Phospho‐STAT5 and phospho‐Akt expression in chronic myeloproliferative neoplasms

• Published in: British journal of haematology Vol. 147; no. 4; pp. 495 - 506
• Main Authors: Grimwade, Lizz F., Happerfield, Lisa, Tristram, Colin, McIntosh, Gary, Rees, Mark, Bench, Anthony J., Boyd, Elaine M., Hall, Marie, Quinn, Amy, Piggott, Nigel, Scorer, Paul, Scott, Mike A., Erber, Wendy N.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.11.2009; Blackwell
• Subjects: Aged; Akt; Biological and medical sciences; Bone Marrow Cells - metabolism; Chronic Disease; Female; Hematologic and hematopoietic diseases; Humans; Janus Kinase 2 - genetics; Leukemias. Malignant lymphomas. Malignant reticulosis. Myelofibrosis; Male; Mastocytosis, Systemic - metabolism; Medical sciences; Megakaryocytes - metabolism; Middle Aged; Myeloproliferative Disorders - genetics; Myeloproliferative Disorders - metabolism; myeloproliferative neoplasms; Neoplasm Proteins - genetics; Neoplasm Proteins - metabolism; Phosphorylation; Proto-Oncogene Proteins c-akt - metabolism; Proto-Oncogene Proteins c-kit - genetics; Receptors, Thrombopoietin - genetics; STAT5; STAT5 Transcription Factor - metabolism; myeloproliferative neoplasms; Myeloproliferative syndrome; Signal transduction; Chronic; Phosphorylation; Hematology; Transcription factor STAT5; STATS; Akt protein kinase; Hemopathy; Transduction factor STAT; Akt
• ISSN: 0007-1048; 1365-2141
• DOI: 10.1111/j.1365-2141.2009.07870.x

Summary The majority of Myeloproliferative Neoplasms (MPNs) are characterised by mutations in genes encoding molecules or receptors involved in cell signalling, the most common being the JAK2 V617F mutation. This mutation leads to ligand‐independent activation of downstream signalling pathways by constitutive phosphorylation. The signalling pathways affected include the Janus kinase‐signal transducers and activators of transcription (JAK‐STAT) and phosphotidylinositide‐3 kinase (PI3K) pathways, which regulate cell survival and apoptosis respectively. Monoclonal antibodies to phospho‐STAT5 and phospho‐Akt were generated and assessed by immunocytochemistry on bone marrow biopsies of MPN patients with JAK2 V617F, JAK2 exon 12, MPL exon 10 and KIT D816V mutations. JAK2 V617F mutation was associated with significantly increased levels of phosphorylated STAT5 and Akt in haemopoietic cells, most marked in megakaryocytes. In contrast, JAK2 exon 12 and MPL exon 10 mutations did not affect the level of phosphorylation. In systemic mastocytosis with KIT D618V mutation there was significantly increased expression of phosphorylated STAT5 and Akt in neoplastic mast cells although there was no change in the expression in other haemopoietic cells. JAK2 V617F is associated with upregulated phosphorylation of STAT5 and Akt in megakaryocytes, and to a lesser extent in other haemopoietic cells. Immunocytochemistry of bone marrow trephines for these phospho‐proteins can be used as a supplementary diagnostic test with a high negative predictive value.