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Robert S. Welner,
Deepak Bararia,
Giovanni Amabile,
Akos Czibere,
Touati Benoukraf,
Christopher Bach,
K. Disnika Senali Abayratna Wansa,
Min Ye,
Hong Zhang,
Tadafumi Iino,
Christopher J. Hetherington,
Koichi Akashi, Daniel G. Tenen
[show abstract]
[hide abstract]
ABSTRACT: Dendritic cells (DCs) are master regulators of the immune system, but molecular regulation of early DC differentiation has been poorly understood. Here, we report the transcription factor C/EBPα coordinates the development of progenitor cells required for production of multiple categories of DCs. C/EBPα was needed for differentiation from stem/progenitor cells to common DC progenitors (CDP), but not for transition of CDP to mature DCs. C/EBPα deletion in mature DC did not impact their numbers or function suggesting this transcription factor is not needed for maintenance of DC in lymphoid tissues. ChIP-seq and microarrays were used to identify candidate genes regulated by C/EBPα and required for DC formation. Genes previously shown to be critical for DC formation were bound by C/EBPα, and their expression was decreased in the earliest hematopoietic compartments in the absence of C/EBPα. These data indicate that C/EBPα is important for the earliest stages of steady-state DC differentiation.
Blood 04/2013; · 9.90 Impact Factor
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Robert S Welner,
Deepak Bararia,
Giovanni Amabile,
Akos Czibere,
Touati Benoukraf,
Christopher Bach,
K Disnika Senali Abayratna Wansa,
Min Ye,
Hong Zhang,
Tadafumi Iino,
Christopher J Hetherington,
Koichi Akashi, Daniel G Tenen
[show abstract]
[hide abstract]
ABSTRACT: Key points C/EBPα is needed for transition from stem/progenitor cells to common DC progenitorsC/EBPα is dispensable in later stages of dendritic cell maturation.
Blood 04/2013; · 9.90 Impact Factor
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Min Ye,
Hong Zhang,
Giovanni Amabile,
Henry Yang,
Philipp B Staber,
Pu Zhang,
Elena Levantini,
Meritxell Alberich-Jordà,
Junyan Zhang,
Akira Kawasaki, Daniel G Tenen
[show abstract]
[hide abstract]
ABSTRACT: In blood, the transcription factor C/EBPa is essential for myeloid differentiation and has been implicated in regulating self-renewal of fetal liver haematopoietic stem cells (HSCs). However, its function in adult HSCs has remained unknown. Here, using an inducible knockout model we found that C/EBPa-deficient adult HSCs underwent a pronounced increase in number with enhanced proliferation, characteristics resembling fetal liver HSCs. Consistently, transcription profiling of C/EBPa-deficient HSCs revealed a gene expression program similar to fetal liver HSCs. Moreover, we observed that age-specific Cebpa expression correlated with its inhibitory effect on the HSC cell cycle. Mechanistically we identified N-Myc as a downstream target of C/EBPa, and loss of C/EBPa resulted in de-repression of N-Myc. Our data establish C/EBPa as a central determinant in the switch from fetal to adult HSCs.
Nature Cell Biology 03/2013; · 19.49 Impact Factor
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Philipp B Staber,
Pu Zhang,
Min Ye,
Robert S Welner,
César Nombela-Arrieta,
Christian Bach,
Marc Kerenyi,
Boris A Bartholdy,
Hong Zhang,
Meritxell Alberich-Jordà, [......],
Felicia Ng,
Junyan Zhang,
Mathias Leddin,
Leslie E Silberstein,
Gerald Hoefler,
Stuart H Orkin,
Berthold Göttgens,
Frank Rosenbauer,
Gang Huang, Daniel G Tenen
[show abstract]
[hide abstract]
ABSTRACT: To provide a lifelong supply of blood cells, hematopoietic stem cells (HSCs) need to carefully balance both self-renewing cell divisions and quiescence. Although several regulators that control this mechanism have been identified, we demonstrate that the transcription factor PU.1 acts upstream of these regulators. So far, attempts to uncover PU.1's role in HSC biology have failed because of the technical limitations of complete loss-of-function models. With the use of hypomorphic mice with decreased PU.1 levels specifically in phenotypic HSCs, we found reduced HSC long-term repopulation potential that could be rescued completely by restoring PU.1 levels. PU.1 prevented excessive HSC division and exhaustion by controlling the transcription of multiple cell-cycle regulators. Levels of PU.1 were sustained through autoregulatory PU.1 binding to an upstream enhancer that formed an active looped chromosome architecture in HSCs. These results establish that PU.1 mediates chromosome looping and functions as a master regulator of HSC proliferation.
Molecular cell 02/2013; · 14.61 Impact Factor
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Meritxell Alberich-Jordà,
Bas Wouters,
Martin Balastik,
Clara Shapiro-Koss,
Hong Zhang,
Annalisa Di Ruscio,
Hanna S Radomska,
Alexander K Ebralidze,
Giovanni Amabile,
Min Ye,
Junyan Zhang,
Irene Lowers,
Roberto Avellino,
Ari Melnick,
Maria E Figueroa,
Peter J M Valk,
Ruud Delwel, Daniel G Tenen
The Journal of clinical investigation 01/2013; 123(1):526. · 15.39 Impact Factor
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Hideyo Hirai,
Naoka Kamio,
Gang Huang,
Akiko Matsusue,
Shinpei Ogino,
Nobuhiko Kimura,
Sakiko Satake,
Eishi Ashihara,
Jiro Imanishi, Daniel G Tenen,
Taira Maekawa
[show abstract]
[hide abstract]
ABSTRACT: In contrast to the definitive role of the transcription factor, CCAAT/Enhancer binding protein α (C/EBPα), in steady-state granulopoiesis, previous findings have suggested that granulopoiesis during emergency situations, such as infection, is dependent on C/EBPβ. In this study, a novel lentivirus-based reporter system was developed to elucidate the molecular switch required for C/EBPβ-dependency. The results demonstrated that two cyclic AMP responsive elements (CREs) in the proximal promoter region of C/EBPβ were involved in the positive regulation of C/EBPβ transcription during granulocyte-macrophage colony-stimulating factor (GM-CSF)-induced differentiation of bone marrow cells. In addition, the transcripts of CRE binding (CREB) family proteins were readily detected in hematopoietic stem/progenitor cells. CREB was upregulated, phosphorylated and bound to the CREs in response to GM-CSF stimulation. Retroviral transduction of a dominant negative CREB mutant reduced C/EBPβ mRNA levels and significantly impaired the proliferation/differentiation of granulocyte precursors, while a constitutively active form of CREB facilitated C/EBPβ transcription. These data suggest that CREB proteins are involved in the regulation of granulopoiesis via C/EBPβ upregulation.
PLoS ONE 01/2013; 8(1):e54862. · 4.09 Impact Factor
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Giovanni Amabile,
Robert S Welner,
Cesar Nombela-Arrieta,
Anna Morena D'Alise,
Annalisa Di Ruscio,
Alexander K Ebralidze,
Yevgenya Kraytsberg,
Min Ye,
Olivier Kocher,
Donna S Neuberg,
Konstantin Khrapko,
Leslie E Silberstein, Daniel G Tenen
[show abstract]
[hide abstract]
ABSTRACT: Lineage-restricted cells can be reprogrammed to a pluripotent state known as Induced Pluripotent Stem cells (iPS) through overexpression of four transcription factors. iPS cells are similar to human Embryonic Stem (hES) cells and have the same ability to generate all the cells of the human body, including blood cells. However, this process is extremely inefficient and to date has been unsuccessful at differentiating iPS into hematopoietic stem cells (HSCs). We hypothesized that iPS cells, injected into NOD.Cg-Prkdc(scid) Il2rg(tm1Wjl)/SzJ immunocompromised (NSG) mice, could give rise to hematopoietic stem/progenitor cells (HSPCs) during teratoma formation. Here, we report a novel in vivo system in which human iPS cells differentiate within teratomas to derive functional myeloid and lymphoid cells. Similarly, HSPCs can be isolated from teratoma parenchyma and reconstitute a human immune system when transplanted into immunodeficient mice. Our data provide evidences that in vivo generation of patient customized cells is feasible, providing materials that could be useful for transplantation, human antibody generation and drug screening applications.
Blood 12/2012; · 9.90 Impact Factor
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Meritxell Alberich-Jordà,
Bas Wouters,
Martin Balastik,
Clara Shapiro-Koss,
Hong Zhang,
Annalisa Diruscio,
Hanna S Radomska,
Alexander K Ebralidze,
Giovanni Amabile,
Min Ye,
Junyan Zhang,
Irene Lowers,
Roberto Avellino,
Ari Melnick,
Maria E Figueroa,
Peter J M Valk,
Ruud Delwel, Daniel G Tenen
[show abstract]
[hide abstract]
ABSTRACT: C/EBPs are a family of transcription factors that regulate growth control and differentiation of various tissues. We found that C/EBPγ is highly upregulated in a subset of acute myeloid leukemia (AML) samples characterized by C/EBPα hypermethylation/silencing. Similarly, C/EBPγ was upregulated in murine hematopoietic stem/progenitor cells lacking C/EBPα, as C/EBPα mediates C/EBPγ suppression. Studies in myeloid cells demonstrated that CEBPG overexpression blocked neutrophilic differentiation. Further, downregulation of Cebpg in murine Cebpa-deficient stem/progenitor cells or in human CEBPA-silenced AML samples restored granulocytic differentiation. In addition, treatment of these leukemias with demethylating agents restored the C/EBPα-C/EBPγ balance and upregulated the expression of myeloid differentiation markers. Our results indicate that C/EBPγ mediates the myeloid differentiation arrest induced by C/EBPα deficiency and that targeting the C/EBPα-C/EBPγ axis rescues neutrophilic differentiation in this unique subset of AMLs.
The Journal of clinical investigation 11/2012; · 15.39 Impact Factor
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Monika Lichtinger,
Richard Ingram,
Rebecca Hannah,
Dorothee Müller,
Deborah Clarke,
Salam A Assi,
Michael Lie-A-Ling,
Laura Noailles,
M S Vijayabaskar,
Mengchu Wu, Daniel G Tenen,
David R Westhead,
Valerie Kouskoff,
Georges Lacaud,
Berthold Göttgens,
Constanze Bonifer
[show abstract]
[hide abstract]
ABSTRACT: Cell fate decisions during haematopoiesis are governed by lineage-specific transcription factors, such as RUNX1, SCL/TAL1, FLI1 and C/EBP family members. To gain insight into how these transcription factors regulate the activation of haematopoietic genes during embryonic development, we measured the genome-wide dynamics of transcription factor assembly on their target genes during the RUNX1-dependent transition from haemogenic endothelium (HE) to haematopoietic progenitors. Using a Runx1-/- embryonic stem cell differentiation model expressing an inducible Runx1 gene, we show that in the absence of RUNX1, haematopoietic genes bind SCL/TAL1, FLI1 and C/EBPβ and that this early priming is required for correct temporal expression of the myeloid master regulator PU.1 and its downstream targets. After induction, RUNX1 binds to numerous de novo sites, initiating a local increase in histone acetylation and rapid global alterations in the binding patterns of SCL/TAL1 and FLI1. The acquisition of haematopoietic fate controlled by Runx1 therefore does not represent the establishment of a new regulatory layer on top of a pre-existing HE program but instead entails global reorganization of lineage-specific transcription factor assemblies.
The EMBO Journal 10/2012; · 9.20 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Mutations that activate the fms-like tyrosine kinase 3 (FLT3) receptor are among the most prevalent mutations in acute myeloid leukemias. The oncogenic role of FLT3 mutants has been attributed to the abnormal activation of several downstream signaling pathways, such as STAT3, STAT5, ERK1/2, and AKT. Here, we discovered that the cyclin-dependent kinase 1 (CDK1) pathway is also affected by internal tandem duplication mutations in FLT3. Moreover, we also identified C/EBPα, a granulopoiesis-promoting transcription factor, as a substrate for CDK1. We further demonstrated that CDK1 phosphorylates C/EBPα on serine 21, which inhibits its differentiation-inducing function. Importantly, we found that inhibition of CDK1 activity relieves the differentiation block in cell lines with mutated FLT3 as well as in primary patient-derived peripheral blood samples. Clinical trials with CDK1 inhibitors are currently under way for various malignancies. Our data strongly suggest that targeting the CDK1 pathway might be applied in the treatment of FLT3ITD mutant leukemias, especially those resistant to FLT3 inhibitor therapies.
The Journal of clinical investigation 07/2012; 122(8):2955-66. · 15.39 Impact Factor
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Yue Zhang,
Xiaomei Yan,
Goro Sashida,
Xinghui Zhao,
Yalan Rao,
Susumu Goyama,
Susan P Whitman,
Nicholas Zorko,
Kelsie Bernot,
Rajeana M Conway,
David Witte,
Qian-Fei Wang, Daniel G Tenen,
Zhijian Xiao,
Guido Marcucci,
James C Mulloy,
H Leighton Grimes,
Michael A Caligiuri,
Gang Huang
[show abstract]
[hide abstract]
ABSTRACT: One mechanism for disrupting the MLL gene in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) is through partial tandem duplication (MLL-PTD); however, the mechanism by which MLL-PTD contributes to MDS and AML development and maintenance is currently unknown. Herein, we investigated hematopoietic stem/progenitor cell (HSPC) phenotypes of Mll-PTD knock-in mice. Although HSPCs (Lin(-)Sca1(+)Kit(+) (LSK)/SLAM(+) and LSK) in Mll(PTD/WT) mice are reduced in absolute number in steady state because of increased apoptosis, they have a proliferative advantage in colony replating assays, CFU-spleen assays, and competitive transplantation assays over wild-type HSPCs. The Mll(PTD/WT)-derived phenotypic short-term (ST)-HSCs/multipotent progenitors and granulocyte/macrophage progenitors have self-renewal capability, rescuing hematopoiesis by giving rise to long-term repopulating cells in recipient mice with an unexpected myeloid differentiation blockade and lymphoid-lineage bias. However, Mll(PTD/WT) HSPCs never develop leukemia in primary or recipient mice, suggesting that additional genetic and/or epigenetic defects are necessary for full leukemogenic transformation. Thus, the Mll-PTD aberrantly alters HSPCs, enhances self-renewal, causes lineage bias, and blocks myeloid differentiation. These findings provide a framework by which we can ascertain the underlying pathogenic role of MLL-PTD in the clonal evolution of human leukemia, which should facilitate improved therapies and patient outcomes.
Blood 06/2012; 120(5):1118-29. · 9.90 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Differentiation of hematopoietic stem and progenitor cells is under strict control of a regulatory network orchestrated by
lineage-specific transcription factors. A block in normal differentiation is a major contributing factor in the development
of solid tumors and leukemias. Cells from patients with acute myeloid leukemia (AML) frequently harbor mutated or dysregulated
transcription factor genes, suggesting their involvement in leukemogenesis. As a consequence, these alterations diminish the
pool of available molecules of a small number of critical transcription factors, such as CCAAT enhancer binding proteins,
PU.1, GATA-1, and AML-1. In this review, we focus on the mechanisms of how this functional pool of transcription factors is
maintained during normal and malignant hematopoiesis, including direct protein-protein interactions, competition for DNA binding,
and the control of transcription factor genes by proximal and distal regulatory elements. Results of recent studies of mice
carrying hypomorphic PU.1 alleles have indicated that reduction in the expression of a single transcription factor is capable
of predisposing mice to AML. The implications of these findings for the study of hematopoiesis in the future as well as novel
approaches to more disease-specific therapies are discussed.
International Journal of Hematology 04/2012; 81(5):368-377. · 1.27 Impact Factor
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Gang Huang,
Xinghui Zhao,
Lan Wang,
Shannon Elf,
Hao Xu,
Xinyang Zhao,
Goro Sashida,
Yue Zhang,
Yan Liu,
Jennifer Lee,
Silvia Menendez,
Youyang Yang,
Xiaomei Yan,
Pu Zhang, Daniel G Tenen,
Motomi Osato,
James J-D Hsieh,
Stephen D Nimer
[show abstract]
[hide abstract]
ABSTRACT: The mixed-lineage leukemia (MLL) H3K4 methyltransferase protein, and the heterodimeric RUNX1/CBFβ transcription factor complex, are critical for definitive and adult hematopoiesis, and both are frequently targeted in human acute leukemia. We identified a physical and functional interaction between RUNX1 (AML1) and MLL and show that both are required to maintain the histone lysine 4 trimethyl mark (H3K4me3) at 2 critical regulatory regions of the AML1 target gene PU.1. Similar to CBFβ, we show that MLL binds to AML1 abrogating its proteasome-dependent degradation. Furthermore, a subset of previously uncharacterized frame-shift and missense mutations at the N terminus of AML1, found in MDS and AML patients, impairs its interaction with MLL, resulting in loss of the H3K4me3 mark within PU.1 regulatory regions, and decreased PU.1 expression. The interaction between MLL and AML1 provides a mechanism for the sequence-specific binding of MLL to DNA, and identifies RUNX1 target genes as potential effectors of MLL function.
Blood 12/2011; 118(25):6544-52. · 9.90 Impact Factor
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Elena Levantini,
Sanghoon Lee,
Hanna S Radomska,
Christopher J Hetherington,
Meritxell Alberich-Jorda,
Giovanni Amabile,
Pu Zhang,
David A Gonzalez,
Junyan Zhang,
Daniela S Basseres,
Nicola K Wilson,
Steffen Koschmieder,
Gang Huang,
Dong-Er Zhang,
Alexander K Ebralidze,
Constanze Bonifer,
Yutaka Okuno,
Bertie Gottgens, Daniel G Tenen
[show abstract]
[hide abstract]
ABSTRACT: The transcription factor RUNX1 is essential to establish the haematopoietic gene expression programme; however, the mechanism of how it activates transcription of haematopoietic stem cell (HSC) genes is still elusive. Here, we obtained novel insights into RUNX1 function by studying regulation of the human CD34 gene, which is expressed in HSCs. Using transgenic mice carrying human CD34 PAC constructs, we identified a novel downstream regulatory element (DRE), which is bound by RUNX1 and is necessary for human CD34 expression in long-term (LT)-HSCs. Conditional deletion of Runx1 in mice harbouring human CD34 promoter-DRE constructs abrogates human CD34 expression. We demonstrate by chromosome conformation capture assays in LT-HSCs that the DRE physically interacts with the human CD34 promoter. Targeted mutagenesis of RUNX binding sites leads to perturbation of this interaction and decreased human CD34 expression in LT-HSCs. Overall, our in vivo data provide novel evidence about the role of RUNX1 in mediating interactions between distal and proximal elements of the HSC gene CD34.
The EMBO Journal 08/2011; 30(19):4059-70. · 9.20 Impact Factor
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Mathias Leddin,
Chiara Perrod,
Maarten Hoogenkamp,
Saeed Ghani,
Salam Assi,
Sven Heinz,
Nicola K Wilson,
George Follows,
Jörg Schönheit,
Lena Vockentanz,
Ali M Mosammam,
Wei Chen, Daniel G Tenen,
David R Westhead,
Berthold Göttgens,
Constanze Bonifer,
Frank Rosenbauer
[show abstract]
[hide abstract]
ABSTRACT: The transcription factor PU.1 occupies a central role in controlling myeloid and early B-cell development, and its correct lineage-specific expression is critical for the differentiation choice of hematopoietic progenitors. However, little is known of how this tissue-specific pattern is established. We previously identified an upstream regulatory cis element whose targeted deletion in mice decreases PU.1 expression and causes leukemia. We show here that the upstream regulatory cis element alone is insufficient to confer physiologic PU.1 expression in mice but requires the cooperation with other, previously unidentified elements. Using a combination of transgenic studies, global chromatin assays, and detailed molecular analyses we present evidence that PU.1 is regulated by a novel mechanism involving cross talk between different cis elements together with lineage-restricted autoregulation. In this model, PU.1 regulates its expression in B cells and macrophages by differentially associating with cell type-specific transcription factors at one of its cis-regulatory elements to establish differential activity patterns at other elements.
Blood 01/2011; 117(10):2827-38. · 9.90 Impact Factor
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Shuxian Jiang,
Meritxell Alberich-Jorda,
Radoslaw Zagozdzon,
Kalindi Parmar,
Yigong Fu,
Peter Mauch,
Naheed Banu,
Alexandros Makriyannis, Daniel G Tenen,
Shalom Avraham,
Jerome E Groopman,
Hava Karsenty Avraham
[show abstract]
[hide abstract]
ABSTRACT: Endocannabinoids are arachidonic acid derivatives and part of a novel bioactive lipid signaling system, along with their G-coupled cannabinoid receptors (CB₁ and CB₂) and the enzymes involved in their biosynthesis and degradation. However, their roles in hematopoiesis and hematopoietic stem and progenitor cell (HSPC) functions are not well characterized. Here, we show that bone marrow stromal cells express endocannabinoids (anandamide and 2-arachidonylglycerol), whereas CB₂ receptors are expressed in human and murine HSPCs. On ligand stimulation with CB₂ agonists, CB₂ receptors induced chemotaxis, migration, and enhanced colony formation of bone marrow cells, which were mediated via ERK, PI3-kinase, and Gαi-Rac1 pathways. In vivo, the CB₂ agonist AM1241 induced mobilization of murine HSPCs with short- and long-term repopulating abilities. In addition, granulocyte colony-stimulating factor -induced mobilization of HSPCs was significantly decreased by specific CB₂ antagonists and was impaired in Cnr2(-/-) cannabinoid type 2 receptor knockout mice. Taken together, these results demonstrate that the endocannabinoid system is involved in hematopoiesis and that CB₂/CB₂ agonist axis mediates repopulation of hematopoiesis and mobilization of HSPCs. Thus, CB₂ agonists may be therapeutically applied in clinical conditions, such as bone marrow transplantation.
Blood 11/2010; 117(3):827-38. · 9.90 Impact Factor
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John A Pulikkan,
Philomina S Peramangalam,
Viola Dengler,
Phoenix A Ho,
Claude Preudhomme,
Soheil Meshinchi,
Maximilian Christopeit,
Oliver Nibourel,
Carsten Müller-Tidow,
Stefan K Bohlander, Daniel G Tenen,
Gerhard Behre
[show abstract]
[hide abstract]
ABSTRACT: The transcription factor, CCAAT enhancer binding protein alpha (C/EBPα), is crucial for granulopoiesis and is deregulated by various mechanisms in acute myeloid leukemia (AML). Mutations in the CEBPA gene are reported in 10% of human patients with AML. Even though the C/EBPα mutants are known to display distinct biologic function during leukemogenesis, the molecular basis for this subtype of AML remains elusive. We have recently showed the significance of deregulation of C/EBPα-regulated microRNA (miR) in AML. In this study, we report that miR-34a is a novel target of C/EBPα in granulopoiesis. During granulopoiesis, miR-34a targets E2F3 and blocks myeloid cell proliferation. Analysis of AML samples with CEBPA mutations revealed a lower expression of miR-34a and elevated levels of E2F3 as well as E2F1, a transcriptional target of E2F3. Manipulation of miR-34a reprograms granulocytic differentiation of AML blast cells with CEBPA mutations. These results define miR-34a as a novel therapeutic target in AML with CEBPA mutations.
Blood 10/2010; 116(25):5638-49. · 9.90 Impact Factor
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Wee-Lee Yeo,
Gregory J Riely,
Beow Y Yeap,
Michelle W Lau,
Jeremy L Warner,
Kelly Bodio,
Mark S Huberman,
Mark G Kris, Daniel G Tenen,
William Pao,
Susumu Kobayashi,
Daniel B Costa
[show abstract]
[hide abstract]
ABSTRACT: The tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib are effective in non-small cell lung cancers (NSCLCs) with epidermal growth factor receptor (EGFR) gene mutations. The usual clinical dose of gefitinib (250 mg/d) is only one third of its maximum tolerated dose, whereas the dose of erlotinib (150 mg/d) is at its maximum tolerated dose. In NSCLC cell lines, both TKIs have similar micromolar inhibitory concentrations. We explored whether erlotinib at 25 mg/d (trough serum concentration similar to gefitinib 250 mg/d) would be efficacious in EGFR-mutated NSCLC.
To study the inhibitory concentrations of gefitinib and erlotinib, we exposed EGFR-mutated cell lines (HCC827, H3255, PC-9, and H1975) to increasing concentrations of these TKIs. Further on, we performed a retrospective evaluation of seven patients with advanced EGFR-mutated (exon 19 deletions and L858R) NSCLC that were given erlotinib at 25 mg/d as their first EGFR TKI.
Gefitinib and erlotinib generated similar inhibitory curves across our panel of EGFR-mutated NSCLC cell lines with overlapping mean 50% inhibitory concentration 95% confidence intervals for HCC827, PC-9, and H1975. Both drugs also displayed a high degree of correlation in mean 50% inhibitory concentration (Pearson's r = 0.99, p = 0.0417). Of the seven patients, five patients (71.5%) had partial responses to erlotinib 25 mg/d. Median progression-free survival was 17 months (95% confidence interval, 6-35 months). Toxicities were minimal, with only two (28.5%) patients having a rash and none experiencing (0%) diarrhea.
In NSCLC cell lines, gefitinib and erlotinib have similar inhibitory profiles. In patients with NSCLC and EGFR-activating mutations, a dose of erlotinib 25 mg/d (equivalent to gefitinib 250 mg/d) leads to impressive response rates and progression-free survival similar to the growing experience with the approved doses of gefitinib (250 mg/d) and erlotinib (150 mg/d). Identifying prospectively the lowest and clinically active dose ranges of erlotinib and gefitinib will help further to personalize care for patients with tumors harboring EGFR mutations.
Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 07/2010; 5(7):1048-53. · 4.55 Impact Factor
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Karen B O'Brien,
Meritxell Alberich-Jordà,
Neelu Yadav,
Olivier Kocher,
Annalisa Diruscio,
Alexander Ebralidze,
Elena Levantini,
Natasha J L Sng,
Manoj Bhasin,
Tyler Caron,
Daehoon Kim,
Ulrich Steidl,
Gang Huang,
Balázs Halmos,
Scott J Rodig,
Mark T Bedford, Daniel G Tenen,
Susumu Kobayashi
[show abstract]
[hide abstract]
ABSTRACT: Coactivator-associated arginine methyltransferase I (CARM1; PRMT4) regulates gene expression by multiple mechanisms including methylation of histones and coactivation of steroid receptor transcription. Mice lacking CARM1 are small, fail to breathe and die shortly after birth, demonstrating the crucial role of CARM1 in development. In adults, CARM1 is overexpressed in human grade-III breast tumors and prostate adenocarcinomas, and knockdown of CARM1 inhibits proliferation of breast and prostate cancer cell lines. Based on these observations, we hypothesized that loss of CARM1 in mouse embryos would inhibit pulmonary cell proliferation, resulting in respiratory distress. By contrast, we report here that loss of CARM1 results in hyperproliferation of pulmonary epithelial cells during embryonic development. The lungs of newborn mice lacking CARM1 have substantially reduced airspace compared with their wild-type littermates. In the absence of CARM1, alveolar type II cells show increased proliferation. Electron microscopic analyses demonstrate that lungs from mice lacking CARM1 have immature alveolar type II cells and an absence of alveolar type I cells. Gene expression analysis reveals a dysregulation of cell cycle genes and markers of differentiation in the Carm1 knockout lung. Furthermore, there is an overlap in gene expression in the Carm1 knockout and the glucocorticoid receptor knockout lung, suggesting that hyperproliferation and lack of maturation of the alveolar cells are at least in part caused by attenuation of glucocorticoid-mediated signaling. These results demonstrate for the first time that CARM1 inhibits pulmonary cell proliferation and is required for proper differentiation of alveolar cells.
Development 07/2010; 137(13):2147-56. · 6.60 Impact Factor
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Mirle Schemionek,
Christian Elling,
Ulrich Steidl,
Nicole Bäumer,
Ashley Hamilton,
Tilmann Spieker,
Joachim R Göthert,
Martin Stehling,
Amy Wagers,
Claudia S Huettner, Daniel G Tenen,
Lara Tickenbrock,
Wolfgang E Berdel,
Hubert Serve,
Tessa L Holyoake,
Carsten Müller-Tidow,
Steffen Koschmieder
[show abstract]
[hide abstract]
ABSTRACT: In a previously developed inducible transgenic mouse model of chronic myeloid leukemia, we now demonstrate that the disease is transplantable using BCR-ABL(+) Lin(-)Sca-1(+)c-kit(+) (LSK) cells. Interestingly, the phenotype is more severe when unfractionated bone marrow cells are transplanted, yet neither progenitor cells (Lin(-)Sca-1(-)c-kit(+)), nor mature granulocytes (CD11b(+)Gr-1(+)), nor potential stem cell niche cells (CD45(-)Ter119(-)) are able to transmit the disease or alter the phenotype. The phenotype is largely independent of BCR-ABL priming before transplantation. However, prolonged BCR-ABL expression abrogates the potential of LSK cells to induce full-blown disease in secondary recipients and increases the fraction of multipotent progenitor cells at the expense of long-term hematopoietic stem cells (LT-HSCs) in the bone marrow. BCR-ABL alters the expression of genes involved in proliferation, survival, and hematopoietic development, probably contributing to the reduced LT-HSC frequency within BCR-ABL(+) LSK cells. Reversion of BCR-ABL, or treatment with imatinib, eradicates mature cells, whereas leukemic stem cells persist, giving rise to relapsed chronic myeloid leukemia on reinduction of BCR-ABL, or imatinib withdrawal. Our results suggest that BCR-ABL induces differentiation of LT-HSCs and decreases their self-renewal capacity.
Blood 04/2010; 115(16):3185-95. · 9.90 Impact Factor
