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

Therapy-related Myelodysplastic Syndromes/Acute Myeloid Leukemias (t-MDS/AML) are one of the most compelling long term adverse events occurring in cancer survivors treated with chemo-radiotherapy regimes. Beside several well-described genetic lesions, a growing amount of data suggests that abnormalities in DNA methylation profile contribute to multistep secondary leukemogenesis. Two distinct alterations of normal DNA methylation patterns may occur in cancer: a global hypomethylation resulting in chromosomal instability and loss of genetic integrity, and promoter specific DNA hypermethylation which leads to silencing of tumor suppressor genes. Cytotoxic drugs and radiation have been shown to affect tissue DNA methylation profile. Radiation is able to induce a stable DNA hypomethylation in both target and bystander tissues. Gene promoter methylation is a common finding in t-MDS/AML and has been associated to a shorter latency period from the treatment of the primary tumor. Among the studied genes, p15 methylation correlated to monosomy/deletion of chromosome 7q, suggesting that it could be a relevant event in alkylating agent-induced leukemogenesis. We found frequent methylation of DAPK in the t-MDS/AML group, especially in patients with a previous lymphoproliferative disease. In patients studied for concurrent methylation of several promoters, t-MDS/AML were significantly more frequently hypermethylated in 2 or more promoter regions than de novo MDS or AML suggesting that promoter hypermethylation of genes involved in cell cycle control, apoptosis and DNA repair pathways is a frequent finding in t-MDS/AML and may contribute to secondary leukemogenesis. However, how the epigenetic machinery is disrupted after chemo/radiotherapy and during secondary carcinogenesis is still unknown, warranting further studies.
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PMID:Epigenetic changes in therapy-related MDS/AML. 1987 6

Detection of aberrant promoter hypermethylation of tumor suppressor genes can be used as a prognostic or predictive marker for carcinogenesis. Since epigenetic modifying agents are FDA approved for treatment of patients with myelodysplastic syndrome, laboratory correlative tools to monitor response to this targeted therapy are important. Methylation specific quantum dot fluorescence resonance energy transfer (MS-qFRET) is a nanotechnology assay that enables the detection of methylation and its changes in a sensitive, quantifiable manner. It utilizes quantum dot-mediated fluorescence resonance energy transfer to achieve highly sensitive detection of DNA methylation. Template DNA is first treated with sodium bisulfite such that unmethylated cytosines are converted to uracil while methylated cytosines remain unconverted. Thereafter, the converted template is amplified using biotinylated methylation-specific primers. Quantum dots, functionalized with streptavidin, serve both as a scaffold to capture amplicons and as a donor for transferring energy to the Cy5 acceptor that is incorporated into the amplicons during PCR. Thus, the status of DNA methylation can be determined according to the level of FRET. In this report, MS-qFRET is validated in cell lines and then used to detect the status of p15(INK4B) methylation in clinical samples from eight patients with acute myeloid leukemia.
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PMID:DNA methylation detection using MS-qFRET, a quantum dot-based nanoassay. 2036 74

Human telomeres (discovery of telomere structure and function has been recently awarded The Nobel Prize) consist of approximately 5-12 kb of tandem repeated sequences (TTAGGG)n and associated proteins capping chromosome ends which prevent degradation, loss of genetic information, end-to-end fusion, senescence and apoptosis. Due to the end-replication problem, telomere repeats are lost with each cell division, eventually leading to genetic instability and cellular senescence when telomeres become critically short. Stabilization of the telomeric DNA through telomerase activation, unique reverse transcriptase, or activation of the alternative mechanism of telomere maintenance is essential if the cells are to survive and proliferate indefinitely. Telomerase is expressed during early development and remains fully active in specific germline cells, but is undetectable in most normal somatic cells. High level of telomerase activity is detected in almost 90% of human tumours and immortalized cell lines. The hematopoietic compartment may develop genetic instability as a consequence of telomere erosion, resulting in aplastic anaemia (AA) and increased risk of myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML). Genetic instability associated with telomere dysfunction (i.e. short telomeres) is an early event in carcinogenesis. The molecular cytogenetic method telomere/centromere fluorescence in situ hybridization (T/C-FISH) can be used to characterize the telomere length of hematopoietic cells. This review describes recent advances in the molecular characterization of telomere system, the regulation of telomerase activity in cancer pathogenesis and shows that the telomeric length could be a potential clinical marker of hematologic neoplasia and prognosis of disease.
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PMID:The role of telomeres and telomerase complex in haematological neoplasia: the length of telomeres as a marker of carcinogenesis and prognosis of disease. 2065 99

A hallmark of cancer is aberrant DNA methylation, consisting of global hypomethylation and regional hypermethylation of tumor suppressor genes. DNA methyltransferase inhibitors have been recognized as promising candidate anticancer drugs. Drug development has focused on DNA methylation inhibitors with the goal of activating tumor suppressor genes silenced by DNA methylation. 5-azacytidine (5-AC; Vidaza), a global DNA methyltransferase inhibitor, was Food and Drug Administration approved to treat myelodysplastic syndromes and is clinically tested for solid tumors. In this paper, it was demonstrated that 5'-aza-2'-deoxycytidine (5-azaCdR) activated both silenced tumor suppressor genes and pro-metastatic genes by demethylation, raising the concern that it would promote metastasis. 5-AzaCdR treatment increased the invasiveness of non-invasive breast cancer cell lines MCF-7 cells and ZR-75-1 and dramatically induced pro-metastatic genes; Urokinase plasminogen activator (uPA), matrix metalloproteinase 2 (MMP2), metastasis-associated gene (H-MTS1; S100A4) and C-X-C chemokine receptor 4 (CXCR4). The hypothesis that the blocking of cellular transformation activity of DNA methyltransferase inhibitor could be separated from the pro-metastatic activity was tested using short interfering RNA (siRNA) targeted to the different DNA methyltransferase (DNMT) genes. Although depletion of DNMT1 had the strongest effect on colony growth suppression in cellular transformation assays, it did not result in demethylation and activation of uPA, S100A4, MMP2 and CXCR4 in MCF-7 cells. Depletion of DNMT1 did not induce cellular invasion in MCF-7 and ZR-75-1 non-invasive breast cancer cell lines. These data have implications on the design of new DNA methyltransferase inhibitor and on the proper utilization of current inhibitors.
Carcinogenesis 2011 Feb
PMID:Effects of specific DNMT gene depletion on cancer cell transformation and breast cancer cell invasion; toward selective DNMT inhibitors. 2098 Mar 50

The relative risk of clonal evolution to either myelodysplasia (MDS) or acute myelogenous leukemia (AML) is high in patients with chronic bone marrow failure. From 10 to 20% of acquired aplastic anemia survivors will develop clonal evolution within the decade following their diagnosis as will 40% of patients with some of the inherited bone marrow failure syndromes. Studies on bone marrow failure states have provided some perspective on molecular pathogenesis of marrow failure and have also provided insights on the adaptive nature of clonal evolution. We review the scientific evidence validating this model, emphasize the importance of the fitness landscape in the stem cell pool, outline the clinical and investigative implications of the model, suggest that the lack of fitness in the starting pool accounts for the phenomenon of oncogene addiction, promote the value of the model for the evaluation of prevention strategies, and argue that experiments focusing attention on the relative phenotypes of neoplastic stem cell clones and pools of unfit stem cells from which they evolved will provide a useful paradigm of carcinogenesis in general.
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PMID:The stem cell fitness landscape and pathways of molecular leukemogenesis. 2119 92

Epigenetic changes frequently occur in human colorectal cancer. Genomic global hypomethylation, gene promoter region hypermethylation, histone modifications, and alteration of miRNA patterns are major epigenetic changes in colorectal cancer. Loss of imprinting(LOI) is associated with colorectal neoplasia. Folate deficiency may cause colorectal carcinogenesis by inducing gene-specific hypermethylation and genomic global hypomethylation. HDAC inhibitors and demethylating agents have been approved by the FDA for myelodysplastic syndrome and leukemia treatment. Non-coding RNA is regarded as another kind of epigenetic marker in colorectal cancer. This review is mainly focused on DNA methylation, histone modification, and microRNA changes in colorectal cancer.
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PMID:Epigenetic changes in colorectal cancer. 2205 7

It is becoming clear that epigenetic mechanisms are associated with disease. To date, a myriad of epigenetic alterations, including altered DNA methylation and aberrant histone post-translational modifications, have been linked with various conditions. The most widely investigated example is the link between aberrant DNA methylation and malignancy that has lead to the clinical use of the DNA methyltransferase inhibitors, azacitidine and decitabine, for the treatment of myelodysplastic syndromes. Similarly, defective histone acetylation status has been associated with malignancy, providing the basis for the clinical use of the histone deacetylase inhibitors suberoylanilide hydroxamic acid and depsipeptide for the treatment of cutaneous T-cell lymphoma. In addition, there is an emerging association between perturbed fetal epigenetic programming and developmental origins of disease due to both nutritional and environmental factors. In particular, epigenetic events associated with metabolic syndrome have been identified. Related epigenetic mechanisms as well potential pharmacological and dietary interventions at critical periods of development form a large part of the discussion in this Forum. Further, this Forum provides an in-depth account of the association between epigenetic mechanisms and carcinogenesis with a focus on disease prevention with dietary chromatin-modifying compounds. Finally, the association between aberrant epigenetic events and neurodegenerative conditions, such as Alzheimer's disease (AD), is becoming apparent. A research article in this Forum identifies a potential new polymorphism associated with one-carbon metabolism that may contribute to the pathogenesis of AD. Overall, this Forum provides a detailed account of known epigenetic processes in developmental programming and human disease.
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PMID:Factors influencing epigenetic mechanisms and related diseases. 2233 52

Inactivation of the DNA mismatch repair pathway manifests as microsatellite instability, an accumulation of mutations that drives carcinogenesis. Here, we determined whether microsatellite instability in acute myeloid leukemia and myelodysplastic syndrome correlated with chromosomal instability and poly (ADP-ribose) polymerase (PARP) inhibitor sensitivity through disruption of DNA repair function. Acute myeloid leukemia cell lines (n=12) and primary cell samples (n=18), and bone marrow mononuclear cells from high-risk myelodysplastic syndrome patients (n=63) were profiled for microsatellite instability using fluorescent fragment polymerase chain reaction. PARP inhibitor sensitivity was performed using cell survival, annexin V staining and cell cycle analysis. Homologous recombination was studied using immunocytochemical analysis. SNP karyotyping was used to study chromosomal instability. RNA silencing, Western blotting and gene expression analysis was used to study the functional consequences of mutations. Acute myeloid leukemia cell lines (4 of 12, 33%) and primary samples (2 of 18, 11%) exhibited microsatellite instability with mono-allelic mutations in CtIP and MRE11. These changes were associated with reduced expression of mismatch repair pathway components, MSH2, MSH6 and MLH1. Both microsatellite instability positive primary acute myeloid leukemia samples and cell lines demonstrated a downregulation of homologous recombination DNA repair conferring marked sensitivity to PARP inhibitors. Similarly, bone marrow mononuclear cells from 11 of 56 (20%) patients with de novo high-risk myelodysplastic syndrome exhibited microsatellite instability. Significantly, all 11 patients with microsatellite instability had cytogenetic abnormalities with 4 of them (36%) possessing a mono-allelic microsatellite mutation in CtIP. Furthermore, 50% reduction in CtIP expression by RNA silencing also down-regulated homologous recombination DNA repair responses conferring PARP inhibitor sensitivity, whilst CtIP differentially regulated the expression of homologous recombination modulating RecQ helicases, WRN and BLM. In conclusion, microsatellite instability dependent mutations in DNA repair genes, CtIP and MRE11 are detected in myeloid malignancies conferring hypersensitivity to PARP inhibitors. Microsatellite instability is significantly correlated with chromosomal instability in myeloid malignancies.
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PMID:Microsatellite instability induced mutations in DNA repair genes CtIP and MRE11 confer hypersensitivity to poly (ADP-ribose) polymerase inhibitors in myeloid malignancies. 2334 4

DNA-demethylating agents activate tumor suppressor genes that are silenced by DNA methylation in cancer and are therefore emerging as a novel approach to cancer therapy. 5-azacytidine (VIDAZA), the first representative of this class of drugs was approved for treatment of myelodysplastic syndromes and is currently being tested on other cancers including solid tumors. However, 5-azacytidine or its deoxy-analog, 5-aza-2'-deoxycytidine (5-azaCdR) could also induce methylated prometastatic genes by DNA demethylation and induce cancer cell invasiveness. Since 5-azacytidine is a potent cancer growth inhibitor, we tested whether combining it with a DNA-methylating agent, the methyl donor S-adenosyl methionine (SAM), would block the adverse demethylating activity of 5-azaCdR while maintaining its growth suppression effects. We show here using several invasive and non-invasive breast cancer cell lines that SAM inhibits global- and gene-specific demethylation induced by 5-azaCdR, prevents 5-azaCdR activation of prometastatic genes uPA and MMP2, resulting in inhibition of cell invasiveness while augmenting the growth inhibitory effects of 5-azaCdR and its effects on tumor suppressor genes. Combination of drugs acting on the DNA methylation machinery at different levels is proposed as a new strategy for epigenetic therapy of cancer.
Carcinogenesis 2014 Jan
PMID:Synergistic anti-breast cancer effect of a combined treatment with the methyl donor S-adenosyl methionine and the DNA methylation inhibitor 5-aza-2'-deoxycytidine. 2398 80

Here, we investigated the role of one gene that has been previously associated with human prostate carcinoma cells-myelodysplasia/myeloid leukemia factor 1 interacting protein (MLF1IP)-in order to better ascertain its role in human prostate carcinogenesis. The prostate cancer cell line PC-3 was lentivirally transfected to silence endogenous MLF1IP gene expression, which was confirmed by real-time quantitative PCR (RT-qPCR). Cellomics ArrayScan VTI imaging and MTT assays were conducted to assess cell proliferation. Cell cycle phase arrest and apoptosis were assayed by flow cytometry. Colony formation was assessed by fluorescence microscopy. MLF1IP gene expression was also analyzed by RT-qPCR in sixteen prostate cancer tissue samples and six healthy control prostate tissue samples from human patients. Cell proliferation was significantly inhibited in MLF1IP-silenced cells relative to control cells. G1 phase, S and G2/M phase cell counts were not significantly changed in MLF1IP-silenced cells relative to control cells. Apoptosis was significantly increased in MLF1IP-silenced cells, while MLF1IP-silenced cells displayed a significantly reduced number of cell colonies, compared to control cells. The 16 human prostate cancer tissue samples revealed no clear upregulation or downregulation in MLF1IP gene expression. MLF1IP significantly promotes prostate cancer cell proliferation and colony formation and significantly inhibits apoptosis without affecting cell cycle phase arrest. Further study is required to conclusively determine whether MLF1IP is upregulated in human prostate cancer tumors and to determine the precise cellular mechanism(s) for MLF1IP in prostate carcinogenesis.
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PMID:MLF1 interacting protein: a potential gene therapy target for human prostate cancer? 2557 10


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