Project description:Hepatic gene expression induced by chromic exposure to high levels of the SV40 LT/st oncoproteins (4P) Affymetrix mouse genome U74Av2 platform was used, duplicate measurements for wild-type and transgenic animals
Project description:Hepatic gene expression induced by chromic exposure to low levels of the SV40 LT/st oncoproteins (4P) Affymetrix mouse genome U74Av2 platform was used, duplicate measurements for wild-type and transgenic animals
Project description:The SV40 large (LT) and small (st) antigens are produced from a single alternatively spliced pre-mRNA, that when co-expressed, transform a variety of cells in vitro and in vivo. However, 17kT, a relatively uncharacterized third protein that is co-linear with LT for the first 131 amino acids, is also produced from the early viral pre-mRNA by removal of an additional intron from the LT transcript. Here we report a line of transgenic mice expressing a liver-specific dox-inducible viral transcript that fails to yield any detectable LT protein, yet produces abundant 17kT. Comparative analysis of livers of transgenic mice expressing either 17kT or LT demonstrates that while 17kT is a potent stimulator of cell proliferation, it is ineffective at inducing liver tumor development, due in part, to the failure of 17kT to effectively induce the expression of growth regulators and reactivate expression of imprinted and developmentally regulated hepatic genes. These studies highlight key functional differences between LT and 17kT in their ability to transform quiescent primary epithelial cells in vivo, and demonstrate how specific functional domains within LT impact cell-specific gene expression to promote oncogenesis. Keywords: genetic modification, SV40, 17kT, LT, Rb, p53, hepatocellular carcinoma, hepatic hyperplasia, differentiation. Affymetrix mouse genome 430 A and B platform was used, single measurements for wild-type and transgenic animals.
Project description:The SV40 large (LT) and small (st) antigens are produced from a single alternatively spliced pre-mRNA, that when co-expressed, transform a variety of cells in vitro and in vivo. However, 17kT, a relatively uncharacterized third protein that is co-linear with LT for the first 131 amino acids, is also produced from the early viral pre-mRNA by removal of an additional intron from the LT transcript. Here we report a line of transgenic mice expressing a liver-specific dox-inducible viral transcript that fails to yield any detectable LT protein, yet produces abundant 17kT. Comparative analysis of livers of transgenic mice expressing either 17kT or LT demonstrates that while 17kT is a potent stimulator of cell proliferation, it is ineffective at inducing liver tumor development, due in part, to the failure of 17kT to effectively induce the expression of growth regulators and reactivate expression of imprinted and developmentally regulated hepatic genes. These studies highlight key functional differences between LT and 17kT in their ability to transform quiescent primary epithelial cells in vivo, and demonstrate how specific functional domains within LT impact cell-specific gene expression to promote oncogenesis. Keywords: genetic modification, SV40, 17kT, LT, Rb, p53, hepatocellular carcinoma, hepatic hyperplasia, differentiation.
Project description:Transgenic expression in mice of two synergistically acting SV40 early region encoded proteins, large (LT) and small (sT) tumor antigens, in the mammary epithelium recapitulates loss of p53 and Rb function and deregulation of PP2A-controlled mitogenic pathways in human breast cancer. In primiparous mice, WAP-promoter driven expression of SV40 proteins induces well and poorly differentiated mammary adenocarcinomas. We performed a correlative aCGH and gene expression analysis of 25 monofocal tumors, representing four histopathological grades, to explore the molecular traits of SV40-induced mammary tumors and to emphasize the relevance of this tumor model for human breast tumorigenesis.
Project description:Transgenic expression in mice of two synergistically acting SV40 early region encoded proteins, large (LT) and small (sT) tumor antigens, in the mammary epithelium recapitulates loss of p53 and Rb function and deregulation of PP2A-controlled mitogenic pathways in human breast cancer. In primiparous mice, WAP-promoter driven expression of SV40 proteins induces well and poorly differentiated mammary adenocarcinomas. We performed a correlative aCGH and gene expression analysis of 25 monofocal tumors, representing four histopathological grades, to explore the molecular traits of SV40-induced mammary tumors and to emphasize the relevance of this tumor model for human breast tumorigenesis.
Project description:Transgenic expression in mice of two synergistically acting SV40 early region encoded proteins, large (LT) and small (sT) tumor antigens, in the mammary epithelium recapitulates loss of p53 and Rb function and deregulation of PP2A-controlled mitogenic pathways in human breast cancer. In primiparous mice, WAP-promoter driven expression of SV40 proteins induces well and poorly differentiated mammary adenocarcinomas. We performed a correlative aCGH and gene expression analysis of 25 monofocal tumors, representing four histopathological grades, to explore the molecular traits of SV40-induced mammary tumors and to emphasize the relevance of this tumor model for human breast tumorigenesis.
Project description: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.
