RESUMO
Janus kinase 1 (JAK1) and JAK3 plays a critical role in lymphocyte proliferation and differentiation. Somatic JAK1 mutations are found in 18% of adult precursor T acute lymphoblastic leukemias and somatic JAK3 mutations are found in 3.3% of cutaneous T cell lymphomas. Some of the mutations are confirmed as a gain-of-function mutation and are assumed to be involved in leukemogenesis. Adult T cell leukemia/lymphoma (ATLL) is a type of T cell neoplasm, and activation of JAK/STAT pathways is sometimes observed in them. We investigated JAK1 and JAK3 mutations in 20 ATLL patients. No JAK1 mutations were found, and five types of single nucleotide polymorphisms were observed in 12 cases, whose frequencies almost match those in Asian populations. As for JAK3, a synonymous mutation was found in one case. JAK1 and JAK3 mutations are unlikely involved in the leukemogenesis of ATLL.
Assuntos
Janus Quinase 1/genética , Janus Quinase 3/genética , Leucemia-Linfoma de Células T do Adulto/genética , Adulto , Diferenciação Celular , Proliferação de Células , Análise Mutacional de DNA , Humanos , Japão , Leucemia-Linfoma de Células T do Adulto/etiologia , Polimorfismo de Nucleotídeo ÚnicoRESUMO
An acquired JAK2 V617F mutation is found in most patients with polycythemia vera (PV), and about half of patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF). Mice transplanted with bone marrow cells in which JAK2 V617F was retrovirally expressed developed PV-like features, but not ET or PMF. To address the contribution of this mutation to the pathogenesis of these three MPDs, we generated two lines of JAK2 V617F transgenic mice. One line showed granulocytosis after 4 months of age. Among 43 mice, 8 (19%) showed polycythemia and 15 (35%) showed thrombocythemia. The second line showed extreme leukocytosis and thromobocytosis. They showed anemia that means Hb value from 9 to 10 g per 100 ml when 1 month old. Myeloid cells and megakaryocytes were predominant in the bone marrow of these animals, and splenomegaly was observed. The expression of JAK2 V617F mRNA in bone marrow cells was 0.45 and 1.35 that of endogenous wild-type JAK2 in the two lines, respectively. In vitro analysis of bone marrow cells from both lines showed constitutive activation of ERK1/2, STAT5 and AKT, and augmentation of their phosphorylations by cytokine stimulation. We conclude that in vivo expression of JAK2 V617F results in ET-, PMF- and PV-like disease.
