Grundlagenforschungs-Einheiten

Die Grundlagenforschung im Westdeutschen Tumorzentrum ist in neun Einheiten organisiert, den Basic Research Units, BRU. Für nähere Informationen klicken Sie bitte auf die jeweilige BRU.

BRU1: Tumor-Immunologie

BRU2: Krebsrelevante Proteine

BRU3: Tumor-Hypoxie

BRU4: Tumor-Stroma-Interaktion und Signaltransduktion

BRU5: DNA-Reparatur

BRU6: Epigenetik

BRU7: Tumorvirologie

BRU8: Angiogenese

BRU9: Strahlenbiologie

BRU1: Tumor-Immunologie

Koordinatoren: Prof. Dr. J. Buer, Prof. Dr. D. Schadendorf

1. Research Topic(s)

BRU1 brings together experts in the fields of immunbiology, stern cell transplantation, medical oncology and pathology to explore the interaction between the immune system and cancer. BRU1 aims to advance new strategies that use the exquisite specificity of the body`s natural defenses to destroy tumors with minimal toxicity to healthy tissues.

Current areas of research include:

• Preclinical and clinical evaluation of novel treatments such as a patient-specific vaccines and cellbased therapies that incite the patient`s own immune defenses to attack his/her cancer
• Identification of new targets for therapeutic monoclonal antibodies
• Generation of novel antibody-based immunotherapeutics
• Function of effector molecules
• Immune escape mechanisms

A) Modulation of Resistance to Adoptive Cancer Immunotherapies,
group leader Schulert

Failure of immunotherapy can be attribute to (i) defective activation of a cancer-specific immune response, and (ii) cancer cell-intrinsic resistance to immune effector mechanisms. The latter immune escape mechanism is addressed by BRU1 members using serveral tumor models in vitro and in vivo. Putative resistance factors are functionally identified by means of expression cloning technology. Following preclinical level as well as validated by target expression analyses in tumor samples from WTZ patients. The goal is to develop pharmacological therapies which increase the efficacy of adoptive cancer immunotherapies, such as antibodies or allogeneic stern cell transplantation.

B) Analysis of immune effector cell functions and tumor immune escape mechanisms,
group leaders Lindemann, Rebmann
Researchers in BRU1 study the basic biochemical mechanisms governing T and NK cell function, including the receptors and ligands involved in their activation and inhibition as well as their interactions with other effector and antigen-presenting cells of the immune system. Researchers hope to identify new opportunities for including tumor-specific, cytotoxic activity by better understanding these signaling pathways. research topics include studies on the cellular, in vitro immune function in immunocompromized individuals such as tumor patients and transplant recipients; analysis of immune escape mechanism of tumor cells (expression analysis of non-classical and classical HLA molecules on tumor cells, clinical and functional relevance of non-classical and classical soluble HLA molecules and their interaction with the cognate lymphocyte inhibitor receptors in cancer patients, analysis of NK cell function); studies to improve T cell-mediated protective immunity by the generation and maintenance of T cell memory; and analysis of regulatory T cells and effector T cells in cancer patients.

C) Tumor immunology of melanoma, group leader Schadendorf
Researchers in BRU1 also focus on the interaction with melanoma cells and tumor environment using in vitro and in vivo model systems. Particular emphasis has recently been put on studies elucidating intracellular peptide processing and its relevance for tumor recognition as well as tumor escape. Alterations of HLA expression and its consequences for T and NK cell recognition are systematically studied. Furthermore, a transgenic mouse model which spontaneously develops melanoma in a subset of mice is used as a model system studying dormancy and interactions between tumor and microenvironment over time.

D) Tumor-Host interaction, Immunotherapy, group leader S. Brandau
The focus of the research group is molecular and cellular interaction of tumor tissue and host immunity with a special emphasis on immunoregulatory and inflammatory cells. Malignant transformation and progression is associated with dramatic changes in the tumor microenvironment and tissue physiology. These changes often resemble an active inflammatory process. Researchers in this group analyze the biology of myeloid and lymphocytic regulatory cells, their reciprocal interaction with tumor cells and tissue, and the potential impact of this interaction on anti-tumor immunity.

In addition to mechanistic studies, the group pursues immunology-based approaches to improve early diagnosis and therapy of cancers of the upper aerodigestive tract. A serum screening technology will be used to identify novel biomarkers in patients with lung cancer and heard and neck cancer. Immunotherapeutic strategies combine established therapeutic principles such as antibodies and radiation with new modalities such as mesenchymal stromal cells and TLR-mediated immunotherapy.

E) Modulation of Tumor-specific Immunity,
group leader J. Buer and A. M. Westendorf
A finally orchestrated balance between activating and inhibitory signals is fundamental for the ability of the immune system to effectively attack and eliminate pathogenic microbes but not to react against self-antigens. Because tumors are intrinsic, generating an effective antitumor immune response requires mounting a substantial autoimmune attack, which involvesbreaking tolerance. Recent work demonstrates that one reason for the lack of tumor rejection is that tumors actively defeat host immunity by producing immunosuppressive factors (e. g. IL 10) and by inducing regulatory T cells. Tregs can inhibit tumor-specific CD8+ and CD4+ T cell effector functions through incompletely understood mechanisms. Different pathways of Treg differentiation in tumors probably lead to heterogeneous populations of infiltrating Tregs, and might account for conflicting reports regarding their mechanism of suppression/phenotype. Targeting the tumor microenvironment in chronic intestinal inflammation and colon cancer to awaken or reawaken immune cells, or to redirect it to an antitumor state, will require understanding of this phenotype. A. M. Westendorf, a newly appointed Junior Professor for Mucosal Immunity will address this issue in a unique T cell receptor transgenic mouse model that has recently developed, whereas J. B. will focus on the characterization of human regulatory T cells in the context of inflammation and cancer. Network-based analysis will be performed to gain dynamic insights into human regulatory T cells from healthy and diseased patients with different cancers and from patients undergoing immunotherapy. Together they aim to identify and modulate molecular pathways in regulatoryT cells that represent new targets for immune-based interventions in patients with cancer.

BRU2: Krebsrelevante Proteine

Koordinator: Prof. Dr. M. Ehrmann

BRU2 links WTZ research activities with activities in the recently founded Center for Medical Biotechnology (ZMB) of the University Duisburg-Essen, Campus Essen. Research groups in biochemistry, developmental biology, genetics, microbiology and bioinformatics have been implemented in the ZMB and complemented research expertise in the WTZ. Currently, there are substantial efforts to foster cooperation between these centers to investigate cancer-related target proteins.

1. Research Topic(s)

Although a tremendous amount has been learned about tumor biology at the RNA or DNA levels, a holistic understanding of tumor biology is impossible without investigating the protein equivalent of the transcriptome. Not only do post-translational modifications generate more than one protein with distinctly different functional qualities per mRNA transcript, but protein functionality is linked to correct subcellular localization. In close cooperation with RCF 5, this program focuses on the analysis of cancer-relevant proteins. As most drug targets are proteins, molecular and functional analysis of proteins is one of the most promising areas for drug and device discovery and development.

BRU2 includes four major research areas:

A) Cellular quality control of proteins, group leader Ehrmann
The HtrA family represents a new class of oligomeric serine proteases in which a catalytic domain is combined with one or more C-terminal PDZ domains. These proteins are widely conserved and can be found in most organisms. Our previous work indicated that human HtrA1 is differentially expressed in various cancers. It is believed to function as a tumor suppressor and was found to be upregulated upon chemotherapy with cisplatin or taxol. In addition HtrA1 mediates taxol- and cisplatin-induced cytotoxicity. Currently, mouse models of colon cancer (HtrA1 null in apc Min) are established as well as high throughput screen for small molecules to isolate modulators of HtrA activity. Since HtrA family proteins function as proteases or chaperones depending on the microenvironment, they are regarded as a model system to analyze the cellular control mechanisms for protein stabilization and destabilization.

B) Protein-protein interaction, group leader Fandrey
This part of BRU2 analyzes protein-protein interactions using fluorescence resonance energy transfer (FRET), fluorescence recovery after photobleaching (FRAP) and fluorescence life-time measurements. FRET allows visualization of the dynamics of protein-protein and protein-DNA interactions necessary to understand molecular functionality. TPM (two-photon microscopy) allows subnuclear localization of proteins and interacting cofactors. Since measurements take place in 3D, it is also possible to reconstruct the spatial structure of protein complexes. The feasibility of this method has been proven by analyzing the interaction of Hif1 alpha with ARNT1, PML and p300 on the subcellular level.

C) Protein structure and posttranslational modifications, group leader Bayer
This part of BRU2 focuses on the elucidation of 3-dimensional protein structures using NMR spectroscopy. The crystallization facility for subsequent X-ray analysis is currently under construction in Essen. Presently, crystal structure is analyzed in collaboration with the MPI for molecular Physiology in Dortmund. The research group has a strong interest in the systematic determination of structures of human proteins during various post-translational modification pathways. Primarily, we will address sumoylation, tyrosine sulphation and proline-directed cis-trans isomerization. Sulfation of proteins is a post-translational modification that has an important role in protein-protein recognition, especially of proteins involved the immune response, and for this reason may be of significance for tumor marker proteins.

D) Design of functional peptides, group leader Hoffmann
This part of BRU2 focuses on the structure-based computational design of conformationally stabilized peptides that expose given functional epitopes. The methods used to this end, include molecular modeling, stochastic optimization, especially evolutionary optimization, alignment methods, machine learning and statistical methods. Applications under development are peptide binding to highly cytopathogenic subspecies of HIV and peptides for use as diagnostic markers in MRT imaging of metastases.

BRU3: Tumor-Hypoxie

Koordinator: Prof. Dr. J. Fandrey

Eine Tumorhypoxie führt durch einen zellulären Selektionsdruck zur Steigerung der Tumoraggressivität, Metastasierungsneigung und Therapieresistenz. Über HIF-1 vermittelte Genexpressionen verstärken die Angiogenese (verstärkte Expression von VEGF und avß3-Integrinen). Verschiedene therapeutische Strategien wurden in den vergangenen Jahren verfolgt um den biologischen Nachteil der Tumorhypoxie in einen therapeutischen Vorteil zu verwandeln, etwa durch Hypoxie-spezifische Chemotherapeutika. Solche ggf. mit einer antiangiogenen Therapie verknüpften individuellen Therapiekonzepte verlangen eine exakte Kenntnis der Ausprägung und der örtlichen Verteilung einer Tumorhypoxie sowie der zugrunde liegenden molekularen Signalwege.

Schwerpunktprojekte dieser Forschungseinheit sind daher Untersuchungen zur sauerstoffabhängigen Genexpression, zur Struktur und Funktion des zellulären Sauerstoffsensors, zur Aktivierung des Transkriptionsfaktorkomplexes HIF-1 und zur molekulare Bildgebung der Zusammensetzung von HIF-1 in Tumorzellen. Hierbei wird die in vivo 2-Photonen-Mikroskopie und eine dreidimensionale Lokalisation intrazellulärer Proteine eingesetzt. Weitere Forschungsthemen sind die Regulation der sauerstoffabhängigen Expression des Erythropoietingens und die Bedeutung der sauerstoffabhängigen Expression von Gefäßwachstumsfaktoren wie VEGF für die Tumorvaskularisierung.

BRU4: Tumor-Stroma-Interaktion und Signaltransduktion

Koordinator: Prof. Dr. E. Gulbins

Ein maligner Tumor stellt nicht nur eine Ansammlung genotypisch, phänotypisch und funktionell pathologisch veränderter Zellen dar, sondern ist ein komplexes Gewebe, dessen zelluläre und strukturelle Komponenten miteinander in Kommunikation stehen und sich gegenseitig beeinflussen. Die für Tumorwachstum, Invasion und Metastasierung entscheidenden Vorgänge, wie Stromareaktion, Angiogenese und Ab- und Umbau extrazellulärer Matrix werden nicht nur durch die Tumorzellen selbst, sondern auch durch infiltrierende Entzündungszellen gesteuert.

BRU5: DNA-Reparatur

Koordinator: Prof. Dr. G. Iliakis

Durch DNA-Reparatur-Mechanismen können Zellen schadhafte Veränderungen der DNA-Struktur in einer Zelle beseitigen. Solche Schäden in der DNA können spontan im Verlauf der DNA-Replikation oder durch die Einwirkung mutagener Substanzen wie extremer Wärme oder ionisierender Strahlung verursacht werden. Sind die komplexen Reparaturmechanismen der Zelle defekt, kann es durch die geschädigte DNA oder infolge von Mutation zu Störungen der Zellteilung kommen und die Zellteilung außer Kontrolle geraten. Es kommt so zur malignen Entartung der Zelle. In den letzten Jahren konnte für viele Gene der DNA-Reparatur ein Zusammenhang zwischen dem Verlust oder der Verminderung der Funktion von Reparatur-Genen und der Entstehung von Krebs nachgewiesen werden.

Die Aktivitäten dieser Forschungseinheit konzentrieren sich auf die Analyse der verschiedenen DNA-Reparaturwege und ihrer Signalelemente in Tumorzellen. In verschiedenen Forschungsprojekten wird der Beitrag der so genannten homologen Rekombinationsreparatur (HRR) und des non-homologen Endjoinings (NHEJ) zur Reparatur strahleninduzierter Doppelstrangbrüche analysiert. Ein verbessertes molekulares Verständnis der Vorgänge bei der Reparatur von DNA-Doppelstrangbrüchen wird wesentlich zu unserem Wissen über die Zusammenhänge von genomischer Instabilität und Krebsentstehung beitragen. Hierdurch lässt sich langfristig die Krebstherapie durch Bestrahlung verbessern.

BRU6: Epigenetik

Koordinatoren: Prof. Dr. B. Horsthemke, Prof. Dr. A. Ehrenhofer-Murray

Forschungen der vergangenen zehn Jahre haben gezeigt, dass epigenetische Veränderungen bei Entstehung und Wachstum von Krebs neben den genetischen Aberrationen (Mutationen) von besonderer Bedeutung sind. Das Studium der epigenetischen Mechanismen und der daran beteiligten Enzyme ist daher zu einem Brennpunkt der Krebsforschung geworden. In dieser Forschungseinheit wird die DNA-Methylierung in Modellsystemen und Krebszellen untersucht, um neue Wege der Krebstherapie und -diagnostik zu finden.

Our research focus is to understand how eukaryotic cells establish and maintain functionally distinct domains of gene expression within their genomes. Some regions are permanently repressed or silenced, a mechanism that is used to ensure appropriate gene expression in a temporal and spatial fashion. The formation of silenced chromatin requires the concerted packaging of DNA into chromatin with specifically modified histones as well as with non-histone proteins at a given time during the cell cycle. After DNA replication, chromatin assembly complexes restore chromatin on freshly replicated DNA. One question is how modification patterns on "old" chromatin are reestablished on newly formed chromatin. We are using the small eukaryote Saccharomyces cerevisiae to investigate the relationship between DNA replication, chromatin assembly and the formation of repressed chromatin.

BRU7: Tumorvirologie

Koordinatoren: Prof. Dr. R. Küppers, Prof. Dr. U. Dittmer

1. Research Topics

A) Role of EBV infection in B cell lymphoma, group leader Küppers
EBV infects nearly all humans worldwide, and after infection establishes a life-long persistence in B Cells.  Infection by EBV is normally harmless. However, EBV is also involved in the pathogenesis of several diseases, such as infectious mononucleosis and several types of B cell lymphomas. By molecular analysis of single microdissected EBV-infected B cells during an acute viral infection (infectious mononucleosis), we revealed viral strategies for spreading within the immune system. Our current work is focused on the influence EBV has on differentiating B cells in the germinal centers and its role in the pathogenesis of posttransplant lymphoproliferative disease.

B) New therapeutic strategies against retrovirus-induced leukemia,
group leader Dittmer
A common feature of most retroviruses is that they transfer hematopoietic cells and include lethal leukemias. We study the role of the adaptive immune responses in controlling viral replication and tumor growth in mice infected with the Friend retrovirus. The main focus is on immune escape of virus-infected tumor cells mediated by regulatory T cells. The targeted manipulation of regulatory T cells is explored as a new therapy to overcome tumor immune escape.

BRU8: Angiogenese

Koordinator: Prof. Dr. S. Ergün

Mechanismen der Vaskulären Destabilisierung versus Stabilisierung bei der Angiogenese / Vaskulogenese sowie ihre Bedeutung

a) beim Tumorwachstum und der Metastasierung sowie anti-angiogenetischer Tumortherapie

I) CEACAMs und ihre Bedeutung bei der Gefäßneubildung sowie Tumordiagnostik

II) LINE-1-Elemente (L1-Elemente) und ihre Bedeutung bei der Differenzierung von Endothelzellen bzw. der genetischen Stabilität der Endothelzellen

III) Charakterisierung neuer Marker/Proteine der Tumorangiogenese

IV) Die Bedeutung von 3-OH-GA bei der Tumorvaskularisierung

V)  Vaskulogenese durch Gefäßwand-residente endotheliale Vorläuferzellen
(VW-EPCs) / mesenchymale Stammzellen

VI) Molekulares Imaging der Tumorgefäße

BRU9: Strahlenbiologie

Koordinatorin: Prof. Dr. V. Jendrossek, Institut für Zellbiologie

Die Strahlentherapie stellt nach der Operation die zweitwichtigste Säule bei der Behandlung solider Tumoren dar. Allerdings limitieren verschiedene biologische Faktoren, darunter z. B. die schlechte Versorgung bestimmter Tumorregionen mit Sauerstoff (Tumorhypoxie) und die hohe Strahlensensitivität der im Bestrahlungsfeld liegenden Normalgewebszellen, die Effizienz dieser Behandlungsmethoden. Daher wird nach neuen Ansätzen gesucht, diesen negativen biologischen Faktoren entgegenzuwirken. Voraussetzung für den Einsatz neuer, zielgerichteter Wirkstoffe zur Steigerung der Strahlensensitivität von Tumorzellen bzw. zur Verminderung der Strahlensensitivität von Normalgewebszellen ist die genaue Kenntnis der beteiligten molekularen Mechanismen und Signalwege.

In BRU9 verfolgen Grundlagenwissenschaftler aus den Bereichen Strahlenbiologie, Zellbiologie, Molekularbiologie, Immunbiologie, Physiologie und Anatomie gemeinsam mit Strahlentherapeuten, klinischen Onkologen und Pathologen das Ziel, die molekularen Mechanismen der Strahlenantwort und modulierender Signalwege zu verstehen. Ein verbessertes Verständnis der molekularen Mechanismen von Strahlensensitivität und Strahlenresistenz soll die Identifikation neuer Zielstrukturen/zielgerichteter Wirkstoffe zur Modulation der Strahlenantwort in Tumor- und Normalgewebszellen ermöglichen. Viel versprechende Ansätze zur Modulation der Strahlenwirkung werden anschließend in präklinischen Modellen variiert, um einen Transfer in klinische Studien vorzubereiten.