Publications by authors named "Joerg Huelsken"

51 Publications

High-content, targeted RNA-seq screening in organoids for drug discovery in colorectal cancer.

Cell Rep 2021 Apr;35(3):109026

Swiss Institute for Experimental Cancer Research (ISREC), École Polytechnique Fédérale de Lausanne-(EPFL-SV), 1015 Lausanne, Switzerland. Electronic address:

Organoids allow the recapitulation of intestinal homeostasis and cancerogenesis in vitro; however, RNA sequencing (RNA-seq)-based methods for drug screens are missing. We develop targeted organoid sequencing (TORNADO-seq), a high-throughput, high-content drug discovery platform that uses targeted RNA-seq to monitor the expression of large gene signatures for the detailed evaluation of cellular phenotypes in organoids. TORNADO-seq is a fast, highly reproducible time- and cost-effective ($5 per sample) method that can probe cell mixtures and their differentiation state in the intestinal system. We apply this method to isolate drugs that enrich for differentiated cell phenotypes and show that these drugs are highly efficacious against cancer compared to wild-type organoids. Furthermore, TORNADO-seq facilitates in-depth insight into the mode of action of these drugs. Our technology can easily be adapted to many other systems and will allow for more systematic, large-scale, and quantitative approaches to study the biology of complex cellular systems.
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http://dx.doi.org/10.1016/j.celrep.2021.109026DOI Listing
April 2021

Genomic Instability Profiles at the Single Cell Level in Mouse Colorectal Cancers of Defined Genotypes.

Cancers (Basel) 2021 Mar 12;13(6). Epub 2021 Mar 12.

Department of Molecular Biology, University of Geneva, 1211 Geneva, Switzerland.

The genomes of many human CRCs have been sequenced, revealing a large number of genetic alterations. However, the molecular mechanisms underlying the accumulation of these alterations are still being debated. In this study, we examined colorectal tumours that developed in mice with , , and targetable alleles. Organoids were derived from single cells and the spectrum of mutations was determined by exome sequencing. The number of single nucleotide substitutions (SNSs) correlated with the age of the tumour, but was unaffected by the number of targeted cancer-driver genes. Thus, tumours that expressed mutant , and alleles had as many SNSs as tumours that expressed only mutant . In contrast, the presence of large-scale (>10 Mb) copy number alterations (CNAs) correlated strongly with inactivation. Comparison of the SNSs and CNAs present in organoids derived from the same tumour revealed intratumoural heterogeneity consistent with genomic lesions accumulating at significantly higher rates in tumour cells compared to normal cells. The rate of acquisition of SNSs increased from the early stages of cancer development, whereas large-scale CNAs accumulated later, after inactivation. Thus, a significant fraction of the genomic instability present in cancer cells cannot be explained by aging processes occurring in normal cells before oncogenic transformation.
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http://dx.doi.org/10.3390/cancers13061267DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7999300PMC
March 2021

Niche-Mediated Integrin Signaling Supports Steady-State Hematopoiesis in the Spleen.

J Immunol 2021 Apr 26;206(7):1549-1560. Epub 2021 Feb 26.

School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Kerala 695551, India;

Outside-in integrin signaling regulates cell fate decisions in a variety of cell types, including hematopoietic stem cells (HSCs). Our earlier published studies showed that interruption of periostin (POSTN) and integrin-αv (ITGAV) interaction induces faster proliferation in HSCs with developmental stage-dependent functional effects. In this study, we examined the role of POSTN-ITGAV axis in lymphohematopoietic activity in spleen that hosts a rare population of HSCs, the functional regulation of which is not clearly known. -mediated deletion of in the hematopoietic system led to higher proliferation rates, resulting in increased frequency of primitive HSCs in the adult spleen. However, in vitro CFU-C assays demonstrated a poorer differentiation potential following deletion. This also led to a decrease in the white pulp area with a significant decline in the B cell numbers. Systemic deletion of its ligand, POSTN, phenocopied the effects noted in mice. Histological examination of -deficient spleen also showed an increase in the spleen trabecular areas. Importantly, these are the myofibroblasts of the trabecular and capsular areas that expressed high levels of POSTN within the spleen tissue. In addition, vascular smooth muscle cells also expressed POSTN. Through CFU-S assays, we showed that hematopoietic support potential of stroma in -deficient splenic hematopoietic niche was defective. Overall, we demonstrate that POSTN-ITGAV interaction plays an important role in spleen lymphohematopoiesis.
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http://dx.doi.org/10.4049/jimmunol.2001066DOI Listing
April 2021

The Periostin/Integrin-αv Axis Regulates the Size of Hematopoietic Stem Cell Pool in the Fetal Liver.

Stem Cell Reports 2020 08 30;15(2):340-357. Epub 2020 Jul 30.

School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, Kerala 695551, India. Electronic address:

We earlier showed that outside-in integrin signaling through POSTN-ITGAV interaction plays an important role in regulating adult hematopoietic stem cell (HSC) quiescence. Here, we show that Itgav deletion results in increased frequency of phenotypic HSCs in fetal liver (FL) due to faster proliferation. Systemic deletion of Postn led to increased proliferation of FL HSCs, albeit without any loss of stemness, unlike Vav-Itgav HSCs. Based on RNA sequencing analysis of FL and bone marrow HSCs, we predicted the involvement of DNA damage response pathways in this dichotomy. Indeed, proliferative HSCs from Postn-deficient FL tissues showed increased levels of DNA repair, resulting in lesser double-strand breaks. Thus POSTN, with its expression majorly localized in the vascular endothelium of FL tissue, acts as a regulator of stem cell pool size during development. Overall, we demonstrate that the duality of response to proliferation in HSCs is developmental stage dependent and can be correlated with DNA damage responses.
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http://dx.doi.org/10.1016/j.stemcr.2020.06.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7419718PMC
August 2020

Specific Gene Expression in Lgr5 Stem Cells by Using Cre-Lox Recombination.

Methods Mol Biol 2020 ;2171:249-255

Division of Cancer & Stem Cells, School of Medicine, Biodiscovery Institute, Centre for Cancer Sciences, University of Nottingham, Nottingham, UK.

Intestinal stem cells are responsible for tissue renewal. The study of stem cell properties has become a major challenge in the field. We describe here a method based on Cre recombinase inducible lentivirus vectors that permits delivery of transgenes, either for overexpression or knockdown, in primary stem cells that can be cultured in an 3D intestinal organoid system. This method is an excellent approach for genetic manipulation and can complement in vivo transgenic experiments.
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http://dx.doi.org/10.1007/978-1-0716-0747-3_16DOI Listing
March 2021

γ-Catenin-Dependent Signals Maintain BCR-ABL1 B Cell Acute Lymphoblastic Leukemia.

Cancer Cell 2019 04;35(4):649-663.e10

Department of Oncology UNIL CHUV, University of Lausanne, Epalinges, Switzerland. Electronic address:

The BCR-ABL1 fusion protein is the cause of chronic myeloid leukemia (CML) and of a significant fraction of adult-onset B cell acute lymphoblastic leukemia (B-ALL) cases. Using mouse models and patient-derived samples, we identified an essential role for γ-catenin in the initiation and maintenance of BCR-ABL1 B-ALL but not CML. The selectivity was explained by a partial γ-catenin dependence of MYC expression together with the susceptibility of B-ALL, but not CML, to reduced MYC levels. MYC and γ-catenin enabled B-ALL maintenance by augmenting BIRC5 and enforced BIRC5 expression overcame γ-catenin loss. Since γ-catenin was dispensable for normal hematopoiesis, these lineage- and disease-specific features of canonical Wnt signaling identified a potential therapeutic target for the treatment of BCR-ABL1 B-ALL.
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http://dx.doi.org/10.1016/j.ccell.2019.03.005DOI Listing
April 2019

Machine Learning Identifies Stemness Features Associated with Oncogenic Dedifferentiation.

Cell 2018 04;173(2):338-354.e15

Poznań University of Medical Sciences, 61701 Poznań, Poland; Greater Poland Cancer Center, 61866 Poznań, Poland; International Institute for Molecular Oncology, 60203 Poznań, Poland. Electronic address:

Cancer progression involves the gradual loss of a differentiated phenotype and acquisition of progenitor and stem-cell-like features. Here, we provide novel stemness indices for assessing the degree of oncogenic dedifferentiation. We used an innovative one-class logistic regression (OCLR) machine-learning algorithm to extract transcriptomic and epigenetic feature sets derived from non-transformed pluripotent stem cells and their differentiated progeny. Using OCLR, we were able to identify previously undiscovered biological mechanisms associated with the dedifferentiated oncogenic state. Analyses of the tumor microenvironment revealed unanticipated correlation of cancer stemness with immune checkpoint expression and infiltrating immune cells. We found that the dedifferentiated oncogenic phenotype was generally most prominent in metastatic tumors. Application of our stemness indices to single-cell data revealed patterns of intra-tumor molecular heterogeneity. Finally, the indices allowed for the identification of novel targets and possible targeted therapies aimed at tumor differentiation.
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http://dx.doi.org/10.1016/j.cell.2018.03.034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5902191PMC
April 2018

A Subset of Cancer-Associated Fibroblasts Determines Therapy Resistance.

Cell 2018 02;172(4):643-644

Laboratory of Translational Oncology, ISREC (Swiss Institute for Experimental Cancer Research), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne CH-1015, Switzerland.

While functional heterogeneity of fibroblastic cells populating the tumor microenvironment is increasingly recognized, lack of definitive markers complicates elucidation of roles among ostensibly distinctive fibroblastic states. In this issue of Cell, Su et al. characterize a new pro-tumorigenic cancer-associated fibroblast subset mediating chemoresistance defined and driven by a novel signaling pathway.
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http://dx.doi.org/10.1016/j.cell.2018.01.028DOI Listing
February 2018

Cross-Tissue Identification of Somatic Stem and Progenitor Cells Using a Single-Cell RNA-Sequencing Derived Gene Signature.

Stem Cells 2017 12 6;35(12):2390-2402. Epub 2017 Nov 6.

Laboratory of Systems Biology and Genetics, Institute of Bioengineering and Swiss Institute of Bioinformatics, CH-1015, Lausanne, Switzerland.

A long-standing question in biology is whether multipotent somatic stem and progenitor cells (SSPCs) feature molecular properties that could guide their system-independent identification. Population-based transcriptomic studies have so far not been able to provide a definite answer, given the rarity and heterogeneous nature of these cells. Here, we exploited the resolving power of single-cell RNA-sequencing to develop a computational model that is able to accurately distinguish SSPCs from differentiated cells across tissues. The resulting classifier is based on the combined expression of 23 genes including known players in multipotency, proliferation, and tumorigenesis, as well as novel ones, such as Lcp1 and Vgll4 that we functionally validate in intestinal organoids. We show how this approach enables the identification of stem-like cells in still ambiguous systems such as the pancreas and the epidermis as well as the exploration of lineage commitment hierarchies, thus facilitating the study of biological processes such as cellular differentiation, tissue regeneration, and cancer. Stem Cells 2017;35:2390-2402.
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http://dx.doi.org/10.1002/stem.2719DOI Listing
December 2017

Long-Term Engraftment of Primary Bone Marrow Stromal Cells Repairs Niche Damage and Improves Hematopoietic Stem Cell Transplantation.

Cell Stem Cell 2017 08;21(2):241-255.e6

École Polytechnique Fédérale de Lausanne (EPFL), ISREC (Swiss Institute for Experimental Cancer Research), Lausanne 1015, Switzerland. Electronic address:

Hematopoietic stem cell (HSC) transplantation represents a curative treatment for various hematological disorders. However, delayed reconstitution of innate and adaptive immunity often causes fatal complications. HSC maintenance and lineage differentiation are supported by stromal niches, and we now find that bone marrow stroma cells (BMSCs) are severely and permanently damaged by the pre-conditioning irradiation required for efficient HSC transplantation. Using mouse models, we show that stromal insufficiency limits the number of donor-derived HSCs and B lymphopoiesis. Intra-bone transplantation of primary, but not cultured, BMSCs quantitatively reconstitutes stroma function in vivo, which is mediated by a multipotent NT5E (CD73) ENG (CD105) LY6A (SCA1) BMSC subpopulation. BMSC co-transplantation doubles the number of functional, donor-derived HSCs and significantly reduces clinically relevant side effects associated with HSC transplantation including neutropenia and humoral immunodeficiency. These data demonstrate the potential of stroma recovery to improve HSC transplantation.
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http://dx.doi.org/10.1016/j.stem.2017.07.004DOI Listing
August 2017

Enhanced Rate of Acquisition of Point Mutations in Mouse Intestinal Adenomas Compared to Normal Tissue.

Cell Rep 2017 06;19(11):2185-2192

Department of Molecular Biology, University of Geneva, 1211 Geneva, Switzerland; Biomedical Research Foundation of the Academy of Athens, 11527 Athens, Greece. Electronic address:

The most prevalent single-nucleotide substitution (SNS) found in cancers is a C-to-T substitution in the CpG motif. It has been proposed that many of these SNSs arise during organismal aging, prior to transformation of a normal cell into a precancerous/cancer cell. Here, we isolated single intestinal crypts derived from normal tissue or from adenomas of Apc mice, expanded them minimally in vitro as organoids, and performed exome sequencing to identify point mutations that had been acquired in vivo at the single-cell level. SNSs, most of them being CpG-to-TpG substitutions, were at least ten times more frequent in adenoma than normal cells. Thus, contrary to the view that substitutions of this type are present due to normal-cell aging, the acquisition of point mutations increases upon transformation of a normal intestinal cell into a precancerous cell.
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http://dx.doi.org/10.1016/j.celrep.2017.05.051DOI Listing
June 2017

Outside-in integrin signalling regulates haematopoietic stem cell function via Periostin-Itgav axis.

Nat Commun 2016 12 1;7:13500. Epub 2016 Dec 1.

Inter-departmental Stem Cell Institute, KU Leuven, 3000 Leuven, Belgium.

Integrins play an important role in haematopoietic stem cell (HSC) maintenance in the bone marrow niche. Here, we demonstrate that Periostin (Postn) via interaction with Integrin-αv (Itgav) regulates HSC proliferation. Systemic deletion of Postn results in peripheral blood (PB) anaemia, myelomonocytosis and lymphopenia, while the number of phenotypic HSCs increases in the bone marrow. Postn mice recover faster from radiation injury with concomitant loss of primitive HSCs. HSCs from Postn mice show accumulation of DNA damage generally associated with aged HSCs. Itgav deletion in the haematopoietic system leads to a similar PB phenotype and HSC-intrinsic repopulation defects. Unaffected by Postn, Vav-Itgav HSCs proliferate faster in vitro, illustrating the importance of Postn-Itgav interaction. Finally, the Postn-Itgav interaction inhibits the FAK/PI3K/AKT pathway in HSCs, leading to increase in p27Kip1 expression resulting in improved maintenance of quiescent HSCs. Together, we demonstrate a role for Itgav-mediated outside-in signalling in regulation of HSC proliferation and stemness.
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http://dx.doi.org/10.1038/ncomms13500DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5146274PMC
December 2016

Phage Selection of Chemically Stabilized α-Helical Peptide Ligands.

ACS Chem Biol 2016 05 11;11(5):1422-7. Epub 2016 Mar 11.

Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne , CH-1015 Lausanne, Switzerland.

Short α-helical peptides stabilized by linkages between constituent amino acids offer an attractive format for ligand development. In recent years, a range of excellent ligands based on stabilized α-helices were generated by rational design using α-helical peptides of natural proteins as templates. Herein, we developed a method to engineer chemically stabilized α-helical ligands in a combinatorial fashion. In brief, peptides containing cysteines in position i and i + 4 are genetically encoded by phage display, the cysteines are modified with chemical bridges to impose α-helical conformations, and binders are isolated by affinity selection. We applied the strategy to affinity mature an α-helical peptide binding β-catenin. We succeeded in developing ligands with Kd's as low as 5.2 nM, having >200-fold improved affinity. The strategy is generally applicable for affinity maturation of any α-helical peptide. Compared to hydrocarbon stapled peptides, the herein evolved thioether-bridged peptide ligands can be synthesized more easily, as no unnatural amino acids are required and the cyclization reaction is more efficient and yields no stereoisomers. A further advantage of the thioether-bridged peptide ligands is that they can be expressed recombinantly as fusion proteins.
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http://dx.doi.org/10.1021/acschembio.5b00963DOI Listing
May 2016

Phage Selection of Peptide Macrocycles against β-Catenin To Interfere with Wnt Signaling.

ChemMedChem 2016 Apr 26;11(8):834-9. Epub 2016 Jan 26.

Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland.

Upregulation of β-catenin, the primary mediator of the Wnt signaling pathway, plays an important role in the tumorigenesis of several types of human cancer. Targeting β-catenin to interfere with its ability to serve as a translational co-activator is considered an attractive therapeutic approach. However, the development of inhibitors has been challenging because of the lack of obvious binding pockets for ligands, and because inhibitors should not interfere with other β-catenin functions. Only two ligands with known molecular interactions with β-catenin have been developed so far, and are based on stabilized α-helical peptides. In this study, we screened a large combinatorial library of bicyclic peptides by phage display. Binders to different surface regions of β-catenin were identified. The binding site of one group of ligands was mapped to the interaction region of the translational Wnt inhibitor ICAT (inhibitor of β-catenin and Tcf), which is a prime target site on β-catenin for therapeutic intervention, and to which no ligands could be developed before.
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http://dx.doi.org/10.1002/cmdc.201500557DOI Listing
April 2016

HOXA5 Counteracts Stem Cell Traits by Inhibiting Wnt Signaling in Colorectal Cancer.

Cancer Cell 2015 Dec;28(6):815-829

École Polytechnique Fédérale de Lausanne (EPFL), ISREC (Swiss Institute for Experimental Cancer Research), Lausanne 1015, Switzerland. Electronic address:

Hierarchical organization of tissues relies on stem cells, which either self-renew or produce committed progenitors predestined for lineage differentiation. Here we identify HOXA5 as an important repressor of intestinal stem cell fate in vivo and identify a reciprocal feedback between HOXA5 and Wnt signaling. HOXA5 is suppressed by the Wnt pathway to maintain stemness and becomes active only outside the intestinal crypt where it inhibits Wnt signaling to enforce differentiation. In colon cancer, HOXA5 is downregulated, and its re-expression induces loss of the cancer stem cell phenotype, preventing tumor progression and metastasis. Tumor regression by HOXA5 induction can be triggered by retinoids, which represent tangible means to treat colon cancer by eliminating cancer stem cells.
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http://dx.doi.org/10.1016/j.ccell.2015.11.001DOI Listing
December 2015

Polycomb Complex PRC1 Preserves Intestinal Stem Cell Identity by Sustaining Wnt/β-Catenin Transcriptional Activity.

Cell Stem Cell 2016 Jan 29;18(1):91-103. Epub 2015 Oct 29.

Department of Experimental Oncology, European Institute of Oncology, Via Adamello 16, 20139 Milan, Italy. Electronic address:

Polycomb repressive complexes (PRCs) are among the most important gatekeepers of establishing and maintaining cell identity in metazoans. PRC1, which plays a dominant role in this context, executes its functions via multiple subcomplexes, which all contribute to H2AK119 mono-ubiquitination (H2Aubq). Despite our comprehensive knowledge of PRC1-dependent H2Aubq in embryonic stem cells and during early development, its role in adult stem cells still remains poorly characterized. Here we show that PRC1 activity is required for the integrity of the intestinal epithelium, regulating stem cell self-renewal via a cell-autonomous mechanism that is independent from Cdkn2a expression. By dissecting the PRC1-dependent transcription program in intestinal stem cells, we demonstrate that PRC1 represses a large number of non-lineage-specific transcription factors that directly affect β-catenin/Tcf transcriptional activity. Our data reveal that PRC1 preserves Wnt/β-catenin activity in adult stem cells to maintain intestinal homeostasis and supports tumor formation induced by the constitutive activation of this pathway.
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http://dx.doi.org/10.1016/j.stem.2015.09.019DOI Listing
January 2016

Complex metastatic niches: already a target for therapy?

Curr Opin Cell Biol 2014 Dec 16;31:29-38. Epub 2014 Jul 16.

École Polytechnique Fédérale de Lausanne (EPFL), ISREC (Swiss Institute for Experimental Cancer Research), Lausanne, Switzerland. Electronic address:

Metastatic spread is an inefficient process which requires generation of supportive microenvironments in which cancer cells can survive, proliferate and escape from immune attack. These niches are induced by systemic and locally produced factors and establish a tumor-supportive and immune suppressive environment which is molecularly and functionally different from the niche at the primary site. Tumor dormancy may result if the niche is not sufficiently supportive/protective. Co-evolution of cancer cells and the surrounding microenvironment creates a large number of such dynamic niches, and we are just beginning to elucidate the complexity of these interactions and their tissue-specific differences. We will discuss exciting possibilities but also challenges which are immanent when trying to target these stromal responses for diagnosis and therapy.
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http://dx.doi.org/10.1016/j.ceb.2014.06.012DOI Listing
December 2014

Autolysosomal β-catenin degradation regulates Wnt-autophagy-p62 crosstalk.

EMBO J 2013 Jul 4;32(13):1903-16. Epub 2013 Jun 4.

Cancer Research UK Colorectal Tumour Biology Group, School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK.

The Wnt/β-catenin signalling and autophagy pathways each play important roles during development, adult tissue homeostasis and tumorigenesis. Here we identify the Wnt/β-catenin signalling pathway as a negative regulator of both basal and stress-induced autophagy. Manipulation of β-catenin expression levels in vitro and in vivo revealed that β-catenin suppresses autophagosome formation and directly represses p62/SQSTM1 (encoding the autophagy adaptor p62) via TCF4. Furthermore, we show that during nutrient deprivation β-catenin is selectively degraded via the formation of a β-catenin-LC3 complex, attenuating β-catenin/TCF-driven transcription and proliferation to favour adaptation during metabolic stress. Formation of the β-catenin-LC3 complex is mediated by a W/YXXI/L motif and LC3-interacting region (LIR) in β-catenin, which is required for interaction with LC3 and non-proteasomal degradation of β-catenin. Thus, Wnt/β-catenin represses autophagy and p62 expression, while β-catenin is itself targeted for autophagic clearance in autolysosomes upon autophagy induction. These findings reveal a regulatory feedback mechanism that place β-catenin at a key cellular integration point coordinating proliferation with autophagy, with implications for targeting these pathways for cancer therapy.
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http://dx.doi.org/10.1038/emboj.2013.123DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3981178PMC
July 2013

Metastasis: New insights into organ-specific extravasation and metastatic niches.

Exp Cell Res 2013 Jul 21;319(11):1604-10. Epub 2013 Feb 21.

Ecole Polytechnique Fédérale de Lausanne, Swiss Institute for Experimental Cancer Research and National Center of Competence in Research "Molecular Oncology", 1015 Lausanne, Switzerland. Electronic address:

The appearance of clinically detectable metastases is the end-point of a complex set of biological processes only few cancer cells are capable to complete. Metastatic colonization comprises the most inefficient metastatic steps as it requires a fine-tuned crosstalk between the disseminated cancer (stem) cells and their host microenvironment. The origin of the cancer cell and its intrinsic properties are factors that together with the organ microenvironment and circulation patterns determine the site of metastatic spread, the dormancy period and the extent of metastasis formation. Recent advances provide novel insights into the molecular components required for organ-specific infiltration, the composition of growth-supportive metastatic niches in different tissues and the cancer cell-niche crosstalk.
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http://dx.doi.org/10.1016/j.yexcr.2013.02.012DOI Listing
July 2013

Lrig1: a new master regulator of epithelial stem cells.

EMBO J 2012 May 20;31(9):2064-6. Epub 2012 Mar 20.

Ecole Polytechnique Fédérale de Lausanne, ISREC (Swiss Institute for Experimental Cancer Research) and National Center of Competence in Research Molecular Oncology, Lausanne, Switzerland.

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http://dx.doi.org/10.1038/emboj.2012.73DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3343471PMC
May 2012

Interactions between cancer stem cells and their niche govern metastatic colonization.

Nature 2011 Dec 7;481(7379):85-9. Epub 2011 Dec 7.

Ecole Polytechnique Fédérale de Lausanne, Swiss Institute for Experimental Cancer Research and National Center of Competence in Research Molecular Oncology, 1015 Lausanne, Switzerland.

Metastatic growth in distant organs is the major cause of cancer mortality. The development of metastasis is a multistage process with several rate-limiting steps. Although dissemination of tumour cells seems to be an early and frequent event, the successful initiation of metastatic growth, a process termed 'metastatic colonization', is inefficient for many cancer types and is accomplished only by a minority of cancer cells that reach distant sites. Prevalent target sites are characteristic of many tumour entities, suggesting that inadequate support by distant tissues contributes to the inefficiency of the metastatic process. Here we show that a small population of cancer stem cells is critical for metastatic colonization, that is, the initial expansion of cancer cells at the secondary site, and that stromal niche signals are crucial to this expansion process. We find that periostin (POSTN), a component of the extracellular matrix, is expressed by fibroblasts in the normal tissue and in the stroma of the primary tumour. Infiltrating tumour cells need to induce stromal POSTN expression in the secondary target organ (in this case lung) to initiate colonization. POSTN is required to allow cancer stem cell maintenance, and blocking its function prevents metastasis. POSTN recruits Wnt ligands and thereby increases Wnt signalling in cancer stem cells. We suggest that the education of stromal cells by infiltrating tumour cells is an important step in metastatic colonization and that preventing de novo niche formation may be a novel strategy for the treatment of metastatic disease.
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http://dx.doi.org/10.1038/nature10694DOI Listing
December 2011

β-catenin represses expression of the tumour suppressor 15-prostaglandin dehydrogenase in the normal intestinal epithelium and colorectal tumour cells.

Gut 2012 Sep 14;61(9):1306-14. Epub 2011 Nov 14.

Cancer Research UK Colorectal Tumour Biology Research Group, School of Cellular and Molecular Medicine, University Walk, University of Bristol, Bristol, UK.

Background: Cyclooxygenase-2 (COX-2) overexpression in colorectal cancer increases levels of its pro-tumorigenic product prostaglandin E2 (PGE(2)). The recently identified colorectal tumour suppressor 15-prostaglandin dehydrogenase (15-PGDH) catalyses prostaglandin turnover and is downregulated at a very early stage in colorectal tumorigenesis; however, the mechanism responsible remains unclear. As Wnt/β-catenin signalling is also deregulated early in colorectal neoplasia, a study was undertaken to determine whether β-catenin represses 15-PGDH expression.

Methods: The effect of modulating Wnt/β-catenin signalling (using β-catenin siRNA, mutant TCF4, Wnt3A or GSK3 inhibition) on 15-PGDH mRNA, protein expression and promoter activity was determined in colorectal cell lines by immunoblotting, qRT-PCR and reporter assays. The effect of β-catenin deletion in vivo was addressed by 15-PGDH immunostaining of β-catenin(-/lox)-villin-creERT2 mouse tissue. 15-PGDH promoter occupancy was determined using chromatin immunoprecipitation and PGE(2) levels by ELISA.

Results: The study shows for the first time that β-catenin knockdown upregulates 15-PGDH in colorectal adenoma and carcinoma cells without affecting COX-2 protein levels. A dominant negative mutant form of TCF4 (dnTCF4), unable to bind β-catenin, also upregulated 15-PGDH; conversely, increasing β-catenin activity using Wnt3A or GSK3 inhibition downregulated 15-PGDH. Importantly, inducible β-catenin deletion in vivo also upregulated intestinal epithelial 15-PGDH. 15-PGDH regulation occurred at the protein, mRNA and promoter activity levels and chromatin immunoprecipitation indicated β-catenin/TCF4 binding to the 15-PGDH promoter. β-catenin knockdown decreased PGE(2) levels, and this was significantly rescued by 15-PGDH siRNA.

Conclusion: These data suggest a novel role for β-catenin in promoting colorectal tumorigenesis through very early 15-PGDH suppression leading to increased PGE(2) levels, possibly even before COX-2 upregulation.
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http://dx.doi.org/10.1136/gutjnl-2011-300817DOI Listing
September 2012

Neural stem cells are increased after loss of β-catenin, but neural progenitors undergo cell death.

Eur J Neurosci 2011 Apr 7;33(8):1366-75. Epub 2011 Mar 7.

Department of Medical Genetics and Microbiology, University of Toronto, Toronto, Canada.

Neurons and glia in the central nervous system originate from neural stem and progenitor cells that reside in the ventricular zones. Here we examine the role of β-catenin in neural stem cell (NSC) regulation in mouse embryos lacking β-catenin specifically in the brain germinal zone. An in vitro clonal neurosphere assay was performed in order to ascertain the status of the NSC population. Intact neurospheres did not form from β-catenin-null cells due to a loss of cell adhesion and the number of expanded cells was reduced. Rescue of β-catenin expression restored adhesion and revealed that the number of NSCs increased in the knockout population. Using a clonal colony-forming assay, which confines precursor cells within a solid collagen matrix, we show that the number of NSCs in the hippocampus is unchanged although the β-catenin knockout striatum actually contains a larger proportion of NSCs. However, these colonies were smaller than those of control cells, due to increased apoptosis in the progenitor population. Furthermore, β-catenin knockout NSCs also retained multipotentiality as shown by their ability to clonally differentiate into neurons and glia. The effects on neural precursor cells were not due to loss of downstream T-cell factor signaling, as this pathway is not active in vivo in regions of the embryonic brain where NSCs and progenitor cells reside, nor is it active in vitro in NSC colonies. These data reveal that β-catenin is not required for the maintenance or differentiation of NSCs, but is required for the adhesion and survival of neural progenitor cells.
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http://dx.doi.org/10.1111/j.1460-9568.2011.07632.xDOI Listing
April 2011

Essential role of the Wnt pathway effector Tcf-1 for the establishment of functional CD8 T cell memory.

Proc Natl Acad Sci U S A 2010 May 10;107(21):9777-82. Epub 2010 May 10.

Ludwig Institute for Cancer Research Ltd., Lausanne Branch and University of Lausanne, Epalinges, Switzerland.

Immune protection from intracellular pathogens depends on the generation of terminally differentiated effector and of multipotent memory precursor CD8 T cells, which rapidly regenerate effector and memory cells during recurrent infection. The identification of factors and pathways involved in CD8 T cell differentiation is of obvious importance to improve vaccination strategies. Here, we show that mice lacking T cell factor 1 (Tcf-1), a nuclear effector of the canonical Wingless/Integration 1 (Wnt) signaling pathway, mount normal effector and effector memory CD8 T cell responses to infection with lymphocytic choriomeningitis virus (LCMV). However, Tcf-1-deficient CD8 T cells are selectively impaired in their ability to expand upon secondary challenge and to protect from recurrent virus infection. Tcf-1-deficient mice essentially lack CD8 memory precursor T cells, which is evident already at the peak of the primary response, suggesting that Tcf-1 programs CD8 memory cell fate. The function of Tcf-1 to establish CD8 T cell memory is dependent on the catenin-binding domain in Tcf-1 and requires the Tcf-1 coactivators and Wnt signaling intermediates beta-catenin and gamma-catenin. These findings demonstrate that the canonical Wnt signaling pathway plays an essential role for CD8 central memory T cell differentiation under physiological conditions in vivo. They raise the possibility that modulation of Wnt signaling may be exploited to improve the generation of CD8 memory T cells during vaccination or for therapies designed to promote sustained cytotoxic CD8 T cell responses against tumors.
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http://dx.doi.org/10.1073/pnas.0914127107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2906901PMC
May 2010

SOX2 is an oncogene activated by recurrent 3q26.3 amplifications in human lung squamous cell carcinomas.

PLoS One 2010 Jan 29;5(1):e8960. Epub 2010 Jan 29.

Département Biologie du Cancer, Institut National de la Santé et de la Recherche Médicale, Institut de Génétique et de Biologie Moléculaire et Cellulaire, U964 Illkirch, France.

Squamous cell carcinoma (SCC) of the lung is a frequent and aggressive cancer type. Gene amplifications, a known activating mechanism of oncogenes, target the 3q26-qter region as one of the most frequently gained/amplified genomic sites in SCC of various types. Here, we used array comparative genomic hybridization to delineate the consensus region of 3q26.3 amplifications in lung SCC. Recurrent amplifications occur in 20% of lung SCC (136 tumors in total) and map to a core region of 2 Mb (Megabases) that encompasses SOX2, a transcription factor gene. Intense SOX2 immunostaining is frequent in nuclei of lung SCC, indicating potential active transcriptional regulation by SOX2. Analyses of the transcriptome of lung SCC, SOX2-overexpressing lung epithelial cells and embryonic stem cells (ESCs) reveal that SOX2 contributes to activate ESC-like phenotypes and provide clues pertaining to the deregulated genes involved in the malignant phenotype. In cell culture experiments, overexpression of SOX2 stimulates cellular migration and anchorage-independent growth while SOX2 knockdown impairs cell growth. Finally, SOX2 over-expression in non-tumorigenic human lung bronchial epithelial cells is tumorigenic in immunocompromised mice. These results indicate that the SOX2 transcription factor, a major regulator of stem cell function, is also an oncogene and a driver gene for the recurrent 3q26.33 amplifications in lung SCC.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0008960PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2813300PMC
January 2010

Genetic dissection of differential signaling threshold requirements for the Wnt/beta-catenin pathway in vivo.

PLoS Genet 2010 Jan 15;6(1):e1000816. Epub 2010 Jan 15.

Ludwig Institute for Cancer Research, Royal Melbourne Hospital, Parkville, Australia.

Contributions of null and hypomorphic alleles of Apc in mice produce both developmental and pathophysiological phenotypes. To ascribe the resulting genotype-to-phenotype relationship unambiguously to the Wnt/beta-catenin pathway, we challenged the allele combinations by genetically restricting intracellular beta-catenin expression in the corresponding compound mutant mice. Subsequent evaluation of the extent of resulting Tcf4-reporter activity in mouse embryo fibroblasts enabled genetic measurement of Wnt/beta-catenin signaling in the form of an allelic series of mouse mutants. Different permissive Wnt signaling thresholds appear to be required for the embryonic development of head structures, adult intestinal polyposis, hepatocellular carcinomas, liver zonation, and the development of natural killer cells. Furthermore, we identify a homozygous Apc allele combination with Wnt/beta-catenin signaling capacity similar to that in the germline of the Apc(min) mice, where somatic Apc loss-of-heterozygosity triggers intestinal polyposis, to distinguish whether co-morbidities in Apc(min) mice arise independently of intestinal tumorigenesis. Together, the present genotype-phenotype analysis suggests tissue-specific response levels for the Wnt/beta-catenin pathway that regulate both physiological and pathophysiological conditions.
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http://dx.doi.org/10.1371/journal.pgen.1000816DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2800045PMC
January 2010

Canonical Wnt signalling plays essential roles.

Eur J Immunol 2009 Dec;39(12):3582-3; author reply 3583-4

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http://dx.doi.org/10.1002/eji.200838982DOI Listing
December 2009

Reciprocal requirements for EDA/EDAR/NF-kappaB and Wnt/beta-catenin signaling pathways in hair follicle induction.

Dev Cell 2009 Jul;17(1):49-61

Departments of Dermatology and Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.

Wnt/beta-catenin and NF-kappaB signaling mechanisms provide central controls in development and disease, but how these pathways intersect is unclear. Using hair follicle induction as a model system, we show that patterning of dermal Wnt/beta-catenin signaling requires epithelial beta-catenin activity. We find that Wnt/beta-catenin signaling is absolutely required for NF-kappaB activation, and that Edar is a direct Wnt target gene. Wnt/beta-catenin signaling is initially activated independently of EDA/EDAR/NF-kappaB activity in primary hair follicle primordia. However, Eda/Edar/NF-kappaB signaling is required to refine the pattern of Wnt/beta-catenin activity, and to maintain this activity at later stages of placode development. We show that maintenance of localized expression of Wnt10b and Wnt10a requires NF-kappaB signaling, providing a molecular explanation for the latter observation, and identify Wnt10b as a direct NF-kappaB target. These data reveal a complex interplay and interdependence of Wnt/beta-catenin and EDA/EDAR/NF-kappaB signaling pathways in initiation and maintenance of primary hair follicle placodes.
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http://dx.doi.org/10.1016/j.devcel.2009.05.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2859042PMC
July 2009

Tissue-specific stem cells: friend or foe?

Authors:
Joerg Huelsken

Cell Res 2009 Mar;19(3):279-81

Ecole Polytechnique Fédérale de Lausanne, Swiss Institute for Experimental Cancer Research, National Center of Competence in Research-Molecular Oncology, Chemin des Boveresses 155, Epalinges, Switzerland.

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http://dx.doi.org/10.1038/cr.2009.24DOI Listing
March 2009

Inducibility of drug-metabolizing enzymes by xenobiotics in mice with liver-specific knockout of Ctnnb1.

Drug Metab Dispos 2009 May 23;37(5):1138-45. Epub 2009 Feb 23.

Institute of Pharmacology and Toxicology, Department of Toxicology, University of Tübingen, Wilhelmstr. 56, 72074 Tübingen, Germany.

Basal as well as xenobiotic-induced expression of the main enzymes from phase I and phase II of drug metabolism is confined to the perivenous areas of the mammalian liver lobule. Whereas signal transduction pathways that govern xenobiotic-induced expression of these enzymes via ligand-activated transcription factors such as constitutive androstane receptor (CAR) or the aryl hydrocarbon receptor (AhR) have been intensively studied, the mechanisms regulating zone-specific basal expression of genes related to drug metabolism and preferential response of perivenous hepatocytes to xenobiotic inducers are still largely unknown. Recent publications by our and other groups point to an important role for the Wnt/beta-catenin pathway in the maintenance of the perivenous hepatocyte gene expression profile including the main hepatic detoxification enzymes, and beta-catenin signaling was recently implicated in the expression of several cytochrome P450 isoenzymes. To analyze, whether the beta-catenin pathway would also affect inducible expression of drug-metabolizing enzymes, mice with liver-specific knockout of the Ctnnb1 gene (encoding beta-catenin) were treated with different model inducers of xenobiotic metabolism. Knockout of beta-catenin led to alterations in basal expression of most drug metabolism-related genes analyzed and resulted in strongly diminished responses to agonists of CAR-, AhR-, and nuclear factor erythroid-related factor 2-dependent transcription. Taken together, the data presented in this study indicate that beta-catenin not only regulates basal expression of drug-metabolizing enzymes but also determines the magnitude and hepatic localization of response to xenobiotic inducers in vivo.
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http://dx.doi.org/10.1124/dmd.108.026179DOI Listing
May 2009