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)

Preleukemia is thought to be a clonal disorder of hemopoietic stem cells. The conversion of a normal cell into a preleukemic and ultimately leukemic state is a multistep process requiring the accumulation of a number of genetic lesions. The myelodysplastic syndromes have become a paradigm for human preleukemia, where nonrandom chromosomal abnormalities, including complete or partial deletions of chromosomes five and seven, trisomy eight and Y chromosome loss suggest specific changes. Of particular significance are 5q deletions, as many genes important in hemopoiesis are located in this region, including the proto-oncogene FMS, which encodes the receptor for the macrophage colony-stimulating factor, CSF-1. Genetic damage such as point mutations in the RAS and FMS genes has been detected in preleukemia patients. The RAS gene family (N, K and H) encodes membrane-bound G proteins, which, like other proto-oncogenes, are components of the intracellular signal transduction pathways controlling mitogenesis and differentiation. The characterization of such lesions may ultimately identify those patients at greatest risk of leukemic transformation.
 ...
PMID:Genetic lesions in preleukemia. 142 Apr 44

Human urinary macrophage colony-stimulating factor (hM-CSF) is a glycoprotein with a molecular weight of 85 kDa which consists of two homologous subunits with a molecular weight of 43 kDa. It stimulates monocyte production through the stimulation of progenitor cells to differentiate to mature monocytes as well as neutrophil production through the stimulation of mature monocytes to produce granulocyte-macrophage and granulocyte CSF. It also enhances platelet production through the production of megakaryocyte potentiator (Meg-POT). Recently, proteoglycan type M-CSF has been found by our group. This type of M-CSF has a molecular weight of greater than 200 kDa and consists of a 43 kDa subunit and a 150-200 kDa subunit, the latter of which contains chondroitin sulfate glycosaminoglycan. This proteoglycan type M-CSF binds to extra-cellular matrix at the part of glycosaminoglycan. In addition to hematopoiesis-stimulating activity, M-CSF has a promoting activity on monocyte tumor-killing, osteoclast production and differentiation of cytotrophoblasts to syncytiotrophoblasts which secrete gonadotropin. M-CSF receptor (M-CSF-R) was found as a product of proto-oncogene, c-fms which consists of 972 amino acids. Mutations at Tyr 969 and Ser 301 of M-CSF-R has been found in patients with myelodysplastic syndrome and monocytic leukemia.
 ...
PMID:[Function,molecular structure and gene expression of macrophage colony-stimulating factor]. 143 77

DNA methylation plays an important role in gene regulation. We have analyzed the methylation status of CCGG sites in and around the human proto-oncogene c-myc in blood cells from patients with acute and chronic leukemias and with myelodysplastic syndromes using restriction endonucleases. The 5' region of c-myc was unequivocally hypomethylated in all the 58 specimens studied, including 10 from normal bone marrow and 1 from human placenta. In contrast, the 3' region was hypermethylated in a great majority of cases. However, this region was hypomethylated in 1 of 12 patients with de novo acute myeloid leukemia, 1 of 6 patients with chronic myeloid leukemia, and 4 of 5 patients with acute myeloid leukemia preceded by a documented stage of myelodysplastic syndromes. One possible mechanism for the 3' region of c-myc to have remained hypomethylated may be a "delayed methylation" during transforming events toward a more aggressive stage of the disease, but the precise mechanism is unknown.
 ...
PMID:Methylation status of c-myc oncogene in leukemic cells: hypomethylation in acute leukemia derived from myelodysplastic syndromes. 146 40

We performed a longitudinal analysis of point mutations of the N-ras proto-oncogene in patients with myelodysplasia and a follow-up of at least 2.5 years after diagnosis. Point mutations at codons 12, 13, and 61 of the N-ras oncogene were analyzed after in vitro amplification of N-ras specific sequences followed by dot-blot hybridization. Lysed cells scraped from archived blood and bone marrow smears were used as template for a polymerase chain reaction. In 3 of 90 patients tested (3.3%), a mutation in codon 12 could be detected in the most recent blood smears. All available blood and bone marrow samples of these patients were subsequently analyzed for the occurrence of that particular mutation. In all three cases the mutation was not detectable at diagnosis, but was acquired later during the course of the disease. In two of these patients this event was associated with rapid deterioration and transformation to acute leukemia. However, the third patient showed a protracted course during a period of 5 years after acquisition of the mutation. These results indicate that activation of the N-ras protooncogene in these three patients represents a secondary phenomenon associated with disease progression in some cases, but compatible with stable disease in others.
 ...
PMID:Longitudinal analysis of point mutations of the N-ras proto-oncogene in patients with myelodysplasia using archived blood smears. 153 50

The ras proto-oncogene family encodes a group of 21 kDa nucleotide-binding proteins. Activating mutations of ras genes are associated with certain types of malignancies, indicating that they are related in some way to the malignant process. We have examined bone marrow cells from nine children with myelodysplastic syndromes (MDS) and 35 with acute myeloid leukemia (AML) for activating point mutations of ras genes by in vitro amplification using polymerase chain reaction (PCR), oligonucleotide hybridization and sequencing of PCR products. We found N-ras mutations in cells from 3 of 9 children (33%) with MDS and only 2 of 35 children with AML (6%; 95% confidence interval is 0.7-19%). All mutations the second nucleotide of codon 12 or the first nucleotide of codon 61 of N-ras. There was no apparent correlation with clinical or laboratory characteristics, including karyotype; however, an association of N-ras activation with the most aggressive type of MDS was noted. Among the patients with MDS, 2 of 6 with monosomy 7 had N-ras mutations; however, three children with monosomy 7 which presented with AML lacked ras mutations. One patient was studied at time of diagnosis of MDS and again after progression to AML. At the preleukemic stage of disease, an N-ras mutation was identified; however, after development of AML this mutation was not present in the leukemic clone. In conclusion, these data show that ras mutations, while not necessary for leukemic transformation, may be important for the initiation of preleukemias evolving into overt AML.
 ...
PMID:Prevalence of N-ras mutations in children with myelodysplastic syndromes and acute myeloid leukemia. 154 47

We describe a novel continuous B-cell line (PV-90) derived from a patient with myelodysplastic syndrome (MDS) and originating from spontaneous infection with the Epstein-Barr virus (EBV). The patient progressed to acute myeloblastic leukaemia (AML) 5 months after clinical onset of MDS. PV-90 is of clonal origin as indicated by the presence of immunoglobulin (Ig) gene rearrangements, monoclonal surface immunoglobulins, and a single DNA restriction fragment corresponding to the EBV genomic termini. PV-90 cells also express a number of myelomonocytic markers, including alpha-naphthyl acetate esterase (ANAE), coagulation factor XIII, and CD68 antigen. Moreover, PV-90 cells constitutively express the c-fms proto-oncogene mRNA as the patient's blast cells did. Whereas a trisomy 11 (+11) was found in the patient's bone marrow cells, PV-90 cells had a normal karyotype initially, but at 4 months showed two different and independent chromosomal abnormalities: 90, XX, -Y, -Y, t(9;16) (q11;p13), and 90, XX, -Y, -Y, t(17;18) (p13;q21), the latter possibly involving the p53 (17,p13) and bcl-2 (18, q21) proto-oncogenes. The early development of these chromosomal aberrations is consistent with a genetic instability of PV-90 cells. Expression of bi-lineage markers and genetic instability may suggest that PV-90 cells originated from transformation of a myelodysplastic progenitor cell capable of both myeloid and B-cell differentiation. The PV-90 cell line might be useful in a number of studies, including the possible role of c-fms in cell differentiation, pathogenetic mechanisms of human preleukaemia and lineage promiscuity in acute leukaemia.
 ...
PMID:Establishment and characterization of a B-cell line derived from a patient with a myelodysplastic syndrome which expresses myelomonocytic and lymphoid markers. 164 72

We have screened a large series of primary human leukemias for activating point mutations at codons 12, 13 and 61 of the N-ras and K-ras proto-oncogenes and at codons 12 and 61 of the H-ras proto-oncogene by using panels of oligonucleotide probes in conjunction with polymerase chain reaction gene amplification. 13 of 64 (20%) acute lymphoblastic leukemia cases had ras gene mutations mostly involving N-ras codon 12/13, G-A (gly-asp) transitions. Consistent with previous studies, a comparable pattern and frequency of ras mutation was found amongst 45 cases of acute myeloid leukemia and myelodysplasia. By contrast, of 30 cases of mature B cell chronic lymphocytic leukemia, only one in terminal prolymphocytoid transformation harboured an activated ras gene. These patterns of mutation did not correlate with ras gene methylation state, a finding not obviously compatible with differential gene accessibility being an important determinant of ras gene mutation patterns in leukemogenesis. Our data suggest that activated ras is more important in tumourigenesis of immature than mature lymphocyte progenitors whilst similar mechanisms associated with aetiology and/or target cell susceptibility probably underlie the similar patterns of ras gene mutations seen in acute leukemias of both myeloid and lymphoid cell lineages.
 ...
PMID:Analysis of ras gene mutations and methylation state in human leukemias. 266 44

The clinical association of an increased incidence of acute myelogenous leukemia (AML) with previous chemoradiotherapy, the detection of specific karyotypic changes in these secondary (therapy-induced) cases of AML and the discovery of increasing levels of oncogene-specific RNA in leukemia cells suggest that one potential site of action of environmental agents might be the proto-oncogenes in human hematopoietic stem cells. The location of human proto-oncogenes at the sites of chromosome breaks and/or translocations in cells from some patients with leukemia or lymphoma is a striking observation. These data stimulated research into the mechanism of activation of specific oncogenes that change the biology of human hematopoietic cells. Recent investigations have focused upon several areas that might alter cell biology including: 1) translocation and/or inversion of chromosome fragments containing a proto-oncogene to a location where other gene sequences can stimulate oncogene activation, 2) replication of copy number of proto-oncogenes or increased transcriptional activity and 3) point mutation in proto-oncogenes leading to a structurally altered protein. The third area of research has recently received significant attention with respect to the potential role of three ras genes (c-Harvey-ras, c-Kirsten-ras and N-ras) in human leukemias and myelodysplastic syndromes. Recent studies have proposed a model for leukemogenic transformation of human hematopoietic cells by the product of a mutated ras oncogene. Mutations at codons 12, 13 or 61 of the first exon of its 4.7 Kb of DNA (for c-Ha-ras) have been described. Other data revealing an absence of such mutations in the ras genes of many human leukemias and the absence of detectable transcription of ras genes in many alkylating agent-associated cases of AML, suggest that while ras mutations may be involved in some settings, there are probably multiple genetic pathways to leukemogenic transformation of human hematopoietic cells.
 ...
PMID:ras mutations in human leukemia and related disorders. 268 41

Abnormalities of chromosome 7 are among the most frequent cytogenetic aberrations found in MDS, including de novo cases and cases secondary to chemo- and/or radiotherapy. Since MET is located on 7q and as Cooper et al (1984) showed that MET proto-oncogene could be activated by a chemical carcinogen, we tried to evaluate whether it could be implicated in some cases of MDS. With specific probes for MET we analysed the DNA of 88 MDS patients (81 de novo and seven secondary cases). In 17 of them the RNA was also studied. We found no rearrangement or aberrant expression of MET in any samples studied. Our results, however, do not rule out point mutations or rearrangement of other regions of MET or adjacent DNA regions.
 ...
PMID:Absence of rearrangement of proto-oncogene MET in 88 cases of myelodysplastic syndromes (MDS). 280 76

Proto-oncogenes, which have been widely implicated in the pathogenesis of malignant human tumors, frequently demonstrate restriction fragment length polymorphism (RFLP). Population studies of such restriction alleles is of potential interest for genetic analysis of cancer susceptibility. Some of the initial date of Krontiris et al (1985) showing a significant increase of rare c-ha-ras-l alleles in individuals with tumors, have been confirmed in certain types of cancer (breast cancer, lung adenocarcinoma), whereas others have been refuted (myelodysplasia, melanoma, colon adenocarcinoma). Other significant associations have been found between other proto-oncogene RLFPs and tumors (c-mos and breast cancer, c-raf and non Hodgkins lymphoma, L-myc and lung carcinoma metastasis). Although they are controversial, these studies should be extended, in order to determine whether the presence of certain alleles is a contributing factor in the development of certain tumors.
 ...
PMID:[Genetic polymorphism and susceptibility to cancer]. 289 51


1 2 3 4 5 Next >>