Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0032463 (polycythemia vera)
 3,374 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The chronic myeloproliferative disorders are clonal hematopoietic stem cell disorders and include chronic myeloid leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), and agnogenic myeloid metaplasia (AMM). These diseases are characterized by clonal expansion of the myeloid compartment, increased marrow angiogenesis, and varying risks for blastic transformation. A clear molecular abnormality exists (t(9;22) leading to the fusion of BCR-Abl) only for CML, which led to effective targeted therapy (STI-571). Since no similar pathogenetic mechanism has been discovered for the t(9;22) negative chronic myeloproliferative disorders, their respective diagnosis is currently based on a variety of rather cumbersome diagnostic criteria. Polycythemia vera is distinguished from reactive erythrocytosis through erythropoietin independent growth of erythroid progenitors in vitro, suppressed levels of endogenous erythropoietin, possible overexpression of PRV-1 (polycythemia rubra vera-1), decreased c-Mpl expression on megakaryocytes, as well as overexpression of bcl-xL, and potentially aberrant activity of the Jak-Stat pathway. ET is defined by thrombocytosis and is distinguished from reactive states by decreased megakaryocyte c-Mpl expression, and a propensity for thrombosis. AMM has been associated with a variety of observations including increased concentrations of pro-fibrotic cytokines, increased angiogenesis, and myeloid expansion. AMM is often indistinguishable clinically and prognostically from the advanced phases of other CMPD (specifically post-polycythemic and post-thrombocythemia myeloid metaplasia), all of which are subentities of a diagnosis of myelofibrosis with myeloid metaplasia (MMM). The management of CMPD patients is quite varied given the broad range of disease severity and survival observed. The role of stem cell transplantation is limited by the age and comorbidities encountered in CMPD patients. Since no broadly applicable therapy effects the mortality of the CMPD, management currently focuses on the prevention/palliation of disease morbidity (i.e. vascular complications, pruritus, organomegaly, constitutional symptoms). Palliative strategies which currently focus on non-specific myelosuppresion, will hopefully be soon replaced by targeted therapies as insight into pathogenetic mechanisms of these diseases evolves.
 ...
PMID:Clinical and scientific advances in the Philadelphia-chromosome negative chronic myeloproliferative disorders. 1243 Sep 25

In order to investigate the biologic processes underlying and resulting from the megakaryocytic hyperplasia that characterizes idiopathic myelofibrosis (IMF), peripheral blood CD34+ cells isolated from patients with IMF, polycythemia vera (PV), and G-CSF-mobilized healthy volunteers were cultured in the presence of stem cell factor and thrombopoietin. IMF CD34+ cells generated 24-fold greater numbers of megakaryocytes (MKs) than normal CD34+ cells. IMF MKs were also shown to have a delayed pattern of apoptosis and to overexpress the antiapoptotic protein bcl-xL. MK hyperplasia in IMF is, therefore, likely a consequence of both the increased ability of IMF progenitor cells to generate MKs and a decreased rate of MK apoptosis. Media conditioned (CM) by CD61+ cells generated in vitro from CD34+ cells were then assayed for the levels of growth factors and proteases. Higher levels of transforming growth factor-beta (TGF-beta) and active matrix metalloproteinase-9 (MMP9) were observed in media conditioned with IMF CD61+ cells than normal or PV CD61+ cells. Both normal and IMF CD61+ cells produced similar levels of VEGF. MK-derived TGF-B and MMP-9, therefore, likely contribute to the development of many pathological epiphenomena associated with IMF.
 ...
PMID:Pivotal contributions of megakaryocytes to the biology of idiopathic myelofibrosis. 1791 55

An increased expression of antiapoptotic molecules is often found in malignant cells, where it contributes to their clonal expansion by conferring an improved survival ability. We found that erythroid precurors derived from patients with polycythemia vera (PV) with medium and high JAK2V617F mutation rates often express elevated levels of the antiapoptotic molecules Bcl-2 and Bcl-X(L) (5 of 12 patients with 3 to 7 times Bcl-2 and 3 of 12 patients with 4 to 7 times Bcl-X(L) than average normal controls) and are more resistant to myelosuppressive drugs than normal erythroblasts. ABT-737, a small-molecule inhibitor of Bcl-2, Bcl-X(L), and Bcl-W, induced apoptosis preferentially in JAK2V617F-high PV erythroid precursors as compared with JAK2V617F-low or normal erythroblasts. ABT-737 inhibited also the proliferation of PV erythroblasts and interfered with the formation of endogenous erythroid colonies by PV hematopoietic progenitors. Altogether, these results suggest that small-molecule inhibitors of Bcl-2/Bcl-X(L) may be used in the treatment of patients with PV with high JAK2V617F allele burden.
 ...
PMID:Activity of the BH3 mimetic ABT-737 on polycythemia vera erythroid precursor cells. 1906 Feb 44