The role of IKKalpha in sporadic and familial colorectal tumorigenesis [Elektronische Ressource] / Serkan İsmail Göktuna

Serko

Sujets

• Biologie

Informations

• Publié par: technische_universitat_munchen
• Publié le: 01 janvier 2010
• Nombre de lectures: 73
• Langue: English
• Poids de l'ouvrage: 34 Mo

Extrait

TECHNISCHE UNIVERSITÄT MÜNCHEN


Lehrstuhl für Humanbiologie


The role of IKKalpha in sporadic and familial colorectal tumorigenesis


Serkan İsmail Göktuna

Vollständiger Abdruck der von der Fakultät Wissenschaftszentrum Weihenstephan für
Ernährung, Landnutzung und Umwelt der Technischen Universität München zur Erlangung des
akademischen Grades eines

Doktors der Naturwissenschaften

genehmigten Dissertation.

Vorsitzende(r): Univ.-Prof.Dr. J. J. Hauner

Prüfer der Dissertation: 1. Univ.-Prof. Dr. M. Schemann
2. Priv.-Doz. Dr. F. R. Greten

Die Dissertation wurde am 02.11.2009 bei der Technischen Universität München eingereicht
und durch die Fakultät Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und
Umwelt am 05.02.2010 angenommen.




ABSTRACT


In this thesis, the role of IKKα in colorectal tumorigenesis was investigated by the use of
chemical and genetic mouse models of colorectal tumors. To do this, an inactive IKKα mutant
mouse was used in conjunction with these tumor models and the development of colorectal
tumors were monitored for morphological and physiological differences. As a result of these
experiments, a distinct phenotype of tumor growth retardation and extended survivals of the
animals were observed in all tumor models with IKKα inactivation.
Molecular analysis of reduced tumor growth in IKKα mutants resulted in a clear IFNγ
upregulation due to myeloid cell recruitment by epithelial secreted factors and autocrine myeloid
cell activation by intrinsic factors like MCP-1 and IL-12. NF-κB activity was found to be crucial
for activation of myeloid cells to release IFNγ, which further caused growth arrest in IKKα
mutant enterocytes.
In conclusion, phospho-activation of IKKα is characterized as an important regulator of
immune responses in colorectal tumorigenesis. Therefore, the primary role of IKKα in colorectal
tumorigenesis is to suppress IFNγ release. However, this role adversely promotes tumor growth in
colorectal cancers. In this respect, these results strongly suggest that IKKα phospho-inactivation
can be a potent therapeutic strategy for the therapy of colorectal tumors.






ZUSAMMENFASSUNG



In der vorliegenden Arbeit die Funktion von IKKα bei der Tumorentstehung wurde durch
chemische und genetische murine kolorektale Karzinom-Modelle untersucht. Inaktivierung von
IKKα führte in allen Modellen durch eine Verzögerung des Tumorwachstums zu einer
signifikanten Verlängerung des Überlebens der Versuchstiere.
Molekularbiologische Untersuchungen zeigten in IKKα defizienten Mäusen eine deutlich
gesteigerte IFNγ Hochregulation aufgrund der Rekrutierung von myeloischen Zellen durch
epithelial sekretierte Faktoren sowie durch autokrine myeloische Zell-Aktivierung durch
intrinsische Faktoren wie MCP-1 und IL-12. Die NF-κB Aktivität ist von entscheidender
Bedeutung, für die Aktivierung der myeloischen Zellen zur Freisetzung von IFNγ, was in Folge
zu konsekutivem Wachstumsstop in IKKα defizienten Enterozyten führt.
Zusammenfassend demonstrieren die Ergebnisse dieser Arbeit, dass die Aktivierung von
IKKα die kolorektale Karzinomentstehung durch Suppression der IFNγ Expression maßgeblich
fördert. Die Möglichkeit einer pharmakologischen Inhibition der IKKα abhängigen IFNγ
Suppression könnte demnach in Zukunft eine neue potentielle Strategie in der Therapie des
kolorektalen Karzinoms darstellen.



ii



ACKNOWLEDGMENTS


First of all, I want to thank Prof. Florian R. Greten for providing this research position in which I have found
plenty of opportunity to develop my technical skills, my theoretical background on various subjects and my scientific
approach to different issues. He is a model scientist for hard-working, commitment to oneself job, critical thinking
and innovative problem solving abilities. He helped me a lot to be able to look subjects from different angles, in
developing skeptic thinking abilities and in finding way out when I was hindered by certain experimentation. It
would not be possible for me to finish this project without his profound guidance. I have every confidence in him
that he will be a leading scientist in his area in the near future. The experience I gained from his advisership will be
one of the most powerful earnings to build up my future academic career. For this reason and many others, it was a
great pleasure and honor for me to have a chance to make research together with him.
I am also thankful to Prof. Roland M. Schmid for being a very good Chief to our department, providing us with
such good facilities and hosting social activities which made each other know.
I am grateful to Prof. Michael Schemann for accepting me as a student in his faculty, being my Doktorvater and
advising me with academic and bureaucratic requirements that helped a lot while preparing this thesis.
I am also thankful to Dr. M. Canan Arkan for her kind collaboration in our research projects and every other
help she gave while I am working in the lab. Moreover, I was benefited from her essential advises both in academic
and personal issues that made my life easier.
Furthermore, I am grateful to Dr. Hana Algül, Dr. Jens Siveke, Dr. Dieter Saur, Dr. Günther Schneider and Dr.
Hassan Nakhai, for their collaboration, advises in research and in personal issues.
I am especially thankful to Dr. Frank Schmidt for invaluable helps in dendritic cell experiments; Dr. Jörg
Magesand Angela Servatius for generating and analyzing Microarray data; Julia Bollrath for excellent and enormous
amount of FACS data that helped a lot in finishing this project; Özge Canlı for exceptional ELISA and macrophage
stimulation data; Tim Nebelsiek for vital kinase assay data and completing expression analysis with double
knockouts; Kristin Retzlaff for brilliant technical assistance for dealing mice genotypes and matings; similarly Birgit
Wittig and Rabea Könitschke for technical assistance and the rest of the lab for providing assistance whenever I was
in the need.
My personal thanks go to my comrades Jamil Khasawneh, Dr. Alexander A. Fingerle, (soon to be Dr.) Moritz
Bennecke, Tim Nebelsiek, Dr. Arun K. Mankan and Özge Canlı for their friendship and assistance in technical and
iii practical problems. I am grateful to them not only being the best colleagues one can have but also being such good
friends. Especially their kind advises and limitless humor helped me a lot in coping with the difficulties of the
research life and persuading me to go on no matter how hard the difficulties I faced.
My other lab mates Julia Bollrath, Sarah Schwitalla, Vivian Daer, Simone Zach, Manon Schulz and Çiğdem
Atay, I am also thankful to you for countless helps and the good times we had in the lab and in extracurricular
ndactivities. Thank you so much all other people from 2 Internal Medicine who helped me in any single way or just
shared their friendship.
I am thankful to Prof. Michael Karin (Univ. of Calif. San Diego, USA), Prof. Yinglin Hu (Univ. of Texas MD
Anderson Cancer Centre, USA), Roland M. Schmid, Prof. Falk Weih (Leibniz Institut für Alterforschung,
Germany), Prof. Makato M. Taketo (Kyoto University, Japan), and Prof. Sylvie Robin (Institut Curie, France) for
kindly providing the mouse models we used in this study. Moreover, I thank Prof. Davis Artis for providing IL-12b
neutralizing antibody.
I am thankful to my friends Dr. Özgür Şahin (DKFZ, Heidelberg), Özlem Sener Şahin (Univ. Heidelberg),
Ufuk Bayburt (METU, Ankara), Dr. Çetin Baloğlu (Cambridge Univ., UK), Dr. Günseli Bayram Akçapınar
(Sabancı Univ., İstanbul), Dr. Çağhan Kızıl (MPI Dresden), Dr. Güneş Özhan Kızıl (MPI Dresden) for personal
assistance they provided to complete my documents, being there whenever I needed somebody to talk and infinite
support and trust they provided.
Lastly, I cannot find words to describe my gratefulness for my parents Nesrin and Mete and my sister Canan
Sezin for providing support in every possible way one can imagine. I am also thankful to my uncle Fethi Göktuna for
his limitless supports and trust that made this thesis possible. And the rest of my family and cousins I could not
mention specifically here, thank you very much.
I am dedicating this thesis to my family and to my beloved cousins Güzide and Levent who were like elder sister
and elder brother to me and have departed from this world to leave me in solitude. I hope you are in peace wherever
you went.



Serkan İsmail Göktuna

Munich, October 2009





iv





Güzide Ablama,

Levent Ağabeyime,

Öncü Dayıma,

ve hiçbir zaman desteklerini

eksik etmeyen aileme







Imagination will often carry us to worlds that never were.
But without it we go nowhere.

Carl Sagan