UNIVERSITY OF CALGARY

UNIVERSITY OF CALGARY
Fatty acid synthesis in colorectal cancer: characterization of lipid metabolism in serum, tumour,
and normal host tissues
by
Emily Megan Mackay
A THESIS
SUBMITTED TO THE FACULTY OF GRADUATE STUDIES
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE
DEGREE OF MASTER OF SCIENCE
DEPARTMENT OF MEDICAL SCIENCE
CALGARY, ALBERTA
FEBRUARY 2015
© Emily Mackay 2015

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Abstract
Reprogrammed energy metabolism is now listed as one of the central hallmarks of cancer
cells. Aberrant fatty acid metabolism contributes to tumourigenesis through provision of
substrates for membrane synthesis, signalling molecules, and synthesis of complex lipids. In this
thesis, the role of fatty acid metabolism is explored in the context of colorectal cancer.
Metabolomics techniques were employed to characterize fatty acid metabolites in serum, and
lipogenic gene expression was quantified in tumour and normal tissues to investigate host
response to cancer. Fatty acid metabolite abundance was increased in the serum of individuals
with colorectal cancer, and a growth factor signalling axis and lipogenic transcription factor
upstream of the endogenous fatty acid synthesis pathway were increased in colorectal liver
metastases. It was concluded that liver metastases have an effect on growth factor production in
the hepatic microenvironment, leading to increased signalling through a pathway that activates
the lipogenic transcription factor that regulates fatty acid synthesis.

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Acknowledgements
I would like to sincerely thank Dr. Oliver Bathe for his guidance and supervision throughout this
degree. He has been an incredible mentor and with his support and encouragement I have been
able to follow my dreams of attending medical school and hope to continue pursuing a career in
the field of oncology.
I would like to thank Dr. Aalim Weljie for his guidance and mentorship and for teaching me
numerous techniques in metabolomics. This project would not have been possible without the
support I received from him. I would like to thank Dr. Weljie for the amazing opportunity to
work in his laboratory at the University of Pennsylvania for several months. This experience was
a highlight of my degree and I sincerely appreciate the opportunity.
I would like to thank Dr. David Schriemer and Dr. Karen Kopciuk for their support throughout
this degree. Their input on mass spectrometry and statistical methodologies was invaluable to the
project and their encouragement and positive feedback over the past several years was a great
support.
I would also like to thank the members of the Bathe and Weljie labs: Kathy Gratton, Farshad
Farshidfar, Nicole Dunse, Omair Sarfaraz, and Ha Dang. Their support over the past several
years has made this an enjoyable experience; each of them has had a positive impact on my
research project and learning process during this degree.

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For my parents, who have supported me each step of the way. Without their love and
encouragement I would not be where I am today.

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Table of Contents
Abstract ............................................................................................................................... ii!
Acknowledgements ............................................................................................................ iii!
List of Tables ................................................................................................................... viii!
List of Figures and Illustrations ......................................................................................... ix!
List of Abbreviations .......................................................................................................... x!
INTRODUCTION ................................................................................. 1!CHAPTER ONE:
1.1 Colorectal Cancer ..................................................................................................... 3!
1.1.1 Sporadic CRC development ............................................................................. 3!
1.1.2 Inherited predisposition to CRC ....................................................................... 4!
1.1.3 Lifestyle factors associated with CRC ............................................................. 5!
1.2 Cancer cell metabolism ............................................................................................. 6!
1.2.1 Metabolic reprogramming: an emerging hallmark of cancer ........................... 6!
1.2.2 The Warburg effect ........................................................................................... 6!
1.2.3 Regulation of cancer cell metabolism .............................................................. 7!
1.3 Lipid metabolism ...................................................................................................... 9!
1.3.1 Lipid classification system ............................................................................... 9!
1.3.2 Fatty acid metabolism ..................................................................................... 10!
1.3.2.1 Fatty acid synthesis ............................................................................... 11!
1.3.2.2 Fatty acid degradation ........................................................................... 11!
1.3.3 Sterol regulatory element binding proteins (SREBPs) ................................... 12!
1.3.4 Aberrant fatty acid metabolism in cancer ....................................................... 12!
1.3.4.1 Expression of FASN in CRC ................................................................ 13!
1.3.5 Desaturases and elongases .............................................................................. 14!
1.4 Insulin-like growth factor signalling and cancer cell metabolism .......................... 15!
1.4.1 IGF-1 and IGF-2 ............................................................................................. 15!
1.4.2 IGF-1 receptor ................................................................................................ 16!
1.4.3 IGF-1 and lipid synthesis ................................................................................ 16!
1.5 Techniques in lipidomics ........................................................................................ 16!
1.5.1 Gas chromatography-mass spectrometry (GC-MS) ....................................... 17!
1.5.2 Liquid chromatography-mass spectrometry (LC-MS) ................................... 17!
1.5.3 Mass spectrometry .......................................................................................... 18!
1.5.4 Lipidomics as a tool to study lipid dysregulation ........................................... 18!
HYPOTHESIS AND RESEARCH AIMS ......................................... 21!CHAPTER TWO:
2.1 Hypothesis .............................................................................................................. 22!
2.2 Research aims ......................................................................................................... 22!
2.2.1 Aim 1: The pattern of abundance of fatty acids in serum will be characterized as a
function of CRC. ............................................................................................. 22!
2.2.2 Aim 2: The expression of the fatty acid synthesis pathway will be examined in
colorectal liver metastases and paired non-cancerous liver tissue. ................. 22!
2.2.3 Aim 3: The host response to colorectal liver metastases will be determined in
normal host tissues. ......................................................................................... 22!
MATERIALS AND METHODS ................................................... 24!CHAPTER THREE:
3.1 Human Samples ...................................................................................................... 25!