Ptch2 loss drives myeloproliferation and myeloproliferative neoplasm progression

Claudius Klein, Anabel Zwick, Sandra Kissel, Christine Ulrike Forster, Dietmar Pfeifer, Marie Follo, Anna Lena Illert, Sarah Decker, Thomas Benkler, Heike Pahl, Robert A.J. Oostendorp, Konrad Aumann, Justus Duyster, Christine Dierks

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


JAK2V617F+ myeloproliferative neoplasms (MPNs) frequently progress into leukemias, but the factors driving this process are not understood. Here, we find excess Hedgehog (HH) ligand secretion and loss of PTCH2 in myeloproliferative disease, which drives canonical and noncanonical HH-signaling. Interestingly, Ptch2-/- mice mimic dual pathway activation and develop a MPN-phenotype with leukocytosis (neutrophils and monocytes), strong progenitor and LKS mobilization, splenomegaly, anemia, and loss of lymphoid lineages. HSCs exhibit increased cell cycling with improved stress hematopoiesis after 5-FU treatment, and this results in HSC exhaustion over time. Cytopenias, LKS loss, and mobilization are all caused by loss of Ptch2 in the niche, whereas hematopoietic loss of Ptch2 drives leukocytosis and promotes LKS maintenance and replating capacity in vitro. Ptch2-/- niche cells show hyperactive noncanonical HH signaling, resulting in reduced production of essential HSC regulators (Scf, Cxcl12, and Jag1) and depletion of osteoblasts. Interestingly, Ptch2 loss in either the niche or in hematopoietic cells dramatically accelerated human JAK2V617F-driven pathogenesis, causing transformation of nonlethal chronic MPNs into aggressive lethal leukemias with >30% blasts in the peripheral blood. Our findings suggest HH ligand inhibitors as possible drug candidates that act on hematopoiesis and the niche to prevent transformation of MPNs into leukemias.

Original languageEnglish
Pages (from-to)273-290
Number of pages18
JournalJournal of Experimental Medicine
Issue number2
StatePublished - 8 Feb 2016
Externally publishedYes


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