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CRISPR and Cancer Treatment

Cancer is the second leading cause of death in today’s society, responsible for one in seven deaths, with painful and long treatment plans. In worst-case scenarios, the patient can have cancer that resists radiation and chemotherapy, or the cancer is too far along that surgery is out of the option. The new and exciting CRISPR technology can bring light into this field. With the use of gene editing, doctors can possibly treat and cure cancers by finding the part of the human gene that causes different types of cancers, and then using CRISPR-Cas9 to edit this faulty gene. This CRISPR technology is currently being studied towards using it to prevent, diagnose, and treat cancer. The most critical factors being looked into are correcting the genome of the cells, making them cancerous, and suppressing the expression of specific proteins.

As previously mentioned, CRISPR-Cas9 is an easy and versatile way for targeted genome editing. A few changes were made so it can be used within human cells to edit DNA. The system is guided by the single-guide RNA (sgRNA) to target specific regions of a genome for editing, the Cas9 protein will cut the DNA in this specific region, and the crRNA will be complementary to the section of DNA of interest. Once the break is made, the DNA will either be degraded or can be repaired and edited.

Applying this technology to treat cancer can get tricky because there are many different types of cancers that affect different tissues and systems in our body. This requires making the CRISPR-Cas9 system to be specific so it doesn’t target and edit undesired genes. In order to find a way to treat some cancers, scientists have to look at specific types and access how CRISPR can be utilized to treat them. Two of them are spoken about below, but there is more research on other kinds of cancers with new advancements occurring frequently.

One of the kinds of cancers CRISPR is being used with is prostate cancer. A significant cause of death in the male population is prostate cancer. Over the years of research, scientists have begun to understand the signalling pathways, single base-pair variants, non-coding RNA and many more that are associated with prostate cancer. A certain study that is using the technology of CRISPR-Cas9 towards treating cancer is looking at disrupting the androgen receptor (AR). Androgen stimulates prostate cancer to grow, so it is only logical to halt the production of androgen by disrupting the AR. By using the CRISPR-Cas9 system to edit the AR gene, scientists can disrupt and completely block the production of androgen which will, in turn, suppress the growth of androgen-sensitive prostate cancer cells.

Another type of cancer that is specific to women is cervical cancer. It has been discovered that the human papillomavirus (HPV) infection has an association with cervical cancer. The mutations within the HPV that cause the cancer are the E7 and E6 genes. These two genes will affect the Rb and p53 proteins that play a role in cell cycle arrest. The Rb and p53 proteins function as checkpoints within the cell cycle to ensure the cell is in good shape to continue along the cell cycle and replicate. If there is something wrong with the cell, like a mutation, these proteins will stop the cell cycle so the cell can’t replicate its faulty genes. The E6 genes will function by facilitating the degradation of the p53 protein, thus overcoming this checkpoint. The E7 gene can also overcome the checkpoint by binding and inhibiting the Rb protein (Figure 1). Researchers looked into using the CRISPR-Cas9 system to edit the E7 and E6 genes in order to halt their negative effects on the cell cycle. Some researchers edited the genes of E7 and E6 using CRISPR-Cas9 and found a decline in cancerous cells in mice. This leads to many more possibilities for future research to progress and hopefully result in human trials.

Figure 1. A diagram representing the effects E6 and E7 genes have on the cell cycle. They will both result in the cells overcoming the checkpoints. This can result in cancer cells that keep replicating and never die, resulting in an overabundance of cells causing tumours.

Overall, the CRISPR-Cas9 system has been used to edit and disrupt genes of human cells in an effort to reveal their functions and hopefully identify targets for tumour types. The main challenge it faces is specificity, which can possibly lead to dysfunction of key genes, translocation in chromosomes, and activation of a gene that has the potential to cause cancer. Despite these challenges, there are still exciting developments with gene editing through the use of CRISPR-Cas9 technology, leading to a hopeful future for cancer research.

Click on the links below for more information: https://link.springer.com/article/10.1007/s10528-022-10193-9#Sec1

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5783506/

https://journals.asm.org/doi/10.1128/JVI.72.2.1131-1137.1998

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Hurdles and New Treatments with CRISPR

CRISPR-Cas9 is an exciting new technology being studied into how it can be used. The most popular demand is applying it in treating and curing diseases. One of the many diseases and disorders that widely affect our population that this technology can be used for is hematological disorders. These disorders cover a wide range of disorders of the blood and blood-forming organs. This includes sickle cell disease mentioned in a previous post.

Hematological disorders are largely caused by mutations within hematopoietic stem cells (HSCs), which are responsible for keeping the stability of the blood and immune systems. These cells can achieve this stability through self-renewal, which is the ability to replicate oneself, and multipotent differentiation, meaning they can develop and mature into different cells, making them useful for many situations. Since these cells are widely used in our systems, fixing the disease-causing mutation can cure many hematological disorders.

CRISPR-Cas9 in gene-editing technology in HSCs for treatments has been used for sickle cell disease, as mentioned in an earlier post. This new paper looks at the potential of using it for other diseases and some possible issues that could be run into. A possible problem is our adaptive response to these gene-therapy reagents. When injecting something foreign into our body that modifies things, our body will react and attack in an attempt to protect itself. This is our adaptive immune response trying to protect our body, but it is an issue that needs to be considered when looking into treatments for these diseases by gene therapy.

The use of CRISPR-Cas9 is a hopeful method of modifying the HSCs to treat a wide variety of hematological disorders.

For more information, click on the link below: https://pubmed.ncbi.nlm.nih.gov/35301483/

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CRISPR, the sickle cell disease silencer.

Genetic diseases affect many people in today’s generation, directly or indirectly. A genetic disease is one where there is a harmful change within the human gene, or a wrong amount of genetic material that causes a disease. If only we could fix those defective genes, these genetic diseases could be cured. Thanks to Doudna and Charpentier and their development of the CRISPR-Cas9, human genetic diseases are getting closer to being cured.

A disease that scientists are studying to cure with this technique is sickle cell disease. The cause of sickle cell disease is a difference of one amino acid within our hemoglobin beta-subunit gene. This mutation causes abnormal hemoglobin, a protein within our red blood cells, causing a deformation of the red blood cell. Red blood cells are usually circular, but patients with sickle cell disease have crescent-shaped red blood cells. This crescent shape is caused due to a lack of oxygen, and the abnormal hemoglobin produces a polymer that will distort its shape. This deformed red blood cell cannot carry oxygen well, resulting in oxygen-deficient blood. Sickle cells are also hard and sticky, leaving them susceptible to clogging the bloodstream. These two factors can cause significant damage to the body and organs, shortening the life expectancy for the patients. Genome editing could be a great way to cure this disease because it could permanently remove the mutation causing the disease.

Back in 1983, the sequence now known as CRISPR was first discovered. CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. It was only in 2007, that its function was brought to light.

The method of CRISPR-Cas9 is based on the bacterial immune system. When a virus infects a bacterium, it injects its deoxyribonucleic acid (DNA) into the bacterium. A Cas nuclease will cut a piece of the viral DNA sequence, and store it within the CRISPR DNA of the bacterial genome between repeated elements, working as an immune memory. This sequence of repeats is what gives CRISPR its name. When the bacterium is infected with the same virus, the stored sequence will be transcribed into RNA. A complex made up of the CRISPR ribonucleic acid (crRNA), a piece of RNA called a trans-activating CRISPR RNA (tracrRNA), and a protein called the CRISPR-associated Cas9, will be formed. The crRNA is complementary to a section of the viral genome, the tracrRNA functions as a scaffold, and the Cas9 protein will cut the DNA. Think of it as cutting paper; the paper is the viral DNA, the hand is the crRNA and tracrRNA, and the scissors is the Cas9 protein. This unit will serve as a guide to locate and bind to the DNA where a similar viral genome is found and then cut it, causing DNA degradation (Figure 1).

Figure 1. A diagram of the process CRISPR-Cas9. 1. The CRISPR-Cas9 complex searches along the DNA for the section that matches its crRNA. 2. The CRISPR-Cas9 complex found the complementary region, has bonded to the DNA, and the DNA has unwound. 3. The complex is making a double-stranded break. 4. The DNA can be degraded or is open for changes to be made directly to the DNA. This figure was made using BioRender.com.

In 2012, the two scientists named Dr. Jennifer Doudna and Dr. Emmanuel Charpentier published a paper on how you can repurpose the CRISPR-Cas9 bacterial immune system to use to our advantage. These scientists received the Nobel prize in Chemistry in 2020.

The changes that these women made were replacing tracrRNA with a single-guide RNA to function as the structural handle to bind to Cas9, and introducing a different crRNA to match with the target site where the DNA changes will be made. Their goal is that this could be used for any RNA sequence part of the human genome that is needed to be changed. Once the CRISPR Cas9 causes a break in the DNA at the desired location, the DNA repair system can be used to insert a specific sequence into the DNA at the break. This will result in an edited gene.

The first CRISPR clinical trials for the treatment of sickle cell disease began. Scientists approached this with cell therapy in 2019. This means they harvested bone marrow cells from patients with sickle cell disease and would edit them in vitro, meaning it was done within a lab. CRISPR was used to knock out a gene that suppresses the fetal hemoglobin gene within the harvested bone marrow cells; this change would cause the cells to produce fetal hemoglobin, hoping it would compensate for the defective hemoglobin sickle cells. Fetal hemoglobin is used in fetuses because it’s better suited for blood transport at this time. In contrast, once they’re born and grow, the fetal hemoglobin is gradually replaced by adult hemoglobin. The fetal hemoglobin is used in the therapy over adult hemoglobin because it interferes with the distortion process of the red blood cells. They then continued to inject the transformed cells back into the patient. There was much success with these trials.

A total of 45 patients partook in the first clinical trials of cell therapy, which has worked for 22 patients. One of these patients who volunteered was Victoria Gray. She lived her life being labelled as the sick kid, unable to live her life to the fullest and dropping out of nursing school as she was constantly in the hospital. After receiving the injection of her transformed cells, she’s better than ever. After a few months, doctors ran tests on her blood and found that her cells were producing fetal hemoglobin. Almost half the hemoglobin in her blood was fetal hemoglobin, which is more than enough of what the doctors think is needed to alleviate the symptoms of sickle cell disease. Since the treatment, Victoria hadn’t had any pain attacks or blood transfusions, which was a sign that it was working.

Although this hasn’t cured sickle cell disease, it still leaves a light at the end of the tunnel for the possibility of curing the disease and many more. At present, researchers are studying other aspects CRISPR can be used for. Who knows, maybe in the future, they will find a cure for certain diseases through the use of CRISPR.

For further information on what was discussed in the blog, visit the links below: https://www.synthego.com/learn/crispr https://www.jax.org/personalized-medicine/precision-medicine-and-you/what-is-crispr# https://www.npr.org/sections/health-shots/2019/12/25/784395525/a-young-mississippi-womans-journey-through-a-pioneering-gene-editing-experiment https://www.nejm.org/doi/full/10.1056/NEJMoa2031054

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Is gene editing ethically correct?

Should gene editing be allowed? With the rise of technologies that will enable scientists to edit genes, like CRISPR, questions arise of whether this is ethically correct. The use of gene editing can be applied to many fields like treatment of diseases, mutations, gene editing of specific tissues, military applications, and DNA editing in human embryos. This extensive range of areas that can use CRISPR technology allows for more benefits to our society. Even though we can significantly benefit from this science, this comes with risks and the potential of negative impacts. As a society, we need to decide our limit to gene editing. The following article provides insight into all the possible implications for how CRISPR technology can be applied. The authors detail the benefits, challenges, and bioethical issues that come with this advance in science.

In my opinion, CRISPR technology in gene editing should be allowed in somatic cells (cells of the human body that do not include the germ line) to treat diseases, but not in germ line cells (cells of the sexual organs to produce eggs and sperm). My reasoning behind this is that if one were to genetically edit a germ line cell and an error occurs, this change would be passed down to subsequent offspring. While on the other hand, editing only the somatic cells will only affect the sole individual and will not have that ripple effect. Before applying gene editing to germ line cells, more research needs to be done.

To better understand the pros and cons of this new advance, click the link below.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7129066/

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Welcome!

Hi everyone! My name is Danica Chamberlain and I am in the fourth year of my biology-chemistry degree at the University of New Brunswick. Throughout the past four years, I have studied many different aspects of biology and chemistry. I have found a passion for how our body functions, and cures and treatments for when our systems can’t function properly due to illness and disease. Outside of my life as a student studying nights on end, you can find me spending quality time with friends and family, or out enjoying our beautiful planet.

Looking more deeply into our human health, it seems that there is a growing number of diseases in the human population affecting day-to-day lives. Wouldn’t it be great if we could find ways to cure all of these diseases? In some cases, it isn’t that easy. Some diseases are genetic disorders from a mutant gene, meaning that someone is born with a difference in the DNA sequence that is not normal. Common genetic disorders are cystic fibrosis, sickle cell disease, Huntington’s disease, and many more. A new technology that is being looked into is CRISPR, which is short for Clustered Regularly Interspaced Short Palindromic Repeat. The hope in using CRISPR technology for gene editing is that scientists will be able to correct that error of the gene that is resulting in the specific disease and hopefully reverse the symptoms of said disease.

The purpose of this blog is to inform you of the new and upcoming use of CRISPR technology in medicine, and more specifically how it is being used for gene editing. While it is still new, there are limitless possibilities for diseases it can treat and cure. The future with CRISPR is exciting, and hopefully, this blog will give some insight into what is to come. The use of CRISPR technology if gene editing is a light at the end of the tunnel for people with genetic disorders.

Thanks, Danica

Image by Genes in Life