Development of MLL-rearranged leukemia is dependent on a transcriptional program orchestradt by C/EBP

Translocations involving the MLL genes are frequently found in Acute Myeloid Leukemia (AML) and are associated with poor prognosis. The MLL fusion proteins act as aberrant transcription factor activating a transcriptional program that transforms the cells, potentially through collaboration with other transcription factors. To investigate this we searched gene expression profiles from patients with MLL-rearranged AML compared with normal hematopoietic progenitor cells for transcriptional regulators and found targets of C/EBP to be up-regulated in the AML samples, suggesting that C/EBP might collaborate with MLL fusion proteins in the initial transformation process. We could show that transformation by MLL fusion proteins is dependent on C/EBP activity both in early progenitors as well as in GMPs. In contrast, C/EBP was found to be indispensable in an already established leukemia. These results suggest that C/EBP play an important role in the early transforming event of leukemogenesis.

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Ohlsson E, Hasemann MS, Willer A, Lauridsen FK, Rapin N, Jendholm J, Porse BT