Recombinant DNA technology may be the key to future cancer research.

ZHANG YUXUAN (yx.zhang.2012@sis.smu.edu.sg), BSc (Information Systems Management), 1st year student, School of Information System Management

1. Executive Summary

Cancer is an incurable disease in the past. In 2007, cancer claimed the lives of about 7.6 million people in the world. In the past, cancer treatments are surgery and basic radiation. Currently, there are some ways to prevent and cure cancer, cancer can be treating or curing by using chemotherapy, immunotherapy, hormone therapy, or gene therapy. All these methods can only control tumours development, but cannot completely cure the cancer.

In addition, everyone has the invisible cancer cells, and all cancers occur due to abnormalities in DNA sequences. That means cancer is the commonest genetic disease. Currently, recombinant DNA is widely used in biotechnology, medicine and research. Hence, with the progress of technology, cancer is no longer an incurable disease. In the future, recombinant DNA can help patient cure the disease.

2. Introduction/Background

2.1 Definition of cancer

Cancer is a kind of diseases characterized by out-of-control cell growth. One report from National Cancer Institute1 shows that there are over 100 different types of cancer, and each is classified by the type of cell that is initially affected.

All cancers begin in cells, and the body is made up of many types of cells. These cells grow and divide in a controlled way to produce more cells as they are needed to keep the body healthy. When cells become old or damaged, they die and are replaced with new cells.

However, sometimes this orderly process goes wrong. The genetic material (DNA) of a cell can become damaged or changed, producing mutations that affect normal cell growth and division. When this happens, cells do not die when they should and new cells form when the body does not need them. The extra cells may form a mass of tissue called a tumour, which can be seen from Figure 1(From National Cancer Institute).

Figure1. Normal and Cancer cell division

Most of cancer is caused by genetic mutations. Single mutations are generally not sufficient to cause cancer, but they produce changes that may predispose cells to malignant growth. Additional mutations in other genes, caused by damage from the environment, continue the cells' malignant transformation. Thus, cancer is a multi-step process involving the interaction between genes and their environment.

2.2 Recombinant DNA technology

Recombinant DNA is the general name for taking a piece of one DNA, and combining it with another strand of DNA. Recombinant DNA is also sometimes referred to as "chimera." By combining two or more different strands of DNA, scientists are able to create a new strand of DNA. This technique makes it possible to take any gene from any specie and place this gene in any other organism or specie. It is similar to cloning because when the foreign gene is incorporated in an organism like bacteria then multiple copies are made through cloning to use the gene in different applications.

From the definition of cancer, we knew that cancer is mostly caused by genetic mutations. Hence, recombinant DNA can change the altered genes and cure diseases.

2.3 Application of Recombinant DNA technology

The use of recombinant DNA technology has become commonplace as new products from genetically altered plants, animals, and microbes have become available for human use.

Genetically Modified Plants
Recombinant DNA technology is used is to genetically alter plants by adding or removing genes. Genes are often added to plants to increase the plant's resistance to bacterial or fungal infection, making herbicides less necessary, or to increase the sweetness of fruit. Genes can also be subtracted to slow the process by which the fruit spoils or to modify the colour of the flowers.

Transgenic Animals
Another use of recombinant DNA technology is to add an outside gene to the DNA of animals, creating a transgenic animal. These genes are added to the animal before it is born. Genes can be inserted into the animal to alter its protein content--for example, to produce a cow with low-lactose milk. Transgenic pigs might have organs that can be used for human transplantation. Creating disease-resistant animals is another possibility with recombinant DNA technology.

Recombinant DNA in Medicine
The recombinant DNA molecules can be used in various ways useful in medicine and human biology. There are many applications for recombinant DNA technology. Cloned complementary DNA has been used to produce various human proteins in microorganisms. Mass production of bacterial and viral antigens with recombinant DNA technology is likely to provide safe and effective vaccines for some disorders for which there is no prevention. The cloned probes for the human α- and β-globin loci, for specific disease genes, such as the Z allele of α-antitrypsin, and for random genomic sequences are proving useful for prenatally diagnosing human genetic disorders and preventing their clinical consequences.

3. Historical Perspective

3.1 Early Experiments
Recombinant DNA technology first emerged in the 1960s and 1970s. However, the basic principle of recombination had been discovered many years earlier. Indeed, in 1928, Frederick Griffith, an English medical officer studying the bacteria responsible for a pneumonia epidemic in London, first demonstrated what he termed "genetic transformation". Living cells took up genetic material released by other cells and became phenotypically "transformed" by the new genetic information. More than a decade later, Oswald Avery repeated Griffith's work and isolated the transforming molecule, which turned out to be DNA. These experiments showed that DNA can be transferred from one cell to another in the laboratory, thus changing the actual genetic phenotype of an organism.

Key Developments in Recombinant DNA Technology
Following these early experiments, four key developments helped lead to construction of the first recombinant DNA organism (Kiermer, 2007). The first two developments revolved around how scientists learned to cut and paste pieces of DNA from different genomes using enzymes. The latter two events involved the development of techniques used to transfer foreign DNA into new host cells.

3.2 Earlier treatment for cancer

Surgery
Surgery is the oldest known treatment for cancer. If a cancer has not metastasized, it is possible to completely cure a patient by surgically removing the cancer from the body. This is often seen in the removal of the prostate or a breast or testicle. After the disease has spread, however, it is nearly impossible to remove all of the cancer cells. Surgery may also be instrumental in helping to control symptoms such as bowel obstruction or spinal cord compression.

Radiation
Radiation treatment, also known as radiotherapy, destroys cancer by focusing high-energy rays on the cancer cells. This causes damage to the molecules that make up the cancer cells and leads them to commit suicide. Radiotherapy utilizes high-energy gamma-rays that are emitted from metals such as radium or high-energy x-rays that are created in a special machine.

4. Current Situation

4.1 Current way to prevent/cure cancer
Cancer treatment depends on the type of cancer. There is no single treatment for cancer, and patients often receive a combination of therapies and palliative care. Treatments usually fall into one of the following categories: surgery, radiation, chemotherapy, immunotherapy, hormone therapy, or gene therapy. Surgery, radiation and chemotherapy are old treatments which have been touched on in historical perspective. Here are the current and new methods.

Radiation
Early radiation treatments caused severe side-effects because the energy beams would damage normal, healthy tissue, but technologies have improved so that beams can be more accurately targeted. Radiotherapy is used as a standalone treatment to shrink a tumour or destroy cancer cells, and it is also used in combination with other cancer treatments.

Chemotherapy
Chemotherapy utilizes chemicals that interfere with the cell division process - damaging proteins or DNA - so that cancer cells will commit suicide. These treatments target any rapidly dividing cells (not necessarily just cancer cells), but normal cells usually can recover from any chemical-induced damage while cancer cells cannot. Chemotherapy is generally used to treat cancer that has spread or metastasized because the medicines travel throughout the entire body. Chemotherapy treatment occurs in cycles so the body has time to heal between doses. However, there are still common side effects such as hair loss, nausea, fatigue, and vomiting. Combination therapies often include multiple types of chemotherapy or chemotherapy combined with other treatment options.

Immunotherapy
Immunotherapy aims to get the body's immune system to fight the tumour. Local immunotherapy injects a treatment into an affected area, for example, to cause inflammation that causes a tumour to shrink. Systemic immunotherapy treats the whole body by administering an agent such as the protein interferon alpha that can shrink tumours. Immunotherapy can also be considered non-specific if it improves cancer-fighting abilities by stimulating the entire immune system, and it can be considered targeted if the treatment specifically tells the immune system to destroy cancer cells. These therapies are relatively young, but researchers have had success with treatments that introduce antibodies to the body that inhibit the growth of breast cancer cells. Bone marrow transplantation can also be considered immunotherapy because the donor's immune cells will often attack the tumour or cancer cells that are present in the host.

Hormone therapy
Several cancers have been linked to some types of hormones, most notably breast and prostate cancer. Hormone therapy is designed to alter hormone production in the body so that cancer cells stop growing or are killed completely. Breast cancer hormone therapies often focus on reducing estrogen levels (a common drug for this is tamoxifen) and prostate cancer hormone therapies often focus on reducing testosterone levels. In addition, some leukemia and lymphoma cases can be treated with the hormone cortisone.

Gene therapy
The goal of gene therapy is to replace damaged genes with ones that work to address a root cause of cancer: damage to DNA. For example, researchers are trying to replace the damaged gene that signals cells to stop dividing (the p53 gene) with a copy of a working gene. Other gene-based therapies focus on further damaging cancer cell DNA to the point where the cell commits suicide. Gene therapy is a very young field and has not yet resulted in any successful treatments.

Using cancer-specific immune system cells to treat cancer
Scientists from the RIKEN Research Centre for Allergy and Immunology in Yokohama, Japan, explained in the journal Cell Stem Cell (January 2013 issue) how they managed to make cancer-specific immune system cells from iPSCs (induced pluripotent stem cells) to destroy cancer cells.

The authors added that their study has shown that it is possible to clone versions of the patients’ own cells to enhance their immune system so that cancer cells could be destroyed naturally.

Hiroshi Kawamoto and team created cancer-specific killer T-lymphocytes from iPSCs. They started off with mature T-lymphocytes which were specific for a type of skin cancer and reprogrammed them into iPSCs with the help of “Yamanaka factors”. The iPSCs eventually turned into fully active, cancer-specific T-lymphocytes - in other words, cells that target and destroy cancer cells.

4.2 Positive/Negative impact s of current technology
By the time you start reading this impact statement, you've probably got a good idea of what Recombinant DNA is, how rDNA is made, how rDNA works, and some general places where rDNA is currently important. You should also be able to see that Recombinant DNA is going to have a large impact on the future. And like a lot of new science technology, Recombinant DNA has the possibility to be used for "good" and "bad" purposes. There is a bit of grey area here, as each person defines good and bad in a different way. The following is a list of ways Recombinant DNA will impact the future, broken up into what are commonly considered good and bad. For the positive impact of Recombinant DNA, it improved medicines, improved Livestock (resistance to disease) improved Crops (resistance to disease, higher yields) , prevention of Genetic Diseases lowering the cost of medicines (i.e. Insulin) and safer Medicines (i.e. Insulin), and reatment for pre-existing conditions (i.e. Cancer)

5. Future Considerations / Possible Problems

Recombinant DNA has been gaining in importance over the last few years, and recombinant DNA will only become more important in the 21st century as genetic diseases become more prevalent and agricultural area is reduced.

Over the past 100 years, knowledge of genetics has grown exponentially. Today, scientists have benefited from years of research and are now successfully exploring the field of genetic engineering. By combining DNA from two different organisms, using a technique called recombinant DNA, many outcomes are possible, and the potential of this science is virtually limitless. The uses of recombinant DNA vary wildly and it is employed in many industries from medicine to agriculture.

5.1 How does Recombinant DNA technology cure cancer?
5.2 Possible problems

6. Conclusion

Recombinant DNA technology may be the key to future cancer research

 

7. References

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Leslie Pray (2008). Recombinant DNA technology and transgenic animals. Nature Education. Received from http://www.nature.com/scitable/topicpage/recombinant-dna-technology-and-transgenic-animals-34513

Amna Adnan. (18 August, 2010). Applications of Recombinant DNA technology in Medicine. Received from http://www.biotecharticles.com/Genetics-Article/Applications-of-Recombinant-DNA-Technology-in-Medicine-350.html

Maureen Malone. Application of Recombinant DNA Technology. Received from http://www.ehow.com/about_6165534_application-recombinant-dna-technology.html

Biochemical Products of Recombinant. Received from
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National Cancer Institute. What Is Cancer? Received from http://www.cancer.gov/cancertopics/cancerlibrary/what-is-cancer

Mayo Clinic staff (2012). Cancer diagnosis? Advice for dealing with what comes next. Received from http://www.mayoclinic.com/health/cancer-diagnosis/HQ00379

Anthony J.F. Griffiths. Recombinant DNA technology. Received from http://global.britannica.com/EBchecked/topic/493667/recombinant-DNA-technology