scholarly journals Megakaryoblastic transformation of therapy-related myeloid neoplasms with concomitant MYC amplification on double minute chromosomes

2017 ◽  
Vol 106 (6) ◽  
pp. 729-731 ◽  
Author(s):  
Katsuya Yamamoto ◽  
Kimikazu Yakushijin ◽  
Yumiko Inui ◽  
Shinichiro Kawamoto ◽  
Kazuyoshi Kajimoto ◽  
...  
Keyword(s):  
Myeloid Neoplasms ◽  
Double Minute ◽  
Double Minute Chromosomes

scholarly journals FLT3 Amplification as Double Minute Chromosomes in a Patient with Chronic Myelomonocytic Leukemia

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Heyang Zhang ◽  
Xiaoxue Wang ◽  
Shibo Li ◽  
Xianfu Wang ◽  
Xianglan Lu ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Gene Amplification ◽  
Chronic Myelomonocytic Leukemia ◽  
Comparative Genomic ◽  
Myeloid Neoplasms ◽  
Double Minute ◽  
Myelomonocytic Leukemia ◽  
Double Minute Chromosomes

Double minute chromosomes (dmins) are a form of gene amplification presenting as small spherical paired chromatin bodies. Dmins are rare in hematologic malignancies and are generally associated with a poor prognosis. Some case reports identified MYC or MLL gene amplification performing as dmin in myeloid neoplasms. FLT3 (FMS-related tyrosine kinase 3) acts as an oncogene in myeloid neoplasms which is associated with several signal transduction pathways. Genomic amplification of FLT3 has not been reported in hematological disease. The current study attempts to demonstrate the existence of double minute chromosomes via FLT3 gene amplification in a patient diagnosed with chronic myelomonocytic leukemia (CMML). Routine G-banded karyotype, array-based comparative genomic hybridization, and fluorescence in situ hybridization analyses were used to characterize the cytogenetic abnormality in the patient’s bone marrow. FLT3 amplification as dmins in a patient with CMML was revealed. This case study reports a rare double minute chromosome via FLT3 amplification in CMML by using array-based comparative genomic hybridization and fluorescence in situ hybridization analyses. The study also proposed another possible mechanism of FLT3 genes in leukemogenesis.

Induction of metallothionein-I mRNA in cultured cells by heavy metals and iodoacetate: evidence for gratuitous inducers

1984 ◽  
Vol 4 (3) ◽  
pp. 484-491
Author(s):  
D M Durnam ◽  
R D Palmiter
Keyword(s):  
Heavy Metals ◽  
Cultured Cells ◽  
Mrna Accumulation ◽  
Mouse Hepatocyte ◽  
Hepatocyte Cell Line ◽  
Regulatory Molecule ◽  
Heavy Metal Detoxification ◽  
Double Minute ◽  
Double Minute Chromosomes

A mouse hepatocyte cell line selected for growth in 80 microM CdSO4 (Cdr80 cells) was used to test the role of metallothioneins in heavy metal detoxification. The cadmium-resistant (Cdr80) cells have double minute chromosomes carrying amplified copies of the metallothionein-I gene and accumulate ca. 20-fold more metallothionein-I mRNA than unselected cadmium-sensitive (Cds) cells after optimal Cd stimulation. As a consequence, the amount of Cd which inhibits DNA synthesis by 50% is ca. 7.5-fold higher in Cdr80 cells than in Cds cells. Cds and Cdr80 cells were compared in terms of their resistance to other heavy metals. The results indicate that although Zn, Cu, Hg, Ag, Co, Ni, and Bi induce metallothionein-I mRNA accumulation in both Cdr80 and Cds cells, the Cdr80 cells show increased resistance to only a subset of these metals (Zn, Cu, Hg, and Bi). This suggests that not all metals which induce metallothionein mRNA are detoxified by metallothionein and argues against autoregulation of metallothionein genes. Metallothionein-I mRNA is also induced by iodoacetate, suggesting that the regulatory molecule has sensitive sulfhydryl groups.

Mathematical models of gene amplification with applications to cellular drug resistance and tumorigenicity.

Genetics ◽  
1990 ◽  
Vol 125 (3) ◽  
pp. 633-644
Author(s):  
M Kimmel ◽  
D E Axelrod
Keyword(s):  
Mathematical Models ◽  
Cell Lines ◽  
Gene Amplification ◽  
Dihydrofolate Reductase ◽  
Gene Copy Number ◽  
Gene Copy ◽  
Published Data ◽  
Reductase Gene ◽  
Double Minute ◽  
Double Minute Chromosomes

Abstract An increased number of copies of specific genes may offer an advantage to cells when they grow in restrictive conditions such as in the presence of toxic drugs, or in a tumor. Three mathematical models of gene amplification and deamplification are proposed to describe the kinetics of unstable phenotypes of cells with amplified genes. The models differ in details but all assume probabilistic mechanisms of increase and decrease in gene copy number per cell (gene amplification/deamplification). Analysis of the models indicates that a stable distribution of numbers of copies of genes per cell, observed experimentally, exists only if the probability of deamplification exceeds the probability of amplification. The models are fitted to published data on the loss of methotrexate resistance in cultured cell lines, due to the loss of amplified dihydrofolate reductase gene. For two mouse cell lines unstably resistant to methotrexate the probabilities of amplification and deamplification of the dihydrofolate reductase gene on double minute chromosomes are estimated to be approximately 2% and 10%, respectively. These probabilities are much higher than widely presumed. The models explain the gradual disappearance of the resistant phenotype when selective pressure is withdrawn, by postulating that the rate of deamplification exceeds the rate of amplification. Thus it is not necessary to invoke a growth advantage of nonresistant cells which has been the standard explanation. For another analogous process, the loss of double minute chromosomes containing the myc oncogene from SEWA tumor cells, the growth advantage model does seem to be superior to the amplification and deamplification model. In a more theoretical section of the paper, it is demonstrated that gene amplification/deamplification can result in reduction to homozygosity, such as is observed in some tumors. Other applications are discussed.

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