Hi, this is another paper that I wrote for my AP Lang & Comp class this year. This paper is more of an academic paper, and all of the sources used are from google scholar. I have always been interested in the CRISPR-Cas system, and having to write a college research paper for my class allowed me to really explore that interest. I learned a great deal more about the CRISPR-Cas system due to this paper, and I hope that you will learn something new as well. While this is a research paper, my teacher wanted everyone to write an engaging narrative as an introduction, so the first part is just my personal experience, the rest is all my research, which I synthesized. I hope you enjoy!
Introduction
Cancer has played a large role in my life. Skin cancer, breast cancer, lung cancer; my mother warned me about each and every one of them. Though, I knew little of what cancer really was, and even less of cancer treatments, despite my mom’s teachings. From then on, I started learning more about cancer. My biology teachers would touch on the subject, though no more than that, almost as if they were afraid of scaring us students. I learned there was no cure, that people had been trying to find a cure for years, though to no avail.
So if there is no cure, the prevention methods are just that, prevention, and the cancer can turn into something just as deadly, what can we do to help? We can make use of CRISPR, or Clustered Regularly Interspaced Short Palindromic Repeats, and change the way we treat patients.
Discovery and Development
I first learned about CRISPR from my older brother. He had, in turn, learned about CRISPR from his 8th grade biology teacher. I was immediately intrigued. This was something that could revolutionize treatments for all sorts of health conditions, especially genetic diseases and disorders. CRISPR was first observed in sequences of DNA from Escherichia coli bacteria in 1987, though the researchers did not recognize the significance of these sequences at the time. It wasn’t until 1995 that researchers started to hypothesize what CRISPR loci was used for and some researchers came to the conclusion “that these unusual loci include fragments of foreign DNA” and part of the immune system of bacteria and archaea. Later, studies found that the target of CRISPR was foreign DNA, not mRNA, and could represent a tool for genomic editing. Certain genes (proteins) are associated with CRISPR repeats and found in close proximity to the CRISPR loci are called Cas proteins and function as a part of the CRISPR-Cas system. The most studied Cas protein is Cas9, which belongs to the system of directional cutting of foreign DNA (Gostimskaya, 2022).CRISPR has the potential to revolutionize genome editing and gene therapy, and we can use this new technology to create innovative treatments for cancer patients, especially since cancer is one of the world’s leading causes of death. If we have the ability to change the treatments that we currently have, we also have the ability to change people’s lives, increase people’s chances of living, and even lower the chances of death by cancer.
So how does CRISPR really work? The CRISPR-Cas system is made up of a guide RNA (gRNA) that targets the gene of interest, and a protein complex (Cas9) that contains a nuclease. Together, the CRISPR-Cas system acts as a molecular scissor to achieve double-stranded DNA cleavage (Stefanoudakis et al., 2023). These Cas proteins are then further categorized, into type and class. Type 1 is Cas3, type 2 is Cas9, and type 3 is Cas10. These proteins are then organized into different classes, class 1 is a multi-subunit crRNA-effector complex, and class 2 is a system that functions solely with a single protein (Mintz et al., 2018). This classification is used to identify which Cas proteins are used for each type of treatment. The most common Cas protein is Cas9, and this protein is used in many types of gene therapy for cancer treatment. Due to the complexity of gene editing, there have been some ethical concerns raised about using CRISPR technology. There is some uncertainty resulting from the difficulty to gauge potential risks and benefits, and these factors hinder “accurate risk/benefit analysis, complicating moral decision making” (Brokowski et al., 2019). These moral questions are currently one of the limitations of CRISPR technology, though with time the technology should improve and quell some of the worries.
Application of CRISPR on Cancer Treatments
Since CRISPR has the ability to edit genes, it can be used to help treat patients with cancer. To start, CRISPR can be used to help with the prevention of cancer. Currently, the most feasible use of “CRISPR in cancer prevention may be to target and eradicate oncogenic viral infections…” (Stefanoudakis et al., 2023). This means that CRISPR technology can be applied towards treatments of “HPV in cervical cancer, HBV and HCV in HCC, and EBV in lymphomas and PTLD” (Stefanoudakis et al., 2023). Through the use of CRISPR to treat these infections, we can prevent cancer from developing, since eliminating HBV and HCV can prevent hepatocellular carcinoma, or liver cancer. In another study, CRISPR was found to have the ability to be “used to repair genetic mutations that cause cancer, such as in the case of inherited forms of cancer caused by BRCA1 and BRCA2 mutations” (Chehelgerdi et al., 2024). With mutations being the main cause of cancer, CRISPR having the ability to manually extract these mutations greatly helps in cancer prevention, stopping the problem before it can even start.
There are a few different approaches towards how to treat cancer through the use of CRISPR. Gene therapy is one of the bigger possibilities, specifically focusing on T cell therapy. It has been found that “CRISPR/Cas9 gene editing can specifically interfere with immune checkpoint genes, enabling TCR-T cell therapy to overcome the genes’ inhibitory effects and enhance anti-tumor responses…” (Wang et al., 2022). This shows that we have the ability to modify one cell, and that modification will increase our bodies’ anti-tumor responses, making it so that we can better combat tumors as they apply to cancer. In some ways, CRISPR is like a claw machine, since it can pluck a gene straight from our DNA, though with much more precision than a real claw machine.This idea is affirmed in other studies as well, one finding that “CRISPR can be used to engineer patient-derived immune cells, such as T cells, to express CARs that enhance their tumor-targeting capabilities in combination with CAR-T cell therapy” (Chehelgerdi et al., 2024). In addition to T cell therapy, there is also the application of CRISPR on broader subjects of gene therapies such as gene editing. CRISPR is like a multi-tool, as it has many functions and can be used for gene deletions, gene insertions, translocations, and single base editing (Pickar-Oliver et al., 2019). All of these methods are beneficial in finding treatments for cancer, and with time they might become more accessible for all individuals. All of these articles address the future of gene therapies, as these capabilities are still being tested and undergoing preclinical trials, though there is so much potential to be unlocked here, and with time, we may be able to use more gene editing as a treatment for cancer.
The application of CRISPR is far reaching as this technology can also be used in developing a more personalized method to treat cancer. One study found that “The individual’s genetic profile can be analyzed using NGS and the mutations identified help us in identifying the therapeutic targets which can be edited with the help of CRISPR gene editing” (Selvakumar et al., 2022). If we have the ability to make treatments more personal for each and every patient, we would be able to provide the best care, and not just follow the method of one size fits all. We would be able to change the world of treatments forever.
Specific Cancers
Some studies focus on the application of CRISPR on specific types of cancer, such as breast cancer and lung cancer. CRISPR can be widely applied to both of these types of cancer, in lung cancer, the most important application of CRISPR-based techniques is found in lung cancer modeling and engineering tumor cells, and “the CRISPR-Cas9 system was exploited to insert several point mutations into a distinct genomic region in order to label and trace tumor cells”(Kordkheyli et al., 2021). Through modeling and tracking the growth of tumor cells, researchers can monitor how the cancer is growing as well as spreading, and this information can then be used to figure out the specific treatments that the patient needs to undergo in the future. The CRISPR-Cas system also has some similar applications in breast cancer research and treatments, being used for detecting and diagnosing tumor-specific biomarkers (Mintz et al., 2018). Being able to use the CRISPR-Cas system for detecting biomarkers, molecules in blood that can signal disease and health, to diagnose cancer is something that we were not able to easily accomplish prior to the development of the CRISPR-Cas system, so having this new technology has increased the reliability of detecting and diagnosing breast cancer, overall benefiting the world of cancer research.
Limitations of CRISPR
Just like with any other piece of technology in the world, the CRISPR-Cas system has some limits to its abilities. These limits directly affect the use of CRISPR as “there is still much to learn regarding the long-term safety of CRISPR use in vivo…” (Stefanoudakis et al., 2023). This significantly limits the use of CRISPR in long term applications, which directly affects the ability to implement CRISPR for the primary prevention or treatment of cancer. There is also the risk of off-target activity, and while studies have found this to be rare, it is still one of the major limitations for the widespread use of the CRISPR-Cas system (Stefanoudaski et al., 2023). If the use of the CRISPR-Cas system is resulting in off target activity, this would be a cause for concern as this system could modify genes that do not need to be modified, which would ultimately result in a bigger problem, and quite possibly, the discontinued use of this powerful tool. Some researchers have also raised concerns about “the potential cost of manufacturing and delivering CRISPR/Cas9 based therapies” and the availability of said therapies outside of an academic setting (Stefanoudakis et al. 2023). If CRISPR does not have the potential to be widely used, as well as widely available and affordable, it would be detrimental to the research community, as they have the technology to help treat and prevent cancer, they cannot share it with the rest of the world.
Conclusion
Overall, the CRISPR-Cas system is a powerful gene editing tool and could, in the future, revolutionize and forever change the way we view cancer research, treatment, and prevention. As researches have put it, “gene therapy is now acquiring attention in cancer treatment research, particularly because of its lower side effects compared to conventional methods such as chemotherapy” (Kordkheyli et al., 2021). The application of CRISPR in cancer research and treatment is undeniably important and impactful on the research world, and with time, this impact will only be increasing. Thus far, CRISPR-based gene editing tech has the ability to “revolutionize the way for testing cancer by allowing for precise and efficient manipulation of the genome to target specific genetic mutations that drive the growth and spread of tumors” (Chehelgerdi et al., 2024). This technology can make such a difference in cancer research, and maybe in the future, we will be able to use CRISPR to develop a cure to cancer. CRISPR is something that we should continue to research and test, simply because of its impact on genetic diseases, conditions, and cancer. CRISPR has a profound impact on cancer research and treatment because of its novel abilities to edit DNA and its future applications in our lives. With new technology like this, the possibilities on what we can accomplish in the medical world are endless.
Abbreviations:
mRNA = messenger RNA
Cas = CRISPR-associated genes
Cas9 = CRISPR-associated nuclease 9
crRNA = CRISPR-associated RNA
NGS = next-generation sequencing
CAR-T cell = Chimeric antigen receptor T cell
TCR = T cell receptor
HCC = Hepatocellular carcinoma
EBV = Epstein-Barr virus
PTLD = Post-transplant Lymphoproliferative disorder
BRCA1 and 2 = Breast cancer gene 1 and 2
Bibliography:
Brokowski, C., & Adli, M. (2019). CRISPR ethics: moral considerations for applications of a powerful tool. Journal of molecular biology, 431(1), 88-101.
Chehelgerdi, M., Chehelgerdi, M., Khorramian-Ghahfarokhi, M., Shafieizadeh, M., Mahmoudi, E., Eskandari, F., … & Mokhtari-Farsani, A. (2024). Comprehensive review of CRISPR-based gene editing: mechanisms, challenges, and applications in cancer therapy. Molecular cancer, 23(1), 9.
Gostimskaya, I. (2022). CRISPR-Cas9: A History of Its Discovery and Ethical Considerations of Its Use in Genome Editing. Biochemistry [Moscow], 87(8), 777+. http://dx.doi.org.ccclibrary.idm.oclc.org/10.1134/S0006297922080090
Kordkheyli, V. A., Rashidi, M., Shokri, Y., Fallahpour, S., Variji, A., Ghara, E. N., & Hosseini, S. M. (2021). CRISPER/CAS system, a novel tool of targeted therapy of drug-resistant lung cancer. Advanced pharmaceutical bulletin, 12(2), 262.
Mintz, R. L., Gao, M. A., Lo, K., Lao, Y. H., Li, M., & Leong, K. W. (2018). CRISPR technology for breast cancer: diagnostics, modeling, and therapy. Advanced biosystems, 2(11), 1800132.
Pickar-Oliver, A., & Gersbach, C. A. (2019). The next generation of CRISPR–Cas technologies and applications. Nature reviews Molecular cell biology, 20(8), 490-507.
Selvakumar, S. C., Preethi, K. A., Ross, K., Tusubira, D., Khan, M. W. A., Mani, P., … & Sekar, D. (2022). CRISPR/Cas9 and next generation sequencing in the personalized treatment of Cancer. Molecular Cancer, 21(1), 83.
Stefanoudakis, D., Kathuria-Prakash, N., Sun, A. W., Abel, M., Drolen, C. E., Ashbaugh, C., … & Drakaki, A. (2023). The potential revolution of cancer treatment with CRISPR technology. Cancers, 15(6), 1813.
Wang, S. W., Gao, C., Zheng, Y. M., Yi, L., Lu, J. C., Huang, X. Y., … & Ke, A. W. (2022). Current applications and future perspective of CRISPR/Cas9 gene editing in cancer. Molecular cancer, 21(1), 57.