Publications by authors named "Oronza A Botrugno"

21 Publications

  • Page 1 of 1

ATR addiction in multiple myeloma: synthetic lethal approaches exploiting established therapies.

Haematologica 2020 10 1;105(10):2440-2447. Epub 2020 Oct 1.

IRCCS San Raffaele Scientific Institute, Milan, Italy.

Therapeutic strategies designed to tinker with cancer cell DNA damage response have led to the widespread use of PARP inhibitors for BRCA1/2-mutated cancers. In the haematological cancer multiple myeloma, we sought to identify analogous synthetic lethality mechanisms that could be leveraged upon established cancer treatments. The combination of ATR inhibition using the compound VX-970 with a drug eliciting interstrand cross-links, melphalan, was tested in in vitro, ex vivo, and most notably in vivo models. Cell proliferation, induction of apoptosis, tumor growth and animal survival were assessed. The combination of ATM inhibition with a drug triggering double strand breaks, doxorucibin, was also probed. We found that ATR inhibition is strongly synergistic with melphalan, even in resistant cells. The combination was dramatically effective in targeting myeloma primary patient cells and cell lines reducing cell proliferation and inducing apoptosis. The combination therapy significantly reduced tumor burden and prolonged survival in animal models. Conversely, ATM inhibition only marginally impacted on myeloma cell survival, even in combination with doxorucibin at high doses. These results indicate that myeloma cells extensively rely on ATR, but not on ATM, for DNA repair. Our findings posit that adding an ATR inhibitor such as VX-970 to established therapeutic regimens may provide a remarkably broad benefit to myeloma patients.
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http://dx.doi.org/10.3324/haematol.2018.215210DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7556682PMC
October 2020

Tranylcypromine-Based LSD1 Inhibitors: Structure-Activity Relationships, Antiproliferative Effects in Leukemia, and Gene Target Modulation.

ChemMedChem 2020 04 14;15(7):643-658. Epub 2020 Feb 14.

Department of Drug Chemistry and Technologies, Sapienza University of Rome, P. le A. Moro 5, 00185, Rome, Italy.

LSD1 is a lysine demethylase highly involved in initiation and development of cancer. To design highly effective covalent inhibitors, a strategy is to fill its large catalytic cleft by designing tranylcypromine (TCP) analogs decorated with long, hindered substituents. We prepared three series of TCP analogs, carrying aroyl- and arylacetylamino (1 a-h), Z-amino acylamino (2 a-o), or double-substituted benzamide (3 a-n) residues at the C4 or C3 position of the phenyl ring. Further fragments obtained by chemical manipulation applied on the TCP scaffold (compounds 4 a-i) were also prepared. When tested against LSD1, most of 1 and 3 exhibited IC values in the low nanomolar range, with 1 e and 3 a,d,f,g being also the most selective respect to monoamine oxidases. In MV4-11 AML and NB4 APL cells compounds 3 were the most potent, displaying up to sub-micromolar cell growth inhibition against both cell lines (3 a) or against NB4 cells (3 c). The most potent compounds in cellular assays were also able to induce the expression of LSD1 target genes, such as GFI-1b, ITGAM, and KCTD12, as functional read-out for LSD1 inhibition. Mouse and human intrinsic clearance data highlighted the high metabolic stability of compounds 3 a, 3 d and 3 g. Further studies will be performed on the new compounds 3 a and 3 c to assess their anticancer potential in different cancer contexts.
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http://dx.doi.org/10.1002/cmdc.201900730DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7125024PMC
April 2020

Novel potent inhibitors of the histone demethylase KDM1A (LSD1), orally active in a murine promyelocitic leukemia model.

Future Med Chem 2017 07 19;9(11):1161-1174. Epub 2017 Jul 19.

Department of Experimental Oncology, Academic Drug Discovery, European Institute of Oncology, Ifom-IEO-Campus, via Adamello 16, 20139 Milan, Italy.

Background: Histone lysine demethylases (KDMs) are well-recognized targets in oncology drug discovery. They function at the post-translation level controlling chromatin conformation and gene transcription. KDM1A is a flavin adenine dinucleotide-dependent amine oxidase, overexpressed in several tumor types, including acute myeloid leukemia, neuroblastoma and non-small-cell lung cancer. Among the many known monoamine oxidase inhibitors screened for KDM1A inhibition, tranylcypromine emerged as a moderately active hit, which irreversibly binds to the flavin adenine dinucleotide cofactor.

Material & Methods: The KDM1A inhibitors 5a-w were synthesized and tested in vitro and in vivo. The biochemical potency was determined, modulation of target in cells was demonstrated on KDM1A-dependent genes and the anti-clonogenic activity was performed in murine acute promyelocytic Leukemia (APL) blasts. An in vivo efficacy experiment was conducted using an established murine promyelocytic leukemia model.

Results: We report a new series of tranylcypromine derivatives substituted on the cyclopropyl moiety, endowed with high potency in both biochemical and cellular assays.

Conclusion: The most interesting derivative (5a) significantly improved survival rate after oral administration in a murine model of promyelocitic leukemia.
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http://dx.doi.org/10.4155/fmc-2017-0003DOI Listing
July 2017

Thieno[3,2-b]pyrrole-5-carboxamides as New Reversible Inhibitors of Histone Lysine Demethylase KDM1A/LSD1. Part 2: Structure-Based Drug Design and Structure-Activity Relationship.

J Med Chem 2017 03 27;60(5):1693-1715. Epub 2017 Feb 27.

Department of Experimental Oncology, Academic Drug Discovery, European Institute of Oncology , Via Adamello 16, 20139 Milano, Italy.

The balance of methylation levels at histone H3 lysine 4 (H3K4) is regulated by KDM1A (LSD1). KDM1A is overexpressed in several tumor types, thus representing an emerging target for the development of novel cancer therapeutics. We have previously described ( Part 1, DOI 10.1021.acs.jmedchem.6b01018 ) the identification of thieno[3,2-b]pyrrole-5-carboxamides as novel reversible inhibitors of KDM1A, whose preliminary exploration resulted in compound 2 with biochemical IC = 160 nM. We now report the structure-guided optimization of this chemical series based on multiple ligand/KDM1A-CoRest cocrystal structures, which led to several extremely potent inhibitors. In particular, compounds 46, 49, and 50 showed single-digit nanomolar IC values for in vitro inhibition of KDM1A, with high selectivity in secondary assays. In THP-1 cells, these compounds transcriptionally affected the expression of genes regulated by KDM1A such as CD14, CD11b, and CD86. Moreover, 49 and 50 showed a remarkable anticlonogenic cell growth effect on MLL-AF9 human leukemia cells.
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http://dx.doi.org/10.1021/acs.jmedchem.6b01019DOI Listing
March 2017

Thieno[3,2-b]pyrrole-5-carboxamides as New Reversible Inhibitors of Histone Lysine Demethylase KDM1A/LSD1. Part 1: High-Throughput Screening and Preliminary Exploration.

J Med Chem 2017 03 27;60(5):1673-1692. Epub 2017 Feb 27.

Department of Experimental Oncology, Academic Drug Discovery, European Institute of Oncology , Via Adamello 16, 20139 Milano, Italy.

Lysine specific demethylase 1 KDM1A (LSD1) regulates histone methylation and it is increasingly recognized as a potential therapeutic target in oncology. We report on a high-throughput screening campaign performed on KDM1A/CoREST, using a time-resolved fluorescence resonance energy transfer (TR-FRET) technology, to identify reversible inhibitors. The screening led to 115 hits for which we determined biochemical IC, thus identifying four chemical series. After data analysis, we have prioritized the chemical series of N-phenyl-4H-thieno[3, 2-b]pyrrole-5-carboxamide for which we obtained X-ray structures of the most potent hit (compound 19, IC = 2.9 μM) in complex with the enzyme. Initial expansion of this chemical class, both modifying core structure and decorating benzamide moiety, was directed toward the definition of the moieties responsible for the interaction with the enzyme. Preliminary optimization led to compound 90, which inhibited the enzyme with a submicromolar IC (0.162 μM), capable of inhibiting the target in cells.
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http://dx.doi.org/10.1021/acs.jmedchem.6b01018DOI Listing
March 2017

Discovery of a Novel Inhibitor of Histone Lysine-Specific Demethylase 1A (KDM1A/LSD1) as Orally Active Antitumor Agent.

J Med Chem 2016 Feb 7;59(4):1501-17. Epub 2016 Jan 7.

Department of Experimental Oncology, Academic Drug Discovery, European Institute of Oncology , Via Adamello 16, 20139 Milan, Italy.

We report the stereoselective synthesis and biological activity of a novel series of tranylcypromine (TCPA) derivatives (14a-k, 15, 16), potent inhibitors of KDM1A. The new compounds strongly inhibit the clonogenic potential of acute leukemia cell lines. In particular three molecules (14d, 14e, and 14g) showing selectivity versus MAO A and remarkably inhibiting colony formation in THP-1 human leukemia cells, were assessed in mouse for their preliminary pharmacokinetic. 14d and 14e were further tested in vivo in a murine acute promyelocytic leukemia model, resulting 14d the most effective. Its two enantiomers were synthesized: the (1S,2R) enantiomer 15 showed higher activity than its (1R,2S) analogue 16, in both biochemical and cellular assays. Compound 15 exhibited in vivo efficacy after oral administration, determining a 62% increased survival in mouse leukemia model with evidence of KDM1A inhibition. The biological profile of compound 15 supports its further investigation as a cancer therapeutic.
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http://dx.doi.org/10.1021/acs.jmedchem.5b01209DOI Listing
February 2016

Redox-Mediated Suberoylanilide Hydroxamic Acid Sensitivity in Breast Cancer.

Antioxid Redox Signal 2015 Jul 27;23(1):15-29. Epub 2015 May 27.

3 Department of Experimental Oncology, European Institute of Oncology , Milan, Italy .

Aims: Vorinostat (suberoylanilide hydroxamic acid; SAHA) is a histone deacetylase inhibitor (HDACi) approved in the clinics for the treatment of T-cell lymphoma and with the potential to be effective also in breast cancer. We investigated the responsiveness to SAHA in human breast primary tumors and cancer cell lines.

Results: We observed a differential response to drug treatment in both human breast primary tumors and cancer cell lines. Gene expression analysis of the breast cancer cell lines revealed that genes involved in cell adhesion and redox pathways, especially glutathione metabolism, were differentially expressed in the cell lines resistant to SAHA compared with the sensitive ones, indicating their possible association with drug resistance mechanisms. Notably, such an association was also observed in breast primary tumors. Indeed, addition of buthionine sulfoximine (BSO), a compound capable of depleting cellular glutathione, significantly enhanced the cytotoxicity of SAHA in both breast cancer cell lines and primary breast tumors.

Innovation: We identify and validate transcriptional differences in genes involved in redox pathways, which include potential predictive markers of sensitivity to SAHA.

Conclusion: In breast cancer, it could be relevant to evaluate the expression of antioxidant genes that may favor tumor resistance as a factor to consider for potential clinical application and treatment with epigenetic drugs (HDACis).
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http://dx.doi.org/10.1089/ars.2014.6189DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4492673PMC
July 2015

Pure enantiomers of benzoylamino-tranylcypromine: LSD1 inhibition, gene modulation in human leukemia cells and effects on clonogenic potential of murine promyelocytic blasts.

Eur J Med Chem 2015 Apr 3;94:163-74. Epub 2015 Mar 3.

Department of Drug Chemistry and Technologies, Sapienza University of Roma, P.le A. Moro 5, 00185 Roma, Italy; Pasteur Institute - Cenci Bolognetti Foundation, Sapienza University of Roma, P.le A. Moro 5, 00185 Roma, Italy. Electronic address:

The pure enantiomers of the N-(2-, 3-, and 4-(2-aminocyclopropyl)phenyl)benzamides hydrochlorides 11a-j were prepared and tested against LSD1 and MAO enzymes. The evaluation of the regioisomers 11a-j highlighted a net increase of the anti-LSD1 potency by shifting the benzamide moiety from ortho to meta and mainly to para position of tranylcypromine phenyl ring, independently from their trans or cis stereochemistry. In particular, the para-substituted 11a,b (trans) and 11g,h (cis) compounds displayed LSD1 and MAO-A inhibition at low nanomolar levels, while were less potent against MAO-B. The meta analogs 11c,d (trans) and 11i,j (cis) were in general less potent, but more efficient against MAO-A than against LSD1. In cellular assays, all the para and meta enantiomers were able to inhibit LSD1 by inducing Gfi-1b and ITGAM gene expression, with 11b,c and 11g-i giving the highest effects. Moreover, 11b and 11g,h strongly inhibited the clonogenic potential of murine promyelocytic blasts.
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http://dx.doi.org/10.1016/j.ejmech.2015.02.060DOI Listing
April 2015

Pure Diastereomers of a Tranylcypromine-Based LSD1 Inhibitor: Enzyme Selectivity and In-Cell Studies.

ACS Med Chem Lett 2015 Feb 8;6(2):173-7. Epub 2014 Dec 8.

Department of Drug Chemistry and Technologies, Sapienza University of Roma , P.le A. Moro 5, 00185 Roma, Italy ; Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Roma , P.le A. Moro 5, 00185 Roma, Italy.

The pure four diastereomers (11a-d) of trans-benzyl (1-((4-(2-aminocyclopropyl)phenyl)amino)-1-oxo-3-phenylpropan-2-yl)carbamate hydrochloride 11, previously described by us as LSD1 inhibitor, were obtained by enantiospecific synthesis/chiral HPLC separation method. Tested in LSD1 and MAO assays, 11b (S,1S,2R) and 11d (R,1S,2R) were the most potent isomers against LSD1 and were less active against MAO-A and practically inactive against MAO-B. In cells, all the four diastereomers induced Gfi-1b and ITGAM gene expression in NB4 cells, accordingly with their LSD1 inhibition, and 11b and 11d inhibited the colony forming potential in murine promyelocytic blasts.
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http://dx.doi.org/10.1021/ml500424zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4329595PMC
February 2015

Synthesis, biological activity and mechanistic insights of 1-substituted cyclopropylamine derivatives: a novel class of irreversible inhibitors of histone demethylase KDM1A.

Eur J Med Chem 2014 Oct 27;86:352-63. Epub 2014 Aug 27.

Drug Discovery Unit, European Institute of Oncology, Via Adamello 16, 20139 Milan, Italy.

Histone demethylase KDM1A (also known as LSD1) has become an attractive therapeutic target for the treatment of cancer as well as other disorders such as viral infections. We report on the synthesis of compounds derived from the expansion of tranylcypromine as a chemical scaffold for the design of novel demethylase inhibitors. These compounds, which are substituted on the cyclopropyl core moiety, were evaluated for their ability to inhibit KDM1A in vitro as well as to function in cells by modulating the expression of Gfi-1b, a well recognized KDM1A target gene. The molecules were all found to covalently inhibit KDM1A and to become increasingly selective against human monoamine oxidases MAO A and MAO B through the introduction of bulkier substituents on the cyclopropylamine ring. Structural and biochemical analysis of selected trans isomers showed that the two stereoisomers are endowed with similar inhibitory activities against KDM1A, but form different covalent adducts with the FAD co-enzyme.
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http://dx.doi.org/10.1016/j.ejmech.2014.08.068DOI Listing
October 2014

A dual role for Hdac1: oncosuppressor in tumorigenesis, oncogene in tumor maintenance.

Blood 2013 Apr 25;121(17):3459-68. Epub 2013 Feb 25.

Department of Experimental Oncology at the IFOM-IEO Campus, European Institute of Oncology, via Adamello 16, Milan, Italy.

Aberrant recruitment of histone deacetylases (HDACs) by the oncogenic fusion protein PML-RAR is involved in the pathogenesis of acute promyelocytic leukemia (APL). PML-RAR, however, is not sufficient to induce disease in mice but requires additional oncogenic lesions during the preleukemic phase. Here, we show that knock-down of Hdac1 and Hdac2 dramatically accelerates leukemogenesis in transgenic preleukemic mice. These events are not restricted to APL because lymphomagenesis driven by deletion of p53 or, to a lesser extent, by c-myc overexpression, was also accelerated by Hdac1 knock-down. In the preleukemic phase of APL, Hdac1 counteracts the activity of PML-RAR in (1) blocking differentiation; (2) impairing genomic stability; and (3) increasing self-renewal in hematopoietic progenitors, as all of these events are affected by the reduction in Hdac1 levels. This led to an expansion of a subpopulation of PML-RAR-expressing cells that is the major source of leukemic stem cells in the full leukemic stage. Remarkably, short-term treatment of preleukemic mice with an HDAC inhibitor accelerated leukemogenesis. In contrast, knock-down of Hdac1 in APL mice led to enhanced survival duration of the leukemic animals. Thus, Hdac1 has a dual role in tumorigenesis: oncosuppressive in the early stages, and oncogenic in established tumor cells.
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http://dx.doi.org/10.1182/blood-2012-10-461988DOI Listing
April 2013

The DNA demethylating agent decitabine activates the TRAIL pathway and induces apoptosis in acute myeloid leukemia.

Biochim Biophys Acta 2013 Jan 6;1832(1):114-20. Epub 2012 Oct 6.

Department of Experimental Oncology, European Institute of Oncology, Milan, Italy.

Although epigenetic drugs have been approved for use in selected malignancies, there is significant need for a better understanding of their mechanism of action. Here, we study the action of a clinically approved DNA-methyltransferase inhibitor - decitabine (DAC) - in acute myeloid leukemia (AML) cells. At low doses, DAC treatment induced apoptosis of NB4 Acute Promyelocytic Leukemia (APL) cells, which was associated with the activation of the extrinsic apoptotic pathway. Expression studies of the members of the Death Receptor family demonstrated that DAC induces the expression of TNF-related apoptosis-inducing ligand (TRAIL). Upregulation of TRAIL, upon DAC treatment, was associated with specific epigenetic modifications induced by DAC in the proximity of the TRAIL promoter, as demonstrated by DNA demethylation, increased DNaseI sensitivity and histone acetylation of a non-CpG island, CpG-rich region located 2kb upstream to the transcription start site. Luciferase assay experiments showed that this region behave as a DNA methylation sensitive transcriptional regulatory element. The CpG regulatory element was also found methylated in samples derived from APL patients. These findings have been confirmed in the non-APL, AML Kasumi cell line, suggesting that this regulatory mechanism may be extended to other AMLs. Our study suggests that DNA methylation is a regulatory mechanism relevant for silencing of the TRAIL apoptotic pathway in leukemic cells, and further elucidates the mechanism by which epigenetic drugs mediate their anti-leukemic effects.
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http://dx.doi.org/10.1016/j.bbadis.2012.10.001DOI Listing
January 2013

HDACs link the DNA damage response, processing of double-strand breaks and autophagy.

Nature 2011 Mar;471(7336):74-79

Fondazione IFOM (Istituto FIRC di Oncologia Molecolare), IFOM-IEO Campus, via Adamello 16, Milan 20139, Italy.

Protein acetylation is mediated by histone acetyltransferases (HATs) and deacetylases (HDACs), which influence chromatin dynamics, protein turnover and the DNA damage response. ATM and ATR mediate DNA damage checkpoints by sensing double-strand breaks and single-strand-DNA-RFA nucleofilaments, respectively. However, it is unclear how acetylation modulates the DNA damage response. Here we show that HDAC inhibition/ablation specifically counteracts yeast Mec1 (orthologue of human ATR) activation, double-strand-break processing and single-strand-DNA-RFA nucleofilament formation. Moreover, the recombination protein Sae2 (human CtIP) is acetylated and degraded after HDAC inhibition. Two HDACs, Hda1 and Rpd3, and one HAT, Gcn5, have key roles in these processes. We also find that HDAC inhibition triggers Sae2 degradation by promoting autophagy that affects the DNA damage sensitivity of hda1 and rpd3 mutants. Rapamycin, which stimulates autophagy by inhibiting Tor, also causes Sae2 degradation. We propose that Rpd3, Hda1 and Gcn5 control chromosome stability by coordinating the ATR checkpoint and double-strand-break processing with autophagy.
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http://dx.doi.org/10.1038/nature09803DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3935290PMC
March 2011

Interplay between oncogene-induced DNA damage response and heterochromatin in senescence and cancer.

Nat Cell Biol 2011 Mar 20;13(3):292-302. Epub 2011 Feb 20.

IFOM Foundation - FIRC Institute of Molecular Oncology Foundation, Milan, Italy.

Two major mechanisms have been causally implicated in the establishment of cellular senescence: the activation of the DNA damage response (DDR) pathway and the formation of senescence-associated heterochromatic foci (SAHF). Here we show that in human fibroblasts resistant to premature p16(INK4a) induction, SAHF are preferentially formed following oncogene activation but are not detected during replicative cellular senescence or on exposure to a variety of senescence-inducing stimuli. Oncogene-induced SAHF formation depends on DNA replication and ATR (ataxia telangiectasia and Rad3-related). Inactivation of ATM (ataxia telangiectasia mutated) or p53 allows the proliferation of oncogene-expressing cells that retain increased heterochromatin induction. In human cancers, levels of heterochromatin markers are higher than in normal tissues, and are independent of the proliferative index or stage of the tumours. Pharmacological and genetic perturbation of heterochromatin in oncogene-expressing cells increase DDR signalling and lead to apoptosis. In vivo, a histone deacetylase inhibitor (HDACi) causes heterochromatin relaxation, increased DDR, apoptosis and tumour regression. These results indicate that heterochromatin induced by oncogenic stress restrains DDR and suggest that the use of chromatin-modifying drugs in cancer therapies may benefit from the study of chromatin and DDR status of tumours.
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http://dx.doi.org/10.1038/ncb2170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3918344PMC
March 2011

Biochemical, structural, and biological evaluation of tranylcypromine derivatives as inhibitors of histone demethylases LSD1 and LSD2.

J Am Chem Soc 2010 May;132(19):6827-33

Department of Genetics and Microbiology, University of Pavia, Via Ferrata 1, 27100 Pavia, Italy.

LSD1 and LSD2 histone demethylases are implicated in a number of physiological and pathological processes, ranging from tumorigenesis to herpes virus infection. A comprehensive structural, biochemical, and cellular study is presented here to probe the potential of these enzymes for epigenetic therapies. This approach employs tranylcypromine as a chemical scaffold for the design of novel demethylase inhibitors. This drug is a clinically validated antidepressant known to target monoamine oxidases A and B. These two flavoenzymes are structurally related to LSD1 and LSD2. Mechanistic and crystallographic studies of tranylcypromine inhibition reveal a lack of selectivity and differing covalent modifications of the FAD cofactor depending on the enantiomeric form. These findings are pharmacologically relevant, since tranylcypromine is currently administered as a racemic mixture. A large set of tranylcypromine analogues were synthesized and screened for inhibitory activities. We found that the common evolutionary origin of LSD and MAO enzymes, despite their unrelated functions and substrate specificities, is reflected in related ligand-binding properties. A few compounds with partial enzyme selectivity were identified. The biological activity of one of these new inhibitors was evaluated with a cellular model of acute promyelocytic leukemia chosen since its pathogenesis includes aberrant activities of several chromatin modifiers. Marked effects on cell differentiation and an unprecedented synergistic activity with antileukemia drugs were observed. These data demonstrate that these LSD1/2 inhibitors are of potential relevance for the treatment of promyelocytic leukemia and, more generally, as tools to alter chromatin state with promise of a block of tumor progression.
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http://dx.doi.org/10.1021/ja101557kDOI Listing
May 2010

Immunocell-array for molecular dissection of multiple signaling pathways in mammalian cells.

Mol Cell Proteomics 2007 May 10;6(5):939-47. Epub 2007 Feb 10.

Tethis S.r.l., Via Russoli 3, 20143 Milan, Italy.

The knowledge of signaling pathways that are triggered by physiological and pathological conditions or drug treatment is essential for the comprehension of the biological events that regulate cellular responses. Recently novel platforms based on "reverse-phase protein arrays" have proven to be useful in the study of different pathways, but they still lack the possibility to detect events in the complexity of a cellular context. We developed an "immunocell-array" of cells on chip where, upon cell plating, growing, drug treatment, and fixation, by spotting specific antibodies we can detect the localization and state of hundreds of proteins involved in specific signaling pathways. By applying this technology to mammalian cells we analyzed signaling proteins involved in the response to DNA damage and identified a chromatin remodeling pathway following bleomycin treatment. We propose our technology as a new tool for the array-based multiplexed analysis of signaling pathways in drug response screening, for the proteomics of profiling patient cells, and ultimately for the high throughput screening of antibodies for immunofluorescence applications.
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http://dx.doi.org/10.1074/mcp.T600051-MCP200DOI Listing
May 2007

Recruitment of the histone methyltransferase SUV39H1 and its role in the oncogenic properties of the leukemia-associated PML-retinoic acid receptor fusion protein.

Mol Cell Biol 2006 Feb;26(4):1288-96

Department of Experimental Oncology, European Institute of Oncology, and Department of Biomolecular Sciences and Biotechnologies, University of Milan, Italy.

Leukemia-associated fusion proteins establish aberrant transcriptional programs, which result in the block of hematopoietic differentiation, a prominent feature of the leukemic phenotype. The dissection of the mechanisms of deregulated transcription by leukemia fusion proteins is therefore critical for the design of tailored antileukemic strategies, aimed at reestablishing the differentiation program of leukemic cells. The acute promyelocytic leukemia (APL)-associated fusion protein PML-retinoic acid receptor (RAR) behaves as an aberrant transcriptional repressor, due to its ability to induce chromatin modifications (histone deacetylation and DNA methylation) and silencing of PML-RAR target genes. Here, we indicate that the ultimate result of PML-RAR action is to impose a heterochromatin-like structure on its target genes, thereby establishing a permanent transcriptional silencing. This effect is mediated by the previously described association of PML-RAR with chromatin-modifying enzymes (histone deacetylases and DNA methyltransferases) and by recruitment of the histone methyltransferase SUV39H1, responsible for trimethylation of lysine 9 of histone H3.
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http://dx.doi.org/10.1128/MCB.26.4.1288-1296.2006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1367206PMC
February 2006

Characterization of the endogenous GIT1-betaPIX complex, and identification of its association to membranes.

Eur J Cell Biol 2006 Jan 8;85(1):35-46. Epub 2005 Nov 8.

Cell Adhesion Unit, Department of Molecular Biology and Functional Genomics, San Raffaele Scientific Institute, Via Olgettina 58, I-20132 Milano, Italy.

G protein-coupled receptor kinase interactors (GITs) are adaptor proteins with ADP-ribosylating factor--GTPase-activating protein (ARF-GAP) activity that form complexes with the p21-activated kinase-interacting exchange factor (PIX) guanine nucleotide exchanging factors for Rac and Cdc42. In this study we have characterized the endogenous GIT1/p95-APP1/Cat1 (GIT1)- PIX complexes in neuronal and non-neuronal cells. In COS7 cells, immunocytochemical analysis shows the localization of endogenous GIT1 in the perinuclear region of the cell, as well as at the cell periphery, where GIT1 co-localizes with filamentous actin. The perinuclear localization of endogenous GIT1 was confirmed in avian fibroblasts. In COS7 cells, immunoprecipitation and microsequencing experiments with either anti-GIT1 or anti-betaPIX antibodies unequivocally show that betaPIX is uniquely associated with GIT1 in lysates from these cells, while GIT2/PKL/p95-APP2/Cat2 (GIT2) is undetectable in the endogenous complexes. Moreover, this analysis demonstrates that betaPIX is the limiting factor for the formation of the endogenous complexes, since a small fraction of GIT1 can be co-immunoprecipitated with most betaPIX from these cells. Saponin treatment of unfixed cells indicates that betaPIX-bound GIT1 is preferentially retained in the saponin-resistant fraction when compared to betaPIX-free GIT1. Moreover, analysis by tissue fractionation shows that a significant fraction of the endogenous GIT1-betaPIX complex is firmly associated to membranes from brain homogenates. Our findings show the specific localization of the complex at intracellular membranes, and indicate a correlation between the association of GIT1 to betaPIX, and the localization of the endogenous complex at membranes.
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http://dx.doi.org/10.1016/j.ejcb.2005.09.018DOI Listing
January 2006

Synergy between LRH-1 and beta-catenin induces G1 cyclin-mediated cell proliferation.

Mol Cell 2004 Aug;15(4):499-509

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Université Louis Pasteur, 67404 Illkirch, France.

LRH-1 is an orphan nuclear receptor predominantly expressed in tissues of endodermal origin, where it controls development and cholesterol homeostasis. We show here that LRH-1 induces cell proliferation through the concomitant induction of cyclin D1 and E1, an effect that is potentiated by its interaction with beta-catenin. Whereas beta-catenin coactivates LRH-1 on the cyclin E1 promoter, LRH-1 acts as a potent tissue-restricted coactivator of beta-catenin on the cyclin D1 promoter. The implication of LRH-1 in cell proliferation highlights an unanticipated crosstalk between LRH-1 and the beta-catenin/Tcf4 signaling pathway, which is relevant for the renewal of intestinal crypt cells.
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http://dx.doi.org/10.1016/j.molcel.2004.07.009DOI Listing
August 2004

Liver receptor homolog 1 controls the expression of the scavenger receptor class B type I.

EMBO Rep 2002 Dec 21;3(12):1181-7. Epub 2002 Nov 21.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/Université Louis Pasteur, 67404 Illkirch, France.

The scavenger receptor class B type I (SR-BI), which mediates selective cellular cholesterol uptake from high-density lipoproteins (HDLs), plays a key role in reverse cholesterol transport. The orphan nuclear receptor liver receptor homolog 1 (LRH-1) and SR-BI are co-expressed in liver and ovary, suggesting that LRH-1 might control the expression of SR-BI in these tissues. LRH-1 induces human and mouse SR-BI promoter activity by binding to an LRH-1 response element in the promoter. Retroviral expression of LRH-1 robustly induces SR-BI, an effect associated with histone H3 acetylation on the SR-BI promoter. The decrease in SR-BI mRNA levels in livers of LRH-1(+/-) animals provides in vivo evidence that LRH-1 regulates SR-BI expression. Our data demonstrate that SR-BI is an LRH-1 target gene and underscore the pivotal role of LRH-1 in reverse cholesterol transport.
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http://dx.doi.org/10.1093/embo-reports/kvf238DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1308324PMC
December 2002

The small heterodimer partner interacts with the liver X receptor alpha and represses its transcriptional activity.

Mol Endocrinol 2002 Sep;16(9):2065-76

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université Louis Pasteur, BP 1042, 67404 Illkirch, France.

The small heterodimer partner SHP (NR0B2) is an unusual nuclear receptor that lacks the typical DNA binding domain common to most nuclear receptors. SHP has been reported to act as a corepressor for several nuclear receptors, but its exact mechanism of action is still elusive. Here we show that SHP can interact with the liver X receptors LXRalpha (NR1H3) and LXRbeta (NR1H2), as demonstrated by glutathione-S-transferase pull-down assays, mammalian two-hybrid, and coimmunoprecipitation experiments. In transfection assays, SHP inhibits the expression of an artificial reporter driven by an LXR-response element and represses the transcriptional activation by LXR of the human ATP-binding cassette transporter 1 (ABCA1) promoter. Treatment of Caco-2 cells with bile acids, which activate farnesoid X receptor and subsequently induce SHP, leads to the repression of the human ABCG1 gene, an established LXR target gene. These results demonstrate that SHP is able to interact with LXR and to modulate its transcriptional activity.
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http://dx.doi.org/10.1210/me.2001-0194DOI Listing
September 2002