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Preclinical Studies of Crosstalk between Pathways in Breast Cancer

Chen, Yilun (2012) MOBN15 20121
Degree Projects in Molecular Biology
Abstract
Abstract

Breast cancer is the most commonly diagnosed type of cancer in women worldwide. Inherited or
acquired aberrations of genes in DNA damage repair, cell cycle checkpoint, apoptosis, and growth
signaling pathways are responsible for the generation of breast cancer. Recently, increasing evidence
shows that signaling pathways can be highly interconnected and are interacting with each other rather
than functioning in isolation. In our projects, we studied the intersection of pathways in the context of
breast cancer from three perspectives: 1) a drug study investigating the interaction between HER2 and
AR pathways by treating the HER2+/AR+ cell line SK-BR-3 with two FDA approved drugs (trastuzumab
and hydroxyflutamide) targeting... (More)
Abstract

Breast cancer is the most commonly diagnosed type of cancer in women worldwide. Inherited or
acquired aberrations of genes in DNA damage repair, cell cycle checkpoint, apoptosis, and growth
signaling pathways are responsible for the generation of breast cancer. Recently, increasing evidence
shows that signaling pathways can be highly interconnected and are interacting with each other rather
than functioning in isolation. In our projects, we studied the intersection of pathways in the context of
breast cancer from three perspectives: 1) a drug study investigating the interaction between HER2 and
AR pathways by treating the HER2+/AR+ cell line SK-BR-3 with two FDA approved drugs (trastuzumab
and hydroxyflutamide) targeting either protein individually or in combination; 2) the interaction between
PI3K/PTEN and NOTCH pathways by comparing the change of PTEN, MYC, and HES1 expression on
transcriptional and translational levels in cells where NOTCH receptors were overexpressed; 3) the
correlation between NEDD4-1, a reported E3 ubiquitin ligase of PTEN, and PTEN by
immunohistochemical staining of breast cancer tissue biopsies. Within this work, new methods such as
xCELLigence real-time cell analysis and digital droplet PCR were applied. We found that trastuzumab
and hydroxyflutamide exhibited synergistic effects in combination with increasing concentrations; MYC
and HES1 were up-regulated when NOTCH was overexpressed, but response of PTEN to change of
NOTCH level seemed to be ambiguous; and the amount of NEDD4-1 protein was not associated to
PTEN protein levels in breast tumors. These results serve as the pilot work for further follow-up studies.

Popular science summary:

Crosstalk: A way to understand and treat cancers

Multicellular organisms can be compared to symphony orchestras. Individual cells perform like instrumentalists on the orchestra, and naturally their behavior must also be coordinated carefully by a good conductor. The intrinsic conductor of the cells is the genome. One copy of the genome lies in the nucleus of each cell, regulating whether the cell should proliferate, dormant, differentiate, have other functions, or even die in what circumstances, in a way that benefits the organism in a whole. Considering that a human genome has 3 billion nucleotide bases, codes more than 20 thousand protein products that function uniquely in all cell activities (e.g. receive biochemical signals from environment, transduce and magnify the signal in the cell, respond to the signal, etc.), and directs trillions of cells in the organism to cooperate, one may speculate it to be much mightier than any greatest conductors of our time. However the genome is sometimes originally imperfect or it may acquire postnatal aberrations that lead to deleterious outcomes. Various types of cancers are among the most unwelcome outcomes.
Perturbed genomes tweak the existing control machinery of cells by coding slightly different protein products that play slightly different roles in the intact regulatory network of the cell, but the accumulation of these changes can ultimately switch the cell behavior drastically. Cancer cells are those that are switched to be “selfish”. They decide what to do exclusively for their own benefit, regardless of what the whole body requires them to do. Such traits harm the organism but give themselves advantages against surrounding cells that are strictly regulated, and that makes cancers hard to be treated.
Over the past several decades, medical researchers have managed to classify cancers into subtypes with iconic phenotypes, and the underlying genetic reasons are being elucidated. As conventional chemotherapies, radiotherapies, and surgery are widely applied in clinic, drugs specifically targeting crucial receptors and signal transducers are also being developed to improve prognosis to the largest extent. Our projects contributed to knowledge of crosstalk between pathways in breast cancer, and may eventually be introduced into clinic. We tested two FDA approved drugs, trastuzumab and flutamide, in breast cancer cells, each of which targeting a receptor protein whose amplifications are associated to generation of certain subtypes of breast cancer. In our study, these two drugs produced a synergistic effect at comparatively higher concentrations in breast cancer cells. That doesn’t only mean they could achieve a “1+1>2” effect, but also makes it possible to minimize the side effect of both drugs in practice. In addition to the functional level, we also studied the basic mechanisms. Two signalling pathways linked, NOTCH and PI3K/PTEN in our case, one is potentially able to treat cancer effectively with another relevant drug when resistance to one drug is developed. There are still much that researchers could do to enrich our knowledge of cancer and potentially turn it into clinical applications.

Advisor: Lao Saal
Master´s Degree Project in Cell and Molecular Biology, 45 credits, 2012
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Chen, Yilun
supervisor
organization
course
MOBN15 20121
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
3563543
date added to LUP
2013-03-12 11:51:51
date last changed
2013-03-26 13:49:43
@misc{3563543,
  abstract     = {Abstract

Breast cancer is the most commonly diagnosed type of cancer in women worldwide. Inherited or
acquired aberrations of genes in DNA damage repair, cell cycle checkpoint, apoptosis, and growth
signaling pathways are responsible for the generation of breast cancer. Recently, increasing evidence
shows that signaling pathways can be highly interconnected and are interacting with each other rather
than functioning in isolation. In our projects, we studied the intersection of pathways in the context of
breast cancer from three perspectives: 1) a drug study investigating the interaction between HER2 and
AR pathways by treating the HER2+/AR+ cell line SK-BR-3 with two FDA approved drugs (trastuzumab
and hydroxyflutamide) targeting either protein individually or in combination; 2) the interaction between
PI3K/PTEN and NOTCH pathways by comparing the change of PTEN, MYC, and HES1 expression on
transcriptional and translational levels in cells where NOTCH receptors were overexpressed; 3) the
correlation between NEDD4-1, a reported E3 ubiquitin ligase of PTEN, and PTEN by
immunohistochemical staining of breast cancer tissue biopsies. Within this work, new methods such as
xCELLigence real-time cell analysis and digital droplet PCR were applied. We found that trastuzumab
and hydroxyflutamide exhibited synergistic effects in combination with increasing concentrations; MYC
and HES1 were up-regulated when NOTCH was overexpressed, but response of PTEN to change of
NOTCH level seemed to be ambiguous; and the amount of NEDD4-1 protein was not associated to
PTEN protein levels in breast tumors. These results serve as the pilot work for further follow-up studies.

Popular science summary:

Crosstalk: A way to understand and treat cancers

Multicellular organisms can be compared to symphony orchestras. Individual cells perform like instrumentalists on the orchestra, and naturally their behavior must also be coordinated carefully by a good conductor. The intrinsic conductor of the cells is the genome. One copy of the genome lies in the nucleus of each cell, regulating whether the cell should proliferate, dormant, differentiate, have other functions, or even die in what circumstances, in a way that benefits the organism in a whole. Considering that a human genome has 3 billion nucleotide bases, codes more than 20 thousand protein products that function uniquely in all cell activities (e.g. receive biochemical signals from environment, transduce and magnify the signal in the cell, respond to the signal, etc.), and directs trillions of cells in the organism to cooperate, one may speculate it to be much mightier than any greatest conductors of our time. However the genome is sometimes originally imperfect or it may acquire postnatal aberrations that lead to deleterious outcomes. Various types of cancers are among the most unwelcome outcomes.
Perturbed genomes tweak the existing control machinery of cells by coding slightly different protein products that play slightly different roles in the intact regulatory network of the cell, but the accumulation of these changes can ultimately switch the cell behavior drastically. Cancer cells are those that are switched to be “selfish”. They decide what to do exclusively for their own benefit, regardless of what the whole body requires them to do. Such traits harm the organism but give themselves advantages against surrounding cells that are strictly regulated, and that makes cancers hard to be treated.
Over the past several decades, medical researchers have managed to classify cancers into subtypes with iconic phenotypes, and the underlying genetic reasons are being elucidated. As conventional chemotherapies, radiotherapies, and surgery are widely applied in clinic, drugs specifically targeting crucial receptors and signal transducers are also being developed to improve prognosis to the largest extent. Our projects contributed to knowledge of crosstalk between pathways in breast cancer, and may eventually be introduced into clinic. We tested two FDA approved drugs, trastuzumab and flutamide, in breast cancer cells, each of which targeting a receptor protein whose amplifications are associated to generation of certain subtypes of breast cancer. In our study, these two drugs produced a synergistic effect at comparatively higher concentrations in breast cancer cells. That doesn’t only mean they could achieve a “1+1>2” effect, but also makes it possible to minimize the side effect of both drugs in practice. In addition to the functional level, we also studied the basic mechanisms. Two signalling pathways linked, NOTCH and PI3K/PTEN in our case, one is potentially able to treat cancer effectively with another relevant drug when resistance to one drug is developed. There are still much that researchers could do to enrich our knowledge of cancer and potentially turn it into clinical applications.

Advisor: Lao Saal
Master´s Degree Project in Cell and Molecular Biology, 45 credits, 2012
Department of Biology, Lund University},
  author       = {Chen, Yilun},
  language     = {eng},
  note         = {Student Paper},
  title        = {Preclinical Studies of Crosstalk between Pathways in Breast Cancer},
  year         = {2012},
}