Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0026986 (myelodysplastic syndrome)
 14,926 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The neurofibromatosis 1 (NF1) gene product, neurofibromin, contains a GTPase-activating protein (GAP)-related domain, or NF1 GRD, that is able to down-regulate p21ras by stimulating its intrinsic GTPase. Since p21ras.GTP is a major regulator of growth and differentiation, mutant neurofibromins resulting from somatic mutations in the NF1 gene might interfere with ras signaling pathways and contribute to the development of tumors. We describe an amino acid substitution in the NF1 GRD, altering Lys-1423, that has occurred in three tumor types: colon adenocarcinoma, myelodysplastic syndrome, and anaplastic astrocytoma, and in one family with neurofibromatosis 1. The GAP activity of the mutant NF1 GRD is 200- to 400-fold lower than that of wild type, whereas binding affinity is unaffected. Thus, germline mutations in NF1 that cause neurofibromatosis 1 can also occur in somatic cells and contribute to the development of sporadic tumors, including tumors not associated with neurofibromatosis 1.
 ...
PMID:Somatic mutations in the neurofibromatosis 1 gene in human tumors. 156 47

The presence of activated transforming genes was investigated in four patients with therapy-related leukemia and in three with therapy-related myelodysplastic syndrome. DNA of bone marrow cells from six of the patients exhibited transforming activity in the tumorigenicity assay. Five of the six patients who were positive in the tumorigenicity assay contained activated N-ras oncogenes, and three contained activated K-ras oncogenes. Thus, concurrent activation of N-ras and K-ras oncogenes was observed in two patients. In vitro DNA amplification followed by oligonucleotide dot-blot analysis was used to investigate mutations in codons 12, 13, and 61 of the N-ras and K-ras oncogenes. Two patients exhibited an N-ras mutation, substituting aspartic acid (GAT) for glycine (GGT), and three patients exhibited an N-ras codon 13 mutation, substituting valine (GTT) for glycine. Two patients exhibited K-ras codon 12 mutations, substituting aspartic acid (GAT) or cysteine (TGT) for glycine (GGT), respectively, and one case exhibited a K-ras codon 61 mutation, substituting lysine (AAA) for glutamic acid (CAA). Cytogenetic analysis revealed that loss of chromosome 7 was frequent (four patients: 57%). Our data indicate that activation of N-ras and K-ras genes, as well as loss of heterozygosity for specific alleles on chromosome 7, plays a more important role in the leukemogenesis of both therapy-related leukemia and myelodysplastic syndrome.
 ...
PMID:Transforming genes and chromosome aberrations in therapy-related leukemia and myelodysplastic syndrome. 185 83

A mutational hotspot in the neurofibromatosis 1 (NF1) gene has recently emerged from the analysis of different malignancies including one patient with myelodysplastic syndrome (MDS). In these cases, Lys 1423 in the GTPase-activating protein (GAP)-related domain of NF1 is substituted which causes a significant reduction of intrinsic GAP activity. We studied 57 MDS patients and 27 cases of acute myelocytic leukemia (AML) for mutations at codon 1423 in the so-called FLR exon of NF1 by an assay based on restriction enzyme digestion. We investigated the entire FLR exon and its flanking intron sequences using single-strand conformation polymorphism (SSCP) analysis of polymerase chain reaction (PCR) products and sequencing. None of the cases exhibited a codon 1423 mutation. However, a patient with chronic myelomonocytic leukemia (CMML) showed a 3 bp deletion within the splice acceptor region in front of the FLR exon. These data suggest that NF1 exon FLR mutations contribute infrequently to the development of MDS and AML.
 ...
PMID:Mutations within the FLR exon of NF1 are rare in myelodysplastic syndromes and acute myelocytic leukemias. 832 Oct 21

One of the first known effects of the endogenous peptide N-acetyl-Ser-Asp-Lys-Pro (AcSDKP) is to inhibit entry into DNA synthesis of pluripotent haematopoietic stem cells (CFU-S) in mice. A specific anti-AcSDKP polyclonal antibody allows the level of the tetrapeptide by to be determined by enzyme immunoassay with good sensitivity and specificity. We present results demonstrating the presence of AcSDKP in humans: serum levels of 34 healthy controls were found to be between 0.7 and 2.5 pm/ml, regardless of age and sex. High levels were found in 44% of asymptomatic controls but only in 8% of AIDS patients out of a total of 37 patients with HIV. Subsequently, studies of serum levels were performed before treatment in 121 subjects with disorders of the nonlymphoid and the lymphoid lineages. Our results did not demonstrate any decrease in serum levels, however a moderate or marked increase was noted in one-third of the subjects, which was greater in disorders of the non-lymphoid lineages (48% of 72 patients) than the lymphoid lineage (21% of 50 patients). The most significant differences were observed between controls versus patients with myeloproliferative disorders (MPD, 24 patients: p < 0.001), controls versus patients with acute myelogenous leukaemia (AML, 15 patients: p < 0.02), as well as patients with AML versus patients with primary myelodysplastic syndromes (PMDS, 10 patients: p < 0.05). The pathophysiology of these abnormalities is discussed.
 ...
PMID:Serum levels of a negative regulator of cell proliferation (AcSDKP) are increased in certain human haemopathies. 850 76

RAS mutations can be detected in a variable number of patients with myeloproliferative disorders such as myelodysplastic syndromes and acute myeloid leukemia, but are rare events in chronic myelogenous leukemia in chronic phase. However, there is good evidence supporting the involvement of RAS signalling pathway in CML and this could be due to alterations in RAS activity regulatory proteins. The neurofibromatosis (NF1) gene down-regulates the RAS signal transduction pathway through the inhibitory function of its GAP-related domain (GRD) on RAS protein. The loss or alteration of neurofibromin (the NF1 protein) may produce a disfunction similar to point mutations in the RAS gene resulting in the permanent stimulation of the RAS signal transduction pathway. Mutations involving the GRD region of the NF1 gene (GRD-NF1) have been described in a variety of tumors such as colon carcinoma and astrocytoma. Germline mutations and deletions in the NF1 gene, as seen in neurofibromatosis type 1, are also associated with certain myeloid disorders. In the present work, we sought to identify mutations in the codons 12/13 and 61 of RAS gene and in the Lys-1423 codon of GRD-NF1, which are well known hot spots in these genes, in a group of 36 adults and ten children with chronic myelogenous leukemia in chronic phase and blast crisis. Using the PCR-SSCP and the allele-specific restriction assay (ASRA) techniques, we were not able to observe any RAS or NF1 detectable mutation. These findings suggest that RAS and GRD-NF1 mutations are not involved either in chronic phase or in the progression to blast crisis in chronic myelogenous leukemia in adults and children.
 ...
PMID:Mutational analysis of N-RAS and GAP-related domain of the neurofibromatosis type 1 gene in chronic myelogenous leukemia. 978 2

Recent studies have shown that point mutations in granulocyte colony-stimulating factor receptor (G-CSFR) are involved in the pathogenesis of severe congenital neutropenia (SCN) and in the transformation of SCN to acute myelogenous leukemia (AML). It is reasonably speculated that the abnormalities in the signal transduction pathways for G-CSF could be partly responsible for the pathogenesis and the development to AML in patients with myelodysplastic syndromes (MDS). Therefore, we investigated the structural and functional abnormalities of the G-CSFR in 14 patients with MDS and 10 normal subjects. In in vitro colony forming assay, MDS samples showed reduced response to growth factors. However, G-CSF, but not GM-CSF and IL-3, enhanced clonal growth in three cases of high risk patients with MDS (RAEB, RAEB-t, and MDS having progressed to acute myeloid leukemia (AML)) and one low risk patient (RA). Eight out of 14 patients including above 4 patients demonstrated a common deletion of the G-CSFR cDNA; a deletion of three nucleotides (2128-2130) in the juxtamembrane domain of the G-CSFR, which resulted in a conversion of Asn(630)Arg(631) to Lys(630). To assess the functional activities of this deletion in the G-CSFR isoform, a mutant with the same three-nucleotide deletion was constructed by site-directed mutagenesis. FDCP-2 cells expressing the G-CSFR isoform responded to G-CSF, and exhibited proliferative responses than did those cells having wild-type G-CSFR. Moreover, these isoforms showed prolonged activation of STAT3 in response to G-CSF than did the wild-type. These results suggest that the deletion in the juxtamembrane domain of the G-CSFR gives a growth advantage to abnormal MDS clones and may contribute to the pathogenesis of MDS.
 ...
PMID:Novel variant isoform of G-CSF receptor involved in induction of proliferation of FDCP-2 cells: relevance to the pathogenesis of myelodysplastic syndrome. 1201 28

The myelodysplastic syndromes (MDS) comprise a group of clonal hemopoietic stem cell disorders characterized by ineffective hematopoiesis with an increased propensity to myeloid leukemic (AML) transformation. The underlying molecular basis for MDS and its leukemic evolution is unclear. Except for patients with 17p syndrome, loss of function of the p53 tumor suppressor gene accounts for <10% of MDS and AML cases. Recently, mutations of the checkpoint gene, CHK2, the human homologue of the yeast CDS1 and RAD53 genes, have been reported in patients with Li-Fraumeni syndrome who also have normal p53. As p53 mutations are rare in MDS and AML, we investigated the status of the CHK2 gene by reverse transcriptase-polymerase chain reaction (RT-PCR) in patients with MDS (n=10) and patients in whom MDS had transformed into AML (n=3). In the MDS group, we found one patient with a conserved mutation (Lys-->Arg) in the forked head-associated (FHA) domain of the CHK2 coding sequence. We also found a deletion in the CHK2 transcript in one patient from the MDS-->AML group, resulting in a truncated protein lacking the kinase domain. We conclude that alterations of CHK2 and possible involvement in the pathogenesis of MDS may be a rare event.
 ...
PMID:Analysis of CHK2 in patients with myelodysplastic syndromes. 1236 65

Several new therapeutic strategies are now considered for acute myelogenous leukaemia (AML), including modulation of protein lysine acetylation through inhibition of histone deacetylases (HDACs): a large group of enzymes that alters the acetylation and, thereby, the function of a wide range of nuclear and cytoplasmic proteins. Firstly, HDACs can deacetylate histones as well as transcription factors, and can modulate gene expression through both these mechanisms. Secondly, acetylation is an important post-translational modulation of several proteins involved in the regulation of cell proliferation, differentiation and apoptosis (e.g., p53, tubulin, heat-shock protein 90). The only HDAC inhibitors that have been investigated in clinical studies of AML are butyrate derivatives, valproic acid and depsipeptide. In the first studies, the drugs have usually been used as continuous therapy for several weeks or months, and in most studies the drugs were used alone or in combination with all-trans retinoic acid for treatment of patients with relapsed or primary resistant AML. Neurological toxicity and gastrointestinal side effects seem to be common for all three drugs. Complete haematological remission lasting for several months has been reported for a few patients (< 5% of included patients), whereas increased peripheral blood platelet counts seem more common and have been described both for patients with AML and myelodysplastic syndromes. Taken together, these studies suggest that HDAC inhibition can mediate antileukaemic effects in AML, but for most patients the clinical benefit seems limited and further studies of combination therapy are required.
 ...
PMID:Protein lysine acetylation in normal and leukaemic haematopoiesis: HDACs as possible therapeutic targets in adult AML. 1644 Dec 28

Five, repeatedly transfused, patients with refractory anemia (RA) or RA with ringed sideroblast (RARS) subtypes of myelodysplastic syndrome (MDS), with serum ferritin (SF) levels of > 2,000 microg/L, and one female with Hb E [beta26(B8)Glu --> Lys]/beta0-thalassemia (thal) with an SF level of 1,760 microg/ L, were treated with deferiprone (L1) at the dose of 4-6 g per day for at least 26 months. Beginning in the second month, all patients received recombinant human erythropoietin (rHuEPO) at the dose of 150 IU/kg thrice weekly, subcutaneously for 24 months. A significant increase in iron excretion after combined administration of L1 and rHuEPO compared to treatment with L1 as a single agent, was observed in all patients. The amount of excreted iron in urine ranged from 7.5 to almost 20 mg per day. In one patient, a response to rHuEPO resulted in transfusion independence and her SF decreased from 2086 to 879 microg/L. In four MDS patients, who remained dependent on red blood cell (RBC) transfusions, simultaneous administration of L1 and rHuEPO enabled the stabilization of SF levels, despite continuing iron load from the transfusions. Combined administration of rHuEPO and oral iron chelators may potentiate mobilization of storage iron and maintain iron balance in transfusion-dependent iron overloaded early MDS patients.
 ...
PMID:Erythropoietin administration may potentiate mobilization of storage iron in patients on oral iron chelation therapy. 1654 Apr 22

Methylation of DNA in combination with histone modifications establishes an epigenetic code that ensures the proper control of gene expression. Although DNA methyltransferases have been shown to interact with histone methyltransferases such as EZH2 (which methylates histone H3 on lysine 27) and G9a (which methylates histone H3 on lysine 9), the relationship between DNA methylation and repressive histone marks has not been fully studied. In cancer cells, promoters of genes are often aberrantly methylated. Accordingly, 5-azacytidine (a DNA demethylating drug) is used for treating patients with myelodysplastic syndrome. However, no genome-scale studies of the effects of this drug have been reported. In this work, we report the effects of 5-azacytidine on global gene expression and analyze ~24,000 human promoters using ChIP-chip to determine how 5-azacytidine treatment effects H3K27me3 and H3K9me3 levels. We found that (1) 5-azacytidine treatment results in large changes in gene regulation with distinct functional categories of genes showing increased (e.g. C2H2 zinc finger transcription factors) and decreased (e.g. genes involved in regulation of mitochondria and oxidoreductase activity) levels; (2) most genes that show altered expression are not regulated by promoters that display DNA methylation prior to the treatment; (3) certain gene classes switch their repression mark upon treatment with 5-azacytidine (from H3K27me3 to H3K9me3 and vice versa); and (4) most changes in gene expression are not due to relief of repression mediated by DNA or histone methylation.
 ...
PMID:5-azacytidine treatment reorganizes genomic histone modification patterns. 2030 84


1 2 3 4 5 Next >>