DNA and oncology

Deoxyribonucleic acid (DNA) is the carrier of genetic information about a person, written in the form of a complex code that contains information about our individual heredity. Every year on September 3, an event such as the discovery of the uniqueness of DNA is celebrated. It was on this day in 1984 that the British geneticist Alec Jeffries discovered that each person has a unique and inimitable. The molecule is able not only to store information, but also to pass it on to the next generations. The data encoded in it set the basis for the development program of a living being, thereby determining the course of his life. Our DNA is flawed. Its weakness is that “errors” can occur in it, which provoke the development of oncological pathologies. What causes such crashes? Who is at risk? Why should we not relax in the absence of hereditary mutations?

Mutations that cause cancer

Cancer develops because a healthy cell in the body undergoes changes in its DNA. How does this happen? Normal cells in the human body live separately without affecting each other. Each of them uses the amount of resources strictly allotted to it, performs its biological functions and dies at the end of the life cycle, making room for the next generations of cells.

In order to replace the old units with new ones, they are constantly divided. Before reproduction, a cell stores a “copy” of hereditary genetic information, which is located in its nucleus. The strands of DNA embedded in the chromosomes inside the nucleus are doubled. And after that, the cell divides, passing each of its daughter copies on an identical set of chromosomes. From one cell, two absolutely the same are obtained, and together with their genetic baggage, each of them receives “knowledge” about which path it needs to go through, what function it should perform, and how many times in its life to share.

Sometimes in the process of division failures occur – mutations. During a person’s life, hundreds of mutations occur daily in the body, but only a “critical mass” of such failures can lead to the development of a malignant tumor. It occurs when cells with mutations transmit erroneous information to their followers and begin to multiply uncontrollably.

From gene to oncogene

A gene is a structural and functional unit of heredity. The main role of genes is to store the “instructions” for protein synthesis. Proteins, in turn, serve as “building blocks” for the body and perform important functions, such as repairing damaged tissues. Gene mutations include any changes in the molecular structure of DNA, regardless of their location and impact on viability. Some mutations have no effect on the structure and function of the corresponding protein.

Genes, changes in which can lead to cancer, are divided into two groups: proto-oncogenes and anti-oncogenes. The first group is the genes that regulate the normal behavior of cells: their growth, division and copying. As a result of mutations, they can turn into oncogenes that can trigger the tumor process. It is possible to single out a number of the most famous and well-studied genes, the mutations of which cause certain types of cancer. For example, the HER2 proto-oncogene produces protein receptors that are involved in the growth and division of breast cells. Many people with breast cancer have a gene mutation in HER2. “Errors” in BRAF are a potential cause of melanoma, and KRAS is one of the most frequently mutated oncogenes that provoke colorectal cancer.

The second group is anti-oncogenes, they are also called tumor suppressor genes. They prevent the development of tumors. According to their functional purpose, anti-oncogenes are antagonists (opponents) of oncogenes. They either interfere with tumor growth by suppressing atypical cells, or are involved in correcting DNA errors. For example, these include BRCA1, BRCA2, mutations in which lead to breast and ovarian cancer.

Risk Factors

DNA damage can be triggered by two aspects: either the mutation has a genetic basis, that is, it is inherited, or it is caused by external factors.

According to WHO ^[1] the occurrence of cancer can be explained by a genetic factor in no more than 5-10% of cases. The remaining 90-95% arise as a result of external or internal factors. An unhealthy lifestyle has a key detrimental effect on the body. Smoking is the main cause of lung cancer. According to a study by the American Lung Association ^[2], it is this bad habit that causes death from lung cancer for 80% of women and 90% of men. It is worth noting that the degree of risk is directly proportional to the number of years during which a person smokes. On average, the development of a malignant tumor in a smoker takes about 15 years.

Improper nutrition, namely the consumption of fatty, smoked or salty foods, can lead to obesity. As a result, the likelihood of developing various types of cancer increases. The fat layer leads to an excess of estrogen and other steroid hormones in the human body, which play a decisive role in the development of breast and endocrine cancer. An association has been established between hepatitis B and C viruses and liver cancer, herpes viruses and, for example, lymphoma, sarcoma or nasopharyngeal cancer, Helicobacter pylori bacteria and stomach cancer.

Ultraviolet radiation also refers to external factors contributing to the development of mutations. The sun’s rays are the key “suppliers” of ultraviolet light. Artificial solarium rays are no less dangerous. Ionizing radiation can mutate the DNA of cells, this process can provoke the development of cancer. Since UV rays do not have enough energy to penetrate deeply, their main effect is focused on the skin, so sunburn and the development of skin cancer are closely related.

Many factors can be abandoned – simply eliminated, others – minimized. Preventive measures include maintaining a healthy weight, being physically active, avoiding smoking and alcohol, limiting exposure to direct sunlight and exposure to various chemical pollutants. As well as vaccinations (from HPV and hepatitis) and other types of prevention of infectious and parasitic diseases. The acquisition, processing and use of genetic data is the future of medicine. It is necessary to further study DNA information for the development of prognostic scales, monitoring and early diagnosis of tumor processes, since the introduction of innovative methods will optimize the tactics of treating patients and increase the effectiveness of ongoing therapy.

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