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Scott A Armstrong - One of the best experts on this subject based on the ideXlab platform.
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a role for dot1l in mll rearranged leukemias
Epigenomics, 2011Co-Authors: Kathrin M Bernt, Scott A ArmstrongAbstract:Leukemias harboring rearrangements of the MLL gene carry a poor prognosis. Over the past 6 years, it has become increasingly clear that fusions of MLL induce widespread epigenetic dysregulation that may mediate much of their transforming activity. The histone methyltransferase DOT1L, which methylates histone 3 on lysine 79 (H3K79) has received particular attention. Several MLL fusions may physically interact with DOT1L. Genome-wide H3K79 methylation profiles in MLL-rearranged leukemias are abnormal, and can serve to distinguish MLL-rearranged from other types of leukemias. Loss of H3K79 methylation affects expression of MLL-target loci and is detrimental to the leukemogenic activity of MLL-rearranged cells, suggesting that transformation in these leukemias is driven by a DOT1L dependent, aberrant epigenetic program. The ‘histone code hypothesis’ proposes that histone modifications, along with proteins that recognize, place and remove these marks, form a sophisticated regulatory network that directly control gene expression. Histone modifications may prime genes for rapid induction after signaling receptor engagement, coordinate individual genes to genetic programs that are coregulated, or organize a sequence of transcriptional events during development. MLL-rearranged leukemias have recently been proposed to rely heavily on epigenetic dysregulation during malignant transformation. In contrast to most other cancers, MLL-rearranged leukemias display a remarkable paucity of DNA sequence alterations: frequently, the only genetic abnormality uncovered by genome-wide technologies in these leukemias is the MLL-translocation. The induction of widespread epigenetic changes could explain the apparent lack of a need for cooperating mutagenesis on a DNA-sequence level. This is significant, since most MLL-rearranged
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HOXA9 is required for survival in human MLL-rearranged acute leukemias
Blood, 2009Co-Authors: Joerg Faber, Matthew C Stubbs, Andrew L Kung, Christian M Zwaan, Andrei V. Krivtsov, Renee Wright, Tina N. Davis, Marry M. Van Den Heuvel-eibrink, Scott A ArmstrongAbstract:Leukemias that harbor translocations involving the mixed lineage leukemia gene (MLL) possess unique biologic characteristics and often have an unfavorable prognosis. Gene expression analyses demonstrate a distinct profile for MLL-rearranged leukemias with consistent high-level expression of select Homeobox genes, including HOXA9. Here, we investigated the effects of HOXA9 suppression in MLL-rearranged and MLL-germline leukemias using RNA interference. Gene expression profiling after HOXA9 suppression demonstrated co–down-regulation of a program highly expressed in human MLL-AML and murine MLL-leukemia stem cells, including HOXA10, MEIS1, PBX3, and MEF2C. We demonstrate that HOXA9 depletion in 17 human AML/ALL cell lines (7 MLL-rearranged, 10 MLL-germline) induces proliferation arrest and apoptosis specifically in MLL-rearranged cells (P = .007). Similarly, assessment of primary AMLs demonstrated that HOXA9 suppression induces apoptosis to a greater extent in MLL-rearranged samples (P = .01). Moreover, mice transplanted with HOXA9-depleted t(4;11) SEMK2 cells revealed a significantly lower leukemia burden, thus identifying a role for HOXA9 in leukemia survival in vivo. Our data indicate an important role for HOXA9 in human MLL-rearranged leukemias and suggest that targeting HOXA9 or downstream programs may be a novel therapeutic option.
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the myocyte enhancer factor 2c mef2c is a direct transcriptional target of hoxa9 and mediates leukemia survival in human mixed lineage leukemias
Blood, 2007Co-Authors: Jorg Faber, Matthew C Stubbs, Andrew L Kung, Scott A Armstrong, Andrei V Krivstov, Marry Van Den Heuveleibrink, Christian M ZwaanAbstract:Leukemias that harbor rearrangements of the mixed-lineage leukemia gene ( MLL ) possess unique clinical and biological characteristics. Aberrant high-level expression of select Homeobox ( HOX ) genes including HOXA9 is a consistent feature of MLL -rearranged leukemias, implicating an important role of dysregulated HOX gene expression in this entity. Applying HOXA9 -directed RNAi, we have previously shown that aberrant HOXA9 expression is a prerequisite for leukemia survival in human MLL -rearranged leukemias and murine Mll -leukemia stem cells as HOXA9 suppression leads to a progressive induction of apoptosis in vitro and in vivo . In this study we aimed to identify potential direct HOXA9 target genes in human MLL -rearranged leukemias utilizing gene expression profiling after shRNA mediated HOXA9 knockdown and subsequent chromatin immunoprecipitation (ChIP) analysis. To establish efficient HOXA9 knockdown, 2 previously validated shRNA constructs targeting human HOXA9 with high efficiency (>80% mRNA suppression) were transduced into t(9;11) MOLM-14 AML cells. 72h after transduction, RNA was hybridized to Affymetrix HU 133A2.0 expression arrays. Supervised analysis identified a large group of genes concomitantly downregulated after HOXA9 suppression. Gene set enrichment analysis demonstrated significant enrichment of the top 300 genes in the HOXA9 suppression signature and genes more highly expressed in human MLL-AML as compared to other genetically defined AML subtypes (p=0.02). Interestingly, genes previously implicated in the pathogenesis of MLL -rearranged leukemias were among the most highly enriched ( HOXA5 , MEIS1 , PBX3 , MEF2C ). To analyze if any of this genes might be a direct physiological HOXA9 target, we performed ChIP assays from FLAG-tagged HOXA9 expressing MOLM-14 cells. Whereas the promotor regions of HOXA5 , MEIS1 and PBX3 did not show HOXA9 binding, the MEF2C promotor region DNA was highly enriched by ChIP. Furthermore HOXA9 binding was confined to the MEF2C promotor region as the regions -5kb 5’-upstream, +5kb and +10kb 3’-downstream of the MEF2C promotor region did not show any enrichment. Motive search analysis of the MEF2C promoter further revealed a perfect consensus binding site (TGATTTAT) for HOXA9 and its DNA binding partner PBX located at −721 to −714 from the transcriptional start site. We then analyzed if direct shRNA mediated targeting of MEF2C also abrogates leukemia survival in human MLL -rearranged leukemias similar to upstream HOXA9 suppression. Analysis of viability after MEF2C knockdown with two different shRNA constructs (>80% mRNA knockdown) in a panel of human 8 AML/ALL cell lines (4 MLL -rearranged; 4 MLL -wildtype) and primary AML patient cells (5 MLL -rearranged; 5 MLL -wildtype) revealed progressive induction of apoptosis which was significantly correlated with the presence of the MLL -fusion oncogene in the cell lines (mean viability at day 7: MLL -rearranged: 14.5% MLL -wildtype: 86.75%: p MEF2C as a direct downstream target of HOXA9 and aberrant MEF2C expression is necessary for survival of MLL -rearranged leukemias. Targeting the HOXA9-MEF2C program may be a novel therapeutic approach.
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HoxA9 Knockdown Inhibits Proliferation and Induces Cell Death in Human MLL-Rearranged Leukemias.
Blood, 2006Co-Authors: Jorg Faber, Matthew C Stubbs, Andrew L Kung, Christian M Zwaan, Andrei V. Krivtsov, Renee Wright, Marry M. Van Den Heuvel-eibrink, Scott A ArmstrongAbstract:Homeobox containing (Hox) genes are implicated in the regulation of normal and leukemic hematopoesis. Using gene expression profiling we and others have previously shown that HoxA9 is highly expressed in lymphoid and myeloid leukemias harboring MLL translocations and that high level HoxA9 expression is associated with poor clinical prognosis. Furthermore, HoxA9 plays variable roles in MLL-fusion induced murine leukemias. In this study we aimed to elucidate the role of aberrant HoxA9 expression in human MLL-rearranged and non-rearranged leukemia’s utilizing an shRNA mediated knockdown approach. To establish an efficient knockdown assay three different shRNA constructs targeting human HoxA9 were synthesized and stably introduced into t(9;11) MOLM14 cells utilizing a lentiviral vector system. The shRNA construct which showed highest efficiency as measured by Taqman quantitative PCR (75–80% knockdown MLL-AF9 RNA) and Western Blot analysis was used for further experiments. In MOLM-14 cells, HoxA9 directed shRNA inhibited cell proliferation starting as early as 48h after transduction as determined by MTT assay, and at 72h demonstrated a markedly increased number of apoptotic cells as measured by Annexin V staining. This effect was rescued by introducing a non-targetable exogenous HoxA9 in MOLM-14 cells. To investigate if the HoxA9 knockdown related effects are specific for MLL rearranged cells we next analyzed cell growth and viability in 17 AML/ALL cell lines (7 MLL-rearranged, 10 non rearranged) after shRNA mediated HoxA9 knockdown. Interestingly, impaired cell proliferation and induction of apoptosis was significantly higher in the MLL rearranged cell lines (mean viability: 51.88%) than in the non-rearranged cells (mean viability: 90.98%; p=0.007). Moreover, the effect was also significantly correlated with the baseline HoxA9 mRNA expression before knockdown, with the greatest effect in cell lines expressing the highest HoxA9 levels (R= 0.8, p=0.00017). These findings prompted us to further analyze the effect of HoxA9 knockdown in MLL rearranged and non-rearranged primary human AML cells (6 MLL rearranged, 6 MLL germline). Similar to our findings in cell lines, we found a significantly higher effect on cell proliferation/viability in association with the presence of an MLL translocation (p=0.005) and a significant correlation with the baseline HoxA9 mRNA expression (R= 0.8, p=0.001). Next, we assessed the in vivo effect of HoxA9 knock down by transplanting luciferase-expressing SEMK2 (t4;11) cells and subsequent bioluminescent imaging. SEMK2 cells were transduced with either HoxA9 directed or control shRNA and intravenously injected into SCID-beige mice. Reconstitution was confirmed by in vivo bioluminescent imaging. 34 days after transplantation all mice in the HoxA9 shRNA group (n=4) are still alive with no signs of leukemia whereas all mice in the control group (n=3) have succumbed. Taken together our data implicates an important role for aberrant HoxA9 expression in human MLL rearranged leukemia cells.
Ronald W Stam - One of the best experts on this subject based on the ideXlab platform.
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Irinotecan Induces Disease Remission in Xenograft Mouse Models of Pediatric MLL-Rearranged Acute Lymphoblastic Leukemia
'MDPI AG', 2021Co-Authors: Mark Kerstjens, Priscilla Wander, Patricia Garrido Castro, Pauline Schneider, Rob Pieters, Sandra S Pinhancos, Ronald W StamAbstract:Acute lymphoblastic leukemia (ALL) in infants (MLL (or KMT2A) gene, which confer highly dismal prognoses on current combination chemotherapeutic regimens. Hence, more adequate therapeutic strategies are urgently needed. To expedite clinical transition of potentially effective therapeutics, we here applied a drug repurposing approach by performing in vitro drug screens of (mostly) clinically approved drugs on a variety of human ALL cell line models. Out of 3685 compounds tested, the alkaloid drug Camptothecin (CPT) and its derivatives 10-Hydroxycamtothecin (10-HCPT) and 7-Ethyl-10-hydroxycamtothecin (SN-38: the active metabolite of the drug Irinotecan) appeared most effective at very low nanomolar concentrations in all ALL cell lines, including models of MLL-rearranged ALL (n = 3). Although the observed in vitro anti-leukemic effects of Camptothecin and its derivatives certainly were not specific to MLL-rearranged ALL, we decided to further focus on this highly aggressive type of leukemia. Given that Irinotecan (the pro-drug of SN-38) has been increasingly used for the treatment of various pediatric solid tumors, we specifically chose this agent for further pre-clinical evaluation in pediatric MLL-rearranged ALL. Interestingly, shortly after engraftment, Irinotecan completely blocked leukemia expansion in mouse xenografts of a pediatric MLL-rearranged ALL cell line, as well as in two patient-derived xenograft (PDX) models of MLL-rearranged infant ALL. Also, from a more clinically relevant perspective, Irinotecan monotherapy was able to induce sustainable disease remissions in MLL-rearranged ALL xenotransplanted mice burdened with advanced leukemia. Taken together, our data demonstrate that Irinotecan exerts highly potent anti-leukemia effects against pediatric MLL-rearranged ALL, and likely against other, more favorable subtypes of childhood ALL as well
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src kinase induced phosphorylation of annexin a2 mediates glucocorticoid resistance in mll rearranged infant acute lymphoblastic leukemia
Leukemia, 2013Co-Authors: J A P Spijkershagelstein, Pauline Schneider, Mimoso S Pinhancos, Rob Pieters, Ronald W StamAbstract:MLL-rearranged infant acute lymphoblastic leukemia (ALL) (<1 year of age) are frequently resistant to glucocorticoids, like prednisone and dexamethasone. As poor glucocorticoid responses are strongly associated with therapy failure, overcoming glucocorticoid resistance may be a crucial step towards improving prognosis. Unfortunately, the mechanisms underlying glucocorticoid resistance in MLL-rearranged ALL largely remain obscure. We here defined a gene signature that accurately discriminates between prednisolone-resistant and prednisolone-sensitive MLL-rearranged infant ALL patient samples, demonstrating that, among other genes, high-level ANXA2 is associated with prednisolone resistance in this type of leukemia. Further investigation demonstrated that the underlying factor of this association was the presence of Src kinase-induced phosphorylation (activation) of annexin A2, a process requiring the adapter protein p11 (encoded by human S100A10). shRNA-mediated knockdown of either ANXA2, FYN, LCK or S100A10, all led to inhibition of annexin A2 phosphorylation and resulted in marked sensitization to prednisolone. Likewise, exposure of prednisolone-resistant MLL-rearranged ALL cells to different Src kinase inhibitors exerting high specificity towards FYN and/or LCK had similar effects. In conclusion, we here present a novel mechanism of prednisolone resistance in MLL-rearranged leukemias, and propose that inhibition of annexin A2 phosphorylation embodies a therapeutic strategy for overcoming resistance to glucocorticoids in this highly aggressive type of leukemia.
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mll rearranged all cells are highly dependent on the expression of ep300 interacting inhibitor of differentiation 1 eid1
Blood, 2012Co-Authors: Marieke H Van Der Linden, Pauline Schneider, Rob Pieters, Ronald W StamAbstract:Abstract 1462 MLL -rearranged acute lymphoblastic leukemia (ALL) remains a difficult to treat type of leukemia, for which alternative and more adequate treatment options are still urgently needed. Various genome-wide transcriptome studies, including ours, have shown that MLL -rearranged ALL patients display highly unique gene expression profiles. In search of new and valid therapeutic targets to which more adequate treatments could be developed, we constantly screen our gene expression profiling data for potential candidates. In the present study we set out to investigate EID1 (EP300-interacting inhibitor of differentiation 1), which we found highly and specifically expressed in MLL -rearranged ALL cells. Validating this observation, quantitative RT-PCR analysis confirmed that EID1 expression was significantly higher in MLL -rearranged ALL cells as compared with other ALL subtypes or healthy bone marrow samples. Next, we performed shRNA-mediated knockdown of EID1 in MLL -rearranged ALL cells, which resulted in a dramatic reduction of viable cells. Subsequently, flow cytometry analyses demonstrated that this rapid reduction of cell viability was due to massive induction of apoptosis as well as an abrupt cell cycle arrest. Consequently, it appeared difficult to study the actual function of EID1 over-expression in MLL -rearranged ALL cells. On the other hand, these features make EID1 an attractive target for therapeutic intervention in MLL -rearranged ALL. Hence, further studies on the function of EID1 in MLL -rearranged ALL and exploring the possibilities to inhibit it are warranted. Disclosures: No relevant conflicts of interest to declare.
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specific promoter methylation identifies different subgroups of mll rearranged infant acute lymphoblastic leukemia influences clinical outcome and provides therapeutic options
Blood, 2009Co-Authors: Dominique J P M Stumpel, Pauline Schneider, Rob Pieters, Eddy H J Van Roon, Judith M Boer, Paola De Lorenzo, Maria Grazia Valsecchi, Renee X De Menezes, Ronald W StamAbstract:MLL-rearranged infant acute lymphoblastic leukemia (ALL) remains the most aggressive type of childhood leukemia, displaying a unique gene expression profile. Here we hypothesized that this characteristic gene expression signature may have been established by potentially reversible epigenetic modifications. To test this hypothesis, we used differential methylation hybridization to explore the DNA methylation patterns underlying MLL-rearranged ALL in infants. The obtained results were correlated with gene expression data to confirm gene silencing as a result of promoter hypermethylation. Distinct promoter CpG island methylation patterns separated different genetic subtypes of MLL-rearranged ALL in infants. MLL translocations t(4;11) and t(11;19) characterized extensively hypermethylated leukemias, whereas t(9;11)-positive infant ALL and infant ALL carrying wild-type MLL genes epigenetically resembled normal bone marrow. Furthermore, the degree of promoter hypermethylation among infant ALL patients carrying t(4; 11) or t(11;19) appeared to influence relapse-free survival, with patients displaying accentuated methylation being at high relapse risk. Finally, we show that the demethylating agent zebularine reverses aberrant DNA methylation and effectively induces apoptosis in MLL-rearranged ALL cells. Collectively these data suggest that aberrant DNA methylation occurs in the majority of MLL-rearranged infant ALL cases and guides clinical outcome. Therefore, inhibition of aberrant DNA methylation may be an important novel therapeutic strategy for MLL-rearranged ALL in infants.
Pauline Schneider - One of the best experts on this subject based on the ideXlab platform.
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high throughput drug screening reveals pyrvinium pamoate as effective candidate against pediatric mll rearranged acute myeloid leukemia
Translational Oncology, 2021Co-Authors: Priscilla Wander, Susan T C J M Arentsenpeters, Sandra S Pinhanҫos, Bianca Koopmans, Emmy M M Dolman, Rijndert Ariese, Frank L Bos, Patricia Garrido Castro, Luke Jones, Pauline SchneiderAbstract:Abstract Pediatric MLL-rearranged acute myeloid leukemia (AML) has a generally unfavorable outcome, primarily due to relapse and drug resistance. To overcome these difficulties, new therapeutic agents are urgently needed. Yet, implementing novel drugs for clinical use is a time-consuming, laborious, costly and high-risk process. Therefore, we applied a drug-repositioning strategy by screening drug libraries, comprised of >4000 compounds that are mostly FDA-approved, in a high-throughput format on primary MLL-rearranged AML cells. Here we identified pyrvinium pamoate (pyrvinium) as a novel candidate drug effective against MLL-rearranged AML, eliminating all cell viability at
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Irinotecan Induces Disease Remission in Xenograft Mouse Models of Pediatric MLL-Rearranged Acute Lymphoblastic Leukemia
'MDPI AG', 2021Co-Authors: Mark Kerstjens, Priscilla Wander, Patricia Garrido Castro, Pauline Schneider, Rob Pieters, Sandra S Pinhancos, Ronald W StamAbstract:Acute lymphoblastic leukemia (ALL) in infants (MLL (or KMT2A) gene, which confer highly dismal prognoses on current combination chemotherapeutic regimens. Hence, more adequate therapeutic strategies are urgently needed. To expedite clinical transition of potentially effective therapeutics, we here applied a drug repurposing approach by performing in vitro drug screens of (mostly) clinically approved drugs on a variety of human ALL cell line models. Out of 3685 compounds tested, the alkaloid drug Camptothecin (CPT) and its derivatives 10-Hydroxycamtothecin (10-HCPT) and 7-Ethyl-10-hydroxycamtothecin (SN-38: the active metabolite of the drug Irinotecan) appeared most effective at very low nanomolar concentrations in all ALL cell lines, including models of MLL-rearranged ALL (n = 3). Although the observed in vitro anti-leukemic effects of Camptothecin and its derivatives certainly were not specific to MLL-rearranged ALL, we decided to further focus on this highly aggressive type of leukemia. Given that Irinotecan (the pro-drug of SN-38) has been increasingly used for the treatment of various pediatric solid tumors, we specifically chose this agent for further pre-clinical evaluation in pediatric MLL-rearranged ALL. Interestingly, shortly after engraftment, Irinotecan completely blocked leukemia expansion in mouse xenografts of a pediatric MLL-rearranged ALL cell line, as well as in two patient-derived xenograft (PDX) models of MLL-rearranged infant ALL. Also, from a more clinically relevant perspective, Irinotecan monotherapy was able to induce sustainable disease remissions in MLL-rearranged ALL xenotransplanted mice burdened with advanced leukemia. Taken together, our data demonstrate that Irinotecan exerts highly potent anti-leukemia effects against pediatric MLL-rearranged ALL, and likely against other, more favorable subtypes of childhood ALL as well
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src kinase induced phosphorylation of annexin a2 mediates glucocorticoid resistance in mll rearranged infant acute lymphoblastic leukemia
Leukemia, 2013Co-Authors: J A P Spijkershagelstein, Pauline Schneider, Mimoso S Pinhancos, Rob Pieters, Ronald W StamAbstract:MLL-rearranged infant acute lymphoblastic leukemia (ALL) (<1 year of age) are frequently resistant to glucocorticoids, like prednisone and dexamethasone. As poor glucocorticoid responses are strongly associated with therapy failure, overcoming glucocorticoid resistance may be a crucial step towards improving prognosis. Unfortunately, the mechanisms underlying glucocorticoid resistance in MLL-rearranged ALL largely remain obscure. We here defined a gene signature that accurately discriminates between prednisolone-resistant and prednisolone-sensitive MLL-rearranged infant ALL patient samples, demonstrating that, among other genes, high-level ANXA2 is associated with prednisolone resistance in this type of leukemia. Further investigation demonstrated that the underlying factor of this association was the presence of Src kinase-induced phosphorylation (activation) of annexin A2, a process requiring the adapter protein p11 (encoded by human S100A10). shRNA-mediated knockdown of either ANXA2, FYN, LCK or S100A10, all led to inhibition of annexin A2 phosphorylation and resulted in marked sensitization to prednisolone. Likewise, exposure of prednisolone-resistant MLL-rearranged ALL cells to different Src kinase inhibitors exerting high specificity towards FYN and/or LCK had similar effects. In conclusion, we here present a novel mechanism of prednisolone resistance in MLL-rearranged leukemias, and propose that inhibition of annexin A2 phosphorylation embodies a therapeutic strategy for overcoming resistance to glucocorticoids in this highly aggressive type of leukemia.
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mll rearranged all cells are highly dependent on the expression of ep300 interacting inhibitor of differentiation 1 eid1
Blood, 2012Co-Authors: Marieke H Van Der Linden, Pauline Schneider, Rob Pieters, Ronald W StamAbstract:Abstract 1462 MLL -rearranged acute lymphoblastic leukemia (ALL) remains a difficult to treat type of leukemia, for which alternative and more adequate treatment options are still urgently needed. Various genome-wide transcriptome studies, including ours, have shown that MLL -rearranged ALL patients display highly unique gene expression profiles. In search of new and valid therapeutic targets to which more adequate treatments could be developed, we constantly screen our gene expression profiling data for potential candidates. In the present study we set out to investigate EID1 (EP300-interacting inhibitor of differentiation 1), which we found highly and specifically expressed in MLL -rearranged ALL cells. Validating this observation, quantitative RT-PCR analysis confirmed that EID1 expression was significantly higher in MLL -rearranged ALL cells as compared with other ALL subtypes or healthy bone marrow samples. Next, we performed shRNA-mediated knockdown of EID1 in MLL -rearranged ALL cells, which resulted in a dramatic reduction of viable cells. Subsequently, flow cytometry analyses demonstrated that this rapid reduction of cell viability was due to massive induction of apoptosis as well as an abrupt cell cycle arrest. Consequently, it appeared difficult to study the actual function of EID1 over-expression in MLL -rearranged ALL cells. On the other hand, these features make EID1 an attractive target for therapeutic intervention in MLL -rearranged ALL. Hence, further studies on the function of EID1 in MLL -rearranged ALL and exploring the possibilities to inhibit it are warranted. Disclosures: No relevant conflicts of interest to declare.
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specific promoter methylation identifies different subgroups of mll rearranged infant acute lymphoblastic leukemia influences clinical outcome and provides therapeutic options
Blood, 2009Co-Authors: Dominique J P M Stumpel, Pauline Schneider, Rob Pieters, Eddy H J Van Roon, Judith M Boer, Paola De Lorenzo, Maria Grazia Valsecchi, Renee X De Menezes, Ronald W StamAbstract:MLL-rearranged infant acute lymphoblastic leukemia (ALL) remains the most aggressive type of childhood leukemia, displaying a unique gene expression profile. Here we hypothesized that this characteristic gene expression signature may have been established by potentially reversible epigenetic modifications. To test this hypothesis, we used differential methylation hybridization to explore the DNA methylation patterns underlying MLL-rearranged ALL in infants. The obtained results were correlated with gene expression data to confirm gene silencing as a result of promoter hypermethylation. Distinct promoter CpG island methylation patterns separated different genetic subtypes of MLL-rearranged ALL in infants. MLL translocations t(4;11) and t(11;19) characterized extensively hypermethylated leukemias, whereas t(9;11)-positive infant ALL and infant ALL carrying wild-type MLL genes epigenetically resembled normal bone marrow. Furthermore, the degree of promoter hypermethylation among infant ALL patients carrying t(4; 11) or t(11;19) appeared to influence relapse-free survival, with patients displaying accentuated methylation being at high relapse risk. Finally, we show that the demethylating agent zebularine reverses aberrant DNA methylation and effectively induces apoptosis in MLL-rearranged ALL cells. Collectively these data suggest that aberrant DNA methylation occurs in the majority of MLL-rearranged infant ALL cases and guides clinical outcome. Therefore, inhibition of aberrant DNA methylation may be an important novel therapeutic strategy for MLL-rearranged ALL in infants.
Rob Pieters - One of the best experts on this subject based on the ideXlab platform.
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Irinotecan Induces Disease Remission in Xenograft Mouse Models of Pediatric MLL-Rearranged Acute Lymphoblastic Leukemia
'MDPI AG', 2021Co-Authors: Mark Kerstjens, Priscilla Wander, Patricia Garrido Castro, Pauline Schneider, Rob Pieters, Sandra S Pinhancos, Ronald W StamAbstract:Acute lymphoblastic leukemia (ALL) in infants (MLL (or KMT2A) gene, which confer highly dismal prognoses on current combination chemotherapeutic regimens. Hence, more adequate therapeutic strategies are urgently needed. To expedite clinical transition of potentially effective therapeutics, we here applied a drug repurposing approach by performing in vitro drug screens of (mostly) clinically approved drugs on a variety of human ALL cell line models. Out of 3685 compounds tested, the alkaloid drug Camptothecin (CPT) and its derivatives 10-Hydroxycamtothecin (10-HCPT) and 7-Ethyl-10-hydroxycamtothecin (SN-38: the active metabolite of the drug Irinotecan) appeared most effective at very low nanomolar concentrations in all ALL cell lines, including models of MLL-rearranged ALL (n = 3). Although the observed in vitro anti-leukemic effects of Camptothecin and its derivatives certainly were not specific to MLL-rearranged ALL, we decided to further focus on this highly aggressive type of leukemia. Given that Irinotecan (the pro-drug of SN-38) has been increasingly used for the treatment of various pediatric solid tumors, we specifically chose this agent for further pre-clinical evaluation in pediatric MLL-rearranged ALL. Interestingly, shortly after engraftment, Irinotecan completely blocked leukemia expansion in mouse xenografts of a pediatric MLL-rearranged ALL cell line, as well as in two patient-derived xenograft (PDX) models of MLL-rearranged infant ALL. Also, from a more clinically relevant perspective, Irinotecan monotherapy was able to induce sustainable disease remissions in MLL-rearranged ALL xenotransplanted mice burdened with advanced leukemia. Taken together, our data demonstrate that Irinotecan exerts highly potent anti-leukemia effects against pediatric MLL-rearranged ALL, and likely against other, more favorable subtypes of childhood ALL as well
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the hdac inhibitor panobinostat lbh589 exerts in vivo anti leukaemic activity against mll rearranged acute lymphoblastic leukaemia and involves the rnf20 rnf40 wac h2b ubiquitination axis
Leukemia, 2018Co-Authors: Garrido P Castro, E H J Van Roon, Sandra S Pinhancos, Livio Trentin, P Schneider, Mark Kerstjens, Te G Kronnie, Olaf Heidenreich, Rob PietersAbstract:MLL-rearranged acute lymphoblastic leukaemia (ALL) represents an aggressive malignancy in infants (<1 year of age), associated with poor outcome. Current treatment intensification is not further possible, and novel therapy strategies are needed. Notably, MLL-rearranged ALL is characterised by a strongly deregulated epigenome and shows sensitivity to epigenetic perturbators. Here we demonstrate the in vivo efficacy of the histone deacetylase inhibitor panobinostat (LBH589) using xenograft mouse models of MLL-rearranged ALL. Panobinostat monotherapy showed strong anti-leukaemic effects, extending survival and reducing overall disease burden. Comprehensive molecular analyses in vitro showed that this anti-leukaemic activity involves depletion of H2B ubiquitination via suppression of the RNF20/RNF40/WAC E3 ligase complex; a pivotal pathway for MLL-rearranged leukaemic maintenance. Knockdown of WAC phenocopied loss of H2B ubiquitination and concomitant cell death induction. These combined data demonstrate that panobinostat cross-inhibits multiple epigenetic pathways, ultimately contributing to its highly efficacious targeting of MLL-rearranged ALL.
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src kinase induced phosphorylation of annexin a2 mediates glucocorticoid resistance in mll rearranged infant acute lymphoblastic leukemia
Leukemia, 2013Co-Authors: J A P Spijkershagelstein, Pauline Schneider, Mimoso S Pinhancos, Rob Pieters, Ronald W StamAbstract:MLL-rearranged infant acute lymphoblastic leukemia (ALL) (<1 year of age) are frequently resistant to glucocorticoids, like prednisone and dexamethasone. As poor glucocorticoid responses are strongly associated with therapy failure, overcoming glucocorticoid resistance may be a crucial step towards improving prognosis. Unfortunately, the mechanisms underlying glucocorticoid resistance in MLL-rearranged ALL largely remain obscure. We here defined a gene signature that accurately discriminates between prednisolone-resistant and prednisolone-sensitive MLL-rearranged infant ALL patient samples, demonstrating that, among other genes, high-level ANXA2 is associated with prednisolone resistance in this type of leukemia. Further investigation demonstrated that the underlying factor of this association was the presence of Src kinase-induced phosphorylation (activation) of annexin A2, a process requiring the adapter protein p11 (encoded by human S100A10). shRNA-mediated knockdown of either ANXA2, FYN, LCK or S100A10, all led to inhibition of annexin A2 phosphorylation and resulted in marked sensitization to prednisolone. Likewise, exposure of prednisolone-resistant MLL-rearranged ALL cells to different Src kinase inhibitors exerting high specificity towards FYN and/or LCK had similar effects. In conclusion, we here present a novel mechanism of prednisolone resistance in MLL-rearranged leukemias, and propose that inhibition of annexin A2 phosphorylation embodies a therapeutic strategy for overcoming resistance to glucocorticoids in this highly aggressive type of leukemia.
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mll rearranged all cells are highly dependent on the expression of ep300 interacting inhibitor of differentiation 1 eid1
Blood, 2012Co-Authors: Marieke H Van Der Linden, Pauline Schneider, Rob Pieters, Ronald W StamAbstract:Abstract 1462 MLL -rearranged acute lymphoblastic leukemia (ALL) remains a difficult to treat type of leukemia, for which alternative and more adequate treatment options are still urgently needed. Various genome-wide transcriptome studies, including ours, have shown that MLL -rearranged ALL patients display highly unique gene expression profiles. In search of new and valid therapeutic targets to which more adequate treatments could be developed, we constantly screen our gene expression profiling data for potential candidates. In the present study we set out to investigate EID1 (EP300-interacting inhibitor of differentiation 1), which we found highly and specifically expressed in MLL -rearranged ALL cells. Validating this observation, quantitative RT-PCR analysis confirmed that EID1 expression was significantly higher in MLL -rearranged ALL cells as compared with other ALL subtypes or healthy bone marrow samples. Next, we performed shRNA-mediated knockdown of EID1 in MLL -rearranged ALL cells, which resulted in a dramatic reduction of viable cells. Subsequently, flow cytometry analyses demonstrated that this rapid reduction of cell viability was due to massive induction of apoptosis as well as an abrupt cell cycle arrest. Consequently, it appeared difficult to study the actual function of EID1 over-expression in MLL -rearranged ALL cells. On the other hand, these features make EID1 an attractive target for therapeutic intervention in MLL -rearranged ALL. Hence, further studies on the function of EID1 in MLL -rearranged ALL and exploring the possibilities to inhibit it are warranted. Disclosures: No relevant conflicts of interest to declare.
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specific promoter methylation identifies different subgroups of mll rearranged infant acute lymphoblastic leukemia influences clinical outcome and provides therapeutic options
Blood, 2009Co-Authors: Dominique J P M Stumpel, Pauline Schneider, Rob Pieters, Eddy H J Van Roon, Judith M Boer, Paola De Lorenzo, Maria Grazia Valsecchi, Renee X De Menezes, Ronald W StamAbstract:MLL-rearranged infant acute lymphoblastic leukemia (ALL) remains the most aggressive type of childhood leukemia, displaying a unique gene expression profile. Here we hypothesized that this characteristic gene expression signature may have been established by potentially reversible epigenetic modifications. To test this hypothesis, we used differential methylation hybridization to explore the DNA methylation patterns underlying MLL-rearranged ALL in infants. The obtained results were correlated with gene expression data to confirm gene silencing as a result of promoter hypermethylation. Distinct promoter CpG island methylation patterns separated different genetic subtypes of MLL-rearranged ALL in infants. MLL translocations t(4;11) and t(11;19) characterized extensively hypermethylated leukemias, whereas t(9;11)-positive infant ALL and infant ALL carrying wild-type MLL genes epigenetically resembled normal bone marrow. Furthermore, the degree of promoter hypermethylation among infant ALL patients carrying t(4; 11) or t(11;19) appeared to influence relapse-free survival, with patients displaying accentuated methylation being at high relapse risk. Finally, we show that the demethylating agent zebularine reverses aberrant DNA methylation and effectively induces apoptosis in MLL-rearranged ALL cells. Collectively these data suggest that aberrant DNA methylation occurs in the majority of MLL-rearranged infant ALL cases and guides clinical outcome. Therefore, inhibition of aberrant DNA methylation may be an important novel therapeutic strategy for MLL-rearranged ALL in infants.
Schatz, Michael C. - One of the best experts on this subject based on the ideXlab platform.
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recovering rearranged cancer chromosomes from karyotype graphs
BMC Bioinformatics, 2019Co-Authors: Aganezov Sergey, Zban Ilya, Aksenov Vitalii, Alexeev Nikita, Schatz, Michael C.Abstract:Background: Many cancer genomes are extensively rearranged with highly aberrant chromosomal karyotypes. Structural and copy number variations in cancer genomes can be determined via abnormal mapping of sequenced reads to the reference genome. Recently it became possible to reconcile both of these types of large-scale variations into a karyotype graph representation of the rearranged cancer genomes. Such a representation, however, does not directly describe the linear and/or circular structure of the underlying rearranged cancer chromosomes, thus limiting possible analysis of cancer genomes somatic evolutionary process as well as functional genomic changes brought by the large-scale genome rearrangements. Results: Here we address the aforementioned limitation by introducing a novel methodological framework for recovering rearranged cancer chromosomes from karyotype graphs. For a cancer karyotype graph we formulate an Eulerian Decomposition Problem (EDP) of finding a collection of linear and/or circular rearranged cancer chromosomes that are determined by the graph. We derive and prove computational complexities for several variations of the EDP. We then demonstrate that Eulerian decomposition of the cancer karyotype graphs is not always unique and present the Consistent Contig Covering Problem (CCCP) of recovering unambiguous cancer contigs from the cancer karyotype graph, and describe a novel algorithm CCR capable of solving CCCP in polynomial time. We apply CCR on a prostate cancer dataset and demonstrate that it is capable of consistently recovering large cancer contigs even when underlying cancer genomes are highly rearranged. Conclusions: CCR can recover rearranged cancer contigs from karyotype graphs thereby addressing existing limitation in inferring chromosomal structures of rearranged cancer genomes and advancing our understanding of both patient/cancer-specific as well as the overall genetic instability in cancer.
