RCAS/SCL-TVA animal model allows targeted delivery of polyoma middle T oncogene to vascular endothelial progenitors in vivo and results in hemangioma development.
OBJECTIVE
To recapitulate the generation of cancer stem cells in the context of an intact animal using a retroviral vector capable of in vivo delivery of oncogenes to primitive endothelial and hematopoietic stem cells.


METHODS
Targeting of these progenitors was achieved using transgenic mice in which the avian TVA retroviral receptor was placed under the control of the stem cell leukemia (scl/tal-1) gene promoter and SCL +19 enhancer.


RESULTS
Injection of an avian retrovirus encoding polyoma middle T (PyMT), an oncogene that transforms endothelial cells, caused rapid lethality in all SCL-TVA mice but not in control TVA(-) littermates. The infected animals exhibited hemorrhagic foci in several organs. Histopathologic analysis confirmed the presence of hemangiomas and the endothelial origin of the PyMT-transformed cells. Surprisingly, the transformed endothelial cells contained readily detectable numbers of TVA(+) cells. By contrast, normal blood vessels had very few of these cells. The presence of TVA(+) cells in the lesions suggests that the cells originally infected by PyMT retained stem cell characteristics. Further analysis showed that the tumor cells exhibited activation of the phosphatidylinositol 3-kinase/Akt and S6/mammalian target of rapamycin pathways, suggesting a mechanism used by PyMT to transform endothelial progenitors in vivo.


CONCLUSIONS
We conclude that this experimental system can specifically deliver oncogenes to vascular endothelial progenitors in vivo and cause a fatal neoplastic disease. This animal model should allow the generation of endothelial cancer stem cells in the natural environment of an immunocompetent animal, thereby enabling the recapitulation of genetic alterations that are responsible for the initiation and progression of human malignancies of endothelial origin.
Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA.
Justin
J
Sausville
Alfredo A
AA
Molinolo
Xiangfei
X
Cheng
Jon
J
Frampton
Naoko
N
Takebe
J Silvio
JS
Gutkind
Ricardo A
RA
Feldman
D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000008:administration & dosage* / Q000235:genetics; D030161:Avian Proteins / Q000235:genetics*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics*; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D002478:Cells, Cultured; D002645:Chickens; D042783:Endothelial Cells / Q000378:metabolism*; D018014:Gene Transfer Techniques; D005822:Genetic Vectors / Q000008:administration & dosage*; D006391:Hemangioma / Q000235:genetics* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D023421:Models, Animal; D041681:NIH 3T3 Cells; D009857:Oncogenes / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D011991:Receptors, Virus / Q000235:genetics*; D013234:Stem Cells / Q000378:metabolism; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D019076:Transgenes
D000952:Antigens, Polyomavirus Transforming; D030161:Avian Proteins; D051792:Basic Helix-Loop-Helix Proteins; D011518:Proto-Oncogene Proteins; D011991:Receptors, Virus; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; C088745:Tva receptor; C067143:TAL1 protein, human