Murine M7 leukemia derived from retroviral insertional mutagenesis of Gata1s fetal progenitors depends on IGF signaling

The goal of this study is to derive a mouse model of human Down Syndrome (DS) megakaryocytic leukemia involving mutations in the hematopoietic transcription factor, GATA1 (called GATA1s mutation). We achieved this through transduction of Gata1s mutant fetal progenitors by MSCV-based retrovirus expressing a GFP marker, followed by in vitro selection (for immortalized cell lines), and then in vivo selection (for transformed cell lines) through transplantation. Here we report one such cell line [T6(6)] that gives rise to megakaryocytic leukemia (M7 leukemia) upon transplantation. We show knockdown of IGF1R in these cells leads to their reduced proliferation. IGF1R was knocked down in these cells using a tet-regulatable shRNA-based lentiviral system. Cells infected with the empty vector or those infected with shRNA construct against IGF1R but in the absence of Doxycycline were used as controls. The latter cells in the presence of Doxycycline exhibited reduced IGF1R at the RNA level.