metallothionein and Leukemia--Myeloid--Acute

Topics: Animals; Cell Differentiation; Cell Division; Cells, Cultured; Copper; DNA Repair; Endoderm; Free Radicals; Gene Expression Regulation; Humans; Interferons; Interleukin-1; Kidney; Leukemia, Myeloid, Acute; Liver; Metallothionein; Metals; Transcription, Genetic; Ultraviolet Rays; Zinc

Although accumulating evidence has revealed that metallothioneins (MTs) and its family member MT2A are strongly linked to the risk of various solid tumors, researches on the occurrence and development of acute myeloid leukemia (AML) have rarely been investigated. Here, we constructed a lentiviral vector with MT2A over-expression and the interfering plasmids with MT2A expression inhibition to study the influence of MT2A on the bioactivities of HL60 cells. After cells were infected with a lentiviral vector containing the MT2A gene, both transcription and translation levels of MT2A were significantly increased in the over-expressed group in comparison with control groups. In vitro experiments, all results demonstrated that cell reproductive capacity was inhibited, but cell apoptosis rate was significantly increased. Together, the expression of apoptosis-related protein Bcl2 was remarkably reduced, while a high expression level of Bax protein was detected. Further experiments revealed that up-regulation of MT2A induced cell apoptosis and promoted G2/M phase arrest. The mechanism may be associated with down-regulated p-IκB-α and cyclinD1 expression and up-regulated IκB-α expression in the nuclear factor-kappaB (NF-κB) pathway. On the contrary, MT2A expression was down-regulated by interfering plasmids. We found that cell proliferative potential was notably increased in the interfering group compared with the negative and untreated group. What's more, MT2A may be closely related to AML cell proliferation and function via the NF-κB signal pathway.

Topics: Apoptosis; Cell Proliferation; Down-Regulation; Gene Expression Regulation, Leukemic; HL-60 Cells; Humans; Leukemia, Myeloid, Acute; Metallothionein; NF-KappaB Inhibitor alpha; Signal Transduction; Up-Regulation

Reactive oxygen species (ROS)-specific mechanisms of drug resistance were explored in paraquat (PQ)-resistant acute myelogenous leukemia cell (OCI/AML-2) sublines. For this, PQ-resistant AML sublines, AML-2/PQ100 and AML-2/PQ400, were selected in the presence of PQ concentrations of 100 microg/ml and 400 microg/ml, respectively. They showed a moderate level of cross resistance to cisplatin and doxorubicin. They were also slightly more resistant than the parental cell (AML-2/WT) to etoposide, camptothecin and daunorubicin. The resistance of PQ-resistant AML-2 sublines to cisplatin seemed to be due to increased amounts of metallothionein, which was not only supported by reversal of resistance to cisplatin by propargylglycin (an inhibitor of metallothionein synthesis) but also confirmed by Western blot analysis and reverse transcription-PCR assay. In addition, both AML-PQ100 and /PQ400 sublines showed increased activities of Cu-, Zn-containing superoxide dismutase (Cu,Zn-SOD) and Mn-containing superoxide dismutase (Mn-SOD), whereas AML-2/PQ400, but not AML-2/PQ100, showed increased glutathione S-transferase activity as compared to that of AML-2/WT. However, there was no difference in other ROS-related cellular antioxidants between AML-2/WT and its PQ-resistant sublines. Taken together, these results strongly suggest that increases in levels of metallothionein, glutathione S-transferase, Cu,Zn-SOD and Mn-SOD play important roles in protective mechanisms against toxicity of PQ or ROS in AML cells.

Topics: Alkynes; Antineoplastic Agents; Camptothecin; Cell Survival; Cisplatin; Daunorubicin; Dose-Response Relationship, Drug; Doxorubicin; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Etoposide; Glutathione Transferase; Glycine; Humans; Leukemia, Myeloid, Acute; Metallothionein; Paraquat; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Superoxide Dismutase; Tumor Cells, Cultured; Vincristine

The multidrug resistance phenomenon can be observed in cases which do not express the P170 protein and these cases are suspected as having activated different resistance phenomena. Four phenomena were studied at the time of diagnosis in a series of 35 lymphoblastic and 25 myeloblastic acute (de novo) leukemias, by an immunocytochemical method. Two energetic drug transport processes were investigated: the classical MDR/P170 and the P110/LRP56 proteins, and two physiological detoxifying activities such as the glutathione transferases (GST alpha, mu, pi) and the metallothioneins (Mts). The results demonstrate that these phenomena are independent but their synergic activity can increase their impact on the outcome. P110/LRP56 positive cases demonstrated 48.8% complete remission (CR) rate compared to 71.4% for negative tests. When P170 and P110 were both positive or negative, the CR rates were 27.3% and 81.8% respectively (p = 0.0120), and survival curves were also different (p = 0.030). The CR rate in AML or ALL is weakly affected by GST pi, alpha or mu but relapses are more frequently observed for Positive-GST pi ALL (p = 0.0658). Patients with both P170 and GST pi positive reactions had a 53.3% CR rate compared to 78.9% for both negative reactions. Survival curves for these two groups were different. The CR rate in AMl was 100% for Mts positive and 43.7% for negative cases (p = 0.050), however the median survival was totally different for these two groups (p = 0.046). CR rates were 26.6% for patients who were P170 positive and Mts negative compared to 100% for P170 negative and Mts positive (p = 0.038) patients. Survival curves were also different (p = 0.0510). We conclude that these four mechanisms induce an independent drug resistance but their synergic action increase their impact on the outcome. The metallothioneins seem to have a major impact on the drug resistance phenomenon and its effect should be investigated with high priority, in the light of these results.

Topics: Adolescent; Adult; Aged; ATP Binding Cassette Transporter, Subfamily B, Member 1; Child; Child, Preschool; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Female; Glutathione Transferase; Humans; Infant; Isoenzymes; Leukemia, Myeloid, Acute; Male; Metallothionein; Middle Aged; Neoplasm Proteins; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Vault Ribonucleoprotein Particles

There is much speculation about fragile sites on human chromosomes predisposing to specific chromosome rearrangements seen in cancer. Acute myelomonocytic leukemia is characterized by neoplastic chromosome rearrangements involving band 16q22 in patients who carry the rare fragile site at 16q22. This specific leukemic breakpoint is within the metallothionein gene cluster, which is here shown to be proximal to the rare fragile site (FRA16B) and to a common fragile site (FRA16C) in this region. Hence neither of these fragile sites are at the breakpoint in this leukemic chromosomal rearrangement.

Topics: Chromosome Fragile Sites; Chromosome Fragility; Chromosome Mapping; Chromosomes, Human, Pair 16; DNA, Neoplasm; Humans; Leukemia, Monocytic, Acute; Leukemia, Myeloid, Acute; Metallothionein; Translocation, Genetic