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MLL leukemia induction by genome editing of human CD34+ hematopoietic cells

Corina Buechele, Erin H. Breese, Dominik Schneidawind, Chiou-Hong Lin, Johan Jeong, Jesus Duque-Afonso, Stephen H.K. Wong, Kevin S. Smith, Robert S. Negrin, Matthew Porteus and Michael L. Cleary

Key points

  • Genome editing of primary human HSPCs generates MLL leukemias that model clinical disease features and molecular pathogenesis.

Abstract

Chromosomal rearrangements involving the mixed-lineage leukemia (MLL) gene occur in primary and treatment-related leukemias, and confer a poor prognosis. Studies based primarily on mouse models have substantially advanced our understanding of MLL leukemia pathogenesis, but often employ supra-physiologic oncogene expression with uncertain implications for human leukemia. Genome editing using site-specific nucleases provides a powerful new technology for gene modification to potentially model human disease, however this approach has not been used to recreate acute leukemia in human cells of origin comparable to disease observed in patients. We applied TALEN-mediated genome editing to generate endogenous MLL-AF9 and MLL-ENL oncogenes through insertional mutagenesis in primary human hematopoietic stem and progenitor cells (HSPCs) derived from human umbilical cord blood. Engineered HSPCs displayed altered in vitro growth potentials and induced acute leukemias following transplantation in immuno-compromised mice at a mean latency of 16 weeks. The leukemias displayed phenotypic and morphologic similarities with patient leukemia blasts including a subset with mixed phenotype, a distinctive feature seen in clinical disease. The leukemic blasts expressed an MLL-associated transcriptional program with elevated levels of crucial MLL target genes, displayed heightened sensitivity to DOT1L inhibition, and demonstrated increased oncogenic potential ex vivo and in secondary transplant assays. Thus, genome editing to create endogenous MLL oncogenes in primary human HSPCs faithfully models acute MLL-rearranged leukemia and provides an experimental platform for prospective studies of leukemia initiation and stem cell biology in a genetic subtype of poor prognosis leukemia.

  • Submitted May 18, 2015.
  • Accepted August 23, 2015.