Publications by authors named "Stuart A Aaronson"

72 Publications

High endogenous CCL2 expression promotes the aggressive phenotype of human inflammatory breast cancer.

Nat Commun 2021 Nov 25;12(1):6889. Epub 2021 Nov 25.

Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA.

Inflammatory Breast Cancer (IBC) is a highly aggressive malignancy with distinct clinical and histopathological features whose molecular basis is unresolved. Here we describe a human IBC cell line, A3250, that recapitulates key IBC features in a mouse xenograft model, including skin erythema, diffuse tumor growth, dermal lymphatic invasion, and extensive metastases. A3250 cells express very high levels of the CCL2 chemokine and induce tumors enriched in macrophages. CCL2 knockdown leads to a striking reduction in macrophage densities, tumor proliferation, skin erythema, and metastasis. These results establish IBC-derived CCL2 as a key factor driving macrophage expansion, and indirectly tumor growth, with transcriptomic analysis demonstrating the activation of multiple inflammatory pathways. Finally, primary human IBCs exhibit macrophage infiltration and an enriched macrophage RNA signature. Thus, this human IBC model provides insight into the distinctive biology of IBC, and highlights potential therapeutic approaches to this deadly disease.
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http://dx.doi.org/10.1038/s41467-021-27108-8DOI Listing
November 2021

Distinct CDK6 complexes determine tumor cell response to CDK4/6 inhibitors and degraders.

Nat Cancer 2021 Apr 1;2(4):429-443. Epub 2021 Mar 1.

Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York NY.

CDK4/6 inhibitors (CDK4/6i) are effective in metastatic breast cancer, but they have been only modestly effective in most other tumor types. Here we show that tumors expressing low CDK6 rely on CDK4 function, and are exquisitely sensitive to CDK4/6i. In contrast, tumor cells expressing both CDK4 and CDK6 have increased reliance on CDK6 to ensure cell cycle progression. We discovered that CDK4/6i and CDK4/6 degraders potently bind and inhibit CDK6 selectively in tumors in which CDK6 is highly thermo-unstable and strongly associated with the HSP90/CDC37 complex. In contrast, CDK4/6i and CDK4/6 degraders are ineffective in antagonizing tumor cells expressing thermostable CDK6, due to their weaker binding to CDK6 in these cells. Thus, we uncover a general mechanism of intrinsic resistance to CDK4/6i and CDK4/6i-derived degraders and the need for novel inhibitors targeting the CDK4/6i-resistant, thermostable form of CDK6 for application as cancer therapeutics.
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http://dx.doi.org/10.1038/s43018-021-00174-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8462800PMC
April 2021

Exploiting Allosteric Properties of RAF and MEK Inhibitors to Target Therapy-Resistant Tumors Driven by Oncogenic BRAF Signaling.

Cancer Discov 2021 Jul 10;11(7):1716-1735. Epub 2021 Feb 10.

Department of Oncological Sciences, The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, New York.

Current clinical RAF inhibitors (RAFi) inhibit monomeric BRAF (mBRAF) but are less potent against dimeric BRAF (dBRAF). RAFi equipotent for mBRAF and dBRAF have been developed but are predicted to have lower therapeutic index. Here we identify a third class of RAFi that selectively inhibits dBRAF over mBRAF. Molecular dynamic simulations reveal restriction of the movement of the BRAF αC-helix as the basis of inhibitor selectivity. Combination of inhibitors based on their conformation selectivity (mBRAF- plus dBRAF-selective plus the most potent BRAF-MEK disruptor MEK inhibitor) promoted suppression of tumor growth in BRAF therapy-resistant models. Strikingly, the triple combination showed no toxicities, whereas dBRAF-selective plus MEK inhibitor treatment caused weight loss in mice. Finally, the triple combination achieved durable response and improved clinical well-being in a patient with stage IV colorectal cancer. Thus, exploiting allosteric properties of RAF and MEK inhibitors enables the design of effective and well-tolerated therapies for BRAF tumors. SIGNIFICANCE: This work identifies a new class of RAFi that are selective for dBRAF over mBRAF and determines the basis of their selectivity. A rationally designed combination of RAF and MEK inhibitors based on their conformation selectivity achieved increased efficacy and a high therapeutic index when used to target BRAF tumors...
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http://dx.doi.org/10.1158/2159-8290.CD-20-1351DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8295204PMC
July 2021

Prostate Cancer in World Trade Center Responders Demonstrates Evidence of an Inflammatory Cascade.

Mol Cancer Res 2019 08 20;17(8):1605-1612. Epub 2019 Jun 20.

Division of Hematology and Medical Oncology, The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, New York.

An excess incidence of prostate cancer has been identified among World Trade Center (WTC) responders. In this study, we hypothesized that WTC dust, which contained carcinogens and tumor-promoting agents, could facilitate prostate cancer development by inducing DNA damage, promoting cell proliferation, and causing chronic inflammation. We compared expression of immunologic and inflammatory genes using a NanoString assay on archived prostate tumors from WTC Health Program (WTCHP) patients and non-WTC patients with prostate cancer. Furthermore, to assess immediate and delayed responses of prostate tissue to acute WTC dust exposure via intratracheal inhalation, we performed RNA-seq on the prostate of normal rats that were exposed to moderate to high doses of WTC dust. WTC prostate cancer cases showed significant upregulation of genes involved in DNA damage and G-M arrest. Cell-type enrichment analysis showed that Th17 cells, a subset of proinflammatory Th cells, were specifically upregulated in WTC patients. In rats exposed to WTC dust, we observed upregulation of gene transcripts of cell types involved in both adaptive immune response (dendritic cells and B cells) and inflammatory response (Th17 cells) in the prostate. Unexpectedly, genes in the cholesterol biosynthesis pathway were also significantly upregulated 30 days after acute dust exposure. Our results suggest that respiratory exposure to WTC dust can induce inflammatory and immune responses in prostate tissue. IMPLICATIONS: WTC-related prostate cancer displayed a distinct gene expression pattern that could be the result of exposure to specific carcinogens. Our data warrant further epidemiologic and cellular mechanistic studies to better understand the consequences of WTC dust exposure. http://mcr.aacrjournals.org/content/molcanres/17/8/1605/F1.large.jpg.
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http://dx.doi.org/10.1158/1541-7786.MCR-19-0115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6684261PMC
August 2019

SHP2 Drives Adaptive Resistance to ERK Signaling Inhibition in Molecularly Defined Subsets of ERK-Dependent Tumors.

Cell Rep 2019 01;26(1):65-78.e5

Department of Oncological Sciences, The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Dermatology, The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Electronic address:

Pharmacologic targeting of components of ERK signaling in ERK-dependent tumors is often limited by adaptive resistance, frequently mediated by feedback-activation of RTK signaling and rebound of ERK activity. Here, we show that combinatorial pharmacologic targeting of ERK signaling and the SHP2 phosphatase prevents adaptive resistance in defined subsets of ERK-dependent tumors. In each tumor that was sensitive to combined treatment, p(Y542)SHP2 induction was observed in response to ERK signaling inhibition. The strategy was broadly effective in TNBC models and tumors with RAS mutations at G12, whereas tumors with RAS(G13D) or RAS(Q61X) mutations were resistant. In addition, we identified a subset of BRAF(V600E) tumors that were resistant to the combined treatment, in which FGFR was found to drive feedback-induced RAS activation, independently of SHP2. Thus, we identify molecular determinants of response to combined ERK signaling and SHP2 inhibition in ERK-dependent tumors.
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http://dx.doi.org/10.1016/j.celrep.2018.12.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6396678PMC
January 2019

Kinesin-2 and IFT-A act as a complex promoting nuclear localization of β-catenin during Wnt signalling.

Nat Commun 2018 12 13;9(1):5304. Epub 2018 Dec 13.

Department of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA.

Wnt/Wg-signalling is critical signalling in all metazoans. Recent studies suggest that IFT-A proteins and Kinesin-2 modulate canonical Wnt/Wg-signalling independently of their ciliary role. Whether they function together in Wnt-signalling and their mechanistic role in the pathway remained unresolved. Here we demonstrate that Kinesin-2 and IFT-A proteins act as a complex during Drosophila Wg-signalling, affecting pathway activity in the same manner, interacting genetically and physically, and co-localizing with β-catenin, the mediator of Wnt/Wg-signalling on microtubules. Following pathway activation, Kinesin-2/IFT-A mutant cells exhibit high cytoplasmic β-catenin levels, yet fail to activate Wg-targets. In mutant tissues in both, Drosophila and mouse/MEFs, nuclear localization of β-catenin is markedly reduced. We demonstrate a conserved, motor-domain dependent function of the Kinesin-2/IFT-A complex in promoting nuclear translocation of β-catenin. We show that this is mediated by protecting β-catenin from a conserved cytoplasmic retention process, thus identifying a mechanism for Kinesin-2/IFT-A in Wnt-signalling that is independent of their ciliary role.
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http://dx.doi.org/10.1038/s41467-018-07605-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6294004PMC
December 2018

Glatiramer Acetate Enhances Myeloid-Derived Suppressor Cell Function via Recognition of Paired Ig-like Receptor B.

J Immunol 2018 09 1;201(6):1727-1734. Epub 2018 Aug 1.

Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029;

Glatiramer acetate (GA; Copaxone) is a copolymer therapeutic that is approved by the Food and Drug Administration for the relapsing-remitting form of multiple sclerosis. Despite an unclear mechanism of action, studies have shown that GA promotes protective Th2 immunity and stimulates release of cytokines that suppress autoimmunity. In this study, we demonstrate that GA interacts with murine paired Ig-like receptor B (PIR-B) on myeloid-derived suppressor cells and suppresses the STAT1/NF-κB pathways while promoting IL-10/TGF-β cytokine release. In inflammatory bowel disease models, GA enhanced myeloid-derived suppressor cell-dependent CD4 regulatory T cell generation while reducing proinflammatory cytokine secretion. Human monocyte-derived macrophages responded to GA by reducing TNF-α production and promoting CD163 expression typical of alternative maturation despite the presence of GM-CSF. Furthermore, GA competitively interacts with leukocyte Ig-like receptors B (LILRBs), the human orthologs of PIR-B. Because GA limited proinflammatory activation of myeloid cells, therapeutics that target LILRBs represent novel treatment modalities for autoimmune indications.
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http://dx.doi.org/10.4049/jimmunol.1701450DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6379207PMC
September 2018

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018.

Cell Death Differ 2018 03 23;25(3):486-541. Epub 2018 Jan 23.

Department of Medicine, Division of Pulmonary and Critical Care Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.

Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field.
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http://dx.doi.org/10.1038/s41418-017-0012-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5864239PMC
March 2018

Extracellular LDLR repeats modulate Wnt signaling activity by promoting LRP6 receptor endocytosis mediated by the Itch E3 ubiquitin ligase.

Genes Cancer 2017 Jul;8(7-8):613-627

Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

The LOW-density lipoprotein related protein 6 (LRP6) receptor is an important effector of canonical Wnt signaling, a developmental pathway, whose dysregulation has been implicated in various diseases including cancer. The membrane proximal low-density lipoprotein (LDL) receptor repeats in LRP6 exhibit homology to ligand binding repeats in the LDL receptor (LDLR), but lack known function. We generated single amino acid substitutions of LRP6-LDLR repeat residues, which are highly conserved in the human LDLR and mutated in patients with Familial Hypercholesteremia (FH). These substitutions negatively impacted LRP6 internalization and activation of Wnt signaling. By mass spectrometry, we observed that the Itch E3 ubiquitin ligase associated with and ubiquitinated wild type LRP6 but not the LDLR repeat mutants. These findings establish the involvement of LRP6-LDLR repeats in the regulation of canonical Wnt signaling.
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http://dx.doi.org/10.18632/genesandcancer.146DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5620007PMC
July 2017

Investigating the Cellular Specificity in Tumors of a Surface-Converting Nanoparticle by Multimodal Imaging.

Bioconjug Chem 2017 05 5;28(5):1413-1421. Epub 2017 May 5.

SyMO-Chem B.V. , Eindhoven 5612 AZ, The Netherlands.

Active targeting of nanoparticles through surface functionalization is a common strategy to enhance tumor delivery specificity. However, active targeting strategies tend to work against long polyethylene glycol's shielding effectiveness and associated favorable pharmacokinetics. To overcome these limitations, we developed a matrix metalloproteinase-2 sensitive surface-converting polyethylene glycol coating. This coating prevents nanoparticle-cell interaction in the bloodstream, but, once exposed to matrix metalloproteinase-2, i.e., when the nanoparticles accumulate within the tumor interstitium, the converting polyethylene glycol coating is cleaved, and targeting ligands become available for binding to tumor cells. In this study, we applied a comprehensive multimodal imaging strategy involving optical, nuclear, and magnetic resonance imaging methods to evaluate this coating approach in a breast tumor mouse model. The data obtained revealed that this surface-converting coating enhances the nanoparticle's blood half-life and tumor accumulation and ultimately results in improved tumor-cell targeting. Our results show that this enzyme-specific surface-converting coating ensures a high cell-targeting specificity without compromising favorable nanoparticle pharmacokinetics.
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http://dx.doi.org/10.1021/acs.bioconjchem.7b00086DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5567755PMC
May 2017

Modeling intratumor heterogeneity through CRISPR-barcodes.

Mol Cell Oncol 2016 6;3(6):e1227894. Epub 2016 Sep 6.

Normandie Univ, UNIROUEN, INSERM, DC2N, Rouen, France; Institute for Research and Innovation in Biomedicine, Rouen, France.

We have devised a barcoding strategy to recapitulate cancer evolution through the emergence of subclonal mutations of interest, whose effects can be monitored in a dynamic manner. This approach can be easily adapted for a variety of applications, including combined modeling of multiple mechanisms of drug resistance or repair of oncogenic driver mutations in addicted cancer cells.
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http://dx.doi.org/10.1080/23723556.2016.1227894DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5160400PMC
September 2016

Emerging roles of p53 and other tumour-suppressor genes in immune regulation.

Nat Rev Immunol 2016 12 26;16(12):741-750. Epub 2016 Sep 26.

Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Building 149 13th Street, Charlestown, Massachusetts 02129, USA.

Tumour-suppressor genes are indispensable for the maintenance of genomic integrity. Recently, several of these genes, including those encoding p53, PTEN, RB1 and ARF, have been implicated in immune responses and inflammatory diseases. In particular, the p53 tumour- suppressor pathway is involved in crucial aspects of tumour immunology and in homeostatic regulation of immune responses. Other studies have identified roles for p53 in various cellular processes, including metabolism and stem cell maintenance. Here, we discuss the emerging roles of p53 and other tumour-suppressor genes in tumour immunology, as well as in additional immunological settings, such as virus infection. This relatively unexplored area could yield important insights into the homeostatic control of immune cells in health and disease and facilitate the development of more effective immunotherapies. Consequently, tumour-suppressor genes are emerging as potential guardians of immune integrity.
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http://dx.doi.org/10.1038/nri.2016.99DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5325695PMC
December 2016

CRISPR-Barcoding for Intratumor Genetic Heterogeneity Modeling and Functional Analysis of Oncogenic Driver Mutations.

Mol Cell 2016 08 21;63(3):526-38. Epub 2016 Jul 21.

Normandie Univ, UNIROUEN, INSERM, DC2N, 76000 Rouen, France; Institute for Research and Innovation in Biomedicine (IRIB), 76000 Rouen, France. Electronic address:

Intratumor genetic heterogeneity underlies the ability of tumors to evolve and adapt to different environmental conditions. Using CRISPR/Cas9 technology and specific DNA barcodes, we devised a strategy to recapitulate and trace the emergence of subpopulations of cancer cells containing a mutation of interest. We used this approach to model different mechanisms of lung cancer cell resistance to EGFR inhibitors and to assess effects of combined drug therapies. By overcoming intrinsic limitations of current approaches, CRISPR-barcoding also enables investigation of most types of genetic modifications, including repair of oncogenic driver mutations. Finally, we used highly complex barcodes inserted at a specific genome location as a means of simultaneously tracing the fates of many thousands of genetically labeled cancer cells. CRISPR-barcoding is a straightforward and highly flexible method that should greatly facilitate the functional investigation of specific mutations, in a context that closely mimics the complexity of cancer.
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http://dx.doi.org/10.1016/j.molcel.2016.06.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5537739PMC
August 2016

Angiomotin stabilization by tankyrase inhibitors antagonizes constitutive TEAD-dependent transcription and proliferation of human tumor cells with Hippo pathway core component mutations.

Oncotarget 2016 May;7(20):28765-82

Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

The evolutionarily conserved Hippo inhibitory pathway plays critical roles in tissue homeostasis and organ size control, while mutations affecting certain core components contribute to tumorigenesis. Here we demonstrate that proliferation of Hippo pathway mutant human tumor cells exhibiting high constitutive TEAD transcriptional activity was markedly inhibited by dominant negative TEAD4, which did not inhibit the growth of Hippo wild-type cells with low levels of regulatable TEAD-mediated transcription. The tankyrase inhibitor, XAV939, identified in a screen for inhibitors of TEAD transcriptional activity, phenocopied these effects independently of its other known functions by stabilizing angiomotin and sequestering YAP in the cytosol. We also identified one intrinsically XAV939 resistant Hippo mutant tumor line exhibiting lower and less durable angiomotin stabilization. Thus, angiomotin stabilization provides a new mechanism for targeting tumors with mutations in Hippo pathway core components as well as a biomarker for sensitivity to such therapy.
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http://dx.doi.org/10.18632/oncotarget.9117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5045355PMC
May 2016

USP7 Enforces Heterochromatinization of p53 Target Promoters by Protecting SUV39H1 from MDM2-Mediated Degradation.

Cell Rep 2016 Mar 10;14(11):2528-37. Epub 2016 Mar 10.

Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Electronic address:

The H3K9me3 repressive histone conformation of p53 target promoters is abrogated in response to p53 activation by MDM2-mediated SUV39H1 degradation. Here, we present evidence that the USP7 deubiquitinase protects SUV39H1 from MDM2-mediated ubiquitination in the absence of p53 stimulus. USP7 occupies p53 target promoters in unstressed conditions, a process that is abrogated with p53 activation associated with loss of the H3K9me3 mark on these same promoters. Mechanistically, USP7 forms a trimeric complex with MDM2 and SUV39H1, independent of DNA, and modulates MDM2-dependent SUV39H1 ubiquitination. Furthermore, we show that this protective function of USP7 on SUV39H1 is independent of p53. Finally, USP7 blocking cooperates with p53 in inducing apoptosis by enhancing p53 promoter occupancy and dependent transactivation of target genes. These results uncover a layer of the p53 transcriptional program mediated by USP7, which restrains relaxation of local chromatin conformation at p53 target promoters.
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http://dx.doi.org/10.1016/j.celrep.2016.02.049DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4884055PMC
March 2016

Stable heteroplasmy at the single-cell level is facilitated by intercellular exchange of mtDNA.

Nucleic Acids Res 2015 Feb 4;43(4):2177-87. Epub 2015 Feb 4.

Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, NY 10029, USA

Eukaryotic cells carry two genomes, nuclear (nDNA) and mitochondrial (mtDNA), which are ostensibly decoupled in their replication, segregation and inheritance. It is increasingly appreciated that heteroplasmy, the occurrence of multiple mtDNA haplotypes in a cell, plays an important biological role, but its features are not well understood. Accurately determining the diversity of mtDNA has been difficult, due to the relatively small amount of mtDNA in each cell (<1% of the total DNA), the intercellular variability of mtDNA content and mtDNA pseudogenes (Numts) in nDNA. To understand the nature of heteroplasmy, we developed Mseek, a novel technique to purify and sequence mtDNA. Mseek yields high purity (>90%) mtDNA and its ability to detect rare variants is limited only by sequencing depth, providing unprecedented sensitivity and specificity. Using Mseek, we confirmed the ubiquity of heteroplasmy by analyzing mtDNA from a diverse set of cell lines and human samples. Applying Mseek to colonies derived from single cells, we find heteroplasmy is stably maintained in individual daughter cells over multiple cell divisions. We hypothesized that the stability of heteroplasmy could be facilitated by intercellular exchange of mtDNA. We explicitly demonstrate this exchange by co-culturing cell lines with distinct mtDNA haplotypes. Our results shed new light on the maintenance of heteroplasmy and provide a novel platform to investigate features of heteroplasmy in normal and diseased states.
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http://dx.doi.org/10.1093/nar/gkv052DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4344500PMC
February 2015

Cdo suppresses canonical Wnt signalling via interaction with Lrp6 thereby promoting neuronal differentiation.

Nat Commun 2014 Nov 19;5:5455. Epub 2014 Nov 19.

Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Samsung Biomedical Research Institute, Suwon 440-746, Republic of Korea.

Canonical Wnt signalling regulates expansion of neural progenitors and functions as a dorsalizing signal in the developing forebrain. In contrast, the multifunctional co-receptor Cdo promotes neuronal differentiation and is important for the function of the ventralizing signal, Shh. Here we show that Cdo negatively regulates Wnt signalling during neurogenesis. Wnt signalling is enhanced in Cdo-deficient cells, leading to impaired neuronal differentiation. The ectodomains of Cdo and Lrp6 interact via the Ig2 repeat of Cdo and the LDLR repeats of Lrp6, and the Cdo Ig2 repeat is necessary for Cdo-dependent Wnt inhibition. Furthermore, the Cdo-deficient dorsal forebrain displays stronger Wnt signalling activity, increased cell proliferation and enhanced expression of the dorsal markers and Wnt targets, Pax6, Gli3, Axin2. Therefore, in addition to promoting ventral central nervous system cell fates with Shh, Cdo promotes neuronal differentiation by suppression of Wnt signalling and provides a direct link between two major dorsoventral morphogenetic signalling pathways.
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http://dx.doi.org/10.1038/ncomms6455DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4412020PMC
November 2014

Scaffold hopping approach on the route to selective tankyrase inhibitors.

Eur J Med Chem 2014 Nov 5;87:611-23. Epub 2014 Oct 5.

Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy. Electronic address:

A virtual screening procedure was applied to identify new tankyrase inhibitors. Through pharmacophore screening of a compounds collection from the SPECS database, the methoxy[l]benzothieno[2,3-c]quinolin-6(5H)-one scaffold was identified as nicotinamide mimetic able to inhibit tankyrase activity at low micromolar concentration. In order to improve potency and selectivity, tandem structure-based and scaffold hopping approaches were carried out over the new scaffold leading to the discovery of the 2-(phenyl)-3H-benzo[4,5]thieno[3,2-d]pyrimidin-4-one as powerful chemotype suitable for tankyrase inhibition. The best compound 2-(4-tert-butyl-phenyl)-3H-benzo[4,5]thieno[3,2-d]pyrimidin-4-one (23) displayed nanomolar potencies (IC50s TNKS-1 = 21 nM and TNKS-2 = 29 nM) and high selectivity when profiled against several other PARPs. Furthermore, a striking Wnt signaling, as well as cell growth inhibition, was observed assaying 23 in DLD-1 cancer cells.
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http://dx.doi.org/10.1016/j.ejmech.2014.10.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4415586PMC
November 2014

Brachyury: a new player in promoting breast cancer aggressiveness.

J Natl Cancer Inst 2014 May 9;106(5). Epub 2014 May 9.

Affiliation of authors: Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY (MMP, SAA).

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http://dx.doi.org/10.1093/jnci/dju094DOI Listing
May 2014

Design, synthesis, crystallographic studies, and preliminary biological appraisal of new substituted triazolo[4,3-b]pyridazin-8-amine derivatives as tankyrase inhibitors.

J Med Chem 2014 Mar 24;57(6):2807-12. Epub 2014 Feb 24.

Dipartimento di Chimica e Tecnologia del Farmaco, Università degli Studi di Perugia , Via del Liceo 1, 06123 Perugia, Italy.

Searching for selective tankyrases (TNKSs) inhibitors, a new small series of 6,8-disubstituted triazolo[4,3-b]piridazines has been synthesized and characterized biologically. Structure-based optimization of the starting hit compound NNL (3) prompted us to the discovery of 4-(2-(6-methyl-[1,2,4]triazolo[4,3-b]pyridazin-8-ylamino)ethyl)phenol (12), a low nanomolar selective TNKSs inhibitor working as NAD isostere as ascertained by crystallographic analysis. Preliminary biological data candidate this new class of derivatives as a powerful pharmacological tools in the unraveling of TNKS implications in physiopathological conditions.
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http://dx.doi.org/10.1021/jm401356tDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4406096PMC
March 2014

Chromatin modifications sequentially enhance ErbB2 expression in ErbB2-positive breast cancers.

Cell Rep 2013 Oct 10;5(2):302-13. Epub 2013 Oct 10.

Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029 USA.

ErbB2 gene amplification occurs in 20%-25% of breast cancers, and its therapeutic targeting has markedly improved survival of patients with breast cancer in the adjuvant setting. However, resistance to these therapies can develop. Because epigenetic mechanisms can importantly influence oncogene expression and be druggable as well, we investigated histone modifications that influence ErbB2 overexpression, independent of gene amplification. We demonstrate here that ErbB2-overexpressing breast carcinomas acquire the H3K4me3 mark on the erbB2 promoter and that receptor-amplified tumors further acquire the H3K9ac mark, which is dependent on H3K4me3 mark acquisition. Targeting WD repeat domain 5 (Wdr5), which is absolutely required for H3K4me3 enrichment, decreased ErbB2 overexpression, associated with a decrease in the H3K4me3 mark on the erbB2 promoter. Of note, Wdr5 silencing cooperated with trastuzumab or chemotherapy in specifically inhibiting the growth of ErbB2-positive breast tumor cells. Thus, our studies illuminate epigenetic steps in the selection for ErbB2 activation.
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http://dx.doi.org/10.1016/j.celrep.2013.09.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3905738PMC
October 2013

The C terminus of p53 regulates gene expression by multiple mechanisms in a target- and tissue-specific manner in vivo.

Genes Dev 2013 Sep;27(17):1868-85

Department of Oncological Sciences.

The p53 tumor suppressor is a transcription factor that mediates varied cellular responses. The C terminus of p53 is subjected to multiple and diverse post-translational modifications. An attractive hypothesis is that differing sets of combinatorial modifications therein determine distinct cellular outcomes. To address this in vivo, a Trp53(ΔCTD/ΔCTD) mouse was generated in which the endogenous p53 is targeted and replaced with a truncated mutant lacking the C-terminal 24 amino acids. These Trp53(ΔCTD/ΔCTD) mice die within 2 wk post-partum with hematopoietic failure and impaired cerebellar development. Intriguingly, the C terminus acts via three distinct mechanisms to control p53-dependent gene expression depending on the tissue. First, in the bone marrow and thymus, the C terminus dampens p53 activity. Increased senescence in the Trp53(ΔCTD/ΔCTD) bone marrow is accompanied by up-regulation of Cdkn1 (p21). In the thymus, the C-terminal domain negatively regulates p53-dependent gene expression by inhibiting promoter occupancy. Here, the hyperactive p53(ΔCTD) induces apoptosis via enhanced expression of the proapoptotic Bbc3 (Puma) and Pmaip1 (Noxa). In the liver, a second mechanism prevails, since p53(ΔCTD) has wild-type DNA binding but impaired gene expression. Thus, the C terminus of p53 is needed in liver cells at a step subsequent to DNA binding. Finally, in the spleen, the C terminus controls p53 protein levels, with the overexpressed p53(ΔCTD) showing hyperactivity for gene expression. Thus, the C terminus of p53 regulates gene expression via multiple mechanisms depending on the tissue and target, and this leads to specific phenotypic effects in vivo.
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http://dx.doi.org/10.1101/gad.224386.113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3778241PMC
September 2013

β-Catenin-independent activation of TCF1/LEF1 in human hematopoietic tumor cells through interaction with ATF2 transcription factors.

PLoS Genet 2013 15;9(8):e1003603. Epub 2013 Aug 15.

Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America.

The role of Wnt signaling in embryonic development and stem cell maintenance is well established and aberrations leading to the constitutive up-regulation of this pathway are frequent in several types of human cancers. Upon ligand-mediated activation, Wnt receptors promote the stabilization of β-catenin, which translocates to the nucleus and binds to the T-cell factor/lymphoid enhancer factor (TCF/LEF) family of transcription factors to regulate the expression of Wnt target genes. When not bound to β-catenin, the TCF/LEF proteins are believed to act as transcriptional repressors. Using a specific lentiviral reporter, we identified hematopoietic tumor cells displaying constitutive TCF/LEF transcriptional activation in the absence of β-catenin stabilization. Suppression of TCF/LEF activity in these cells mediated by an inducible dominant-negative TCF4 (DN-TCF4) inhibited both cell growth and the expression of Wnt target genes. Further, expression of TCF1 and LEF1, but not TCF4, stimulated TCF/LEF reporter activity in certain human cell lines independently of β-catenin. By a complementary approach in vivo, TCF1 mutants, which lacked the ability to bind to β-catenin, induced Xenopus embryo axis duplication, a hallmark of Wnt activation, and the expression of the Wnt target gene Xnr3. Through generation of different TCF1-TCF4 fusion proteins, we identified three distinct TCF1 domains that participate in the β-catenin-independent activity of this transcription factor. TCF1 and LEF1 physically interacted and functionally synergized with members of the activating transcription factor 2 (ATF2) family of transcription factors. Moreover, knockdown of ATF2 expression in lymphoma cells phenocopied the inhibitory effects of DN-TCF4 on the expression of target genes associated with the Wnt pathway and on cell growth. Together, our findings indicate that, through interaction with ATF2 factors, TCF1/LEF1 promote the growth of hematopoietic malignancies in the absence of β-catenin stabilization, thus establishing a new mechanism for TCF1/LEF1 transcriptional activity distinct from that associated with canonical Wnt signaling.
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http://dx.doi.org/10.1371/journal.pgen.1003603DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3744423PMC
March 2014

Wnt pathway activation predicts increased risk of tumor recurrence in patients with stage I nonsmall cell lung cancer.

Ann Surg 2013 Mar;257(3):548-54

Division of Thoracic Surgery, The Mount Sinai Medical Center, New York, NY 10029, USA.

Objective: To determine the incidence of Wnt pathway activation in patients with stage I NSCLC and its influence on lung cancer recurrence.

Background: Despite resection, the 5-year recurrence with localized stage I nonsmall cell lung cancer (NSCLC) is 18.4%-24%. Aberrant Wnt signaling activation plays an important role in a wide variety of tumor types. However, there is not much known about the role the Wnt pathway plays in patients with stage I lung cancer.

Methods: Tumor and normal lung tissues from 55 patients following resection for stage I NSCLC were subjected to glutathione S-transferase (GST) E-cadherin pulldown and immunoblot analysis to assess levels of uncomplexed β-catenin, a reliable measure of Wnt signaling activation. The β-catenin gene was also screened for oncogenic mutations in tumors with activated Wnt signaling. Cancer recurrence rates were correlated in a blinded manner in patients with Wnt pathway-positive and -negative tumors.

Results: Tumors in 20 patients (36.4%) scored as Wnt positive, with only 1 exhibiting a β-catenin oncogenic mutation. Patients with Wnt-positive tumors experienced a significantly higher rate of overall cancer recurrence than those with Wnt-negative tumors (30.0% vs. 5.7%, P = 0.02), with 25.0% exhibiting distal tumor recurrence compared with 2.9% in the Wnt-negative group (P = 0.02).

Conclusions: Wnt pathway activation occurred in a substantial fraction of Stage I NSCLCs, which was rarely due to mutations. Moreover, Wnt pathway activation was associated with a significantly higher rate of tumor recurrence. These findings suggest that Wnt pathway activation reflects a more aggressive tumor phenotype and identifies patients who may benefit from more aggressive therapy in addition to resection.
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http://dx.doi.org/10.1097/SLA.0b013e31826d81fdDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3546156PMC
March 2013

Expression of the p53 target CDIP correlates with sensitivity to TNFα-induced apoptosis in cancer cells.

Cancer Res 2012 May;72(9):2373-82

Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, USA.

TNFα is a pleiotropic cytokine that signals for both survival and apoptotic cell fates. It is still unclear that the dual role of TNFα can be regulated in cancer cells. We previously described an apoptotic pathway involving p53→CDIP→TNFα that was activated in response to genotoxic stress. This pathway operated in the presence of JNK activation; therefore, we postulated that CDIP itself could sensitize cells to a TNFα apoptotic cell fate, survival, or death. We show that CDIP mediates sensitivity to TNFα-induced apoptosis and that cancer cells with endogenous CDIP expression are inherently sensitive to the growth-suppressive effects of TNFα in vitro and in vivo. Thus, CDIP expression correlates with sensitivity of cancer cells with TNFα, and CDIP seems to be a regulator of the p53-mediated death versus survival response of cells to TNFα. This CDIP-mediated sensitivity to TNFα-induced apoptosis favors pro- over antiapoptotic program in cancer cells, and CDIP may serve as a predictive biomarker for such sensitivity.
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http://dx.doi.org/10.1158/0008-5472.CAN-11-3369DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3349239PMC
May 2012
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