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THE APPLICATION OF CRISPR-CAS9 GENOME EDITING IN CANCER
RESEARCH AND TREATMENT
Patrick Iyasele, [email protected], Budny 10:00, Mateus Pinho, [email protected], Budny 10:00
Abstract— DNA is the essential building block for life on
Earth. It is the biological code for creating proteins that lead
to the creation of enzymes and chemicals which are vital for
any organism to live and function. Because of its complexity,
any errors made during the DNA replication process can lead
to serious diseases like cancer and death. However, the new
technology CRISPR- Cas9 (Clustered Regularly Interspaced
Short Palindromic Repeats) has made it accessible and
manageable to alter an organism’s DNA. The CRISPR-Cas9
system, often abbreviated just as CRISPR, is a two-component
system that contains a guide sequence of RNA that targets any
DNA sequence of interest and the Cas9 protein that cuts the
DNA at that point. In cancer research, the CRISPR-Cas9
system can be used to create experimental models for cancer
research. Models, organisms, and cell cultures that have been
specially designed for experimental testing, can potentially
help identify malignant sequences within the genomes of
cancer cells and thus help alter them later. The possibilities
of CRISPR-Cas9 when used for cancer research and clinical
treatment has extraordinary potential, giving scientists and
doctors a powerful tool that can save and improve many lives.
This paper is meant to describe CRISPR technology, its
current and potential uses in research, how in the future how
CRISPR-Cas9 will sustain and improve quality of life, and its
integration into cancer research for the sake of discovering
another treatment for cancer.
large enough to impede the functions of surrounding cells.
Because cancer originates from a person’s own cells, genetic
engineering can be used to cure such a disease. Although
genetic engineering has existed for many years, the accuracy
and speed of modification techniques limited what could be
done with the technology. This changed in the year 2013 with
the development of CRISPR (Clustered Regularly Interspaced
Short Palindromic Repeats). CRISPR works in conjunction
with the protein Cas9 which can perform alterations and
mutations to a cell’s DNA. Other genetic engineering
technologies often have low efficiency and much higher rates
of accidental mutations, but CRISPR has a consistent targeting
system [1]. When using specially tailored strands of genetic
information, scientists can confidently use CRISPR to target
specific areas in the DNA and modify them with relative ease.
Following the procedure, they can see how the altered strand
of DNA affects the organism’s cell [1]. When applied to cancer
research, the CRISPR-Cas9 system can be used to identify
sequences and sections within the genome that are prone to the
development of cancer [1]. Altering the DNA of an organism
or cell can also facilitate the process of creating models that
simulate a cancerous tumor or growth, helping scientists
observe the effects of different treatments on an organism or a
cell. No other genetic modification tool offers such high
versatility and efficiency in the field of genetic engineering.
While CRISPR does outperform other genetic engineering
tools, the technology still requires further development to
improve its performance and versatility. The current
limitations of CRISPR technology restrict it as a tool only for
experimentation, but it is still a useful tool in cancer research,
helping scientists understand and learn the different details
present in a complex cancerous growth. The potential of this
technology is not contained only to this purpose but also to the
treatment of genetic diseases. With the advancement of this
technology, also comes ethical concerns. There are fears that
once this technology is applied to humans, it might lead to an
abuse of power with people recklessly editing their genome.
Although revolutionary, because of the newness of this
technology and the ethical issues surrounding the use of
CRISPR-Cas9 technology in human subjects, the introduction
of this technology into clinical treatment is well into the future.
Key Words— Bio Ethics, Cancer Modeling, Cancer Research,
CRISPR-Cas9, Genetics, Genetic Engineering, Genome
Editing, RNA, Sustainability
CRISPR: A NEW FORM OF GENETIC
ENGINEERING
Genetic engineering has enormous potential for its use in
the medical field, especially in the treatment of genetic
diseases which typically have no cure. Cancer, for the most
part, is a genetic disease. Cancer is caused by a mutation in a
cell’s DNA which affects the replication process. This can
cause that cell to replicate exponentially without undergoing
apoptosis (programed cell death). Those cells eventually grow
University of Pittsburgh, Swanson School of Engineering
Submission Date 26.01.2017
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If the time comes that CRISPR-Cas9 is inducted into standard
medical practice, many genetic diseases would be eradicated,
greatly improving and sustaining the quality of life for many
people. As the technology continues to improve, one day it
may have the potential to treat cancer caused by genetic
mutations, thus being one of the most promising technologies
in the fight against cancer.
THE NATURAL PROCESS OF CRISPR
GENOME EDITING
Genetic engineering, for many years, was solely based on
probability and luck. Many scientists relied on specially
engineered viruses, commonly known as viral vectors, to
introduce new segments of genetic information into a cell. The
discovery of the CRISPR method revolutionized genetic
engineering, allowing scientists to target specific sections of
the DNA and alter their specimens with better efficiency.
CRISPR’s name comes from the organization of short,
partially palindromic repeated DNA sequences naturally found
in the genomes of certain microorganisms [2]. Following the
discovery of this system, scientists then applied the same
principals to different organisms and helped develop it into the
technology it is today.
Figure 1 [3]
Diagram depicting CRISPR and the Cas9
performing a genetic alteration
CRISPR-Cas9 Systems Found in Organisms
After hybridizing with tracrRNA, the two form a
complex called gRNA. The gRNA interacts with Cas9, a
protein naturally found inside bacteria. The Cas9 protein uses
the protospacer identified in CRISPR as a guide and cuts the
section of DNA that matches the protospacer and when there
is a Protospacer Adjacent Motif (PAM) sequence directly
down sequence of the desired sequence. In the case of a
bacteria, if the DNA of a virus that has entered the bacteria
matches the protospacer, the Cas9 protein will cut that virus’
DNA, thus removing the potentially harmful DNA. If a new
virus enters the cell, the bacteria will still be attacked, but part
of its genetic sequence will be added to the cell’s DNA as a
new protospacer. This naturally occurring defense mechanism
is unique to bacteria and some microorganisms, but the same
principals can be altered and applied to different organisms,
such as human cells.
CRISPR, along with the associated Cas9 protein, was
first discovered in bacteria as a natural defense mechanism
against foreign DNA, which often came from viruses and
plasmids. Scientists saw CRISPR in bacteria and then altered
it in a way that can be applied in different scenarios. Figure 1
shows the process of how CRISPR edits a DNA strand.
According to Dr. Jeffry Sander in his paper “CRISPR-Cas9
systems for editing, regulating and targeting genomes,”
“CRISPR systems incorporate sequences from invading DNA
between CRISPR repeat sequences encoded as arrays within
the bacterial host genome” [3]. As seen near the top left of
Figure 1, the different segments of invading DNA, called
protospacers, are separated by CRISPR repeats. The
protospacers come from DNA of viruses that have previously
attacked the host cell. Therefore, spacers serve as a ‘genetic
memory’ of previous infections [2]. Copies of the CRISPR
sequence and invading DNA are made and processed into
CRISPR RNAs (crRNAs). Also, seen in Figure 1, the crRNAs
then hybridize with another type of CRISPR RNA, referred to
as transactivating CRISPR RNA (tracrRNA).
CRISPR as a Method for Genetic Engineering
For the CRISPR method to be used in different
organisms, Cas9 proteins and a specially designed gRNA must
be introduced into the cell. The Cas9 protein is not naturally
found in multicellular organisms, and the gRNA is what allows
for targeted genome editing. To target a specific section of
DNA, a 20 nucleotide protospacer must be created, displayed
as the crRNA in Figure 1 part b. When cutting the DNA with
the Cas9 protein, there are small factors that, when exploited,
can lead to the desired alteration in the organism’s DNA. When
the targeted DNA is cut, the cell attempts to repair the
sequence but cannot fully do so. Because of this, the gene at
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that point is disrupted. As shown in Figure 2 on the right side,
if another DNA strand is introduced with the gRNA, it is
possible to insert the new DNA into the disrupted sequence,
thus will be integrated into the DNA of the organism. This
process of repairing the DNA with a new segment of DNA,
called annealing, is the desired process that genetic engineers
strive for when using CRISPR. For cancer in particular, this
will allow scientists to induce cancerous mutations in cell
tissues or animals, which can help lead to treatment methods
that can more accurately combat such mutations.
as a tool to help create effective models for testing different
treatments.
Creating Models
Often when an experiment needs to be done, creating a
model is necessary to test a hypothesis. A model, in a
biomedical setting, is a live animal or cell culture that is
designed to simulate different scenarios, like tumor growth.
These simulations can help scientists experiment with different
treatments, helping them understand the advantages and
disadvantages of the treatment prior to applying it on a human
patient. Before the discovery of CRISPR, handling live
organisms to create the perfect model was difficult and time
consuming. With the use of CRISPR technology, the process
of creating a desired model for an experiment is much easier,
and frequently more cost efficient. In an article by Randall J.
Platt and Sidi Chen and others, the team was experimenting
with CRISPR for genome editing and cancer modeling. In the
experiment, they used CRISPR to create a mouse that had a
dependency to the Cre recombinase enzyme. All they needed
to do was insert a specific strand of genetic information into
the associated section of DNA [6]. By using CRISPR, they
successfully made the model they were looking for without the
meticulous intermediate steps that are usually done when
making live mice models. Along with creating the desired
mouse model, when the mouse model was bred with other
mice, “The constitutive Cas9-expressing mice were fertile, had
normal litter sizes, presented no morphological abnormalities,
and were able to breed to homozygosity” [6]. Making sure the
offspring are viable candidates for modeling is important in
order to make sure the experiment is economically sustainable.
Many other techniques of genetic modification leave the
mouse model sterile, or unable to produce offspring that can
be used for modeling. This increases the cost of the overall
experiment, forcing the scientists to repeat the process of
creating the model in order to achieve the same results.
CRISPR avoids this complication, allowing for an
economically feasible way to create live models. At the
cellular level, the offspring and parents showed no
abnormalities and differences in the natural rate of cell death,
meaning that these models were perfectly viable subjects [6].
While the current efficacy of CRISPR can be low in live
animal models, the CRISPR-Cas9 system still serves as an
excellent tool that can be applied to many different situations,
often saving time and money for those using it. As the
technology develops and its efficiency increases, CRISPR will
lead to better results when used by scientists to alter the DNA
of live organisms.
FIGURE 2 [4]
Diagram of how gRNA overlaps DNA and slices or edits
One of the main reasons why CRISPR is being
considered revolutionary is due to its effective results and
relatively easy delivery, especially compared to site-directed
mutagenesis (SDM), one of more common forms of gene
editing, CRISPR outshines. SDM requires the use of multiple
enzymes to cut at the desired point in the sequence, making it
more complicated and difficult to manage. Those enzymes
may also create unwanted cleavages at different places in the
sequence. Because CRISPR requires the protospacer to be the
same as the target DNA, the chances of unwanted cleavages to
occur significantly decreases, thus meaning the chances of
creating unintended genetic defects is very small. This
specificity makes CRISPR a highly-preferred method for
conducting research and provides scientists the desired
precision for complex genome editing.
CURRENT USAGE OF CRISPR IN
RESEARCH
Even though CRISPR has only recently been discovered,
most biomedical laboratories have already incorporated the
technology into their procedures when conducting
experiments. Especially when testing different variables
within the genome, CRISPR allows for precise and focused
gene editing [6]. In most cases, CRISPR serves as a tool for
changing disease mutations or phenotypes, but it can also serve
Changing Mutations and Phenotypes
One of the main advantages of CRISPR is that it can
repair the genome where mutations have occurred. In a
publication by Nature Biotechnology, CRISPR technology
corrected a disease mutation and phenotype in mice. In this
experiment, scientists “…used a mouse model of hereditary
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tyrosinemia type I (HTI), a fatal genetic disease…” [5]. To try
and cure the mouse’s disease, they created a single guide RNA
(sgRNA) strand that is complementary to the target region in
the DNA that causes the disease. The components of the
CRISPR-Cas9 system, including the sgRNA, were then
injected into the mouse’s liver, where the disease causes the
most damage. After applying CRISPR, the mouse regained
weight and displayed corrections to the diseased phenotype,
giving an “…observed initial genetic correction rate of ~1/250
cells” [5]. Although the genetic correction rate is still low,
previous studies that used adeno-associated viruses as a form
of gene therapy yielded similar results while requiring several
rounds of pharmaceutical drugs and recovery to remain alive.
Therefore, the CRISPR-Cas9 system is far more efficient than
other gene therapy techniques, requiring less chemicals to keep
the cell tissues alive. It should be noted that “…improvements
to CRISPR delivery methods and repair efficiency will be
required for its broad therapeutic application, in particular to
increase the rate of gene correction and to target other tissues”
[5]. Nevertheless, correction of genetic diseases in a live
organism was demonstrated with the use of CRISPR
technology. When dealing with human genetic diseases, it is
necessary to solve these limitations prior to human treatment.
Using CRISPR on a human patient today could lead to
ineffective treatment, performing little to no beneficial
changes. When there have been improvements to the delivery
and repair mechanisms, CRISPR will have the capacity to be
used to cure and treat genetic disease in humans.
genome of cells and specifically target the oncogenes or
tumor-suppressor genes to create a more accurate model for
cancer research.
FIGURE 3 [7]
Diagram displaying pathways for CRISPR-induced
cancer cell models and other possible genome edits
As shown in Figure 3 above, creating CRISPR-mediated
cells with specific properties can be tailored to any experiment.
After creating a desired model, “Cell lines carrying one or
more targeted mutations can then be tested using a series of
cell-based and in vivo assays to examine the effects of the
mutation (or mutations) on cancer-associated phenotypes” [7].
By experimenting with these cells, a better understanding of
the treatment, prior to human application, can be discovered.
This can help gain new insight and knowledge about different
ways to tackle cancer, furthering the general understanding of
cancer without the associated risks of human testing.
Furthermore, when analyzing the complex interaction of
genes, known as epistasis, CRISPR induced cancer cells often
have less factors that may alter or affect its ability to properly
model cancer cells [7]. By creating a perfect model with little
to no imperfections, an extraordinary tool for experimentation
is available for researchers.
Although modeling cancer cells on the cellular level is an
essential aspect of cancer research, the complexity of large
multicellular organisms lead to other factors that affect
development and modeling of cancer. While the added
complexity from a multicellular organism may make it more
difficult to create a desired model, the complex model comes
closer to representing a human body.
CURRENT AND FUTURE USAGE OF
CRISPR IN CANCER RESEARCH
CRISPR provides extraordinary versatility when it comes
to being applied for biomedical research. Especially when it
comes to tackling an issue such as cancer, CRISPR can be a
very useful tool to make new developments in research. As
mentioned in the article “Applications of the CRISPR- Cas9Cas9 system in cancer biology” by Francisco Sánchez-Rivera
and Tyler Jacks, two MIT faculty members, CRISPR “…is
rapidly revolutionizing the field of genetic engineering,
allowing researchers to alter the genomes of a large range of
organisms with relative ease. Experimental approaches based
on this versatile technology have the potential to transform the
field of cancer genetics” [7]. When approaching cancer
research through modeling and experimentation, CRISPR can
be an essential tool to facilitate this process.
In Vivo Cancer Modeling
When it comes to live animal or organism modeling, also
known as in vivo modeling, there are certain advantages and
disadvantages that arise when performing an experiment. One
of the major advantages of in vivo modeling is that it will be a
representation of the human body and therefore serve as a
better tool for experiments. However, creating the perfect
model is often costly and difficult to achieve. As mentioned in
the current usage of CRISPR section, creating mouse models
is one of the main in vivo models of choice. The genetically
engineered mouse models (GEMMs) “…have played a critical
Cancer Cell Modeling
CRISPR, in cancer research, is primarily used to alter a
cell’s oncogenes and tumor-suppressor genes. These two
categories of genes are the primary factors that promote or
inhibit the development of cancer, respectively. Taking
advantage of the CRISPR-Cas9 system, scientists can alter the
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part in uncovering several fundamental aspects of tumor
initiation, maintenance and progression. In addition, they have
emerged as faithful models with which to test a range of
anticancer agents and to uncover mechanisms of drug
resistance” [7]. The normal process of creating GEMMs is
slow and expensive, requiring extensive embryonic stem (ES)
cell editing followed by careful mouse breeding; with
CRISPR, the process for creating the desired GEMM is
facilitated.
Regardless of the potential complications, CRISPR can
still be used to create better models for cancer because of its
ability to replicate the exact mutation of interest. With time,
CRISPR could be tailored for individuals, creating a
personalized model of a patient’s cancer. As mentioned in
Sánchez-Rivera’s publication, “The successful deployment of
sophisticated
genetic-profiling
technologies
for
comprehensive characterization of a patient's tumor is
generating detailed roadmaps to instruct the development of
tailored cell-based or whole animal-based experimental
systems. These systems will serve as personalized platforms
with which researchers will rapidly and systematically identify
genotype-specific vulnerabilities and synthetic lethal
interactions…” [7]. These personalized models can provide
doctors with a vital tool to help figure out the necessary care
their patient needs to cure their disease. As coined by SánchezRivera, these personalized models can be the roadmap to
discovering the best treatment to better approach to a patient’s
cancer. The personalized model will also give a better
understanding of side effects and risks that may arise when
applying the treatment to the actual patient, giving the insight
for patients to prepare what they may have to endure.
Furthermore, “…such personalized platforms could be studied
in parallel to the patients, potentially allowing for the rapid
identification of resistance mechanisms and the development
of strategies to overcome such shortcomings” [7]. Similar
cases will ultimately arise when studying different cancers,
and, with proper documentation, these personalized models
can help doctors find the most efficient approach to a specific
form or type of cancer. While personalized models for cancer
research may not be available in the foreseeable future,
developments in cancer research can still occur, and may still
appear in the near future with the help of CRISPR technology.
FIGURE 4 [7]
Diagram showing different methods to create GEMMs
As show in Figure 4, there are many different processes
to create GEMMs for cancer research, and they can be used for
various reasons. For example, in the article by Platt and Chen,
they were modeling lung cancer mutations. In their
experiment, they were trying to induce a mutation in the
oncogene Kras, an oncogene associated with lung cancers. To
do this they designed an HDR donor template, a specific
genomic sequence which is like a region in the genome. With
this and the Cas9 enzyme, they induced the mutation into the
cells. Approximately four percent of the altered sequence
matched the original donor sequence, meaning that the
CRISPR gene modification was successful. This means that
cells now had the G12D mutation and other associated
mutations [6]. Following the Kras mutation all animals
developed tumors in the lung. The size of the tumors increased
significantly over time, “…which is the complexity observed
in human tumors” [6]. To summarize the results, the CRISPRCas9 successfully created representative GEMMs which could
be used in future cancer research experiments.
With GEMMs and other models behaving similarly to the
human body, more studies can be done to find out the causes
and potential cures for cancer. As CRISPR develops and
becomes more advanced, better models can be attained and
serve as better representations of the human body.
ETHICAL CONCERNS ASSOCIATED WITH
CRISPR TECHNOLOGY
Genetic engineering is not a new idea. Humans have been
modifying the genetic structures of different plants and
animals through selective breeding. Domestication is the major
vehicle which has led to our modern way of life. Because of
domestication, the farming of animals and more efficient
farming methods became possible. Modern genetic
engineering techniques now allow for the manipulation of
more plants and animals. Professor Ming Zheng at Gordon
College states that, “Medical applications of genetic
engineering include diagnosis for genetic and other diseases;
treatment for genetic disorders; regenerative medicine using
pluripotent (stem) cells; production of safer and more effective
vaccines, and pharmaceuticals; and the prospect of curing
genetic disorders through gene therapy” [8]. Even so,
genetically modifying organisms has always sparked major
ethical debate. When it pertains to genetically altering human
cells, concerns always arise. On another note, creating
GEMMs also leads to controversy due to the very nature of
Future of CRISPR and Cancer Research
As CRISPR technology develops, its usefulness as a tool
for research will continue to grow. As CRISPR becomes more
precise and advanced, questions of using CRISPR directly on
the human body arise. While it may be appealing to use
CRISPR directly on a patient, this could lead to harmful
consequences when improperly done, such as altering a gene
which should not have been altered, which could cost the
patient’s life.
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animal experimentation. With widespread debate and
controversy, it is important to discuss ethical concerns with
CRISPR technology.
believe that if this is allowed, then people will start modifying
babies for aesthetic designs and not only to prevent diseases.
Professor Phillip Brey from the University of Twente writes in
an article, “It is controversial because it leads to inheritable
modifications of the genome that are passed on to future
generations. The long-term side effects of such engineering are
currently unpredictable, and there are also concerns that such
engineering violates the rights of future generations or
amounts to ‘playing God’. Also controversial is genetic
engineering to enhance human traits such as intelligence or
strength, whether practiced on somatic cells or germline cells.
Such genetic enhancement is controversial for the same
reasons that apply to other types of human enhancement” [11].
If CRISPR is allowed to treat a disease such as cancer, there
could be a push for gene editing in other cases that have more
ethical concerns. Whether it be editing a fetus’s genes to
prevent a disorder like Huntington’s disease or editing genes
to slow down aging, a precedent will be set, opening Pandora’s
box for the free editing of genes if CRISPR becomes a diseasetreatment norm.
When including the subject to cancer research, there lies
an ethical grey zone. While it is undisputable that editing
embryonic and mature cells can be considered unethical,
cancer cells lie in a different category. Since cancer cells are
technically a disease, it could be considered as curing a
patient’s illness, but it could easily be adapted to the genome
for other benefits. This hypothetical situation is just one of the
concerns when using CRISPR for direct treatment of cancer.
Questions concerning the restrictions that should be set in
place for genetic modification are difficult to answer, and often
varies depending on culture and legislation in the country
where the research is being made. Hopefully when advanced
genome editing is achieved in the future, a general consensus
can be achieved in a way that both those who need the
treatment, and the concerned public can be pleased.
CRISPR and Animal Testing
Because of in vivo modeling with CRISPR, there is an
underlying concern for ethics. Most animal testing in the
United States is done under strict regulation to minimize
ethical concerns and public backlash. For example, the
National Institutes of Health (NIH), under the U.S. Department
of Health and Human Services states, “The goal of clinical
research is to develop generalizable knowledge that improves
human health or increases understanding of human biology”
[9]. While regulations are set in place, there are still concerns
from the public that strive to end animal testing. Organizations
such as People for the Ethical Treatment of Animals (PETA)
are notorious for their crusade against animal testing. PETA
notes that mice that are used to create GEMMs are
“…excluded from the meager federal Animal Welfare Act
provisions that extend at least some protection to these other
species. Because mice and rats are not protected by the law,
experimenters don’t even have to provide them with pain
relief” [10]. Concerns like these drive debate against animal
testing in labs. While the actual process of injecting CRISPR
may not require pain relief, the resulting effects of the altered
genes do bring up concern. The tumors that CRISPR induces
may cause pain to GEMMs or impede their ability to walk,
breathe, or eat, depending on the location of the tumor, but it
would ruin the integrity of the experiment to give them pain
relief. Therefore, it is difficult to ensure the well-being of the
GEMMs without ruining the validity of the experiment and
potentially altering the results.
Unfortunately, the dilemma of a maintaining GEMMs
health and the validity of the experiment has no answer. In vivo
research directly affects the health of the mouse, and often
observing how the experiment affects the GEMMs’ health is
an essential aspect of reports. The only way to avoid
compromising the health of the animal is to avoid
experimentation. Until there is a viable alternative that can
simulate aspects of a large living organism, resorting to live
animal testing is the best course of action to model a human
body. With only in vitro modeling with CRISPR, scientists
may miss vital information because cancer in an organism can
affect various cell types.
SUSTAINING HUMAN QUALITY OF LIFE
THROUGH CANCER RESEARCH
Once CRISPR-Cas9 technology further developed and
inducted into clinical practice as a treatment tool, it will sustain
and improve the quality of life for all those whose disease it
can cure. For the purposes of this paper, sustainability is about
maintaining and improving the quality of life of those in the
community to achieve a balance among, the social, economic
and environmental pieces of a community. Other genetic
engineering techniques, such as adeno-associated viruses and
SDM, require drugs and enzymes that require the use of
hazardous materials to generate. Mercury, although used in
many drugs and chemical processes, is one of the main
hazardous materials used in research. Dr. Neeti Rustagi from
the Maulana Azad Medical College in New Delhi conducted
research about the waste produced by medical research. In his
paper, he writes, “Health care facilities are one of the main
sources of mercury release into the atmosphere because of
Genetic Modification of Humans
Human genome editing is always a major topic of
discussion when examining the future of genetics. Tools like
CRISPR allow for the modification of the human genome, but
there are always heated debates on the ethical concerns around
these experiments. One of the major sources of debate for
genetic engineering is whether fetuses should be modified to
correct birth defects and genetic dispositions to health
conditions like high blood pressure and obesity. Some people
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emissions from the incineration of medical waste. In some
places, it is as much as fourth-largest source of mercury in the
environment. In the USA, according to the US Environmental
Protection Agency (EPA) in a 1997 report, medical waste
incinerators were responsible for as much as 10% of all
mercury air releases. The water bodies get polluted with the
mercury used in the health care sector” [12]. Medical waste
and other toxins can infiltrate water systems, exposing and
contaminating the wildlife to these harmful chemicals. The
CRISPR-Cas9 system, on the other hand, requires less
materials than other contemporary methods of genetic
engineering and does not use any hazardous materials lowering
the amount of mercury waste produced by medical research
centers. CRISPR-Cas9 can also be used to improve the quality
of life for cancer patients. Currently for cancer, there are three
main treatment options: chemotherapy, radiation therapy, and
surgery. Surgery is only an option for when a tumor has gotten
large enough and has to be followed with a chemotherapy or
radiation therapy treatment. Radiation therapy is the use of
high energy electromagnetic waves, such as x-rays and gamma
rays, to kill cancer cells [13]. Chemotherapy is the use of a
drug to treat cancer. All those treatment options have major
side effects that worsen the patient’s quality of life. Dr. Hwang
from Gachon University College of Nursing in South Korea,
conducted research on the quality of life of breast cancer
patients by taking surveys and comparing the responses to a
control group. In her paper, she writes, “In conclusion,
adjuvant chemotherapy for breast cancer significantly affects
QOL (Quality of Life) and the effects of chemotherapy on
QOL appear to vary according to time since surgery. Breast
cancer patients receiving chemotherapy experience the adverse
effects of adjuvant chemotherapy up to 1 year after surgery on
overall aspects of QOL and tend to recover later years” [14].
Dr. Hwang’s research confirms that there is a significant
difference in the quality of life of cancer patients. Both
radiation therapy and chemotherapy cause side effects such as
fatigue, hair loss, anemia, and nausea. CRISPR-Cas9
technology has the potential to replace these methods, and
would rid the patient of these side effects. CRISPR treatment
would only consist of a shot containing the target DNA, the
insert DNA, and the protein Cas9. As a future treatment option
CRISPR-Cas9 technology can help determine the specific
sequences in the patient’s cells that are causing the cancer or
could also edit the patient’s immune cells to be more effective
at locating and killing cancer cells. CRISPR-Cas9 as a
treatment option would improve a patient’s quality of life and
would sustain the social and economic atmosphere of the
community.
the very nature of aging, it is a difficult disease to avoid.
Although it is difficult to prevent, cancer is fundamentally tied
with genetics, making CRISPR an appealing tool to use.
Current experiments and clinical studies done with CRISPR
show promising results as a tool for cancer research and
modeling. While CRISPR technology may not prove a viable
solution to directly treat cancer, modeling serves as a way to
help find better treatments. A better model provides scientists
and researchers the opportunity to experiment their
hypothesized treatments without the underlying concerns that
arise when applying their experimental treatment to a human
patient. Although the efficacy of CRISPR may be low at times,
its precision and accuracy as a tool remains high, providing
excellent results and successfully creating models that can
better represent human tumors. Furthermore, as CRISPR
technology develops and becomes more advanced, its
efficiency and capacity will grow, and may one day be used to
directly treat cancer [5]. Using CRISPR as a clinical tool has
the potential to avoid the side effects of regular cancer
treatments, therefore sustaining the quality of life of patients
and potentially saving their lives. Ethical concerns about
CRISPR will likely remain prevalent in the foreseeable future,
but current experiments still provide excellent insights and
results that can be used. Hopefully with enough time and
development, CRISPR technology, along with the use of other
technologies, can lead to finding feasible solutions that can
effectively and safely treat cancer.
SOURCES
[1] J. Doudna, E. Charpentier. “The new frontier of genome
engineering with CRISPR-Cas9-Cas9”. Science. 11.28.2014
Accessed 1.26.2016. http://science.sciencemag.org/content/3
46/6213/1258096.
[2] Addgene. "CRISPR/Cas9 History." Addgene. N.p., n.d.
Web. 10.30. 2016. Accessed 3.3.2017.
[3] J. Sander, J. Joung. "CRISPR-Cas Systems for Editing,
Regulating and Targeting Genomes." Nature Biotechnology.
2.3.2014. Accessed 3.3.2017. http://www.nature.com/nbt/jo
urnal/v32/n4/full/nbt.2842.html%3Fmessageglobal%3Dremove.
[4] E.Pak. “CRISPR: A game-changing genetic engineering
technique.” STIN Harvard. 7.31.2014. Accessed 3.3.2017.
http://sitn.hms.harvard.edu/flash/2014/crispr-a-gamechanging-genetic-engineering-technique/.
[5] H. Yin, W. Xue, S. Chen, R. Bogorad, E. Benedetti, M.
Grompe, V. Koteliansky, P. Sharp, T. Jacks, D. Anderson.
"Genome Editing with Cas9 in Adult Mice Corrects a Disease
Mutation and Phenotype." Nature Biotechnology. 3.30.2014.
Accessed 3.3.2017. http://www.nature.com/nbt/journal/v
32/n6/full/nbt .2884.html.
[6] R. Platt, S. Chen, Y. Zhou, M. Yim, L. Swiech, H.
Kempton, J. Dahlman, O. Parnas, T. Eisenhaure, M.
Jovanovic, D.Graham, S.Jhunjhunwala, M.Heidenreich,
R.Xavier, R.Langer, D.Anderson, N.Hacohen, A.Regev,
G.Feng, P.Sharp, F.Zhang. “CRISPR-Cas9 Knockin Mice for
CONQUERING THE EMPEROR OF ALL
MALADIES
The abnormal behavior of cancer makes it a difficult
disease to tackle. There is an overabundance of substances and
factors that can lead to the development of cancer, and due to
7
Patrick Iyasele
Mateus Pinho
Genome Editing and Cancer Modeling.” Cell. 10.9.2014.
Accessed
3.3.2017..
http://dx.doi.org/10.1016/j.cell.2014.09.01 4.
[7] F. Sánchez-Rivera, T. Jacks. “Applications of the
CRISPR- Cas9-Cas9 system in cancer biology.” Nature
[8] Zheng, Ming Y., Ph.D. "Genetic Engineering." (n.d.): n.
page. Gordon College. Gordon College. Web. 31 Oct. 2016.
http://www.gordon.edu/download/pages/SalemGenetic%2E
ngineering2003.pdf
[9] NIH. "NIH Clinical Center: Ethics in Clinical Research."
U.S National Library of Medicine.10.20.2016. Accessed
3.3.2017. http://cl inicalcenter.nih.gov/recruit/ethics.ht ml.
[10] PETA “Mice and Rats in Laboratories”. PETA Accessed
3.3.2017.
http://www.peta.org/issues/animals-used-for-ex
peri mentation/animals-laboratories/mice-rats-laboratories/
[11] P. Brey. (2009). ‘Biomedical Engineering Ethics.’ Eds.
Berg-Olsen, J., Pedersen, S., Hendricks, V. (eds.), A
Companion to Philosophy of Technology. Blackwell.
[12] Rustagi, Neeti, and Ritesh Singh. "Mercury and Health
Care." Indian Journal of Occupational and Environmental
Medicine. Medknow Publications, Aug. 2010. Web. 30 Mar.
2017.
[13] American Cancer Society. "Information and Resources
about for Cancer: Breast, Colon, Lung, Prostate, Skin."
American Cancer Society. American Cancer Society, n.d.
Web. 30 Mar. 2017.
[14] Hwang, Sook Yeon, Sun Ju Chang, and Byeong-Woo
Park. "Does Chemotherapy Really Affect the Quality of Life
of Women with Breast Cancer?" Journal of Breast Cancer.
Korean Breast Cancer Society, June 2013. Web. 30 Mar. 2017.
Reviews
Cancer.
6.4.2105.
http://www.nature.com/nrc/
journal/v15/n7/full/nrc3950.html.
Accessed
3.3.2017.
His quirks and charm has made the class fun and entertaining,
teaching us to enjoy every day while balancing engineering.
ADDITIONAL SOURCES
R.Sivapatham. "Ethical Implications of Human Genetic
Engineering." SAGE: Science of Aging. Buck Institute,
8.19.2015.
Accessed
3.3.2017.
http://sage.buckin
stitute.org/ethical-implications-of-human-geneticengineering-2/.
W.Xue, S.Chen, H.Yin, T.Tammela, T.Papagiannakopoulos,
N.Joshi, W.Cai, G.Yang, R.Bronson, D .Crowley, F.Zhang,
D.Anderson, P.Sharp, T. Jacks. “CRISPR-mediated
directmutation of cancer genes in the mouse liver.” Nature.
10.16.2014.
Accessed
1.26.2017.
http://www.nature.
com/nature/journal/v51 4/n7522/full/nature13589.html
ACKNOWLEDGMENTS
We would like to acknowledge a few people who have
guided us down our path to becoming bioengineers. Patrick
would like to acknowledge Dr. Joseph Barbieri for helping him
decide to become a Bioengineer. Mateus would like to
acknowledge Laura Wilcox for helping him discover his
passion for biology. We would also like to acknowledge Dr.
Daniel Budny for being an excellent ENGR 0012 instructor.
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