Proteomic analysis reveals a novel mechanism induced by the leukemic oncogene Tel/PDGFRI super(2) in stem cells: Activation of the interferon response pathways

Objective proteomic analysis offers opportunities for hypothesis generation on molecular events associated with pathogenesis in stem cells. Relative quantification mass spectrometry was employed to identify pathways affected by Tel/PDGFRI super(2), an oncogene associated with myeloproliferative neoplasia (MPN). Its effects on over 1800 proteins were quantified with high confidence. Of those up-regulated by Tel/PDGFRI super(2) several were involved in the interferon gamma (IFNI super(3)) response. To validate these observations we employed embryonic and myeloid stem cells models which revealed Tel/PDGFRI super(2)-induced STAT1 up-regulation and activation was responsible for modulating the interferon response. A STAT1 target highly up-regulated was ICSBP, a transcriptional regulator of myeloid and eosinophilic differentiation. ICSBP interacts with CBP/p300 and Ets transcription factors, to promote transcription of additional genes, including the Egr family, key regulators of myelopoiesis. These interferon responses were recapitulated using IFNI super(3) stimulation of stem cells. Thus Tel/PDGFRI super(2) induces aberrant IFN signaling and downstream targets, which may ultimately impact the hematopoietic transcriptional factor network to bias myelomonocytic differentiation in this MPN.