Total gene expression analysis of LMP2A/λ-MYC and λ-MYC tumors

We have developed a transgenic mouse model for Epstein-Barr virus-associated Burkitt's lymphoma. Transgenic mice that express LMP2A and MYC in B cells develop spontaneous lymph node tumors at different rates. Tumor onset occurs at approximately 40-60 days in LMP2A/λ-MYC mice and at 100-200 days in λ-MYC mice. This study compared total gene expression in the tumor cells from each genotype, as well as in B cells isolated from 3 week old mice prior to tumor onset. Comparison of total gene expression in tumor cells from LMP2A/λ-MYC and λ-MYC transgenic mice identified a short list of differentially expressed genes. Comparison of gene expression in B cells from the spleens of 3 week old mice, in contrast, identified a 10-fold increase in the number of differentially expressed genes. B cells from the spleens of 3 week old LMP2A/λ-MYC (n=5), λ-MYC (n=5), LMP2A (n=3), and WT (n=3) transgenic mice were purified using magnetic-activated cell sorting (MACS) beads purchased from Miltenyi for CD19 positive selection. Total RNA was isolated from these purified B cells, as well as from cervical lymph node tumor cells that developed in LMP2A/λ-MYC (n=7) and λ-MYC (n=5) transgenic mice using RNeasy RNA extraction kit from QIAGEN. Cervical lymph node tumor cells were >90% positive for the B cell marker B220, and were not further purified. Total gene expression was assessed in each sample, along with heart and brain reference samples using MouseRef-8 v2.0 Expression Bead Chips purchased from Illumina. GeneSpring analysis software was used to analyze the expression data and identify significantly differentially expressed genes (fold change >1.5-fold and false discovery rate< 0.05).