Cell-type Specific Regulation of Gene Expression by Simian Virus 40 T antigens

SV40 transforms cells through the action of two oncoproteins, large T antigen and small t antigen. Small t antigen targets phosphatase PP2A, while large T antigen stimulates cell proliferation and survival by action on multiple proteins, including the tumor suppressors Rb and p53. Large T antigen also binds components of the transcription initiation complex and several transcription factors. We examined global gene expression in SV40-transformed mouse embryo fibroblasts, and in enterocytes obtained from transgenic mice. SV40 transformation alters the expression of approximately 800 cellular genes in both systems. Much of this regulation is observed in both MEFs and enterocytes and is consistent with T antigen action on the Rb-E2F pathway. However, the regulation of many genes is cell-type specific, suggesting that unique signaling pathways are activated in different cell types upon transformation, and that the consequences of SV40 transformation depends on the type of cell targeted. We used the Affymetrix RGU34A microarrays to probe the global mRNA expression from two wild-type REF52neo and three REF52neoT stable cell lines. For the MEF microarrays, we used a dye-flip reference design (Churchill GA, 2002, Nature Genetics, Vol. 32, p.490-495) to compare a pool of MEF total RNA to three independent T antigen MEF cell lines. All REF52 and MEF cells were grown to two days post-confluence and harvested. For the mouse small intestine microarrays, we used three different intestinal preparations: Whole, Villi and Vlcm in a replicated dye-flip design (Churchill GA) using three (Vlcm) or four (Whole and Villi) T+ mice and the same number of their wild-type littermates for each intestinal preparation. We used the Agilent Mouse cDNA (G4104A) array for the MEF and small intestine experiments.