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Related Collections Neoplasia Oncogenes and Tumor Suppressors Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  Blood, 1 August 2002, Vol. 100, No. 3, pp. 1008-1013 NEOPLASIA Targeted removal of PML-RAR protein is required prior to inhibition of histone deacetylase for overcoming all-trans retinoic acid differentiation resistance in acute promyelocytic leukemia Yongkui Jing, Lijuan Xia, and Samuel Waxman From the Division of Medical Oncology, Department of Medicine, Mount Sinai School of Medicine, New York, NY.     Abstract Top Abstract Introduction Materials and methods Results Discussion References All-trans retinoic acid (tRA)-induced differentiation in NB4 cells, a cell line derived from an acute promyelocytic leukemia patient with t(15;17) translocation, is markedly facilitated by sodium butyrate (NaB), a histone deacetylase inhibitor (HDACI), or by hexamethylene bisacetamide (HMBA), a non-HDACI tRA-differentiation inducer, as determined by nitroblue tetrazolium reduction. The tRA-induced expression of RIG-G, Bfl-1/A1, and p21waf1 and, to a lesser extent, of CCAAT/enhancer binding protein- (C/EBP) are also enhanced by such combined treatments. Both responses are associated with a facilitated diminution of the leukemogenic PML-RAR protein and retained PML-RAR, a cleavage product. Treatment with tRA in tRA differentiation-resistant NB4 subclones R4 and MR-2 does not result in PML-RAR diminution and the tested gene expressions. Moreover, the addition of HMBA or NaB with tRA results in only minimal increase of differentiation in the tRA differentiation-resistant subclones. The increases in acetylated histone H3 (AcH3) and AcH4 in NaB-treated NB4, R4, and MR-2 cells are similar and do not correlate with the extent of differentiation induction when NaB and HMBA are given in combination with tRA. Arsenic trioxide (As2O3) treatment results in the total degradation of PML-RAR without increasing AcH3 or AcH4 or inducing differentiation in R4 cells. As2O3 in combination with tRA induces gene (Bfl-1/A1 and C/EBP) expression and partial differentiation. Both NaB and HMBA addition to As2O3-plus-tRA-treated R4 cells further enhances differentiation. These results suggest that elimination of the dominant negative PML-RAR protein is required prior to inhibition of histone deacetylase to fully overcome tRA-differentiation resistance in APL cells. (Blood. 2002;100:1008-1013) © 2002 by The American Society of Hematology.     Introduction Top Abstract Introduction Materials and methods Results Discussion References All-trans retinoic acid (tRA), a potent differentiation inducer, results in clinical remission in acute promyelocytic leukemia (APL) patients with PML-RAR fusion protein, the leukemogenic product of t(15;17) translocation.1-3 Other leukemias, including APL with t(11;17) translocation, are insensitive to tRA therapy.4 Although tRA in combination with chemotherapy results in long-term remission in 70% of APL patients,5,6 there may be a relapse of the disease in a form that is resistant to further tRA and chemotherapy treatment.7-9 Therefore, agents that effectively enhance tRA-induced differentiation or overcome tRA resistance need to be identified. The APL leukemogenic fusion protein PML-RAR functions as a dominant negative receptor over wild-type RAR, resulting in transcriptional repression.10,11 The dominant negative effect of PML-RAR is thought to result from tighter binding of corepressors N-CoR, Sin3, and histone deacetylase (HDAC) relative to RAR.11-14 It has been suggested that pharmacological tRA dissociates the corepressors from PML-RAR and restores tRA-modulated myeloid differentiation.15 HDAC inhibitors (HDACIs) sodium butyrate (NaB) and trichostatin A (TSA) enhance tRA-induced differentiation in NB4 cells, a t(15;17) APL cell line, probably by abrogating corepressor activity associated with PMLRAR.11,15-17 Since PML-RAR protein undergoes proteolytic cleavage in APL cells after tRA treatment,18-22 these agents may in addition enhance tRA-induced differentiation by facilitating proteolytic cleavage of PML-RAR. Few studies have been performed to test whether HDACIs can overcome tRA resistance in APL cells. There was a case report showing that a patient with a relapse of APL thought to be tRA resistant responded to tRA treatment in combination with phenylbutyrate,23 a putative HDACI. However 5 additional patients failed to respond to this combination.24 In contrast, 90% of tRA-resistant APL patients treated with arsenic trioxide (As2O3), shown to target and totally degrade PML-RAR protein, undergo complete remission.20,25-28 The correlation between PML-RAR proteolysis, HDAC inhibition, and tRA-induced differentiation and target-gene expresssion in APL cells has not been tested. In the present communication, PML-RAR proteolysis, histone acetylation, and differentiation are compared in tRA-sensitive and tRA-resistant APL cells after treatment with tRA in combination with As2O3, NaB (an HDACI differentiation inducer), and hexamethylene bisacetamide (HMBA), a non-HDACI differentiation inducer. Our results suggest that targeted PML-RAR removal is a fundamental event that enables tRA-induced APL cell differentiation.     Materials and methods Top Abstract Introduction Materials and methods Results Discussion References Reagents The tRA, HMBA, and NaB were purchased from Sigma Chemical (St Louis, MO). As2O3 (0.1%) was provided by Dr Ting-tong Zhang (Harbin, China). Anti-RAR (F region) antibody RP(F) was kindly provided by Dr P. Chambon (Strasburg, France). Cell culture NB4 cells (kindly provided by Dr M. Lanotte) were maintained in RPMI 1640 medium supplemented with 10% fetal bovine serum.29 MR-2 (nonmutated PML-RAR) and R4 (mutated PML-RAR in the ligand-binding domain) (kindly provided by Dr W. H. Miller Jr) cells were subclones of NB4 that were resistant to tRA-induced differentiation.30 Cell treatment and differentiation Cells were treated with 0.1 or 1 µM tRA, 2 mM HMBA, and 0.5 mM NaB, alone or tRA in combination with HMBA or NaB. The percentage of viable cells was determined by trypan blue exclusion. Differentiation was determined by nitroblue tetrazolium (NBT) reduction.17 Western blot analysis Protein extracts (50 µg) prepared with RIPA lysis buffer (50 mM Tris-HCl, 150 mM NaCl, 0.1% sodium dodecyl sulfate [SDS], 1% NP-40, 0.5% sodium deoxycholate, 1 mM phenylmethyl sulfonyl fluoride, 100 µM leupeptin, and 2 µg/mL aprotinin, pH 8.0) were separated on an 8% SDS-polyacrylamide gel and transferred to nitrocellulose membranes. The membranes were stained with 0.2% Ponceau S red to assure equal protein loading and transfer. After blocking with 5% nonfat milk, the membranes were incubated with anti-RAR antibody.31 Acetylated H3 (AcH3) and AcH4 were isolated and fractionated according to the manufacturer's instructions (Upstate Biochemical, Lake Placid, NY) and were probed with anti-AcH3 and anti-AcH4 antibodies. The immunocomplex was visualized by chemiluminescence. Northern blot analysis Total RNA was isolated with PURESCRIPT (Gentra Systems, Minneapolis, MN) from 106 cells. Then, 20 µg RNA was sized-fractionated on a 1.2% agarose/2.2 M formaldehyde gel, transferred to hybrid-N+ membrane (Amersham, Buckinghamshire, United Kingdom) in 20× SSC, and UV-cross-linked (Stratalinker) (Stratagene, La Jolla, CA). RIG-G (provided by Dr Z. Chen),32 P21waf1(provided by Dr J. Manfredi),33 CCAAT/enhancer binding protein - (C/EBP) (provided by Dr P. H. Koeffler),34 Bfl-1/A1 (provided by Dr G. Chinnadurai),35 and glyceraldehyde phosphate dehydrogenase (obtained from Ambion, Austin, TX) cDNAs were used for probing the filters. The probes were labeled with 32P-deoxycytidine 5'-triphosphate by random priming to a specific activity of 0.5 to 1 × 109 cpm/ng. The membranes were prehybridized for 4 hours at 42°C in 30 mL of 50% formamide, 6 × sodium chloride-sodium phosphate-EDTA buffer, 5 × Denhardt reagent, and 0.2 mL of 1 mg/mL single-stranded DNA, and then hybridized with radiolabeled probes.     Results Top Abstract Introduction Materials and methods Results Discussion References HMBA or NaB enhances tRA-induced differentiation in NB4 cells, but not in R4 or MR-2 cells NB4 cells and its 2 subclones, R4 and MR-2 cells, were treated with tRA alone and in combination with HMBA or NaB. Treatment for 3 days with tRA (107 M) alone, induced differentiation in 25% of NB4 cells as determined by NBT reduction, whereas cells showing 80% differentiation were obtained by treatment with tRA combined with 0.5 mM NaB or 2 mM HMBA. Neither tRA, HMBA, nor NaB alone induced differentiation (fewer than 5% NBT+) in R4 and MR-2 cells, whereas the combinations demonstrated minimal increases in differentiation (fewer than 15% NBT+ cells) (Figure 1). These data demonstrate that HMBA and NaB markedly enhance tRA-induced differentiation in tRA-sensitive APL cells, but this is only minimal in tRA-resistant APL cells. View larger version (31K): [in this window] [in a new window]   Figure 1. Effect of HMBA and NaB on tRA-induced differentiation in NB4, MR-2, and R4 cells. HMBA and NaB enhanced tRA-induced differentiation in NB4 cells, but not in MR-2 or R4 cells. NB4, MR-2, and R4 cells were treated with 107 µM tRA, 0.5 mM NaB, and 2 mM HMBA, alone or in combination as labeled in the bottom of the Figure, for 3 days. Differentiation was determined by NBT reduction assay. The data were the mean of 3 independent experiments with SD. HMBA or NaB enhances tRA-inducible gene expression in NB4 cells, but not in R4 or MR-2 cells The expression of RIG-G, Bfl-1/A1, P21waf1, and C/EBP has been shown to be up-regulated by tRA in NB4 cells.36 RIG-G, P21waf1, and Bfl-1/A1 were further induced after combined treatment with HMBA or NaB (Figure 2). In contrast, the tRA-induced strong expression of C/EBP was minimally enhanced by HMBA but not by NaB (Figure 2). None of the tested genes were induced by tRA alone or in combination with HMBA or NaB in R4 cells, except that the weak induction of P21waf1 by NaB was further increased by tRA (Figure 2). As in R4 cells, we have found that C/EBP and Bfl-1/A1 were not induced by tRA alone or in combination with HMBA or NaB in MR-2 cells (data not shown). View larger version (43K): [in this window] [in a new window]   Figure 2. Northern blot analysis of gene expressions induced by tRA alone or in combination with HMBA or NaB in NB4 and R4 cells. The cells were treated with 107 µM tRA, 2 mM HMBA, and 0.5 mM NaB, alone or in combination as labeled, for 3 days. Increasing AcH3 and AcH4 content does not correlate with differentiation induction The levels of AcH3 and AcH4 in NB4, R4, and MR-2 cells were analyzed by Western blot analysis. NaB similarly increased AcH3 and AcH4 in NB4, R4, and MR-2 cells (Figure 3), but facilitated differentiation was detected only in NB4 cells (Figure 1). As expected, tRA and HMBA or their combination did not increase AcH3 and AcH4 levels in NB4, R4, or MR-2 cells (Figure 3). View larger version (29K): [in this window] [in a new window]   Figure 3. Western blot analysis of AcH3 and AcH4 in NB4 and R4 cells treated with tRA combined with HMBA or NaB. The cells were treated with 107 µM tRA, 2 mM HMBA, and 0.5 mM NaB, alone or in combination as labeled, for 3 days. AcH3 and AcH4 were isolated and detected as described in "Materials and methods." NaB- and HMBA-enhanced tRA-induced differentiation correlates with facilitation of PML-RAR cleavage The tRA (107 M) treatment resulted in partial proteolytic cleavage of PML-RAR protein, forming a truncated product, PML-RAR, in NB4 cells but not in R4 and MR-2 cells (Figure 4). NaB or HMBA treatment alone did not induce PML-RAR cleavage in either cell line. However, HMBA or NaB added with tRA induced total cleavage of PML-RAR to PML-RAR in NB4 cells (Figure 4). Neither HMBA nor NaB could elicit PML-RAR cleavage in combination with tRA in R4 and MR-2 cells (Figure 4). The total PML-RAR cleavage to PML-RAR in NB4 cells correlates with the observed enhanced differentiation and gene induction by tRA plus NaB or HMBA (Figures 1 and 2), suggesting that the NaB and HMBA enhancement of tRA-induced gene expression and differentiation may be mediated in part by removal of PML-RAR, the dominant negative receptor, or that the cleavage product PML-RAR may enhance differentiation. View larger version (32K): [in this window] [in a new window]   Figure 4. Western blot analysis of PML-RAR cleavage in NB4 and R4 cells treated by tRA combined with HMBA or NaB. The cells were treated with 107 µM tRA, 2 mM HMBA, and 0.5 mM NaB, alone or in combination as labeled, for 3 days. Anti-RAR antibody was used to detect PML-RAR and PML-RAR. Enhanced differentiation and gene induction by triple combination of tRA and As2O3 with butyrate or HMBA in R4 cells As2O3 (0.5 µM) or tRA (1 µM) alone did not induce differentiation (fewer than 5% NBT+) in R4 cells, whereas As2O3 enhanced tRA-induced differentiation (30% NBT+ cells) (Figure 5A) and Bfl-1/A1 and C/EBP expression (Figure 5B). HMBA or NaB added with As2O3 further enhanced tRA-induced differentiation, with 90% of the cells becoming NBT+ (Figure 5A). The addition of HMBA or NaB with As2O3 and tRA further decreased the expression of MPO, the differentiation marker, but not the induced expression of Bfl-1/A1 and C/EBP (Figure 5B). As2O3 treatment (0.5 µM) alone totally degraded PML-RAR (Figure 5C). Increased AcH3 and AcH4 were observed only in cells that included NaB in the treatment (Figure 5C). View larger version (52K): [in this window] [in a new window]   Figure 5. Differentiation, gene induction, PML-RAR degradation, and histone acetylation by different combinations of As2O3, tRA, and HMBA or NaB in R4 cells. R4 cells were treated with 106 M tRA, 0.5 µM As2O3, and 2 mM HMBA or 0.5 mM NaB, alone or as in indicated combinations, for 3 days. (A) Differentiation. Differentiation was determined by NBT reduction. (B) Gene induction. Bfl-1/A1, C/EBP and myeloperoxidase (MPO) were determined by Northern blot analysis. (C) PML-RAR degradation and histone acetylation. PML-RAR, AcH3, and AcH4 protein levels were detected by Western blot analysis.     Discussion Top Abstract Introduction Materials and methods Results Discussion References Our data suggest (1) that HMBA and NaB enhance tRA-induced differentiation in NB4 cells by different pathways, both HDACI dependent (NaB) and HDACI independent (HMBA), and (2) that treatment with tRA and NaB or HMBA would be minimally effective in tRA-resistant APL patients since tRA resistance in R4 and MR-2 cells is only minimally improved by these combinations. It has been reported that an APL case resistant to tRA responded to tRA plus phenylbutyrate (PB).23 We found that similarly to NaB, PB did not significantly increase tRA-induced differentiation in R4 or MR-2 cells although AcH3 was increased (data not shown). Consistent with these observations, additional case studies show that tRA-resistant APL patients failed to respond to tRA plus PB.24 Thus, the increased levels of AcH3 and AcH4 in peripheral mononuclear cells found in the tRA-resistant APL case23 may not be sufficient to explain the clinical response to PB plus tRA since increased AcH3 and AcH4 were also observed in NaB-plus-tRA-treated resistant R4 and MR-2 cells without significant differentiation induction. These data and a previous report17 suggest that either HMBA or NaB can be used to enhance tRA differentiation-induced remission in tRA-responsive but not tRA-resistant APL patients. Treatment by tRA induces a proteolytic cleavage of PML-RAR, yielding PML-RAR in tRA-sensitive NB4,19,20,22,37 but not in tRA-resistant R4 and MR-2, cells.20 Since PML-RAR functions as a dominant negative receptor, the cleavage product PML-RAR may release the dominant repressive effect. The enhanced tRA differentiation by NaB and HMBA correlates with facilitated PML-RAR cleavage in NB4 cells (Figure 4), but this does not occur in R4 cells and MR-2 (Figure 4). It has been shown that tRA induced PML-RAR cleavage through caspases and proteasome-mediated pathways.21,38 It is speculated that these agents accelerate the cleavage/degradation process. This needs to be tested further. However, tRA-induced differentiation in leukemia cells without the PML-RAR product was also enhanced by HMBA, NaB, or other HDACI.39-42 Thus, HMBA and NaB may also enhance tRA-induced differentiation by a pathway independent of PML-RAR proteolysis. Another possibility is that the expression and functions of tRA-up-regulated genes are enhanced by these agents. HMBA and NaB enhance the expression of tRA-inducible genes (RIG-G, P21waf1, and Bfl-1/A1) in NB4 cells (Figure 2). Recently, it has been shown that the transcription factor C/EBP is induced by tRA in NB4 cells, but not in tRA-resistant APL cells.34,43 Similarly, we found that C/EBP was induced by tRA in NB4 cells, but not in R4 and MR-2 cells (Figure 2). Since a retinoic acid response element sequence was identified in the C/EBP promoter, we predicted that HMBA and NaB would facilitate tRA-induced differentiation by increasing tRA induction of C/EBP expression. As reported by Chih et al,44 we also found that the tRA-induced expression of C/EBP was minimally increased by HMBA, but not by NaB, in NB4 cells (Figure 2) even though differentiation induction was markedly enhanced (Figure 1). U937, LG, and 32Dcl3 cells stably transfected with C/EBP driven by an inducible promoter, like tRA-treated NB4 cells, undergo granulocytic differentiation.43,45,46 We suggest that HMBA and NaB may synergize tRA-induced differentiation by enhancing the transactivation function of C/EBP after induction by tRA. A major impairment to successful treatment of APL patients is tRA resistance. There appear to be multiple mechanisms for tRA clinical resistance, so many tRA-resistant NB4 subclones have been established.47 R4 and several other tRA-resistant clones contain a mutation in the ligand-binding domain of PML-RAR, which is thought to mediate resistance.30 MR-2 cells are without mutant PML-RAR, demonstrating that multiple mechanisms mediate tRA-differentiation resistance.30 Increased AcH3 and AcH4 are observed following treatment with NaB, but NaB minimally increase tRA differentiation in these cells (Figures 1 and 3). This is similar to the modest tRA-enhancing effect of TSA, a stronger and more toxic HDACI in tRA differentiation-resistant cells.16,42 Thus, it is important to design other strategies to overcome tRA resistance. On the basis of our current data obtained in NB4 cells after tRA treatment, we hypothesize that at least 2 factors are needed for overcoming tRA differentiation resistance in APL cells: (1) removal of PML-RAR and (2) induction and activation of RA response genes. Clinical remission following As2O3 treatment in tRA-resistant APL patients requires the presence25,27,48 and subsequent degradation of PML-RAR. However, As2O3 alone does not induce cell differentiation in vitro (Figure 5A), suggesting that PML-RAR degradation is insufficient for differentiation induction. The addition of tRA to As2O3 increased differentiation of R4 or MR-2 cells (Figure 5A).20 This may be similar to the modest differentiation of APL cells seen in patients treated with As2O3.27,48,49 This is thought to result from the ability of endogenous physiological retinoids or some other factor to induce functional gene expression once PML-RAR has been degraded by As2O3 treatment. Correlated with differentiation induction, tRA response genes were induced by tRA plus As2O3 in R4 cells even though they were not induced by each agent alone (Figure 5B). However, the differentiation of R4 cells following treatment by As2O3 plus tRA is much less than NB4 cells after tRA treatment and correlates with less expression of tRA-inducible genes. The tRA induces more Bfl-1/A1 and C/EBP messenger RNAs in NB4 cells than in R4 cells after treatment with tRA plus As2O3 (Figures 2 and 5B).20 PML-RAR-transfected U937/PR9 cells demonstrated an increased response to tRA-induced differentiation50 and an increased induction of C/EBP and other gene expressions.43 This suggests that PML-RAR also provides a positive signaling for tRA-response genes after pharmacological tRA treatment. The complete degradation of PML-RAR by As2O3 may remove both the negative and the positive signaling of PML-RAR. We and others have found that As2O3 decreased tRA-induced differentiation and gene induction in NB4 cells.20,51 The tRA-plus-As2O3-induced differentiation in R4 cells was further enhanced by addition of NaB or HMBA (Figure 5A), although the expression of the tRA-up-regulated genes studied was not further increased (Figure 5B). Interestingly, further down-regulation of MPO was observed. NaB and HMBA may enhance tRA-induced differentiation in As2O3-plus-tRA-induced differentiation in R4 cells by enhancing tRA-induced gene activation through an HDAC-dependent and an HDAC-independent pathway, respectively. Since strong differentiation induction is obtained in tRA-resistant R4 cells with such combinations, it may be worthwhile to take advantage of the clinical experience with each single agent (As2O3, tRA, and butyrate) to treat tRA-relapsed APL patients. Moreover, leukemic fusion proteins have been detected in more than 50% of acute myeloid leukemia (AML) patients.52 The clinical response of APL to both tRA and As2O3, which trigger proteolysis of PML-RAR by different pathways53 and which can be augmented by HDACIs, provides a rationale to identify additional agents that target degradation of specific leukemogenic proteins for treatment of AML.     Footnotes Submitted June 28, 2001; accepted March 28, 2002. Supported partly by American Institute for Cancer Research National Institutes of Health grant 5R01-CA85478 and the Samuel Waxman Cancer Research Foundation. The publication costs of this article were defrayed in part by page charge payment. Therefore, and solely to indicate this fact, this article is hereby marked "advertisement" in accordance with 18 U.S.C. section 1734. Reprints: Yongkui Jing, Division of Medical Oncology, Department of Medicine, Box 1178, Mount Sinai School of Medicine, 1 Gustave L. Levy Pl, New York, NY 10029-6547; e-mail: yongkui.jing{at}mssm.edu.     References Top Abstract Introduction Materials and methods Results Discussion References 1. Huang ME, Ye YC, Chen SR, et al. Use of all-trans retinoic acid in the treatment of acute promyelocytic leukemia. Blood. 1988;72:567-572[Abstract/Free Full Text]. 2. Warrell RP Jr, Frankel SR, Miller WH Jr, et al. Differentiation therapy of acute promyelocytic leukemia with tretinoin (all-trans-retinoic acid). N Engl J Med. 1991;324:1385-1393[Abstract]. 3. Degos L, Dombret H, Chomienne C, et al. All-trans-retinoic acid as a differentiating agent in the treatment of acute promyelocytic leukemia [comment appears in Blood. 1995;86:3264-3265]. Blood. 1995;85:2643-2653[Free Full Text]. 4. Licht JD, Chomienne C, Goy A, et al. Clinical and molecular characterization of a rare syndrome of acute promyelocytic leukemia associated with translocation (11;17). Blood. 1995;85:1083-1094[Abstract/Free Full Text]. 5. Mandelli F, Diverio D, Avvisati G, et al. Molecular remission in PML/RAR alpha-positive acute promyelocytic leukemia by combined all-trans retinoic acid and idarubicin (AIDA) therapy. Gruppo Italiano-Malattie Ematologiche Maligne dell'Adulto and Associazione Italiana di Ematologia ed Oncologia Pediatrica Cooperative Groups. Blood. 1997;90:1014-1021[Abstract/Free Full Text]. 6. Tallman MS. Therapy of acute promyelocytic leukemia: all-trans retinoic acid and beyond. Leukemia. 1998;12(suppl 1):S37-S40[Medline] [Order article via Infotrieve]. 7. Delva L, Cornic M, Balitrand N, et al. Resistance to all-trans retinoic acid (ATRA) therapy in relapsing acute promyelocytic leukemia: study of in vitro ATRA sensitivity and cellular retinoic acid binding protein levels in leukemic cells. Blood. 1993;82:2175-2181[Abstract/Free Full Text]. 8. Ding W, Li YP, Nobile LM, et al. Leukemic cellular retinoic acid resistance and missense mutations in the PML-RARalpha fusion gene after relapse of acute promyelocytic leukemia from treatment with all-trans retinoic acid and intensive chemotherapy. Blood. 1998;92:1172-1183[Abstract/Free Full Text]. 9. Imaizumi M, Suzuki H, Yoshinari M, et al. Mutations in the E-domain of RAR portion of the PML/RAR chimeric gene may confer clinical resistance to all-trans retinoic acid in acute promyelocytic leukemia. Blood. 1998;92:374-382[Abstract/Free Full Text]. 10. Grignani F, Fagioli M, Alcalay M, et al. Acute promyelocytic leukemia: from genetics to treatment. Blood. 1994;83:10-25[Free Full Text]. 11. Guidez F, Ivins S, Zhu J, Soderstrom M, Waxman S, Zelent A. Reduced retinoic acid-sensitivities of nuclear receptor corepressor binding to PML- and PLZF-RARalpha underlie molecular pathogenesis and treatment of acute promyelocytic leukemia. Blood. 1998;91:2634-2642[Abstract/Free Full Text]. 12. He LZ, Guidez F, Tribioli C, et al. Distinct interactions of PML-RARalpha and PLZF-RARalpha with co-repressors determine differential responses to RA in APL. Nat Genet. 1998;18:126-135[CrossRef][Medline] [Order article via Infotrieve]. 13. Collins SJ. Acute promyelocytic leukemia: relieving repression induces remission. Blood. 1998;91:2631-2633[Free Full Text]. 14. Grignani F, De Matteis S, Nervi C, et al. Fusion proteins of the retinoic acid receptor-alpha recruit histone deacetylase in promyelocytic leukaemia. Nature. 1998;391:815-818[CrossRef][Medline] [Order article via Infotrieve]. 15. He LZ, Merghoub T, Pandolfi PP. In vivo analysis of the molecular pathogenesis of acute promyelocytic leukemia in the mouse and its therapeutic implications. Oncogene. 1999;18:5278-5292[CrossRef][Medline] [Order article via Infotrieve]. 16. Lin RJ, Nagy L, Inoue S, Shao W, Miller WH Jr, Evans RM. Role of the histone deacetylase complex in acute promyelocytic leukaemia. Nature. 1998;391:811-814[CrossRef][Medline] [Order article via Infotrieve]. 17. Chen A, Licht JD, Wu Y, Hellinger N, Scher W, Waxman S. Retinoic acid is required for and potentiates differentiation of acute promyelocytic leukemia cells by nonretinoid agents. Blood. 1994;84:2122-2129[Abstract/Free Full Text]. 18. Yoshida H, Kitamura K, Tanaka K, et al. Accelerated degradation of PML-retinoic acid receptor alpha (PML-RARA) oncoprotein by all-trans-retinoic acid in acute promyelocytic leukemia: possible role of the proteasome pathway. Cancer Res. 1996;56:2945-2948[Abstract/Free Full Text]. 19. Raelson JV, Nervi C, Rosenauer A, et al. The PML/RAR alpha oncoprotein is a direct molecular target of retinoic acid in acute promyelocytic leukemia cells. Blood. 1996;88:2826-2832[Abstract/Free Full Text]. 20. Jing Y, Wang L, Xia LJ, et al. Combined effect of all-trans retinoic acid and arsenic trioxide in acute promyelocytic leukemia cells in vitro and in vivo. Blood. 2001;97:264-269[Abstract/Free Full Text]. 21. Zhu J, Gianni M, Kopf E, et al. Retinoic acid induces proteasome-dependent degradation of retinoic acid receptor alpha (RARalpha) and oncogenic RARalpha fusion proteins. Proc Natl Acad Sci U S A. 2000;96:14807-14812. 22. Idres N, Benoit G, Flexor MA, Lanotte M, Chabot GG. Granulocytic differentiation of human NB4 promyelocytic leukemia cells induced by all-trans retinoic acid metabolites. Cancer Res. 2001;61:700-705[Abstract/Free Full Text]. 23. Warrell RPJ, He LZ, Richon V, Calleja E, Pandolfi PP. Therapeutic targeting of transcription in acute promyelocytic leukemia by use of an inhibitor of histone deacetylase. J Natl Cancer Inst. 1998;90:1621-1625[Abstract/Free Full Text]. 24. Novick S, Camacho L, Gallagher R, et al. Initial clinical evaluation of transcription therapy for cancer: all-trans retinoic acid plus phenylbutyrate [abstract]. Blood. 1999;94(suppl 1):60a. 25. Shen ZX, Chen GQ, Ni JH, et al. Use of arsenic trioxide (As2O3) in the treatment of acute promyelocytic leukemia (APL), II: clinical efficacy and pharmacokinetics in relapsed patients. Blood. 1997;89:3354-3360[Abstract/Free Full Text]. 26. Zhang P, Wang SY, Hu X. Arsenic trioxide treated 72 cases of acute promyelocytic leukemia. Chin J Hematol. 1996;17:58-61. 27. Soignet SL, Maslak P, Wang ZG, et al. Complete remission after treatment of acute promyelocytic leukemia with arsenic trioxide. N Engl J Med. 1998;339:1341-1348[Abstract/Free Full Text]. 28. Chen GQ, Zhu J, Shi XG, et al. In vitro studies on cellular and molecular mechanisms of arsenic trioxide (As2O3) in the treatment of acute promyelocytic leukemia: As2O3 induces NB4 cell apoptosis with downregulation of Bcl-2 expression and modulation of PML-RAR alpha/PML proteins. Blood. 1996;88:1052-1061[Abstract/Free Full Text]. 29. Lanotte M, Martin Thouvenin V, Najman S, Balerini P, Valensi F, Berger R. NB4, a maturation inducible cell line with t(15;17) marker isolated from a human acute promyelocytic leukemia (M3). Blood. 1991;77:1080-1086[Abstract/Free Full Text]. 30. Rosenauer A, Raelson JV, Nervi C, Eydoux P, DeBlasio A, Miller WH Jr. Alterations in expression, binding to ligand and DNA, and transcriptional activity of rearranged and wild-type retinoid receptors in retinoid-resistant acute promyelocytic leukemia cell lines. Blood. 1996;88:2671-2682[Abstract/Free Full Text]. 31. Dai J, Weinberg RS, Waxman S, Jing Y. Malignant cells can be sensitized to undergo growth inhibition and apoptosis by arsenic trioxide through modulation of the glutathione redox system. Blood. 1999;93:268-277[Abstract/Free Full Text]. 32. Yu M, Tong JH, Mao M, et al. Cloning of a gene (RIG-G) associated with retinoic acid-induced differentiation of acute promyelocytic leukemia cells and representing a new member of a family of interferon-stimulated genes. Proc Natl Acad Sci U S A. 1997;94:7406-7411[Abstract/Free Full Text]. 33. Tang HY, Zhao K, Pizzolato JF, Fonarev M, Langer JC, Manfredi JJ. Constitutive expression of the cyclin-dependent kinase inhibitor p21 is transcriptionally regulated by the tumor suppressor protein p53. J Biol Chem. 1998;273:29156-29163[Abstract/Free Full Text]. 34. Chumakov AM, Grillier I, Chumakova E, Chih D, Slater J, Koeffler HP. Cloning of the novel human myeloid-cell-specific C/EBP-epsilon transcription factor. Mol Cell Biol. 1997;17:1375-1386[Abstract]. 35. D'Sa-Eipper C, Subramanian T, Chinnadurai G. bfl-1, a bcl-2 homologue, suppresses p53- induced apoptosis and exhibits potent cooperative transforming activity. Cancer Res. 1996;56:3879-3882[Abstract/Free Full Text]. 36. Liu TX, Zhang JW, Tao J, et al. Gene expression networks underlying retinoic acid-induced differentiation of acute promyelocytic leukemia cells. Blood. 2000;96:1496-1504[Abstract/Free Full Text]. 37. Gianni M, Koken MH, Chelbi-Alix MK, et al. Combined arsenic and retinoic acid treatment enhances differentiation and apoptosis in arsenic-resistant NB4 cells. Blood. 1998;91:4300-4310[Abstract/Free Full Text]. 38. Nervi C, Ferrara FF, Fanelli M, et al. Caspases mediate retinoic acid-induced degradation of the acute promyelocytic leukemia PML/RARalpha fusion protein. Blood. 1998;92:2244-2251[Abstract/Free Full Text]. 39. Taimi M, Chen ZX, Breitman TR. Potentiation of retinoic acid-induced differentiation of human acute promyelocytic leukemia NB4 cells by butyric acid, tributyrin, and hexamethylene bisacetamide. Oncol Res. 1998;10:75-84[Medline] [Order article via Infotrieve]. 40. Hassan HT, Zyada LE, Ragab MH, Rees JK. New synergistic combinations of differentiation inducing agents in the treatment of acute myeloid leukaemia. Eur J Clin Pharmacol. 1991;41:531-536[CrossRef][Medline] [Order article via Infotrieve]. 41. Breitman TR, He RY. Combinations of retinoic acid with either sodium butyrate, dimethyl sulfoxide, or hexamethylene bisacetamide synergistically induce differentiation of the human myeloid leukemia cell line HL60. Cancer Res. 1990;50:6268-6273[Abstract/Free Full Text]. 42. Kosugi H, Towatari M, Hatano S, et al. Histone deacetylase inhibitors are the potent inducer/enhancer of differentiation in acute myeloid leukemia: a new approach to anti-leukemia therapy. Leukemia. 1999;13:1316-1324[CrossRef][Medline] [Order article via Infotrieve]. 43. Park DJ, Chumakov AM, Vuong PT, et al. CCAAT/enhancer binding protein epsilon is a potential retinoid target gene in acute promyelocytic leukemia treatment. J Clin Invest. 1999;103:1399-1408[Medline] [Order article via Infotrieve]. 44. Chih DY, Chumakov AM, Park DJ, Silla AG, Koeffler HP. Modulation of mRNA expression of a novel human myeloid-selective CCAAT/enhancer binding protein gene (C/EBP epsilon). Blood. 1997;90:2987-2994[Abstract/Free Full Text]. 45. Watanabe N, Nakajima H, Ikeda Y, Handa M. A critical role for CAAT-enhancer binding protein epsilon in cell cycle arrest and apoptosis during myeloid differentiation [abstract]. Blood. 2000;96:284a. 46. Khanna-Gupta A, Zibello T, Lekstrom-Himes J, Berliner N. C/EBP mediates myeloid differentiation and is regulated by the CCAAT displacement protein (CDP/cut) in 32Dcl3 cells [abstract]. Blood. 2000;96:282a. 47. Roussel MJ, Lanotte M. Maturation sensitive and resistant t(15;17) NB4 cell lines as tools for APL physiopathology: nomenclature of cells and repertory of their known genetic alterations and phenotypes. Oncogene. 2001;20:7287-7291[CrossRef][Medline] [Order article via Infotrieve]. 48. Niu C, Yan H, Yu T, et al. Studies on treatment of acute promyelocytic leukemia with arsenic trioxide: remission induction, follow-up, and molecular monitoring in 11 newly diagnosed and 47 relapsed acute promyelocytic leukemia patients. Blood. 1999;94:3315-3324[Abstract/Free Full Text]. 49. Shen Y, Shen ZX, Yan H, et al. Studies on the clinical efficacy and pharmacokinetics of low-dose arsenic trioxide in the treatment of relapsed acute promyelocytic leukemia: a comparison with conventional dosage. Leukemia. 2001;15:735-741[CrossRef][Medline] [Order article via Infotrieve]. 50. Grignani F, Ferrucci PF, Testa U, et al. The acute promyelocytic leukemia-specific PML-RAR alpha fusion protein inhibits differentiation and promotes survival of myeloid precursor cells. Cell. 1993;74:423-431[CrossRef][Medline] [Order article via Infotrieve]. 51. Shao W, Fanelli M, Ferrara FF, et al. Arsenic trioxide as an inducer of apoptosis and loss of PML/RAR alpha protein in acute promyelocytic leukemia cells. J Natl Cancer Inst. 1998;90:124-133[Abstract/Free Full Text]. 52. Look AT. Oncogenic transcription factors in the human acute leukemias. Science. 1997;278:1059-1064[Abstract/Free Full Text]. 53. Zhu J, Lallemand-Breitenbach V, de The H. Pathways of retinoic acid- or arsenic trioxide-induced PML/RARalpha catabolism, role of oncogene degradation in disease remission. Oncogene. 2001;20:7257-7265[CrossRef][Medline] [Order article via Infotrieve]. © 2002 by The American Society of Hematology.   CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: M. G. Wade, A. Kawata, A. Williams, and C. Yauk Methoxyacetic Acid-Induced Spermatocyte Death Is Associated with Histone Hyperacetylation in Rats Biol Reprod, May 1, 2008; 78(5): 822 - 831. [Abstract] [Full Text] [PDF] R. Rasooly, G. U. Schuster, J. P. Gregg, J.-H. Xiao, R. A. S. Chandraratna, and C. B. 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