Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent studies have indicated a close relationship between inactivation of tumor suppressor genes (TSGs) and disease progression. The genes encoding the cyclin-dependent kinase inhibitors p16INK4A and p15INK4B are potent TSGs, and correlations between their inactivation and disease progression have also been reported in various malignancies. In this study, we analyzed the methylation status of p16INK4A and p15INK4B gene promoters in plasma cell dyscrasias (PCDs) by methylation-specific PCR (MSP). In analyses using DNAs extracted from bone marrow mononuclear cells (BM-MNCs), patients with multiple myeloma (MM) showed frequent hypermethylation of the p16INK4A gene (15/37, 41%), whereas p15INK4B gene methylation was not so frequent (5/37, 14%). Many patients whose BM-MNC showed dense methylation of the p16INK4A gene had extramedullary plasmacytoma (extra-PC), and all available extra-PC samples showed alterations of the p16INK4A gene (4; dense methylation, 1; homozygous deletion). In contrast to MM, hypermethylation of the p16INK4A gene was significantly infrequent in indolent PCDs (2/22, 9%, P= 0.0055). The infrequency in indolent PCDs was also confirmed by analyses using DNAs extracted from BM smears (1/29, 3%). It is possible that hypermethylation of the p16INK4A gene promoter contributes to progression to aggressive MM from indolent PCD, especially to extra-PC development.
Leukemia 2001 Jan
PMID:Hypermethylation of p16INK4A gene promoter during the progression of plasma cell dyscrasia. 1124 84

The proto-oncogene c-myb is constitutively expressed in murine leukemia virus-induced myeloid leukemia (MML) due to the integration of virus at this locus. Our recent focus has been the determination of genes regulated by this transcription factor that may be involved in transformation. Data presented here, using conditional expression of Myb in myeloid cells, show that c-Myb directly transactivates the endogenous c-myc and Bcl-2 genes, which explains at least in part how c-Myb regulates proliferation and survival. In addition, c-Myb prevents expression at the RNA level of the tumor suppressor INK4b gene. This gene encodes a cyclin-dependent kinase inhibitor, p15INK4b, that is normally upregulated at the mRNA level during myeloid differentiation and promotes growth arrest. The MMLs are generally characterized as differentiated monocytic tumors and possess the phenotype that is normally associated with p15INK4b expression. c-Myb inhibits expression of this gene, however, and therefore acts to promote a pathway which is abnormal in mature cells. This activity of c-Myb collaborates with its maintenance of c-myc expression to promote growth.
 ...
PMID:Three genes with different functions in transformation are regulated by c-Myb in myeloid cells. 1125 71

The tumor suppressor genes p15INK4B and p16INK4A, located in the chromosomal region 9p21, are frequently inactivated by homo- or hemizygous deletions, point mutation or promotor methylation in various types of cancer. No commercial probe is yet available that allows the detection of such deletions by FISH. Long distance (LD)-PCR was successfully used to generate a FISH probe, that covers a sequence stretch of 11.68 kb, located between the tumor suppressor genes p15 and p16. The LD-PCR amplicon was cloned and biotinylated by DOP-PCR (degenerated oligonucleotide primed-PCR) or nick translation. The FISH probe was hybridized on different samples of 16 patients with leukemia (3 T-ALL, 13 CML) and normal controls. Loss of at least one FISH-signal was found in 2/3 (67%) of the T-ALL- and 2/13 (15%) of the CML-cases. The new FISH probe presented here was proven to be advantageous for the detection of deletions in chromosomal region 9p21, especially between p15 and p16.
 ...
PMID:A long distance-PCR derived FISH probe detects a deletion between p15 and p16 in CML and T-ALL patients. 1135 Dec 70

P15INK4B methylation and expression was studied in bone marrow cells obtained from normal individuals, from patients who had been cured of lymphoma, and from patients with either MDS or AML. The level of p15 methylation was very low in normal BM cells and in CD34+ and CD34- subpopulations (0-6.5%; med, = 2.5%). P15INK4B transcripts were present in each of these cell populations. In contrast, methylation was the usual situation in MDS and AML marrows. The presence of methylation of the p15INK4B gene did not always indicate an absence of expression nor was expression always present if methylation was absent. P15INK4B methylation was studied in the marrows of nine patients (one studied twice) who had been cured of lymphoma and in whom hemopoiesis was believed to be normal. Increased methylaton was present in all 10 marrows. These data indicate that p15INK4B methylation is likely to be a very early event in the development of the secondary hematologic disorders.
Leukemia 2001 Oct
PMID:P15INK4B gene methylation and expression in normal, myelodysplastic, and acute myelogenous leukemia cells and in the marrow cells of cured lymphoma patients. 1158 17

Natural killer (NK) cell neoplasms, which are derived from mature or precursor NK cells, are rare diseases and are observed predominantly in Asian countries. We analyzed the status of the Rb, p53, p15INK4B, p16INK4A and p14ARF genes in these diseases by Southern blot, polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) and western blot analysis. We used 31 NK cell neoplasms, including four cell lines derived from NK cell neoplasms, 3 myeloid / NK cell precursor acute leukemias, 4 blastic NK cell lymphoma / leukemias, 4 aggressive NK cell leukemia / lymphomas, 4 nasal NK cell lymphomas, and 12 chronic NK lymphocytosis. We found gene amplification of the p53 gene in one nasal NK cell lymphoma, and point mutations of the p53 gene in one blastic NK cell lymphoma / leukemia and one chronic NK lymphocytosis. In addition, homozygous deletions of p15, p16 and p14 genes in 5 out of 31 samples were detected; 3 were from nasal NK cell lymphoma and 2 from blastic NK cell lymphoma / leukemia. Also hemizygous deletion of the Rb gene in one blastic NK cell lymphoma was detected. Rb proteins were highly expressed in one cell line as well as two myeloid / NK cell precursor acute leukemias. In other cell lines, complete loss and an aberrant migration pattern of Rb protein expression were observed. Comparative genomic hybridization suggested that the homozygous deletions of the p15, p16 and p14 were subtle chromosomal deletions and could not be identified by standard karyotyping in some cases. Although the number of cases we analyzed was not large, alterations identified in the Rb, p53, p16, p15 and p14 genes are of significance and might be associated with tumorigenesis in NK cell neoplasms.
 ...
PMID:Molecular analysis of tumor suppressor genes, Rb, p53, p16INK4A, p15INK4B and p14ARF in natural killer cell neoplasms. 1167 55

Karyotypic alterations, including whole chromosome loss or gain, ploidy changes, and a variety of chromosome aberrations are common in cancer cells. If proliferating cells fail to coordinate centrosome duplication with DNA replication, this will inevitably lead to a change in ploidy, and the formation of monopolar or multipolar spindles will generally provoke abnormal segregation of chromosomes. Indeed, it has long been recognized that errors in the centrosome duplication cycle may be an important cause of aneuploidy and thus contribute to cancer formation. This view has recently received fresh impetus with the description of supernumerary centrosomes in almost all solid human tumors. As the primary microtubule organizing center of most eukaryotic cells, the centrosome assures symmetry and bipolarity of the cell division process, a function that is essential for accurate chromosome segregation. In addition, a growing body of evidence indicates that centrosomes might be important for initiating S phase and completing cytokinesis. Centrosomes undergo duplication precisely once before cell division. Recent reports have revealed that this process is linked to the cell division cycle via cyclin-dependent kinase (cdk) 2 activity that couples centriole duplication to the onset of DNA replication at the G(1)/S phase transition. Alterations in G(1)/S phase regulating proteins like the retinoblastoma protein, cyclins D and E, cdk4 and 6, cdk inhibitors p16(INK4A) and p15(INK4B), and p53 are among the most frequent aberrations observed in human malignancies. These alterations might not only lead to unrestrained proliferation, but also cause karyotypic instability by uncontrolled centrosome replication. Since several excellent reports on cell cycle regulation and cancer have been published, this review will focus on the role of centrosomes in cell cycle progression, as well as causes and consequences of aberrant centrosome replication in human neoplasias.
Leukemia 2002 May
PMID:Centrosome replication, genomic instability and cancer. 1198 36

In order to explore the role of p15(INK4B) gene with highly methylated CpG island in the pathogenesis of leukemia, the expression levels of p15(INK4B) gene was detected in patients with AML and CML. Methylation-specific PCR (MSP) assay was employed in the experiments. The methylation incidence was 83.9% (26/31) in AML and 0% (0/28) in CML. The results showed that methylation of p15(INK4B) gene was the one of the major ways for inactivation of the gene, and the methylation could be appeared in clinical development of the disease and patients condition worsened. Methylation of p15(INK4B) did not occur and its function probably is normal in CML.
 ...
PMID:[Study on Methylation of p15(INK4B) Gene in Acute Myeloid Leukemia and Chronic Myeloid Leukemia] 1257 63

To clarify the clinical and genetic features of Burkitt lymphoma with or without leukemic presentation, we have conducted clinical, cytogenetic, and genetic studies. Of 40 Japanese patients with Burkitt lymphoma examined by cytogenetic and/or fluorescence in situ hybridization analysis or Southern blot analysis using MYC probes, 35 patients had t(8;14) translocations, and 5 had t(8;22). Breakpoints were located far upstream of MYC in 4 (12%) of 33 tumors with t(8;14), and Epstein-Barr virus infection was found in 3 (8%) of 40 tumors. These findings are similar to those reported for non-Japanese patients with the sporadic form of Burkitt lymphoma. Clinical and genetic characteristic were compared for 30 patients presenting with lymphoma and 10 presenting with leukemia. The overall survival was shorter in aggressively treated leukemia patients than in aggressively treated lymphoma patients (P = .003); however, the incidence rates of TP53 mutation, p16INK4a deletion, and p15INK4b deletion that were found in 6 (15%) of 40,3 (9%) of 35, and 2 (6%) of 35 tumors, respectively, were similar between the 2 subtypes. Thus, the present study has shown the different prognoses for the 2 subtypes of Burkitt lymphoma but has failed to clarify the genetic backgrounds that may explain the different outcomes.
 ...
PMID:Clinical and genetic characteristics of Japanese Burkitt lymphomas with or without leukemic presentation. 1284 88

The p14(ARF), p15(INK4B), and p16(INK4A) genes are important negative cell-cycle regulators often inactivated by deletions, mutations, or hypermethylation in malignancy. Hypermethylation of the three genes was studied in 81 patients with therapy-related myelodysplasia (t-MDS) or acute myeloid leukemia (t-AML) by methylation-specific PCR, and p15 methylation additionally by bisulfite genomic sequencing. In all, 55 patients disclosed p15 methylation, five patients showed p16 methylation, whereas p14 methylation was not observed. Methylation of p15 was closely associated with deletion or loss of chromosome arm 7q (P=0.0006). In t-MDS, the p15 methylation frequency and the p15 methylation density both increased significantly by stage (P=0.004 and 0.0002), and p15 methylation frequency increased with an increasing percentage of myeloblasts in the bone marrow (P=0.006). In a two-variable Cox model including the percentage of myeloblasts, p15 methylation was an independent prognostic factor (P=0.005). Methylation of p15 was less common in t-AML of subtype M5 than in other FAB subtypes (P=0.03). Methylation of p15 was unrelated to type of previous therapy, to latent period from start of therapy, to platelet count, and to p53 mutations. Inactivation of p15 and deletion of genes on chromosome arm 7q possibly cooperate in leukemogenesis.
Leukemia 2003 Sep
PMID:Methylation of p15INK4B is common, is associated with deletion of genes on chromosome arm 7q and predicts a poor prognosis in therapy-related myelodysplasia and acute myeloid leukemia. 1297 Jul 81

Cancer is also an epigenetic disease. The main epigenetic modification in humans is DNA methylation. Transformed cells undergo a dramatic change in their DNA methylation patterns: certain CpG islands located in the promoter regions of tumor-suppressor genes become hypermethylated and the contiguous gene rests silenced and this phenomenon occurs in an overall genomic environment of DNA hypomethylation. The profile of CpG island hypermethylation in hematologic malignancies is an epigenetic signature unique for each subtype of leukemia or lymphoma. Although the most widely studied genes are the cell-cycle inhibitors p15INK4b and p16INK4a (specially in AML and ALL), the list of methylation-repressed genes in these neoplasms is expanding very rapidly, including MGMT, RARB2, CRBP1, SOCS-1, CDH1, DAPK1, and others. A necessary cross-talk between genetic alterations and DNA methylation exists: certain chromosomal translocations may induce hypermethylation, such as the PML-RARa, or attract methylation, such as BCR-ABL, but DNA hypomethylation can be the culprit behind the genesis of certain abnormal recombination events. From a translational standpoint, hypermethylation can be used as a marker of recurrent disease or progression, for example, in MDS, or response to chemotherapy, such as MGMT methylation in B-cell non-Hodgkin's lymphoma. Furthermore, promising studies using DNA demethylating agents and histone deacetylase inhibitors are underway to awake these dormant tumor-suppressor genes for a better treatment of the patient with a hematologic malignancy.
 ...
PMID:Profiling aberrant DNA methylation in hematologic neoplasms: a view from the tip of the iceberg. 1458 79


<< Previous 1 2 3 4 5 Next >>