Authors: Milica Vukovic, Amelie V. Guitart, Catarina Sepulveda, Arnaud Villacreces, Eoghan O'Duibhir, Theano I. Panagopoulou, Alasdair Ivens, Juan Menendez-Gonzalez, Juan Manuel Iglesias, Lewis Allen, Fokion Glykofrydis, Chithra Subramani, Alejandro Armesilla-Diaz, Annemarie E.M. Post, Katrin Schaak, Deniz Gezer, Chi Wai Eric So, Tessa L. Holyoake, Andrew Wood, Dónal O'Carroll, Peter J. Ratcliffe and Kamil R. Kranc
Summary: Leukemogenesis occurs under hypoxic conditions within the bone marrow (BM). Knockdown of key mediators of cellular responses to hypoxia with shRNA, namely hypoxia-inducible factor-1α (HIF-1α) or HIF-2α, in human acute myeloid leukemia (AML) samples results in their apoptosis and inability to engraft, implicating HIF-1α or HIF-2α as therapeutic targets. However, genetic deletion of Hif-1α has no effect on mouse AML maintenance and may accelerate disease development. Here, we report the impact of conditional genetic deletion of Hif-2α or both Hif-1α and Hif-2α at different stages of leukemogenesis in mice. Deletion of Hif-2α accelerates development of leukemic stem cells (LSCs) and shortens AML latency initiated by Mll-AF9 and its downstream effectors Meis1 and Hoxa9. Notably, the accelerated initiation of AML caused by Hif-2α deletion is further potentiated by Hif-1α codeletion. However, established LSCs lacking Hif-2α or both Hif-1α and Hif-2α propagate AML with the same latency as wild-type LSCs. Furthermore, pharmacological inhibition of the HIF pathway or HIF-2α knockout using the lentiviral CRISPR-Cas9 system in human established leukemic cells with MLL-AF9 translocation have no impact on their functions. We therefore conclude that although Hif-1α and Hif-2α synergize to suppress the development of AML, they are not required for LSC maintenance.
Source:
The Journal of Experimental Medicine; (12/07/15)