Valproic Acid Induces Cell Cycle Arrest and Differentiation of t(15;17) Positive Leukemic Cells Independent from ATRA Sensitivity and Has No Effect on CD34pos Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2834-2834 ◽  
Author(s):  
Bettina Drescher ◽  
Kerstin Goerlich ◽  
Dagmar Reile ◽  
Axel Doehring ◽  
Arnold Ganser ◽  
...  
Keyword(s):  
Valproic Acid ◽  
Cell Line ◽  
Acute Promyelocytic Leukemia ◽  
Hdac Inhibitor ◽  
Anticonvulsant Drug ◽  
Promyelocytic Leukemia ◽  
Leukemic Cells ◽  
Inhibition Of Proliferation ◽  
Nb4 Cells ◽  
Clonogenic Growth

Abstract The translocation t(15;17) in acute promyelocytic leukemia results in the PML/RARα fusion protein. PML/RARα recruits histone deacetylases (HDAC) and represses target genes of wild-type RARα. Recently, the anticonvulsant drug valproic acid (VPA) has been described as an HDAC inhibitor. In order to evaluate the role of VPA in the treatment of acute promyelocytic leukemia, the effect of VPA on the t(15;17) positive cell line NB4 was examined. To exclude toxicity on non malignant stem cells, CD34pos cells were analyzed. In NB4 cells, VPA led to an increase of acetylated histone H4. Histone acetylation was associated with a dose dependent inhibition of proliferation. Furthermore, inhibition of NB4 clonogenic growth was observed. In contrast, clonogenic growth of CD34pos cells was not affected by the presence of VPA. The VPA induced inhibition of cell growth in malignant cells was not caused by altered apoptosis. Rather an arrest at the G1/G0 phase was observed in the presence of VPA. In agreement with p21 expression of leukemic cell lines not harboring the t(15;17) translocation, VPA induced p21 mRNA expression also in t(15;17) positive cells. However, no induction of p21 was observed in normal CD34pos cells. VPA triggered the differentiation of NB4 cells measured by NBT test and surface expression of CD11b and CD11c. Flow cytometry of colonies from CD34pos cells showed an increased fraction of CD34pos cells in the presence of VPA. Thus, VPA does not induce differentiation in non malignant hematopoiesis. To study whether VPA and ATRA induced differentiation are mediated via identical pathways, the process of differentiation was studied in NB4 cells and ATRA resistant NB4-R2 cells. While differentiation in the presence of ATRA led to induction of C/EBPβ and C/EBPε, no change in the expression of these transcription factors was observed after VPA treatment. Downregulation of c-myc was detected upon ATRA as well as VPA treatment, an additive effect was seen after the combination. Resistance to ATRA did not interfere with effects of VPA on cell differentiation. However, upon ATRA treatment no c-myc downregulation was observed in the NB4-R2 cell line. Taken together, VPA acts as an HDAC inhibitor in t(15;17) positive cells and induces myeloid differentiation by mechanisms distinct from ATRA and independent of ATRA-resistance. Moreover, VPA does not interfere with normal hematopoiesis. Therefore, this substance might be helpful in patients with APL - especially in ATRA-resistant disease.

scholarly journals Retinoid-induced differentiation of acute promyelocytic leukemia involves PML-RARalpha-mediated increase of type II transglutaminase

Blood ◽  
1996 ◽  
Vol 87 (5) ◽  
pp. 1939-1950 ◽  
Author(s):  
L Benedetti ◽  
F Grignani ◽  
BM Scicchitano ◽  
AM Jetten ◽  
D Diverio ◽  
...  
Keyword(s):  
Cell Line ◽  
Signaling Pathway ◽  
Acute Promyelocytic Leukemia ◽  
Molecular Mechanisms ◽  
Growth Arrest ◽  
Promyelocytic Leukemia ◽  
Leukemic Cells ◽  
Type Ii ◽  
Granulocytic Differentiation ◽  
Nb4 Cells

All-trans retinoic acid (t-RA) administration leads to complete remission in acute promyelocytic leukemia (APL) patients by inducing growth arrest and differentiation of the leukemic clone. In the present study, we show that t-RA treatment dramatically induced type II transglutaminase (type II TGase) expression in cells carrying the t(15;17) translocation and expressing the PML-RARalpha product such as the APL-derived NB4 cell line and fresh leukemic cells from APL patients. This induction correlated with t-RA-induced growth arrest, granulocytic differentiation, and upregulation of the leukocyte adherence receptor beta subunit (CD18) gene expression. The increase in type II TGase was not abolished by cycloheximide treatment, suggesting that synthesis of a protein intermediate was not required for the induction. t-RA did not significantly alter the rate of growth arrest and did not stimulate differentiation and type II TGase activity in NB4.306 cells, a t-RA-resistant subclone of the NB4 cell line, or in leukemic cells derived from two patients morphologically defined as APL but lacking the t(15;17). However, in NB4.306 cells, t-RA treatment was able to increase CD18 mRNA expression in a manner similar to NB4 cells. The molecular mechanisms involved in the induction of these genes were investigated. In NB4 cells, using novel receptor-selective ligands such as 9-cis-RA, TTNPB, AM580, and SR11217, we found that RAR- and RARalpha- selective retinoids were able to induce growth arrest, granulocytic differentiation, and type II TGase, whereas the RXR-selective retinoid SR11217 was inactive. Moreover, an RAR alpha-antagonist completely inhibited the expression of type II TGase and CD18 induced by these selective retinoids in NB4 cells. In NB4.306 cells, an RARalpha- dependent signaling pathway was found involved in the modulation of CD18 expression. In addition, expression of the PML-RARalpha gene in myeloid U937 precursor cells resulted in the ability of these cells to induce type II TGase in response to t-RA. On the basis of these results we hypothesize a specific involvement of a signaling pathway involving PML-RAR alpha for the induction of growth arrest, granulocytic differentiation, and type II TGase by retinoids in APL cells.

scholarly journals Retinoid-induced differentiation of acute promyelocytic leukemia involves PML-RARalpha-mediated increase of type II transglutaminase

Blood ◽  
1996 ◽  
Vol 87 (5) ◽  
pp. 1939-1950 ◽  
Author(s):  
L Benedetti ◽  
F Grignani ◽  
BM Scicchitano ◽  
AM Jetten ◽  
D Diverio ◽  
...  
Keyword(s):  
Cell Line ◽  
Signaling Pathway ◽  
Acute Promyelocytic Leukemia ◽  
Molecular Mechanisms ◽  
Growth Arrest ◽  
Promyelocytic Leukemia ◽  
Leukemic Cells ◽  
Type Ii ◽  
Granulocytic Differentiation ◽  
Nb4 Cells

Abstract All-trans retinoic acid (t-RA) administration leads to complete remission in acute promyelocytic leukemia (APL) patients by inducing growth arrest and differentiation of the leukemic clone. In the present study, we show that t-RA treatment dramatically induced type II transglutaminase (type II TGase) expression in cells carrying the t(15;17) translocation and expressing the PML-RARalpha product such as the APL-derived NB4 cell line and fresh leukemic cells from APL patients. This induction correlated with t-RA-induced growth arrest, granulocytic differentiation, and upregulation of the leukocyte adherence receptor beta subunit (CD18) gene expression. The increase in type II TGase was not abolished by cycloheximide treatment, suggesting that synthesis of a protein intermediate was not required for the induction. t-RA did not significantly alter the rate of growth arrest and did not stimulate differentiation and type II TGase activity in NB4.306 cells, a t-RA-resistant subclone of the NB4 cell line, or in leukemic cells derived from two patients morphologically defined as APL but lacking the t(15;17). However, in NB4.306 cells, t-RA treatment was able to increase CD18 mRNA expression in a manner similar to NB4 cells. The molecular mechanisms involved in the induction of these genes were investigated. In NB4 cells, using novel receptor-selective ligands such as 9-cis-RA, TTNPB, AM580, and SR11217, we found that RAR- and RARalpha- selective retinoids were able to induce growth arrest, granulocytic differentiation, and type II TGase, whereas the RXR-selective retinoid SR11217 was inactive. Moreover, an RAR alpha-antagonist completely inhibited the expression of type II TGase and CD18 induced by these selective retinoids in NB4 cells. In NB4.306 cells, an RARalpha- dependent signaling pathway was found involved in the modulation of CD18 expression. In addition, expression of the PML-RARalpha gene in myeloid U937 precursor cells resulted in the ability of these cells to induce type II TGase in response to t-RA. On the basis of these results we hypothesize a specific involvement of a signaling pathway involving PML-RAR alpha for the induction of growth arrest, granulocytic differentiation, and type II TGase by retinoids in APL cells.

AM580, a stable benzoic derivative of retinoic acid, has powerful and selective cyto-differentiating effects on acute promyelocytic leukemia cells

Blood ◽  
1996 ◽  
Vol 87 (4) ◽  
pp. 1520-1531 ◽  
Author(s):  
M Gianni ◽  
M Li Calzi ◽  
M Terao ◽  
G Guiso ◽  
S Caccia ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Cell Line ◽  
Acute Promyelocytic Leukemia ◽  
Retinoic Acid Receptor ◽  
Chromosomal Translocation ◽  
Promyelocytic Leukemia ◽  
Myelogenous Leukemia ◽  
Leukemic Cells ◽  
Stable Phase ◽  
Differentiation Markers

All-trans retinoic acid (ATRA) is successfully used in the cyto- differentiating treatment of acute promyelocytic leukemia (APL). Paradoxically, APL cells express PML-RAR, an aberrant form of the retinoic acid receptor type alpha (RAR alpha) derived from the leukemia- specific t(15;17) chromosomal translocation. We show here that AM580, a stable retinobenzoic derivative originally synthesized as a RAR alpha agonist, is a powerful inducer of granulocytic maturation in NB4, an APL-derived cell line, and in freshly isolated APL blasts. After treatment of APL cells with AM580 either alone or in combination with granulocyte colony-stimulating factor (G-CSF), the compound induces granulocytic maturation, as assessed by determination of the levels of leukocyte alkaline phosphatase, CD11b, CD33, and G-CSF receptor mRNA, at concentrations that are 10- to 100-fold lower than those of ATRA necessary to produce similar effects. By contrast, AM580 is not effective as ATRA in modulating the expression of these differentiation markers in the HL-60 cell line and in freshly isolated granulocytes obtained from the peripheral blood of chronic myelogenous leukemia patients during the stable phase of the disease. In NB4 cells, two other synthetic nonselective RAR ligands are capable of inducing LAP as much as AM580, whereas RAR beta- or RAR gamma-specific ligands are totally ineffective. These results show that AM580 is more powerful than ATRA in modulating the expression of differentiation antigens only in cells in which PML-RAR is present. Binding experiments, using COS-7 cells transiently transfected with PML-RAR and the normal RAR alpha, show that AM580 has a lower affinity than ATRA for both receptors. However, in the presence of PML-RAR, the synthetic retinoid is a much better transactivator of retinoic acid-responsive element-containing promoters than the natural retinoid, whereas, in the presence of RAR alpha, AM580 and ATRA have similar activity. This may explain the strong cyto-differentiating potential of AM580 in PML-RAR-containing leukemic cells.

The Acute Promyelocytic Leukemia-Associated Fusion Protein PML/RAR Blocks t-RA-Induced Differentiation in a Subset of Cells with Stem Cell Potential.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1175-1175
Author(s):  
Xiaomin Zheng ◽  
Anita Seshire ◽  
Elena Puccetti ◽  
Hilal Gul ◽  
Tim Beissert ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Fusion Protein ◽  
Cell Line ◽  
Acute Promyelocytic Leukemia ◽  
Fusion Proteins ◽  
Side Population ◽  
Promyelocytic Leukemia ◽  
Molecular Remission ◽  
Nb4 Cells

Abstract Acute promyelocytic leukemia (APL) is distinguished from other AMLs by cytogenetic, clinical, as well as biological characteristics. The hallmark of APL is the t(15;17) which leads to the expression of the PML/RAR fusion protein. PML/RAR is the central leukemia-inducing lesion in APL and is directly targeted by all trans retinoic acid (t-RA). Patients suffering from APL undergo complete hematologic but not molecular remission upon treatment with t-RA. Virtually all patients treated with t-RA-monotherapy had a rapid relapse within few months. But in the combination with an anthracycline, such as doxorubicin or idarubicin, t-RA improved the long term outcome of APL-patients dramatically. Nothing is known about why t-RA-monotherapy is unable to eradicate completely the leukemic population and how it increases the response to chemotherapy. In vitro, the exposure of early hemopoietic stem cells (HSCs) to t-RA does not induce differentiation but selects immature progenitors. Moreover, mice lacking the t-RA-specific receptor RARalpha do not exhibit an impairment of granulopoiesis or hemopoiesis. The indication, that t-RA may be involved in the hemopoietic differentiation, is given by the HL-60 cell line which undergoes granulocytic differentiation at the pharmacological dosages (10−6M) of t-RA. Furthermore vitamin A-deficient mice or mice treated with a antagonist of t-RA accumulate more immature granulocytes in the bone marrow. PML/RAR mediates the response of APL blasts to t-RA, but it is completely unclear, which effect t-RA exerts on the PML/RAR-positive leukemic stem cells which maintains the blast population and represents the source of relapse. Therefore we investigated the effect of t-RA on a cell population with stem cell capacity expressing PML/RAR isolated from the APL cell line NB4 as well as from CD34+/CD38- KG-1 cells transfected with PML/RAR. Here we report that i) the NB4 cells engrafted in NOD/SCID mice indicating the presence of a subpopulation with stem cell capacity in NB4 cells; ii) NB4 had a Hoechst 3342 excluding side population (SP) representing about 1% of the whole cell population; iii) t-RA reduced but did not deplete the side population in NB4 cells; iv) the expression of PML/RAR increased CD34+/CD38- population in KG-1 cells from 75% to over 95%; v) t-RA reduced the CD34+/CD38- population from 75% to 3,5% in mock transfected KG-1 confirming its capacity to induce differentiation, whereas in PML/RAR-positive KG-1 cells it led only to a reduction from 98% to a 25%, which still maintain the capacity to engraft in NOD-SCID mice; vi) also the expression of other fusion proteins, such as AML-1/ETO or PLZF/RAR, associated with t-RA-resistant AML-subtypes, increased the percentage of CD34+/CD38- KG-1 cells over 90%, which was reduced by t-RA only to 35% and 19%, respectively. Taken together these data suggest that a subset of early HSC expressing PML/RAR exhibit the same t-RA-resistant phenotype as HSC expressing fusion proteins associated with AML-subtypes which, in contrast to APL, do not respond to t-RA. These data may give an explanation, why APL-patients do not achieve complete molecular remission upon t-RA monotherapy and undergo early relapse.

Proteome Analysis of the Proteins Associated with All-Trans Retinoic Acid Resistance in Acute Promyelocytic Leukemia Cells

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5042-5042
Author(s):  
Pengcheng He ◽  
Mei Zhang ◽  
Jun Qi ◽  
Xiaoning Wang ◽  
Jieying Xi ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Protein Expression ◽  
Cell Line ◽  
Acute Promyelocytic Leukemia ◽  
Comparative Proteomics ◽  
Promyelocytic Leukemia ◽  
Differentially Expressed ◽  
Nb4 Cells ◽  
Trans Retinoic Acid ◽  
All Trans Retinoic Acid

Abstract Although 90% patients with untreated acute promyelocytic leukemia(APL) obtain complete remission because of the usage of all-trans retinoic acid(ATRA), patients with ATRA-resistance are increased gradually. ATRA-resistance has become one of the main causes which affect the long-term therapeutic efficacy of APL. The mechanisms of ATRA-resistance are complex, which probably involve the metabolism of ATRA, abnormal expression of cellular retinoic acid binding protein(CRABP) and P-glycoprotein(P-gp), mutation of RARα and aberration translocation of APL. However, in these previous researches, it was one or a few proteins but not the entirety proteins that were emphasized on the mechanisms of ATRA-resistance. Comparative proteomics can analyze the entire protein expression in cells in whole and has the superiority in screening the drug-resistance proteins differentially expressed. In order to investigate the mechanisms of ATRA-resistance in APL in whole, we compared and analyzed the protein expression profiles between MR2 cells(APL cell line with ATRA-resistance) and NB4 cells(APL cell line with ATRA-sensitiveness) by comparative proteomics. After the total proteins of MR2 cells and NB4 cells were extracted respectively, they were separated by two-dimensional electrophoresis(2-DE). The differences in proteome profile between MR2 cells and NB4 cells analyzed by ImageMaster™ 2D Platinum software. The average protein spots in 2-DE maps of MR2 and NB4 cells were 1160±51 and 1068±33 respectively. 8 protein spots were selected to be identified by Matrix-assisted laser desorption/ionization time of flight-mass spectrometry (MALDI-TOF-MS), in which the quantity of the protein differentially expressed was more than two times(≥2 or ≤0.5) between MR2 and NB4 cells’ 2-DE map. They were all successfully identified and their definite information was obtained. Among them, 6 proteins were probably involved in the mechanisms of ATRA-resistance in APL and they were Cofilin-1, Elongation factor 1-beta (EF-1β), Tropomyosin isoform(TM), High mobility group protein B1(HMGB1), Ran-specific GTPase-activating protein (RanGAP1) and Galectin-1. Moreover, so far there was no related report on the roles of HMGB1, RanGAP1 and Galectin-1 in the mechanisms of ATRA-resistance in APL. These differential proteins identified provide the new clues for us to further elucidate the mechanisms of ATRA-resistance from multiple factor.

Metabolic Rewiring Drives Resistance to Arsenic Trioxide in Acute Promyelocytic Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3956-3956 ◽  
Author(s):  
Nithya Balasundaram ◽  
Saravanan Ganesan ◽  
Hamenth Kumar Palani ◽  
Ansu Abu Alex ◽  
Sachin David ◽  
...  
Keyword(s):  
Glucose Uptake ◽  
Acute Promyelocytic Leukemia ◽  
Cell Lines ◽  
Conflicts Of Interest ◽  
Resistant Cell ◽  
Promyelocytic Leukemia ◽  
Leukemic Cells ◽  
Synergistic Activity ◽  
Normal Peripheral Blood ◽  
Nb4 Cells

Abstract The focus of ATO resistance in acute promyelocytic leukemia (APL) has centered on mutations in PML-RARA gene (Blood 2011, NEJM 2014). However such mutations are rare and cannot explain the majority of relapses seen in the clinic. To evaluate the mechanisms of ATO resistance, we generated ATO resistant NB4 sub clone NB4-EVAsR1 (A216V - VAF-91.7%) in our laboratory. We also had another ATO resistant cell line (UF1) which does not have the A216V mutation. In an expression array we noted that redox signaling, AMPK signaling and energy metabolism pathways were significantly dysregulated in the ATO resistant cell lines compared to naïve NB4 cells. Towards validating the microarray data and to characterize the ATO resistant cell lines we measured the basal levels of reactive oxygen species (ROS), glutathione(GSH), mitochondrial membrane potential (MMP), glucose uptake and their sensitivity to glycolytic inhibitor 2-Deoxy glucose (2-DG) in comparison to naïve NB4 cells. We observed that resistant cell lines have significantly lower ROS, MMP, glucose uptake (Fig 1a) and increased GSH. We also observed that the resistant cell lines were significantly less susceptible to treatment with 2-DG in comparison to naïve NB4 cells (Fig 1b) suggesting that resistant cell lines were less dependent on glycolysis. ATO has been reported to directly inhibit the glycolytic pathway, this effect is believed to contribute to its cytotoxic effect (PNAS 2015). However, we did not observe any cytotoxic synergy between ATO and 2-DG on naïve NB4 cells and neither did this combination restore sensitivity to ATO in the resistant cell lines (Fig 1b). Next we assessed the sensitivity of these resistant cell lines to oxidative phosphorylation (OXPHOS) inhibitors. We used an uncoupler (FCCP at 10uM) of OXPHOS which promotes uncoupled respiration by deregulating the proton gradient which drives ATP synthesis via ATP synthase. We observed that the FCCP treatment alone did not reduced the viability of naïve NB4 cells. Similarly, viability of ATO resistant cell lines also did not reduce significantly suggesting the ability of these cells to uncouple their metabolic pathway from OXPHOS to glycolysis when inhibited. However, when FCCP was combined with ATO it significantly restored the sensitivity of the resistant cell lines to ATO (Fig 1c). The same combination did not have any additive effect on naïve NB4 cells. The combination not only restored the sensitivity of the ATO resistant cell lines but also sensitized the conventionally ATO resistant cell lines such U937 (Fig 1c) and THP1. In spite of the profound effect on leukemic cells we also observed a significant bystander effect on the normal peripheral blood mononuclear cells (Fig 1c). The data suggests that the sensitivity of these resistant cell lines could be potentially restored by combining ATO with an OXPHOS uncoupler. A number of molecules that are FDA approved and used in the clinic also have OXPHOS uncoupling activity and could potentially be evaluated for their synergistic activity with ATO in leukemia. This data also draws attention to possible severe systemic off-target toxicity of such combinations which may be inadvertently used in the clinic. Disclosures No relevant conflicts of interest to declare.

scholarly journals Retinoic acid is required for and potentiates differentiation of acute promyelocytic leukemia cells by nonretinoid agents

Blood ◽  
1994 ◽  
Vol 84 (7) ◽  
pp. 2122-2129 ◽  
Author(s):  
A Chen ◽  
JD Licht ◽  
Y Wu ◽  
N Hellinger ◽  
W Scher ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Cell Line ◽  
Acute Promyelocytic Leukemia ◽  
Drug Exposure ◽  
Primary Cultures ◽  
Leukemia Cell ◽  
Promyelocytic Leukemia ◽  
Leukemia Cell Line ◽  
Granulocytic Differentiation ◽  
Nb4 Cells

Abstract Patients with acute promyelocytic leukemia (APL) associated with the t(15;17) translocation and fusion of the promyelocytic leukemia (PML) and retinoic acid receptor-alpha (RAR-alpha) genes achieve complete remission but not cure with all-trans retinoic acid (RA), NB4, a cell line derived from a patient with t(15;17) APL that undergoes granulocytic differentiation when treated with pharmacologic doses of RA, was used as a model for differentiation therapy of APL. We found that NB4 cells are resistant to differentiation by nonretinoid inducers such as hexamethylene bisacetamide (HMBA), butyrates, vitamin D3, or hypoxanthine, all of which can induce differentiation in the commonly used HL60 leukemia cell line. Preexposure of NB4 cells to low concentrations of RA for a period as short as 30 minutes abolished resistance to nonretinoids and potentiated differentiation. Sequential RA and HMBA treatment yielded maximal differentiation by 3 days of drug exposure, whereas the effect of RA alone peaked after 6 days and yielded a smaller percentage of differentiated cells. RA also reversed NB4 cell resistance to butyrates and allowed for synergistic differentiation by these agents. Pretreatment with HMBA before exposure to RA failed to stimulate differentiation. Sequential RA/HMBA treatment also markedly increased the extent of differentiation of primary cultures of bone marrow and peripheral blood mononuclear cells from three APL patients. In one case RA/HMBA treatment overcame resistance to RA in vitro. Together, these results suggest that intermittent low doses of RA followed by either HMBA or butyrates may be a useful combination in the treatment of APL. This clinical strategy may help prevent or overcome RA resistance in APL.

Arsenic Trioxide Selectively Induces Acute Promyelocytic Leukemia Cell Apoptosis Via a Hydrogen Peroxide-Dependent Pathway

Blood ◽  
1999 ◽  
Vol 94 (6) ◽  
pp. 2102-2111 ◽  
Author(s):  
Yongkui Jing ◽  
Jie Dai ◽  
Ruth M.E. Chalmers-Redman ◽  
Willam G. Tatton ◽  
Samuel Waxman
Keyword(s):  
Acute Promyelocytic Leukemia ◽  
Leukemia Cell ◽  
Promyelocytic Leukemia ◽  
Point Of View ◽  
Leukemic Cells ◽  
Monocytic Leukemia ◽  
Cytochrome C Release ◽  
Nb4 Cells ◽  
H2o2 Content ◽  
High Concentrations

Abstract Low concentrations of As2O3 (≤1 μmol/L) induce long-lasting remission in patients with acute promyelocytic leukemia (APL) without significant myelosuppressive side effects. Several groups, including ours, have shown that 0.5 to 1 μmol/L As2O3 induces apoptosis in APL-derived NB4 cells, whereas other leukemic cells are resistant to As2O3 or undergo apoptosis only in response to greater than 2 μmol/L As2O3. In this report, we show that the ability of As2O3 to induce apoptosis in leukemic cells is dependent on the activity of the enzymes that regulate cellular H2O2 content. Thus, NB4 cells have relatively low levels of glutathione peroxidase (GPx) and catalase and have a constitutively higher H2O2content than U937 monocytic leukemia cells. Glutathione-S-transferase π (GSTπ), which is important for cellular efflux of As2O3, is also low in NB4 cells. Moreover, As2O3 further inhibits GPX activity and increases cellular H2O2 content in NB4 but not in U937 cells. Selenite pretreatment of NB4 cells increases the activity of GPX, lowers cellular H2O2 levels, and renders NB4 cells resistant to 1 μmol/L As2O3. In contrast, concentrations of As2O3 that alone are not capable of inducing apoptosis in NB4 cells induce apoptosis in the presence of the GPx inhibitor mercaptosuccinic acid. Similar effects are observed by modulating the activity of catalase with its inhibitor, aminotriazol. More important from a therapeutic point of view, U937 and HL-60 cells, which require high concentrations of As2O3 to undergo apoptosis, become sensitive to low, clinically acceptable concentrations of As2O3 when cotreated with these GPx and catalase inhibitors. The induction of apoptosis by As2O3 involves an early decrease in cellular mitochondrial membrane potential and increase in H2O2 content, followed by cytochrome c release, caspase 3 activation, DNA fragmentation, and the classic morphologic changes of apoptosis.

Arsenic Trioxide Selectively Induces Acute Promyelocytic Leukemia Cell Apoptosis Via a Hydrogen Peroxide-Dependent Pathway

Blood ◽  
1999 ◽  
Vol 94 (6) ◽  
pp. 2102-2111 ◽  
Author(s):  
Yongkui Jing ◽  
Jie Dai ◽  
Ruth M.E. Chalmers-Redman ◽  
Willam G. Tatton ◽  
Samuel Waxman
Keyword(s):  
Acute Promyelocytic Leukemia ◽  
Leukemia Cell ◽  
Promyelocytic Leukemia ◽  
Point Of View ◽  
Leukemic Cells ◽  
Monocytic Leukemia ◽  
Cytochrome C Release ◽  
Nb4 Cells ◽  
H2o2 Content ◽  
High Concentrations

Low concentrations of As2O3 (≤1 μmol/L) induce long-lasting remission in patients with acute promyelocytic leukemia (APL) without significant myelosuppressive side effects. Several groups, including ours, have shown that 0.5 to 1 μmol/L As2O3 induces apoptosis in APL-derived NB4 cells, whereas other leukemic cells are resistant to As2O3 or undergo apoptosis only in response to greater than 2 μmol/L As2O3. In this report, we show that the ability of As2O3 to induce apoptosis in leukemic cells is dependent on the activity of the enzymes that regulate cellular H2O2 content. Thus, NB4 cells have relatively low levels of glutathione peroxidase (GPx) and catalase and have a constitutively higher H2O2content than U937 monocytic leukemia cells. Glutathione-S-transferase π (GSTπ), which is important for cellular efflux of As2O3, is also low in NB4 cells. Moreover, As2O3 further inhibits GPX activity and increases cellular H2O2 content in NB4 but not in U937 cells. Selenite pretreatment of NB4 cells increases the activity of GPX, lowers cellular H2O2 levels, and renders NB4 cells resistant to 1 μmol/L As2O3. In contrast, concentrations of As2O3 that alone are not capable of inducing apoptosis in NB4 cells induce apoptosis in the presence of the GPx inhibitor mercaptosuccinic acid. Similar effects are observed by modulating the activity of catalase with its inhibitor, aminotriazol. More important from a therapeutic point of view, U937 and HL-60 cells, which require high concentrations of As2O3 to undergo apoptosis, become sensitive to low, clinically acceptable concentrations of As2O3 when cotreated with these GPx and catalase inhibitors. The induction of apoptosis by As2O3 involves an early decrease in cellular mitochondrial membrane potential and increase in H2O2 content, followed by cytochrome c release, caspase 3 activation, DNA fragmentation, and the classic morphologic changes of apoptosis.

scholarly journals Retinoic acid is required for and potentiates differentiation of acute promyelocytic leukemia cells by nonretinoid agents

Blood ◽  
1994 ◽  
Vol 84 (7) ◽  
pp. 2122-2129 ◽  
Author(s):  
A Chen ◽  
JD Licht ◽  
Y Wu ◽  
N Hellinger ◽  
W Scher ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Cell Line ◽  
Acute Promyelocytic Leukemia ◽  
Drug Exposure ◽  
Primary Cultures ◽  
Leukemia Cell ◽  
Promyelocytic Leukemia ◽  
Leukemia Cell Line ◽  
Granulocytic Differentiation ◽  
Nb4 Cells

Patients with acute promyelocytic leukemia (APL) associated with the t(15;17) translocation and fusion of the promyelocytic leukemia (PML) and retinoic acid receptor-alpha (RAR-alpha) genes achieve complete remission but not cure with all-trans retinoic acid (RA), NB4, a cell line derived from a patient with t(15;17) APL that undergoes granulocytic differentiation when treated with pharmacologic doses of RA, was used as a model for differentiation therapy of APL. We found that NB4 cells are resistant to differentiation by nonretinoid inducers such as hexamethylene bisacetamide (HMBA), butyrates, vitamin D3, or hypoxanthine, all of which can induce differentiation in the commonly used HL60 leukemia cell line. Preexposure of NB4 cells to low concentrations of RA for a period as short as 30 minutes abolished resistance to nonretinoids and potentiated differentiation. Sequential RA and HMBA treatment yielded maximal differentiation by 3 days of drug exposure, whereas the effect of RA alone peaked after 6 days and yielded a smaller percentage of differentiated cells. RA also reversed NB4 cell resistance to butyrates and allowed for synergistic differentiation by these agents. Pretreatment with HMBA before exposure to RA failed to stimulate differentiation. Sequential RA/HMBA treatment also markedly increased the extent of differentiation of primary cultures of bone marrow and peripheral blood mononuclear cells from three APL patients. In one case RA/HMBA treatment overcame resistance to RA in vitro. Together, these results suggest that intermittent low doses of RA followed by either HMBA or butyrates may be a useful combination in the treatment of APL. This clinical strategy may help prevent or overcome RA resistance in APL.

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