Search results for "azacitidine"
showing 10 items of 38 documents
Hypomethylating agents in relapsed and refractory AML: outcomes and their predictors in a large international patient cohort.
2018
Although hypomethylating agents (HMAs) are frequently used in the frontline treatment of older acute myeloid leukemia (AML) patients, little is known about their effectiveness in relapsed or primary treatment–refractory (RR)-AML. Using an international multicenter retrospective database, we studied the effectiveness of HMAs in RR-AML and evaluated for predictors of response and overall survival (OS). A total of 655 patients from 12 centers received azacitidine (57%) or decitabine (43%), including 290 refractory (44%) and 365 relapsed (56%) patients. Median age at diagnosis was 65 years. Best response to HMAs was complete remission (CR; 11%) or CR with incomplete count recovery (CRi; 5.3%). …
DNA demethylation caused By 5-Aza-2'-Deoxycytidine induces mitotic alterations and aneuploidy
2016
Aneuploidy, the unbalanced number of chromosomes in a cell, is considered a prevalent form of genetic instability and is largely acknowledged as a condition implicated in tumorigenesis. Epigenetic alterations like DNA hypomethylation have been correlated with cancer initiation/progression. Furthermore, a growing body of evidence suggests the involvement of epigenome-wide disruption as a cause of global DNA hypomethylation in aneuploidy generation. Here, we report that the DNA hypomethylating drug 5-aza-2′-deoxycytidine (DAC), affects the correct ploidy of nearly diploid HCT-116 human cells by altering the methylation pattern of the chromosomes. Specifically, we show that a DAC-induced reduc…
DNA Hypomethylation and Histone Variant macroH2A1 Synergistically Attenuate Chemotherapy-Induced Senescence to Promote Hepatocellular Carcinoma Progr…
2016
Abstract Aging is a major risk factor for progression of liver diseases to hepatocellular carcinoma (HCC). Cellular senescence contributes to age-related tissue dysfunction, but the epigenetic basis underlying drug-induced senescence remains unclear. macroH2A1, a variant of histone H2A, is a marker of senescence-associated heterochromatic foci that synergizes with DNA methylation to silence tumor-suppressor genes in human fibroblasts. In this study, we investigated the relationship between macroH2A1 splice variants, macroH2A1.1 and macroH2A1.2, and liver carcinogenesis. We found that protein levels of both macroH2A1 isoforms were increased in the livers of very elderly rodents and humans, a…
Blastic plasmacytoid dendritic cell neoplasm: genomics mark epigenetic dysregulation as a primary therapeutic target
2018
Blastic Plasmacytoid Dendritic Cell Neoplasm is a rare and aggressive hematological malignancy currently lacking an effective therapy. To possibly identify genetic alterations useful for a new treatment design, we analyzed by whole-exome sequencing fourteen Blastic Plasmacytoid Dendritic Cell Neoplasm patients and the patient-derived CAL-1 cell line. The functional enrichment analysis of mutational data reported the epigenetic regulatory program as the most significantly undermined (P<.0001). In particular, twenty-five epigenetic-modifiers were found mutated (e.g., ASXL1, TET2, SUZ12, ARID1A, PHF2, CHD8); ASXL1 was the most frequently affected (28.6% of cases). To evaluate the impact of …
Patterns of differentiation in extraosseous Ewing's sarcoma cells. An in vitro study.
1994
BACKGROUND In vitro, tissue culture-associated differentiation assays have facilitated the identification of multiple tumor-cell types. METHODS We have investigated the capability of differentiation of three extraosseous Ewing's sarcoma cell lines toward a neural and muscular direction by in vitro stimulation with dibutyryl cyclic adenosine-monophosphate (db cAMP) and 5-azacytidine, respectively. RESULTS Elongation of cytoplasmic processes and increase of neural markers chromogranin, S-100 protein, and glial fibrillary acidic protein were observed after db cAMP treatment of these lines and neurosecretory granules as well as myelin figures were demonstrated ultrastructurally. These results s…
Demethylation treatment restores hic1 expression and impairs aggressiveness of head and neck squamous cell carcinoma.
2010
Promoter hypermethylation of tumor suppressor genes is a common feature of primary cancer cells. However, at date the somatic epigenetic events that occur in head and neck squamous cell carcinoma (HNSCC) tumorigenesis are not yet been well defined. In the present study we analysed the methylation status of the gene hypermethylated in cancer-1 (hic1), a gene located on chromosome 17p13.3, a region frequently lost in HNSCC. We analysed 22 HNSCC samples and three cell lines using methylation specific PCR (MSP). We found hic1 methylated in 21 out of 22 samples and in all three cell lines. Treatment of the cell lines with the demethylating agent 5-Azacytidin (5-Aza) resulted in the demethylation…
The DNA methylation inhibitor 5-azacytidine modulates 6-thioguanine toxicity in mammalian cells
2003
In order to assess the effects of combining two antimetabolites used separately to treat human leukemias, we carried out an experimental study by exposing V79 Chinese hamster cells, a 6-thioguanine (6-tG)-sensitive cell line, to sequential and concurrent treatments with 5-azacytidine (5-azaC) and 6-tG. In this paper, we demonstrate that there is a clear dependency for the way in which this combination was tested. Pre-treatment with 5-azaC made V79 cells more resistant to 6-tG by a substantial reduction in 6-tG incorporation into DNA; this effect could still be detected for several cell divisions after the removal of 5-azaC, and was achieved neither by reduced cell growth nor by the inductio…
Acquired resistance of melanoma cells to the antineoplastic agent fotemustine is caused by reactivation of the DNA repair gene mgmt
2001
Acquired resistance to antineoplastic agents is a frequent obstacle in tumor therapy. Malignant melanoma cells are particularly well known for their unresponsiveness to chemotherapy; only about 30% of tumors exhibit a transient clinical response to treatment. In our study, we investigated the molecular mechanism of acquired resistance of melanoma cells (MeWo) to the chloroethylating drug fotemustine. Determination of O6-methylguanine-DNA methyltransferase (MGMT) activity showed that MeWo cells that acquired resistance to fotemustine upon repeated treatment with the drug display high MGMT activity, whereas the parental cell line had no detectable MGMT. The resistant cell lines exhibit cross-…
Analysis of Possible Mechanisms Accounting for Raf-1 Kinase Inhibitor Protein Downregulation in Hepatocellular Carcinoma
2012
Abstract Raf-1 kinase inhibitor protein (RKIP) is a tumor and metastasis suppressor that promotes drug-induced apoptosis in cancer cells. It is frequently downregulated, both at the mRNA and protein level, in hepatocellular carcinoma (HCC), but the mechanisms leading to this reduction are obscure. We sequenced the whole RKIP gene in three human HCC cell lines (HA22T/VGH, HepG2, and Hep3B), and in five clinical HCC samples, but could not find any gene variant that might account for their low RKIP levels. We also examined whether gene methylation may be responsible for the altered RKIP expression. No methylation of the RKIP gene was found in the tumor samples, while among the cell lines only …
Differential Promotion of Glutamate Transporter Expression and Function by Glucocorticoids in Astrocytes from Various Brain Regions
2005
Steroids that activate glucocorticoid receptors (GRs) and mineralocorticoid receptors have important regulatory effects on neural development, plasticity, and the body's stress response. Here, we investigated the role of corticosteroids in regulating the expression of the glial glutamate transporters glial glutamate transporter-1 (GLT-1) and glutamate-aspartate transporter (GLAST) in rat primary astrocytes. The synthetic glucocorticoid dexamethasone provoked a marked increase of GLT-1 transcription and protein levels in cortical astrocytes, whereas GLAST expression remained unaffected. Up-regulation of GLT-1 expression was accompanied by an enhanced glutamate uptake, which could be blocked …