Tribl and Evil cooperate with Hoxa and Meis1 in myeloid leukemogenesis. Commentary

Cooperative activation of Meis1 and Hoxa9 perturbs myeloid differentiation and eventually leads myeloid progenitors to leukemia, yet it remains to be clarified what kinds of subsequent molecular processes are required for development of overt leukemia. To understand the molecular pathway in Hoxa9/Meis1-induced leukemogenesis, retroviral insertional mutagenesis was applied using retrovirus-mediated gene transfer. The mice that received Hoxa9/Meis1-transduced bone marrow cells developed acute myeloid leukemia (AML), and Tribi, Evil, Ahi1, Rara, Pitpnb, and AK039950 were identified as candidate cooperative genes located near common retroviral integration sites. Tribi and Evil were up-regulated due to retroviral insertions, and coexpression of these genes significantly accelerated the onset of Hoxa9/Meis1-induced AML, suggesting that Tribi and Evil are the key collaborators. Furthermore, Tribi by itself is a novel myeloid oncogene, enhancing phosphorylation of ERK, resulting in inhibition of apoptosis. These results demonstrate the importance of specific oncogene interaction in myeloid leukemogenesis.