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  • 1
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2011
    In:  Cancer Research Vol. 71, No. 8_Supplement ( 2011-04-15), p. 2527-2527
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 71, No. 8_Supplement ( 2011-04-15), p. 2527-2527
    Abstract: Naphthalimides derivatives have been extensively studied as anti-cancer agents. Amonafide (5-amino-2-[2-(dimethylamino)ethyl]-1H-benzo[de] isoquinoline-1,3(2H)-dione) showed clinical activity especially in some groups of AML patients. Amonafide has been shown to target topoisomerase II (Top2), and to stabilize Top2 covalent complexes. Therefore, the agent is a Top2 poison, however, the compound shows some unusual properties. Unlike most Top2 poisons, the action of amonafide against Top2 is largely ATP independent; In addition, amonafide leads to cleavage of DNA at a very restricted set of sites compared to other Top2 poisons such as mitoxantrone or etoposide. These findings have led to suggestions that amonafide may target Top2 in an unconventional way. Another obstacle to the clinical use of amonafide is variable drug metabolism. Felder and colleagues showed that amonafide is metabolized by N-acetyl transferase 2 (NAT2) to form N-acetyl amonafide (NAA). Toxicity of amonafide regimens is associated with higher levels of NAT2 activity 2. The mechanism of NAA toxicity has not been reported. We have used the ICE assay developed by Muller and colleagues to assess Top2 covalent complex levels in cells treated with either amonafide or NAA. We found that amonafide induces Top2 mediated DNA cleavage, and that covalent complexes formed by both Top2 alpha and Top2 beta were seen. Interestingly, NAA induced higher levels of Top2 covalent complexes than the parent compound. In addition, the level of Top2 covalent complexes increased with increasing NAA dose, whereas a plateau in the level of Top2 covalent complexes was seen with amonafide at relatively low doses. We are currently comparing the action of amonafide and NAA against purified human topoisomerases. We suggest that NAA is a Top2 poison, and a plausible hypothesis is that NAA may act more like a conventional Top2 poison, while amonafide may show a better therapeutic index because it has more limited potential for forming Top2 covalent complexes. These results may be useful in the further development of amonafide derivatives with a favorable therapeutic profile. (1) Felder, T. B.; McLean, M. A.; Vestal, M. L.; Lu, K.; Farquhar, D.; Legha, S. S.; Shah, R.; Newman, R. A. Drug Metab Dispos 1987, 15, 773. (2) Ratain, M. J.; Rosner, G.; Allen, S. L.; Costanza, M.; Van Echo, D. A.; Henderson, I. C.; Schilsky, R. L. J Clin Oncol 1995, 13, 741. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2527. doi:10.1158/1538-7445.AM2011-2527
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2011
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  • 2
    In: Blood, American Society of Hematology, Vol. 124, No. 21 ( 2014-12-06), p. 618-618
    Abstract: β-catenin acts as a co-activator for the T-cell factor (TCF) 4/lymphoid enhancer factor (LEF) 1 bipartite transcription factor at the promoters of the WNT-β-catenin target genes, including cyclin D1, c-Myc and survivin. The canonical WNT-β-catenin pathway is documented to be essential for self-renewal, growth and survival of the AML stem and blast progenitor cells (BPCs), which has also been correlated with a poor prognosis in AML. In AML stem/BPCs expressing mutant FLT3-ITD, increased PI3K/AKT activity causes phosphorylation and inactivation of GSK3β, thereby preventing degradation, promoting stabilization and nuclear localization of β-catenin. Additionally, FLT3 can also directly mediate the tyrosine phosphorylation of β-catenin, thereby stabilizing and promoting the nuclear localization and binding of β-catenin to TCF4. TBL1 (transducin beta-like) is an adaptor protein, which binds to nuclear β-catenin and promotes its co-factor activity with TCF4/LEF1 in mediating transcription of the target genes, including c-Myc, cyclin D1 and survivin. Therefore, we hypothesized that targeted disruption of TBL1-β-catenin binding or depletion of TBL1 would abrogate the pro-growth and oncogenic signaling of β-catenin in AML BPCs, especially those expressing FLT3-ITD. Here, we demonstrate that treatment with 20 to 100 nM of BC2059 (β-Cat Pharmaceuticals), a small molecule, anthraquinone oxime-analog, disrupts the binding of β-catenin to TBL1 (by anti-TBL1 pull down and immunofluorescence analyses) and promotes proteasomal degradation of β-catenin, thereby attenuating the nuclear levels of β-catenin in the cultured (OCI-AML3, MOLM13 and MV4-11), as well as in primary (p) AML BPCs. Concomitantly, BC2059 treatment inhibited the mRNA and protein expression of c-Myc, cyclin D1 and survivin, while de-repressing p21 and Axin2. BC2059 also dose dependently inhibited growth and induced apoptosis of cultured and CD34+ pAML BPCs expressing FLT3-ITD (40 to 60%), but not of normal CD34+ bone marrow progenitor cells (p 〈 0.01). Transient knockdown of TBL1 or beta catenin (60 to 70%) by lentivirus-transduced shRNA caused loss of viability in MOLM13 cells, which was significantly enhanced by treatment with BC2059 (p 〈 0.01). BC2059 also induced apoptosis of MOLM13-TKIR cells that were isolated in vitro to exhibit resistance to FLT3 antagonists (approximately 50-fold). Notably, BC2059 treatment (10 mg/kg, t.i.w., by IV injection) also exerted potent in vivo anti-AML activity and significantly improved the survival of immune depleted mice engrafted with cultured and patient-derived pAML BPCs (p 〈 0.001). Since compared to the control OCI-AML3 cells, BC2059 demonstrated significantly greater lethality against the OCI-AML3 cells ectopically overexpressing FLT3-ITD (approximately 8-fold), we hypothesized that co-treatment with a FLT3 antagonist would further reduce the nuclear levels of β-catenin and enhance the lethal activity of FLT3-antagonist against AML BPCs expressing FLT3-ITD. Indeed, co-treatment with BC2059 (50 nM) and the FLT3-antagonist quizartinib or ponatinib (100 to 200 nM), versus each agent alone, caused more reduction in the nuclear levels and binding of β-catenin to TBL1 (by confocal immunofluorescence analysis). This was associated with greater decline in the expression of c-Myc, cyclin D1 and survivin, but increase in the levels of p21 and BIM. Compared to each agent alone, co-treatment with BC2059 and quizartinib or ponatinib also synergistically induced apoptosis of the FLT3-ITD expressing cultured (MOLM13 and MV4-11) and pAML BPCs (combination indices of 〈 1.0, by isobologram analyses) but not of normal CD34+ progenitor cells. Treatment with BC2059 (25 to 100 nM) also significantly increased the apoptosis observed by the shRNA mediated incomplete knockdown of TBL1 or β-catenin (approximately 70%) in MOLM13 cells (p 〈 0.01). Collectively, our findings support that targeted inhibition of the levels and binding of β-catenin to TBL by BC2059 and FLT3-antagonist is a promising approach to exert lethal activity against AML BPCs expressing FLT3-ITD. Further pre-clinical development of this combination therapy against FLT3-ITD expressing AML is progressing. Disclosures No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2014
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  • 3
    In: Molecular Cancer Therapeutics, American Association for Cancer Research (AACR), Vol. 21, No. 1 ( 2022-01-01), p. 170-183
    Abstract: Oncogenic RAS signaling is an attractive target for fusion-negative rhabdomyosarcoma (FN-RMS). Our study validates the role of the ERK MAPK effector pathway in mediating RAS dependency in a panel of H/NRASQ61X mutant RMS cells and correlates in vivo efficacy of the MEK inhibitor trametinib with pharmacodynamics of ERK activity. A screen is used to identify trametinib-sensitizing targets, and combinations are evaluated in cells and tumor xenografts. We find that the ERK MAPK pathway is central to H/NRASQ61X dependency in RMS cells; however, there is poor in vivo response to clinically relevant exposures with trametinib, which correlates with inefficient suppression of ERK activity. CRISPR screening points to vertical inhibition of the RAF–MEK–ERK cascade by cosuppression of MEK and either CRAF or ERK. CRAF is central to rebound pathway activation following MEK or ERK inhibition. Concurrent CRAF suppression and MEK or ERK inhibition, or concurrent pan-RAF and MEK/ERK inhibition (pan-RAFi + MEKi/ERKi), or concurrent MEK and ERK inhibition (MEKi + ERKi) all synergistically block ERK activity and induce myogenic differentiation and apoptosis. In vivo assessment of pan-RAFi + ERKi or MEKi + ERKi potently suppress growth of H/NRASQ61X RMS tumor xenografts, with pan-RAFi + ERKi being more effective and better tolerated. We conclude that CRAF reactivation limits the activity of single-agent MEK/ERK inhibitors in FN-RMS. Vertical targeting of the RAF–MEK–ERK cascade and particularly cotargeting of CRAF and MEK or ERK, or the combination of pan-RAF inhibitors with MEK or ERK inhibitors, have synergistic activity and potently suppress H/NRASQ61X mutant RMS tumor growth.
    Type of Medium: Online Resource
    ISSN: 1535-7163 , 1538-8514
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2022
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    SSG: 12
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  • 4
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2013
    In:  Cancer Research Vol. 73, No. 8_Supplement ( 2013-04-15), p. 4480-4480
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 73, No. 8_Supplement ( 2013-04-15), p. 4480-4480
    Abstract: Topoisomerase poisons are important anti-cancer drugs, and include agents such as etoposide and doxorubicin that target eukaryotic topoisomerase II. Most topoisomerase II poisons act as interstitial inhibitors. This mode of inhibition depends on the coordination of the enzyme and DNA substrate to form a drug binding site. While recent structural studies have localized topoisomerase II poisons to the drug/DNA interface, our understanding of the mechanism of enzyme inhibition remains incomplete. We have combined genetic, biochemical, and structural approaches to identify regions of topoisomerase II that are important for drug action and identified sites near the active site tyrosine that contribute to drug sensitivity. Interestingly, we also identified amino acids near the C-terminal dimerization domain that also control DNA cleavage. Mutations in the C-terminal dimerization domain exhibit several unique characteristics. Importantly, we identified two mutants in the dimerization domain of yeast Top2 that could not be viably expressed in yeast mutants defective in double strand break repair. Expression of these mutants in repair proficient strains led to elevated rates of homologous recombination, suggesting that these mutant proteins are able to generate DNA damage even in the absence of topoisomerase II targeting agents. We purified the mutant proteins and demonstrated that they possess elevated levels of drug independent DNA cleavage, compared to wild type proteins. Elevated cleavage was only seen in the presence of ATP, indicating that the mutant proteins are likely defective in DNA religation at a specific step in the catalytic cycle, and that the C-terminal dimerization and DNA religation occurs by a coordinated process. Finally, we have also shown that homologous mutations in human topoisomerase II alpha generate effects similar to those described for the yeast protein. Taken together, these results suggest that it may be possible to identify potent allosteric inhibitors of topoisomerase II directed against the C-terminal catalytic domain of the protein. These hypothetical inhibitors may have unique therapeutic potential, especially because they represent an approach for isoform specific topoisomerase poisons. Citation Format: Anna Rogojina, Karin C. Nitiss, John L. Nitiss. New approaches to changing an enzyme into a cytotoxic agent: A novel way to stimulate DNA cleavage by topoisomerase II. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4480. doi:10.1158/1538-7445.AM2013-4480
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2013
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  • 5
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 83, No. 7_Supplement ( 2023-04-04), p. 3572-3572
    Abstract: Background: Cancer causes significant mortality and morbidity in children. Current therapies are effective but can cause long-term health problems for patients. Development of new therapies relies on faithful preclinical models. Patient-derived xenografts (PDXs) are an important tool for pre-clinical testing in childhood cancer research. It remains incompletely understood how well genomically PDXs recapitulate primary patient tumors (PTs), particularly in rare cancers. Method: To characterize the fidelity of early passage subcutaneous PDXs derived from pediatric solid tumors, we established 70 early passage PDX models from 16 cancer types. The cohort comprises some very rare cancers such as hepatoblastoma (n=13), germ cell tumor (n=10), osteosarcoma (n=13), and Wilms tumor (n=14). We performed low pass whole genome, exome, and RNA sequencing on these PDXs, their matched PTs and germline samples when materials were available. Result: Overall, we observed low somatic mutation rates in these tumors; however, prior chemotherapy was associated with higher mutation rate. Of the 25 PT/PDX pairs, 20 showed high mutation similarity. The five pairs with low mutation similarity showed evidence of clonal selection. We observed high genomic instability in osteosarcoma. Consistently, more fusions were identified in this cancer type. PTs and PDXs showed high similarity in the copy number pattern, including both broad and focal events. GISTIC analysis identified recurrently amplified or deleted genes including MYC, CCNE1, TP53, PTEN, and BCL2. On the transcriptional level, though PTs and PDXs were generally similar, their expression is more reflective of tissue of origin. We identified fusions that are characteristic of the cancer type such as BCOR-CCND3 in an Ewing like sarcoma. We also identified an NTRK fusion in an osteosarcoma. In summary, we show that PDXs generally recapitulate PTs in mutations, copy number changes, and expression. The dataset represents a valuable resource for future preclinical and mechanistic studies. Citation Format: Funan He, Abhik M. Bandyopadhyay, Laura Klesse, Anna Rogojina, Erin Butler, Taylor Hartshorne, Trevor Holland, Luz Perez Prado, Anne-Marie Langevan, Allison C. Grimes, Chatchawin Assanasen, Zhao Lai, Yi Zou, Dias Kurmashev, Lin Xu, Yang Xie, Yidong Chen, Xiaojing Wang, Gail E. Tomlinson, Stephen X. Skapek, Raushan T. Kurmasheva, Peter J. Houghton, Siyuan Zheng. Genomic profiling of subcutaneous patient derived xenograft models of solid childhood cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3572.
    Type of Medium: Online Resource
    ISSN: 1538-7445
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2023
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  • 6
    In: Nature Medicine, Springer Science and Business Media LLC, Vol. 25, No. 12 ( 2019-12), p. 1938-1947
    Type of Medium: Online Resource
    ISSN: 1078-8956 , 1546-170X
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
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  • 7
    Online Resource
    Online Resource
    Wiley ; 2012
    In:  Current Protocols in Pharmacology Vol. 57, No. 1 ( 2012-06)
    In: Current Protocols in Pharmacology, Wiley, Vol. 57, No. 1 ( 2012-06)
    Abstract: Topoisomerases are nuclear enzymes that play essential roles in DNA replication, transcription, chromosome segregation, and recombination. All cells have two major forms of topoisomerases: type I enzymes, which make single‐stranded cuts in DNA, and type II enzymes, which cut and pass double‐stranded DNA. DNA topoisomerases are important targets of approved and experimental anti‐cancer agents. The protocols described in this unit are for assays used to assess new chemical entities for their ability to inhibit both forms of DNA topoisomerase. Included are an in vitro assay for topoisomerase I activity based on relaxation of supercoiled DNA, and an assay for topoisomerase II based on the decatenation of double‐stranded DNA. The preparation of mammalian cell extracts for assaying topoisomerase activity is described, along with a protocol for an ICE assay to examine topoisomerase covalent complexes in vivo, and an assay for measuring DNA cleavage in vitro. Curr. Protoc. Pharmacol . 57:3.3.1‐3.3.27. © 2012 by John Wiley & Sons, Inc.
    Type of Medium: Online Resource
    ISSN: 1934-8282 , 1934-8290
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2012
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  • 8
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2020
    In:  Proceedings of the National Academy of Sciences Vol. 117, No. 43 ( 2020-10-27), p. 26876-26884
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 117, No. 43 ( 2020-10-27), p. 26876-26884
    Abstract: Topoisomerase II (Top2) is an essential enzyme that resolves catenanes between sister chromatids as well as supercoils associated with the over- or under-winding of duplex DNA. Top2 alters DNA topology by making a double-strand break (DSB) in DNA and passing an intact duplex through the break. Each component monomer of the Top2 homodimer nicks one of the DNA strands and forms a covalent phosphotyrosyl bond with the 5′ end. Stabilization of this intermediate by chemotherapeutic drugs such as etoposide leads to persistent and potentially toxic DSBs. We describe the isolation of a yeast top2 mutant ( top2-F1025Y,R1128G ) the product of which generates a stabilized cleavage intermediate in vitro. In yeast cells, overexpression of the top2-F1025Y,R1128G allele is associated with a mutation signature that is characterized by de novo duplications of DNA sequence that depend on the nonhomologous end-joining pathway of DSB repair. Top2-associated duplications are promoted by the clean removal of the enzyme from DNA ends and are suppressed when the protein is removed as part of an oligonucleotide. TOP2 cells treated with etoposide exhibit the same mutation signature, as do cells that overexpress the wild-type protein. These results have implications for genome evolution and are relevant to the clinical use of chemotherapeutic drugs that target Top2.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2020
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    SSG: 11
    SSG: 12
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  • 9
    In: iScience, Elsevier BV, Vol. 26, No. 11 ( 2023-11), p. 108171-
    Type of Medium: Online Resource
    ISSN: 2589-0042
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2023
    detail.hit.zdb_id: 2927064-9
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  • 10
    Online Resource
    Online Resource
    Elsevier BV ; 2008
    In:  Journal of Biological Chemistry Vol. 283, No. 43 ( 2008-10), p. 29239-29250
    In: Journal of Biological Chemistry, Elsevier BV, Vol. 283, No. 43 ( 2008-10), p. 29239-29250
    Type of Medium: Online Resource
    ISSN: 0021-9258
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2008
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    detail.hit.zdb_id: 1474604-9
    SSG: 12
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