Mutations in the breakpoint cluster region-Abelson murine leukemia 1 gene in Brazilian patients with chronic myeloid leukemia

ABSTRACT Introduction: Mutations in the breakpoint cluster region-Abelson murine leukemia 1 gene are the leading cause of resistance to treatment with tyrosine kinase inhibitors in chronic myeloid leukemia patients. Mutations have been detected throughout the extension of the kinase domain of this gene and it is important to investigate their positions because there may be a difference in clinical relevance. Objective: To evaluate mutations in the transcripts of the BCR-ABL1 gene in Brazilian patients with chronic myeloid leukemia under tyrosine kinase inhibitor treatment in the Hospital de Clínicas of the Universidade Federal do Paraná. Methods: This retrospective observational cross-sectional study analyzed mutation data of BCR-ABL1 gene transcripts. Three hundred and thirty peripheral blood samples from 193 patients were evaluated with the search for mutations being achieved by Sanger sequencing. Results: Sixteen mutation types were identified in 48/193 (24.87%) patients with T315I (20.83%) being the most common. Furthermore, four polymorphisms (T240T, K247R, E275E and Y275Y) were identified. The highest incidence of mutations (19/53: 35.85%) occurred in the P-loop of the tyrosine kinase domain, whereas no mutation was found in the A-loop. In 43/48 (89.58%) patients only one mutation was found and more than one mutation was found in 5/48 (10.42%). The simultaneous presence of two mutations (E189G/V299L and E255K/T315I) was observed in 2/5 patients while the different mutations were seen in sequential samples of the other three patients (Y253Y/T315I, T315I/E255K and E255K/T315I). Conclusions: This molecular characterization contributed to the identification of the resistance profile to tyrosine kinase inhibitors in Brazilian patients, thus enabling the use of adequate therapeutic strategies in a timely manner.

Mechanism underlying tumorigenesis induced by Bcr-Abl oncogene and A-MuLV virus / 生物工程学报

The Bcr-Abl oncogene is produced by the reciprocal translocation between c-Abl gene on chromosome 9 and the Bcr gene on chromosome 22 in human genome. The encoded Bcr-Abl fusion protein is responsible for the pathogenesis of certain human leukemias. Abelson murine leukemia virus (A-MuLV) is a retrovirus that could lead to transformation of B lymphocyte in mice, and v-Abl is the oncogene of A-MuLV. Abl oncoproteins (such as Bcr-Abl and v-Abl) play critical roles in tumorigenesis of certain cell types. Several signal transduction pathways, including JAK/STAT/Pim, PI3K/AKT/mTOR and RAS/RAF/MEK signaling pathway, are involved in Abl-mediated tumorigenesis. In addition, Abl-mediated tumorigenesis is associated with mutation or abnormal modification of key signal molecules as well as dysregulation of some critical long noncoding RNAs (lncRNAs). Here, we review the molecular mechanisms by which Abl oncogenes activate three major signaling pathways, and provide a scientific basis for therapy of Abl oncoprotein-induced tumors.

E ffect of Nitric Oxide (NO) or Hydrogen Peroxide (H2O2) in the Nickel Induced cytotoxicity in RAW 264.7 Cell / 대한산업의학회지

OBJECTIVES: Nickel (Ni) is present in many industrial working environments and consumer products, and is one of the leading cause of allergic contact dermatitis, which is a typical delayed (type IV) hypersensitivity reaction. However, the mechanism by which nickel causes this pathology is not well known. The contact dermatitis induced by nickel is mediated, primarily, through macrophages. This property was similar to autotoxicity related nitric oxide (NO) production. NO mediated cytotoxicity was dependent on both H2O2 and peroxynitrite (OONO-). The purpose of this study was to elucidate the role of NO/H2O2 in the cytotoxicity induced by nickel. Therefore, this study was designed to examine whether nickel could modulate NO/H2O2 production and how the Ni may affect ATP production, intracellular GSH level, and cell viability. METHODS: This study was based on the observations of cultures of RAW 264.7 cells, which originated from a tumor in a Balb/c mouse that had been induced by the Abelson murine leukemia virus. RAW 264.7 cells were treated with either Ni, N- onomethyl-L- arginine (NMLA), catalase, and DTT for 24-72 h. The cytotoxicity of the nickel was measured via the cell viability and NO2-, H2O2, GSH, and the mitochondrial function was evaluated by the adenosine triphosphate (ATP) production in the RAW 264.7 cells. RESULTS: The NO2- synthesis of RAW 264.7 cells increased with the increase in concentrations of Ni up to 50-micrometer, after 24 and 48 h of exposure, but then decreased at concentrations greater than 50-micrometer, and with time periods exceeding 48 h. In contrast, viability of cells and intracellular GSH level decreased in the presence of Ni in a dose and time dependent manner. However, the H2O2 synthesis of RAW 264.7 cells was not changed in the all experimental conditions. The NO2- synthesis of the cells was higher than control, whereas ATP, GSH and viability were lower than control in addition of Ni and the pretreatment of catalase or DTT prior to addition of Ni. CONCLUSIONS: These results suggest that NO plays an important role in the cytotoxicity of Ni. Cytotoxicity of Ni may exert through modulation of NO production and associate with a decrease in intracellular GSH levels.

Effect of Glutathione on Lead Induced Modulation of NO Synthesis in RAW 264.7 Cell / 예방의학회지

OBJECTIVES: To evaluate the effect of glutathione(GSH) on lead induced modulation of nitric oxide(NO) synthesis, and to examine how lead modulates NO production in macrophages. METHODS: This study was observed in a culture of RAW 264.7 cells, which originated from a tumor in a Balb/c mouse that was induced by the Abelson murine leukemia virus. The compounds investigated were lead chloride, N-acetyl-cystein(NAC), and Buthionine Sulfoximine(BSO). RESUJLTS: ATP synthesis in RAW 264.7 cells was unchanged by each lead concentration exposure in a dose dependent manner. The NO synthesis was decreased when exposed to lead(PbCl2) concentration 0.5 micro M. The presence of 300 micro M NAC, used as a pretreatment in the culture medium, caused the recovery of the lead induced decrease in NO synthesis, but in the presence of 300 micro M BSO as a pretreatment, there was no recoverey. Pretreatment with NAC and BSO had no affect on ATP synthesis at any of the lead concentrations used. CONCLUSIONS: These results indicated that GSH has a protective effect toward lead toxicity, and suggested that the inhibition of NO production in macrophage due to lead toxicity may be related to cofactors of iNOS (inducible nitric oxide synthase)

Effect of Glutathione on Lead Induced Modulation of NO Synthesis in RAW 264.7 Cell / 예방의학회지

OBJECTIVES: To evaluate the effect of glutathione(GSH) on lead induced modulation of nitric oxide(NO) synthesis, and to examine how lead modulates NO production in macrophages. METHODS: This study was observed in a culture of RAW 264.7 cells, which originated from a tumor in a Balb/c mouse that was induced by the Abelson murine leukemia virus. The compounds investigated were lead chloride, N-acetyl-cystein(NAC), and Buthionine Sulfoximine(BSO). RESUJLTS: ATP synthesis in RAW 264.7 cells was unchanged by each lead concentration exposure in a dose dependent manner. The NO synthesis was decreased when exposed to lead(PbCl2) concentration 0.5 micro M. The presence of 300 micro M NAC, used as a pretreatment in the culture medium, caused the recovery of the lead induced decrease in NO synthesis, but in the presence of 300 micro M BSO as a pretreatment, there was no recoverey. Pretreatment with NAC and BSO had no affect on ATP synthesis at any of the lead concentrations used. CONCLUSIONS: These results indicated that GSH has a protective effect toward lead toxicity, and suggested that the inhibition of NO production in macrophage due to lead toxicity may be related to cofactors of iNOS (inducible nitric oxide synthase)

Role of Nitric Oxide in the Nickel and Cobalt Induced Cytotoxicity in RAW 264.7 cell / 대한산업의학회지

OBJECTIVES: The nickel and cobalt present in many industrial working environments and consumer products. They are two of the leading causes of allergic contact dermatitis, which is a typical delayed(type IV) hypersensitivity reaction. However, the mechanism by which nickel and cobalt causes this pathology is not well known. The nickel and cobalt induced contact dermatitis is mediated primarily through macrophages. This mechanism is similar to the autotoxicity procedure for NO. Therefore, this study was designed to examine whether the metals could modulate NO production and how the metals may affect ATP production and cell viability. In summary, the purpose of this study was to elucidate the role of NO in the nickel and cobalt induced cytotoxicity. METHODS: This study is based on observations of cultures of RAW 264.7 cells which are originated from a tumor of Balb/c mouse that was induced by Abelson murine leukemia virus. RAW 264.7 cells were treated with either Ni, Co, Ni plus Co, or Nmonomethyl-L- arginine(NMLA) for 24-72 h. The cytotoxicity of the nickel and cobalt was measured by cell viability and NO2-, and mitochondrial function was evaluated by adenosine triphosphate(ATP) production in RAW 264.7 cells. In addition, the morphology of cells was observed using an inverted microsope. RESULTS: The NO2- synthesis of RAW 264.7 cells increased with increasing concentrations of Ni and Co up to 50 microM after 24 and 48 h of exposure to Ni and Co but then decreased if the concentration was greater than 50 microM and the time period was greater than 48 h. However, the viability of cells was decreased by Ni and Co exposure in a dose and time dependent manner. Therefore, 50 microM Ni or Co and 48 h of treatment were used in this study. A complete inhibition of NO2- synthesis by Ni or/and Co occurred when iNOS inhibitor, NMLA, were pretreated prior to addition of Ni or/and Co, whereas Ni or/and Co induced decrease of synthesis of ATP and viability completely recovered when NMLA were pretreated prior to addition of Ni or/and Co. Ni or/and Co(50 microM) induced the characteristic morphological features of cytotoxicity which is characterized by a shrinkage of cytoplasm and irregular shape of the cells, but the pretreatment of NMLA resulted in a recovered morphological change of the cells to their normal appearance. CONCLUSIONS: These results suggest that NO plays an important role in the pathogenesis of the cytotoxicity of nickel and cobalt, and nickel and cobalt may exert their toxicities by means of modulation of NO production. The results from this study may facilitate further understanding the role of NO on nickel and cobalt induced immune and inflammatory processes.