Biology Assignment: CRISPR Cas9 – A Gene Editing Therapy For Cancer Treatment

Question

Task: Prepare a detailed and well-researched biology assignment on the topic: CRISPR Cas-9 genome editing in Cancer treatment.

Answer

Summary
Cancer is one of the leading fatal diseases that is a headache for every medical facility. The treatment of cancer has not been completely reached. But there are promising processes that are being developed and formulated while investigating for its effectiveness. The biology assignmentis about CRISPR Cas9 methodology which adopts genetic engineering for cloning RNA with DNA to reverse the process of the cancer cell. The process has been promising and effective in the treatment of tumors and other genetic disorders. The paper is directed towards understanding the process and its implication. The objective of the paper is to present systematic literature on the subject.

Aims and Background
The aim of this grant proposal is to prepare a scientific paper on – “CRISPR CAS – 9 Genome Editing in Cancer Treatment”. The paper is towards understanding the technicality of industrialization in medicine and the excessive progress of xenobiotics. Cancer is already the biggest lump in the throat for medical professionals. The paper attempts to discuss the process of genome editing to seek possibilities in treatment. Several types of research and studies in molecular biology have portrayed the ability to alter the genome and seek functional changes in the cells which are done using gene – editing technologies for genetic modulation. In the past several types of treatment have been proposed and carried out for malignant cancer that usually affects the cells of the body. There have been numerous therapies employed with the help of advancement in molecular biology for oncology and cancer biology. The processes of genome editing have showcased a plethora of benefits in molecular biology.

The paper is about Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) which is associated with a protein 9 also known as Cas9. It is a powerful technological treatment for cancer therapy that has proven to be efficient and accurate. CRISPR Cas9 is a powerful and effective genome editing tool that has proven to be a robust strategy that has altered the genome of organizations and presented a potential arsenal for the treatment of tumors. The effectiveness of the process can be seen by targeting novel points that provided the researcher’s information and observation about the response of tumors to drug therapy. The ongoing research and practice are focused on increasing the efficiency and effectiveness of the process that is repressing off target effects and sequence specific targeting. The functioning of CRISPR Cas9 is based on convalescent mutations of specific proteins at the genetic level. The process of CRISPR Cas9, there is a system of Cas9 protein which is guided by RNA for harnessing endonuclease gene mutation. This further carries out a process of DNA insertion or deletion, repression or transcriptional activation, manipulation of 20 – nucleotide components of RNA for multiplex targeting. Earlier, the use of the CRISPR Cas9 system was done by bacteria to defend themselves against different bacteriophages, which recently received a noteworthy appreciation for its potential in the treatment of carcinogenesis and genetic disorders. The CRISPR Cas9 system plays a crucial role for developing complete genomic libraries which can be used by cancer patients (Akram, et al. 2020).

Significance and Innovation
Cancer is one of the leading diseases that is fatal and counts a large number of deaths every year. It has been already established that survival rate of cancer patients in advance stage is quite minimum. It is still a foremost cause of economic and social burden on individuals across the globe. In the pursuance of researches taking place across several medical institutions have come to a common point that is genome editing which seems to be promising and has shown substantial results too. The fundamental cause behind investigating molecular biology for conducting research in order to treat cancer through genetic methodologies came into existence after learning that change in DNA causes cancer. Since this awareness, many gene editing technologies and processes have been researched to comprehend its effectiveness for manipulating DNA. The new research that CRISPR Cas9 believed to be shifting the impossible to possible and it has become mainstream process to be studied for cancer biology. The inspiration of CRISPR Cas9 was taken from nature that is bacteria. These bacteria capture the DNA of intruders that is viruses and store them in segments that are known as CRISPR that is a cluster interspersed short palindromic repeats (Driehuis and Clevers, 2017).

CRISPR – Cas9 is used to engineer immune cells and oncolytic viruses which is advanced application for therapeutic cancer. The biggest elemental benefit of this process is that it precisely edits the genes in human being which has already been tested on model organism. Though for humans, it carries on permission regarding therapeutic analysis. The element of innovation in the tool is that it has two main actors that are DNA – cutting enzyme and a guide RNA. They both are commonly known as Cas9. In this process, DNA is mirrored by the guide RNA which partners with Cas until target DNA is matched. Further, the DNA gets cut by Cas (Asmamaw and Zawdie, 2021).

Despite promising clinical results, the majority of patients with epithelial cancer did not respond to TIL (tumour-infiltrating lymphocyte) therapy. Deterioration and depletion of TIL can cause poor response, as TIL can become "precursor exhausted" before being expanded ex vivo. After rapid proliferation, T cells reach a state of final differentiation. Studies show that patients with melanoma, who have a high rate of precursor TIL depletion, have a longer reaction time to immune checkpoint inhibition. Precursor-depleted TILs can respond to checkpoint blocks, but depleted TILs cannot. Analysis of the TIL phenotype also showed that poorly differentiated CD39-CD69 strain-like TIL phenotype was associated with complete tumor response and longer TIL persistence in patients receiving TIL therapy. Therefore, the effectiveness of TIL therapy can be further enhanced by using CRISPR / Cas9 gene editing tools to reverse the dysfunctional T cell state and maintain a strain-like TIL phenotype. The metabolism-related factor Regnase I was found to be a negative regulator of the antitumor response of T cells. Turning off RegnaseI reprograms T cells into long-lived effector cells, improving their infiltration and persistence into the tumour microenvironment and improving the therapeutic effect of ACT. Another study found that the zinc finger transcription factor Gata3 causes CD8 + TIL dysfunction. Disruption of Gata3 in naive CD8 + T cells improved the antitumor function of T cells. However, few studies have been reported on the development of TIL to improve T cell function and proliferative activity using the CRISPR / Cas9 system. It was once reported that only zinc finger nucleases target the gene encoding human PD1 in melanoma tumour infiltrating lymphocytes. PD1 knockout TIL can be extended to clinical scale. In addition, treated TIL showed improved ex vivo effector function and significantly increased cytokine release compared to untreated TIL.

Methods and Materials
CRISPR Cas9 is an extremely powerful method that employs genetic engineering technology with modern modifications for implications in cancer treatment. The conceptual methodology is based on the adaptive immune system of bacteria. The prominence of this process is that it has helped in engineering genomes for defining a set of expressions for genes. The process of CRISPR is based on the mechanism of tumorigenesis by identifying the targets implying drug development Mechanically, two different RNAs (CRISPR transactivating RNA (tracrRNA) and targeting (crRNA)) activate and induce the Cas9 protein to bind to the viral DNA pattern and then cleave. The Type II system, which is a subset of these CRISPR systems, is particularly attractive as a tool for editing the genome because it depends on a single Cas9 protein for targeting a defined DNA sequence. Thesingle guide RNA (sgRNA) is made by combination of crRNA and tracrRNA which further simplifies the system. After being unwound, the DNA isbonded to PAM and it forms DNA sgRNA hybrid, in which double-strand breaks (DSBs) is introduced with two nuclease domains into the target sequence. The DSB with two different repair mechanisms gets response from host cell.

Apart from using wild-type SpCas9 for cleavage of DNA, a nuclease-deficient SpCas9 modification (dCas9) development takes place. To mediate specific local DNA manipulations, dCas9 is fused to multiple effector domains.CRISPR activation (CRISPRa) and CRISPR interference (CRISPRi) use fusion transcription factors to suppress.On the other hand, gene transcription is induced when the transcription start site of the target gene is targeted v=by dCas9. In most of the cases, the interference system of CRISPR downregulates gene transcription by relying on the KRAB repressor domain with dCas9 fusion. Interestingly, the enhancer region can be modified by dCas9KRAB via altering the methylation state of the target site which eventually suppresses gene transcription.

Feasibility
Clustered regularly interspaced, Short Palindromic Repeat (CRISPR)-Cas9 usually edits the immune checkpoint gene which probably improves the effectiveness of T cell therapy. Though, initially, the first effort required for its realization and safety is to understand the possibilities. The results in the first non-human clinical trial of CRISPR-Cas9 phase 1, the PD1 treated T cells in patients with advanced lung cancer. The primary endpoint was feasibility and safety, while the efficacy was the secondary endpoint. The processing of T cells is part of exploratory goals where all predefined endpoints have been achieved. Among the total of 22 patients, 17 had enough treated T cells for injection and 12 can be treated. The gradings of side effects related to every treatment were 1/2. In peripheral blood, the edited T cells were detectable after injection. The SpCas9 (Streptococcus pyogenes) was the first variant that was used outside prokaryotic cells. They were reprogrammed so that they can be used on mammalian cells. There are a series of genes that can initiate or progress based on the deregulated expression and mutations such as tumor suppressing gene, metabolism – related genes, oncogenes, chemo resistant genes, and cancer stem – cell related genes. The main goal of the treatment of cancer is to suppress and restrain the progress and growth of tumors which eventually corrects the mutations and restore the genes that have been dysregulated.

Benefit
When the patients are diagnosed early and detected, then cancer treatment is possible which eventually improves the quality of life. Despite several techniques have been used for cancer treatment, they still need to improve in terms of efficiency, speed, and specificity. The genetic diagnosis has helped in identifying sensitive genes which can be crucial for prevention of cancer. In this particular case that is association with genetic engineering, the process of CRISPR Cas9 has been a pioneering and most promising methodology. Another application of the tool is acronym as SHERLOCK which stands for Specific High Sensitivity Enzymatic Reporter Unlocking. The application of CRISPR Cas9 in oncology is quite promising as the proposition of genome editing has opened a possibility for the range of cancer treatment. The multistep process of complex interactions between host immune systems and cancer cells is called tumorigenesis. This combination of cancer immunotherapy and CRISPR Cas9 technique has been effective application to combat with carcinogenic virus infection.

The CRISPR has become modern and technologically advanced method which is rapidly evolving to be efficient and stable gene editing technology. The method has impacted many fields but its foremost application lies in oncology. The primary concern associated with the procedure is that it has to be made more efficient which would require improvement on many scales Another concern is the response of human body and immunity to Cas9 protein. Some researchers have seen that human body makes antibodies in response to this foreign gene interfering RNA. It was found that SpCas9 formed antibodies in 58% of the subjects while SaCas9 formed antibodies in 78% of the subjects (Desai, et al. 2021).

Communication of Results
CRISPR Cas9 is widely used in cancer research as a diversified gene editing technology. It was first use as a genomic editing tool in cells of mammal in 2013. the application of the CRISPR Cas9 system has expanded rapidly due to its high flexibility and efficiency. CRISPR Cas9 is widely used in establishing cancer models to validate essential genes as drug-eligible targets, study drug resistance mechanisms, and fully understand the function of non-gene coding regions. A detailed discussion of CRISPR / Ca9 in cancer research has recently been discussed in detail elsewhere, but is not covered in this review. The combination of CRISPR Cas9 and cancer immunotherapy is two innovative technologies in cancer research and treatment that have the potential to extend the application of immunotherapy to even more cancer patients. Recent developments in CRISPR Cas9 technology in cancer immunotherapy, including the construction of CART cells, the design of TCRT cells, the inhibition of immune checkpoint signalling pathways, and the screening of new drugs in immunotherapy.

Solid tumours such as lung, breast, prostate, LIVER, and colon cancers are quite common tumour types which has been less successful in gene therapy than non-solid tumours such as leukemia. With the development of CRISPR Cas9, this situation has changed rapidly. Previously published data suggest that CRISPR Cas9 can effectively target cancer cells and suppress tumour growth by inducing apoptosis and inhibiting cell proliferation and metastasis. A single guideRNA (sgRNA), the endonuclease enzyme Cas9, is two fundamental components of the CRISPR system that induces CRISPR technology to treat cancer cells. The Cas9 protein induced double-stranded DNA breaks (DSB) at the target site. It initiates the DNA repair process through a non-homologous end joining (NHEJ) repair mechanism that inserts and removes a small portion of the sequence. However, Cas9 can perform other routes in the repair mechanism, such as homology-oriented repair (HDR) using template DNA. CRISPR Cas9 technology was first used in animal and mammalian cells six years ago. It has been used as the most original and versatile strategy for cancer display and treatment (Park, et al. 2017).

The main purpose of this review is to investigate the potential therapeutic properties of CRISPR / Cas9 for solid tumours such as breast, lung, liver, colon and prostate cancers. This review also examines structure, mechanics, current challenges, future prospects, and delivery of CRISPR Cas9 to its destination. In addition, many gene mutations in genes associated with cancer treatment with CRISPR Cas9 are being discussed in the current comprehensive review to focus researchers on the translation of laboratory studies in the clinic.Nature has been inspiration for the researcher and medical scientists to develop the process of CRISPR Cas9. It has been a convincing example of cancer therapeutic treatment with an immense success rate. The process is perfect example of learning from mother nature and implying in the research. The process has given hope to millions of people that they can be treated and get free from cancer. There have been notable results in the cases of animal welfare and xenotransplantation. This has been a substantial beneficial for ending and minimising the suffering of the animals.

References
Akram, F., Ul Haq, I., Ahmed, Z., Khan, H. and Ali, M.S., 2020. CRISPR-Cas9, a promising therapeutic tool for cancer therapy: A review. Protein and peptide letters, 27(10), pp.931-944. https://www.ingentaconnect.com/contentone/ben/ppl/2020/00000027/00000010/art00002
Driehuis, E. and Clevers, H., 2017. CRISPR/Cas 9 genome editing and its applications in organoids. American Journal of Physiology-Gastrointestinal and Liver Physiology, 312(3), pp.G257-G265. https://journals.physiology.org/doi/full/10.1152/ajpgi.00410.2016
Asmamaw, M. and Zawdie, B., 2021. Mechanism and applications of CRISPR/Cas-9-mediated genome editing. Biology assignmentBiologics: Targets & Therapy, 15, p.353. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8388126/
Desai, A.G., Naicy, T., Bhat, V., Akhil, G.H. and Aravindakshan, T.V., 2021. CRISPR Cas 9–A New Era in Genome Editing and its Applications. https://www.researchgate.net/profile/Akshatha-Desai/publication/349632715_CRISPR_CAS_9_-_A_NEW_ERA_IN_GENOME_EDITING_AND_ITS_APPLICATION/links/61482996a3df59440b9ba5e8/CRISPR-CAS-9-A-NEW-ERA-IN-GENOME-EDITING-AND-ITS-APPLICATION.pdf Park, M.Y., Jung, M.H., Eo, E.Y., Kim, S., Lee, S.H., Lee, Y.J., Park, J.S., Cho, Y.J., Chung, J.H., Kim, C.H. and Yoon, H.I., 2017. Generation of lung cancer cell lines harboring EGFR T790M mutation by CRISPR/Cas9-mediated genome editing. Oncotarget, 8(22), p.36331. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5482658/