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Absence of NKG2D ligands on leukemia-initiating cells links stemness to immune evasion

English title Absence of NKG2D ligands on leukemia-initiating cells links stemness to immune evasion
Applicant Lengerke Claudia
Number 179239
Funding scheme Project funding (Div. I-III)
Research institution Abteilung Hämatologie, Onkologie Department Innere Medizin Universitätsklinikum Tübingen
Institution of higher education Other Research Institutes - FINST
Main discipline Experimental Cancer Research
Start/End 01.04.2018 - 31.03.2022
Approved amount 600'000.00
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Keywords (5)

acute myeloid leukemia; NK cells; leukemia stem cells; PARP1; hematopoietic stem cells

Lay Summary (German)

Lead
Die Krebsentstehung wird durch verschiedene Hypothesen erklärt. Eine erste Hypothese besagt, dass Tumore aus bestimmten Untergruppen von Tumorzellen hervorgehen, den sogenannten Tumorstammzellen, die sich selbst erneuern und gesunden Stammzellen ähneln. Eine zweite wichtige Hypothese postuliert, dass Zellen die entartet sind durch das körpereigene Abwehrsystem erkannt und vernichtet werden; Tumore können daher nur im Falle eines Versagens dieser Immunüberwachung entstehen. Hier wird am Beispiel der menschlichen akuten myeloischen Leukämie die Verbindung zwischen diesen zwei Hypothesen untersucht.
Lay summary

Lead

Die Krebsentstehung wird durch verschiedene Hypothesen erklärt. Eine erste Hypothese besagt, dass Tumore aus bestimmten Untergruppen von Tumorzellen hervorgehen, den sogenannten Tumorstammzellen, die sich selbst erneuern und gesunden Stammzellen ähneln. Eine zweite wichtige Hypothese postuliert, dass Zellen die entartet sind durch das körpereigene Abwehrsystem erkannt und vernichtet werden; Tumore können daher nur im Falle eines Versagens dieser Immunüberwachung entstehen. Hier wird am Beispiel der menschlichen akuten myeloischen Leukämie die Verbindung zwischen diesen zwei Hypothesen untersucht.

Inhalt und Ziele des Forschungsprojekts

Akute myeloische Leukämien (AML) werden durch sogenannte leukämische Stammzellen (LSZ) ausgelöst, die in vielen Fällen resistent gegenüber Chemotherapie-Behandlungen sind, und für Rückfälle der Erkrankung sorgen. Die Zusammenhänge zwischen menschlichen LSZ und ihrer Fähigkeit, sich vor Immunzellen zu schützen sind bisher weitestgehend unerforscht. 

Vorbereitende Arbeiten zum vorliegenden Projekt haben gezeigt, dass Moleküle der NKG2DL Familie, welche Zielzellen durch Immunzellen vom Natural Killer (NK) Subtyp angreifbar machen, auf bestimmten Untergruppen von Leukämiezellen ausgeschaltet sind. Hier untersuchen wir, ob diese sogenannten NKG2DL-negativen Untergruppen ebenfalls Stammzelleigenschaften aufweisen, bzw. als LSZ identifiziert werden können. Des Weiteren untersuchen wir, ob und wie LSZ der Überwachung durch NK Zellen entkommen können, und wie ihre Erkennbarkeit durch NK Zellen gesteigert werden kann.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

Unsere Erkenntnisse könnten zwei wichtige Hypothesen der Krebsentstehung zusammenführen, die Tumorstammzellhypothese und die Hypothese des Entkommen bezüglich Immunüberwachung. Die Identifizierung von Methoden für eine verbesserte Erkennung der LSZ durch NK Zellen könnte die Behandlung der akuten myeloischen Leukämien entscheidend verbessern.

Direct link to Lay Summary Last update: 24.04.2018

Responsible applicant and co-applicants

Employees

Project partner

Publications

Publication
Modeling hematopoietic disorders in zebrafish
Konantz Martina, Schürch Christoph, Hanns Pauline, Müller Joëlle S., Sauteur Loïc, Lengerke Claudia (2019), Modeling hematopoietic disorders in zebrafish, in Disease Models & Mechanisms, 12(9), dmm040360-dmm040360.
Absence of NKG2D ligands defines leukaemia stem cells and mediates their immune evasion
Paczulla Anna M., Rothfelder Kathrin, Raffel Simon, Konantz Martina, Steinbacher Julia, Wang Hui, Tandler Claudia, Mbarga Marcelle, Schaefer Thorsten, Falcone Mattia, Nievergall Eva, Dörfel Daniela, Hanns Pauline, Passweg Jakob R., Lutz Christoph, Schwaller Juerg, Zeiser Robert, Blazar Bruce R., Caligiuri Michael A., Dirnhofer Stephan, Lundberg Pontus, Kanz Lothar, Quintanilla-Martinez Leticia, Steinle Alexander, et al. (2019), Absence of NKG2D ligands defines leukaemia stem cells and mediates their immune evasion, in Nature, 572(7768), 254-259.

Datasets

Absence of NKG2D ligands defines human leukaemia stem cells and mediates their immune evasion

Author Raffel, Simon; Falcone, Mattia; Trumpp, Andreas
Persistent Identifier (PID) GSE127959
Repository GEO
Abstract
Patients with acute myeloid leukaemia (AML) often achieve remission yet subsequently die of disease relapse, which is commonly driven by chemotherapy-resistant leukaemic stem cells (LSCs). LSCs are defined by their capacity to initiate leukaemia in immuno-compromised mice. This precludes an analysis of their interaction with lymphocytes as components of anti-tumour immunity, which LSCs must escape in order to induce cancer7. Here we propose that stemness and immune evasion are closely intertwined in human AML. Using human AML xenograft and syngeneic mouse leukemia models, we show that ligands of the danger detector NKG2D, a critical mediator of anti-tumour immunity by cytotoxic lymphocytes such as natural killer (NK) cells, are generally expressed on bulk AML cells but not on LSCs. Functional LSCs can be isolated by their lack of NKG2D ligand (NKG2DL) expression, even in human AMLs not expressing the conventional LSC marker CD34. NKG2DL expressing AML cells are cleared by NK cells while NKG2DLneg leukaemic cells isolated from the same individuals escape NK cell killing. These NKG2DLneg AML cells show an immature morphology, display molecular and functional stemness characteristics, can initiate serially re-transplantable leukaemia and survive chemotherapy in patient-derived xenotransplants (PDX). Mechanistically, poly-ADP-ribose polymerase 1 (PARP1) negatively regulates NKG2DL and PARP1 inhibition (PARPi) induces NKG2DL surface expression in LSCs. Consequently, co-treatment with PARPi and NK cells suppresses leukaemogenesis in PDX models. Low expression of surface NKG2DL as well as high PARP1 expression are associated with inferior clinical outcome in patients with AML. In summary, our data link the concept of LSCs to immune escape and indicate absence of immunostimulatory NKG2DL as a novel method to identify LSCs across genetic AML subtypes. Moreover, we provide a strong rationale for targeting therapy resistant LSCs by PARP1 inhibition rendering them amenable to NK cell control in vivo.

Gene expression data from sorted primary human acute myeloid leukemia (AML) samples

Author Konantz, Martina; Lengerke, Claudia
Persistent Identifier (PID) GSE127200
Repository GEO


Collaboration

Group / person Country
Types of collaboration
Prof. Dr. Jürg Schwaller Switzerland (Europe)
- Publication
Andreas Trumpp Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Dr. Robert Zeiser Germany (Europe)
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
ahrestagung der DGHO, ÖGHO, SGH & SGMO Talk given at a conference Immuntherapeutische Ansätze bei AML 11.10.2019 Berlin, Germany Lengerke Claudia;
Jahrestagung der DGHO, ÖGHO, SGH & SGMO Talk given at a conference Immune protection of leukemia initiating stem cells 11.10.2019 Berlin, Germany Lengerke Claudia;
German Stem Cell Network - 7th Annual Conference Talk given at a conference Acute myeloid leukemia stem cells selectively evade immune surveillance by natural killer cells 23.09.2019 Berlin, Germany Lengerke Claudia;
Kick-off meeting des Stem Cell Networks NRW Talk given at a conference Stemness-mediated immune escape in acute myeloid leukemia 13.05.2019 Düsseldorf, Germany Lengerke Claudia;
Hematopoietic Stem Cell X (international conference and workshop) Talk given at a conference Leukemia stem cells & immune evasion 19.09.2018 Tübingen, Germany Lengerke Claudia;


Communication with the public

Communication Title Media Place Year
Other activities Pressemitteilung Uni Tübingen und DKFZ Heidelberg International 2019
Other activities Pressemitteilung Universität Basel German-speaking Switzerland International 2019

Abstract

Patients treated for leukemia often achieve remission yet subsequently die of relapse. Human Acute Myeloid Leukaemia (AML) initiation and relapse are thought to be mediated by leukaemic stem cells (LSCs), defined by their ability to initiate leukaemia in immunodeficient mice. To induce disease, LSCs must also escape immunosurveillance. Links between human LSCs and immune evasion are not accounted for by experimental paradigms using immunocompro-mised animals, and thus remain largely unexplored. Here we hypothesize that immune evasion and stemness are closely intertwined in human AML. We analyzed 175 primary AML samples and found that ligands of the danger de-tector NKG2D (NKG2DL), a critical mediator of anti-tumour immunity by cytotoxic lymphocytes including natural killer (NK) cells, are heterogeneously expressed on leukemic blasts from individual patients. Intra-patient comparisons between NKG2DL positive (NKG2DLpos) and negative (NKG2DLneg) subpopulations indicate that NKG2DLneg AML cells selectively escape NK cell killing in vitro and in NOD/SCID/IL2R?null (NSG) mice co-transplanted with NK cells. Furthermore, NKG2DLneg AML cells LSCs display stem cell characteristics such as immature morphology, stemness-associated gene expression signatures, enhanced in vitro clonogenicity and unique ability to initiate leukaemia in NSG mice. When compared to NKG2DLpos AML cells of the same patient, NKG2DLneg LSCs show differential expression of several other inflammatory response genes, providing further evidence for their distinct interaction with the immune system. In particular, NKG2DLneg AML LSCs show enriched expression of poly-ADP-ribose polymerase 1 (PARP1), and PARP1 inhibition using an inhibitory drug or PARP1 siRNAs selectively induces NKG2DL expression on CD34+ LSCs. The current proposal follows up on these results and addresses following aims:Aim 1: Investigation of PARP1 inhibition for in vivo sensitization of LSCs to NK cell attack in human AML xenograftsAim 2: Exploration of the effects of PARP1 inhibition on NKG2DL expression in healthy hematopoietic cells Aim 3: Mechanistic investigation of NKG2DL expression suppression in LSCsAim 4: Analysis of absence of NKG2DL expression for LSC enrichment in conjunction with other LSC markers Significance: These data provide a conceptual frame-work for the integration of two central hypotheses of cancer development - the concepts of cancer stem cells and immune escape. Furthermore, they point out detection of absence of NKG2DL expression as a method that can enriches AML LSCs. Stemness-associated immune escape might represent a novel biological principle that extends to other cancers, and perhaps even healthy tissues, which opens up exciting new research avenues. The results of this study are also important from a translational point of view: adoptive NK cell transfer is currently being tested in more than hundred registered clinical trials for treatment of AML (see https://clinicaltrials.gov/ct2/results?cond=Acute+Myeloid+Leukemia&term=NK&cntry1). Our data indicate that these efforts may fail to achieve cure, since they may not target disease-initiating and relapse-relevant LSCs unless additional co-treatments are provided (e.g., as suggested by this work, PARP1 inhibitory drugs).
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