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

Polycythemia vera (PV) is a chronic myeloproliferative disorder with an expansion of multipotent hematopoietic progenitor cells. Although it is known that hematopoietic progenitors in PV are erythropoietin independent and hypersensitive to several cytokines, the molecular oncogenic mechanisms in PV are largely unknown. In this study, we examined gene expression profiles of CD34(+) cells from bone marrow of patients with de novo PV and from healthy volunteers to identify molecular changes associated with the malignant growth of hematopoietic stem and progenitor cells in this myeloproliferative disorder. Using cDNA arrays, we found significant differences (P < .01) in the expression of 107 genes. Proapoptotic genes (CASP2, CASP3, DAPK1, ALG2) were expressed at lower levels in PV-CD34(+) cells, reflecting a lower apoptotic activity. Fibrosis-stimulating growth factors (transforming growth factor beta1, transforming growth factor beta2, bone morphogenetic protein 2, and endothelial growth factor) were expressed at significantly higher levels in PV-CD34(+) cells. Furthermore, PV-CD34(+) cells overexpressed several receptors, protein kinases, and proteasome subunits, which might be targets for directed therapeutic approaches. It is interesting that three retinoid receptors were overexpressed in PV-CD34(+) cells--retinoic acid receptor beta (RARbeta), retinoid X receptor beta (RXRbeta), and cellular retinoic acid binding protein 2 (CRABP2). Using methylcellulose colony-forming assays, we found that the formation of erythroid colonies derived from PV hematopoietic progenitors was inhibited by all-trans-retinoic acid (ATRA), a natural ligand of those receptors, in a dose-dependent manner, showing a maximum inhibition of 89% at 10 microM; the growth of myelomonocytic colonies was not significantly affected. These data suggest that the use of ATRA could be of therapeutic benefit for patients with PV.
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PMID:Distinct gene expression pattern of malignant hematopoietic stem and progenitor cells in polycythemia vera. 1595 2

The pathogenesis of acquired myeloperoxidase (MPO) deficiency, a rare phenomenon observed in patients with Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs), is unknown. MPO is a glycoprotein (GP) chaperoned by calreticulin (CALR) in the endoplasmic reticulum. Mutations in CALR are frequently found in patients with myelofibrosis (MF) and essential thrombocythemia (ET) with nonmutated Janus kinase 2 (JAK2). We hypothesized that acquired MPO deficiency in MPN could be associated with the presence of CALR mutations. A cohort of 317 patients with MPN (142 polycythemia vera [PV], 94 ET, and 81 MF) was screened for MPO deficiency. MPO deficiency was observed in 6/81 MF patients (7.4%), but not in PV or ET patients. Susceptibility to infections had been documented in 2/6 (33%) MPO-deficient patients. Five out of 6 patients with MPO deficiency carried a homozygous CALR mutation and were also deficient in eosinophilic peroxidase (EPX). In contrast, 1 patient with MF, a JAK2-V617F mutation, and MPO deficiency, carried 2 previously reported MPO mutations and showed normal EPX activity. Patients with homozygous CALR mutations had reduced MPO protein, but normal MPO messenger RNA (mRNA) levels supporting a posttranscriptional defect in MPO production. Finally, we demonstrate in vitro that in the absence of CALR, immature MPO protein precursors are degraded in the proteasome. Therefore, 4 decades after the first description of acquired MPO deficiency in MPN, we provide the molecular correlate associated with this phenomenon and evidence that CALR mutations can affect the biosynthesis of GPs.
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PMID:Homozygous calreticulin mutations in patients with myelofibrosis lead to acquired myeloperoxidase deficiency. 2734 Feb 51