Gene expression profile of mutated and wild-type PMF CD34+ cells

Primary mielofibrosis (PMF) is a rare chronic myeloproliferative disorder characterized by the accumulation of abnormal megakaryocytes (Mks) in the bone marrow (BM), variable degrees of BM fibrosis, osteosclerosis and angiogenesis, immature myeloid and erythroid cells, and tear-drop erythrocytes in the peripheral blood (PB), and extramedullary hematopoiesis. The identification of the JAK2V617F mutation represented a seminal discovery in the field of Philadelphia-chromosome–negative chronic myeloproliferative neoplasms (MPNs), providing clues to the pathogenesis, prompting a revision of the diagnostic criteria, and culminating in the development of clinical trials with JAK2 (and JAK1) inhibitors. The JAK2V617F mutation occurs in almost all patients with polycythemia vera (PV) and in 50%-70% of those with essential thrombocythemia (ET) and primary myelofibrosis (PMF). Soon after the identification of the JAK2V617F mutation, mutations in JAK2 exon 12 were described in rare patients with JAK2V617F-negative PV and mutations in MPL were reported in 5%-10% of ET or PMF subjects. The complexity of the molecular pathogenesis of MPNs is reinforced by discovery of additional mutations in TET2, ASXL1, CBL, IDH1/IDH2, EZH2 and IKZF1. These mutations are detected in a minority of patients at different phases of the disorder, including leukemic transformation, and are variably associated each other and with JAK2 or MPL mutations. In order to better characterize biological differences between mutated and wild-type PMF cell populations we performed a gene expression profiling on 9 samples carrying at least one mutation in ASXL1, SRSF2 or EZH2 genes and 11 wild-type samples using the Affymetrix GeneChip technology. After data preprocessing and filtering a supervised analysis approach was used to define a gene expression signature for mutated samples. PMF samples carrying at least one mutation in ASXL1, SRSF2 or EZH2 genes exhibit a specific molecular signature as compared with WT samples.