UNIVERSITY OF CALGARY PIK3CA by

UNIVERSITY OF CALGARY
The Role of PIK3CA in Cisplatin Resistance of Cervical Cancer
by
Cole Merry
A THESIS
SUBMITTED TO THE FACULTY OF GRADUATE STUDIES
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE
DEGREE OF MASTER OF SCIENCE
GRADUATE PROGRAM IN MEDICAL SCIENCE
CALGARY, ALBERTA
JUNE, 2016
© Cole Merry 2016

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Abstract
Cervical cancer is a significant public health issue. A recent study (McIntyre et al; 2013)
suggested that phosphatidyl inositol 3 kinase (PI3K) catalytic subunit α (PIK3CA) is an
important marker for the prognosis of cervical cancer patients treated with chemoradiotherapy
(CRT), with PIK3CA-mutant tumour bearing patients having poorer survival than PIK3CA-wt
patients. Activating mutations in PIK3CA promote increased PI3K signalling, and tumorigenesis
in vivo. I investigated the role that E545K, identified by McIntyre et al (2013) as the most
common mutation in PIK3CA in cervical cancer, may play in radiation and cisplatin resistance of
cervical cancer cell lines. This study indicated a potential role of PIK3CA in cisplatin resistance,
although cisplatin resistance was not a universal characteristic of cells expressing PIK3CA-
E545K, and was not reversed with the use of the PI3K inhibitor GDC-0941. The cisplatin
resistant cell line showed sensitivity to GDC-0941, suggesting PI3K inhibitors as an alternative
to cisplatin.

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Acknowledgements
I would like to acknowledge my Supervisor Dr. Susan Lees-Miller for providing me the
opportunity to work in her lab, and for being an excellent mentor and advocate throughout my
studies. A special thank you to my supervisory committee members Dr. Corinne Doll and Dr.
Savraj Grewal for taking the time to provide me guidance and feedback for my research, and to
Dr. Randal Johnston and Dr. Guido van Marle for participating in my evaluation. I would also
like to acknowledge Dr. Arjumand Wani for being a great support and excellent teammate
throughout my studies, I enjoyed our time working together. Thank you to Dr. Aru Narendran
and Manika Perinpan for providing the inhibitors, reagents, and assistance for my drug screens.
Thank you Dr. Karen Kopciuk for assisting me with my statistical analyses. Thank you to all of
my other past and present fellow researchers, associates, and technicians in the Lees-Miller lab
for your support: Dr. Pauline Douglas, Ruiqiong Ye, Shujuan Fang, YapingYu, Shilpa Salgia,
Carin Pihl, Dr. Chen Wang, Dr. Edward Bartlett, Dr. Lucy Swift, Dr. Sarvan Kumar, Nick Jette,
Maryam Ataeian, Cortt Piett, Elias Saba, Daniel Moussienko, and Michelle Love, thank you all
for making the Lees-Miller lab a great place to do research. Lastly, I would like to thank my
Family: David, Melanie, Ross and Brittany Merry, and Corinna Liu for supporting me
throughout my education, for always believing in me, and for pushing me to do my greatest.

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Dedication
I would like to dedicate this work to a brilliant young mind who was taken too soon.
“Good friends are hard to find, harder to leave, & impossible to forget.”
Rest in Peace
Max Milaney
24/02/1993 - 11/02/2016

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Table of Contents
Abstract ............................................................................................................................... ii
Acknowledgements ............................................................................................................ iii
Dedication .......................................................................................................................... iv
Table of Contents .................................................................................................................v
List of Tables ................................................................................................................... viii
List of Figures and Illustrations ......................................................................................... ix
List of Symbols, Abbreviations and Nomenclature ........................................................... xi
CHAPTER ONE: INTRODUCTION ..................................................................................1
1.1 Cervical cancer ..........................................................................................................1
1.1.1 Cervical cancer is a significant global health problem. .....................................1
1.1.2 Human papilloma virus (HPV) plays a large role in the development of cervical
cancer. ................................................................................................................1
1.2 Radiation and cisplatin are currently the standard treatments for locally advanced
cervical cancer, given concurrently as chemoradiotherapy (CRT). .........................5
1.2.1 DNA damage from Ionizing Radiation (IR) ......................................................5
1.2.2 Cisplatin damage to DNA .................................................................................5
1.2.3 Cisplatin combined with radiation shows increased efficacy in killing cancer
cells. ...................................................................................................................6
1.3 Several repair pathways are involved in the repair of cisplatin and IR damage to cells.
..................................................................................................................................9
1.3.1 DNA damage response to IR involves PI3K related kinases. ...........................9
1.3.2 NHEJ .................................................................................................................9
1.3.3 HR ......................................................................................................................9
1.3.4 NER (global NER and TCR) ...........................................................................10
1.3.5 Fanconi Anemia pathway ................................................................................11
1.3.6 MMR ...............................................................................................................13
1.3.7 BER .................................................................................................................15
1.4 Phosphatidylinositol-4,5-bisphosphate 3-kinases (PI3Ks) ......................................16
1.4.1 PI3Ks are a large group of receptor associated lipid kinases that regulate
important growth, metabolism and survival pathways. ...................................16
1.4.2 Active AKT has many nuclear and cytosolic targets that control cell growth, cell
death, and metabolism. ....................................................................................19
1.4.3 Mutations leading to up-regulation of PI3K/AKT/mTOR signalling have been
implicated in tumour progression and resistance to drug therapy. ..................21
1.4.4 Recent clinical studies have identified PI3K as a novel prognostic marker for
clinical outcome in cervical cancer patients. ...................................................22
1.4.5 PI3K inhibitors have been used in vitro and in vivo to increase sensitivity to
radiation and cisplatin. .....................................................................................24
1.5 Cisplatin resistance ..................................................................................................24
1.5.1 Several mechanisms of cisplatin resistance have been identified. ..................24
1.5.2 Potential mechanistic links between PI3K and cisplatin or radiation resistance25
1.6 Hypothesis ...............................................................................................................26
1.7 Objectives ................................................................................................................27