Dissecting the role of hypoxia-inducible factor 1 (HIF-1) in JAK2V617F-positive myeloproliferative neoplasms (MPN)

• Untersuchung der Rolle von Hypoxia-Inducible Factor 1 (HIF-1) in JAK2V617F-positiven myeloproliferativen Neoplasien (MPN)

Baumeister, Julian; Wagner, Wolfgang (Thesis advisor); Koschmieder, Steffen (Thesis advisor)

Aachen (2020)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2020

Abstract

Classical BCR-ABL-negative myeloproliferative neoplasms (MPN) are a heterogeneous group of hematologic malignancies including polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). The JAK2V617F mutation plays a central role in these disorders and can be found in 90% of PV and approximately 50-60% of ET and PMF. Hypoxia-inducible factor 1 (HIF-1) is a master transcriptional regulator of the response to decreases in cellular oxygen levels, also referred to as hypoxia. Within this thesis, the role of HIF-1 in JAK2V617F-positive MPN was examined. HIF-1α protein levels were significantly elevated in Jak2V617F expressing 32D cells compared to Jak2WT control cells. Pharmacological inhibition of HIF-1 binding to hypoxia response elements (HREs) with echinomycin impaired growth and survival by inducing apoptosis and cell cycle arrest in Jak2V617F transduced 32D cells, but not Jak2WT controls. Attenuation of DNA binding was verified by chromatin immunoprecipitation experiments. Findings from the pharmacologic intervention were corroborated by shRNA-mediated knockdown (KD) of HIF-1α in JAK2V617F-positive cells upon simultaneous inhibition of HIF-2, which was upregulated in HIF-1α KD cells in a compensatory manner. Echinomycin selectively abrogated growth, survival and clonogenic potential of bone marrow and peripheral blood mononuclear cells from JAK2V617F-positive patients, while cells from healthy donors were unaffected by the treatment. The efficacy was confirmed in JAK2V617F-positive iPS cell-derived progenitors from PV patients, whereas JAK2WT cells were unaffected by the treatment. HIF-1 target genes involved in modulating the energy metabolism to aerobic glycolysis were identified as a possible underlying mechanism, with increased expression of Pdk1, Glut1, Pfkfb3 and others. These findings were substantiated by transcriptome analysis of CD34+ cells from primary MPN patients. Collectively, the findings obtained during this doctoral thesis provide a greater understanding of the role of HIF-1 in JAK2V617F-positive cells and indicate that HIF-1 is a new potential therapeutic target in classical BCR-ABL negative MPN.

Institutions

• Department of Biology [160000]
• [811002-2]