the 2DGE images, analysis of variance tests were performed and statistically significant spots were identified. Seven proteins from the cell lines were increased compared with the tumors (P < 0.05), whereas 10 proteins were significantly decreased from cell lines compared with the tumors. Proteins identified included transcription factors, tumor suppressor genes, cytoskeletal proteins, and cellular metabolic proteins. CONCLUSION: Global protein and proteomic differences were identified between primary GBM tumor samples and human GBM cell lines. The proteins identified elucidate some of the selection pressures of in vitro culture, expose certain advantages and limitations of cell culture, and may enhance our understanding of gliomagenesis and spur development of new therapeutics.