Abstract 1199: Global proteomic evaluation of the relationship between Epstein-Barr virus (EBV) and c-myc deregulation in endemic versus sporadic Burkitt lymphoma (BL)

Abstract

Abstract Endemic BL (eBL) is characteristically positive(100%) for EBV, contrasting with sporadic(sBL) BL(∼30% EBV+). eBL vs sBL have different breakpoint regions within c-myc. The different mechanisms of lymphomagenesis however, remain unknown. Global analysis of proteins expressed in the different subtypes may provide insights into biologic, pathogenetic, and molecular differences. Objectives: To compare the proteomic expression profile and signal transduction pathways of EBV+ eBL with EBV+/- sBL and EBV+/- normal B-cells. Normal B-cells (EBV+/-) were isolated from leukopacks obtained from the NY Blood Center using Magnetic Cell Sorting CD20 MicroBeads (Miltenyi biotec, CA). Whole cell lysates obtained from EBV+ eBL Raji, EBV+ sBL NC37, EBV- sBL Ramos, and EBV± B-cells were digested and labeled with iTRAQ reagents. The peptides were resolved by 2D-LC technique. MS/MS spectra were acquired using an Orbitrap XL Tandem Mass Spectrometer (ThermoFisher). MS/MS data was searched using X! Tandem TPP software against human IPI database (v3.50) appended with decoy sequences. iTRAQ ratios of proteins (ProteinProphet probability of >0.9) were normalized and differentially expressed proteins were selected for further analysis. Over 400 proteins were identified; 827 binary differential protein expressions were established with a False Discovery Rate (FDR) of <0.4. Hierarchical clustering of the expression profiles grouped the 3 lymphoma cell lines and the 2 normal B-cell specimens. Specific cellular functions were implicated by differential protein expressions (with associated proteins in parentheses) including apoptotic signaling (AK2, C1QBP, DIABLO, PCNA, PPIF, SERPIN8&9, SET), viral pathogenesis (DDX3X, SYNCRIP, EIF5A), cell proliferation pathways and oncogenes (ANXA6, DDX5, DEK, GNB2L1, NME2, RAP1A&B, RIPK4, STMN1), c-myc expression regulation (ENO1, FUBP1), heat shock and ubiquitination (HSP90AB1, HSP90B1, HSPA5, UCHL1). There are several proteins with established links to malignancy (RPL15, PSMA4, SLC3A2, TLX2, VIM) including TUBB2C, whose overexpression is found in pediatric BL and potential biomarkers for disease (IGHM, IGSF3, LDHA, LDHB, PPBP, LSP1, LYZ, DEFA1, DEFA3). We identified 41 proteins within the c-myc network, 21 of which are c-myc targets. Our results suggest that there are potentially different mechanisms driving cell proliferation and resistance to apoptosis in the different BL subtypes. Confirmatory studies will be required to establish the correlation between EBV, c-myc, and geographical subtype and how they may be involved in promoting lymphomagenesis. Ultimately, identification of proteins unique to the distinct disease subtypes will serve to establish tumor markers that may enable development of new diagnostic, prognostic, and therapeutic strategies. * Drs. Lim and Cairo are equal senior authors. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1199.