BioProject

To explore oncogene addiction programs in a genetically defined leukemia context we developed an AML mouse model driven by a conditional MLL-AF9 allele together with oncogenic Ras, which enabled us to examine the consequences of MLL-AF9 inhibition in established disease. More...

To explore oncogene addiction programs in a genetically defined leukemia context we developed an AML mouse model driven by a conditional MLL-AF9 allele together with oncogenic Ras, which enabled us to examine the consequences of MLL-AF9 inhibition in established disease. In order to produce a tightly regulated system that was easy to monitor, we constructed two retroviral vectors containing dsRed-linked MLL-AF9 under control of a tetracycline response element promoter, and KrasG12D or NrasG12D linked to the “Tet-off” tet-transactivator, which activates TRE expression in a doxycycline repressible manner. Leukemias were generated by retroviral cotransduction of both vectors into hematopoietic stem and progenitor cells, which were transplanted into syngeneic mice. Cells harboring both constructs induced aggressive myelomonocytic leukemia. Five independent primary leukemia cell lines were established from bone marrow of terminal mice. Treatment of these lines with doxycycline rapidly turned off MLL-AF9 expression, and induced terminal myeloid differentiation and complete disease remission in vivo. To identify molecular mechanisms underlying addiction to MLL-AF9, we analyzed global gene expression changes following doxycycline-induced suppression of MLL-AF9. Overall design: Independent primary acute myeloid leukemia lines induced by cotransduction of Tet-off MLL-AF9 together with either KrasG12D or NrasG12D were grown in culture and treated with doxycycline for 6 days to inactivate MLL-AF9 expression. In addition, primary acute myeloid leukemia lines with constitutive MLL-AF9 and KrasG12D were included to control for the effects of doxycycline. Untreated and treated cells were harvested for RNA extraction and hybridization to Affymetrix arrays. Less...