Establishment of a transgenic mouse to model ETV7 expressing human tumors

The ETS transcription factor ETV7 has been characterized as a hematopoietic oncoprotein, which requires cooperating mutations for its leukemogenic activity. Although the ETV7 gene is highly conserved among vertebrates, part of the rodents, including Mus musculus, deleted the Etv7 gene locus. Many human hematopoietic malignancies upregulate ETV7 expression but contrary to ETV7's role in oncogenesis, its physiological role in normal tissues is unknown. To determine the physiological function of ETV7 in vivo and determine its role in tumorigenesis in a mouse model, we have generated an ETV7 transgenic mouse that carries a single copy of human BAC DNA containing the ETV7 gene locus and its regulatory sequences. ETV7 heterozygous (ETV7Tg^+/WT) mice were fertile, normal in size and born at a normal Mendelian frequency. They had a normal blood count, did not display any gross physical or behavioral abnormalities, and were not tumor-prone. The ETV7 expression pattern in hematopoietic cells of ETV7Tg^+/WT mice is very similar to that in human hematopoietic cells. To examine the oncogenic potential of ETV7 in vivo, we crossed ETV7Tg^+/WT mice with tumor-prone mouse models. ETV7 greatly accelerated loss of Pten (phosphatase and tensin homolog)-evoked leukemogenesis in Pten^Δ/ΔETV7Tg^+/WT mice after deletion of the conditional Pten allele. Consistent with this observation, ETV7 expression enhanced the colony-forming and self-renewal activities of primary myeloid Pten^-/- cells. In this study we established a transgenic mouse in which we can more accurately model ETV7-associated human tumorigenesis in vivo.