Deoxyribonucleic acid (DNA) is a 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, such an event 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 every person has a unique and unique personality. The molecule is able not only to store information, but also to pass it on to the next generations. The data encoded in it sets the basis for the development program of a living being, thereby determining the course of his life. Our DNA is flawed. Its weak side is that “errors” may occur in it, which provoke the development of oncological pathologies. What causes such failures? Who is at risk? Why should we not relax in the absence of hereditary mutations?
Mutations that cause cancer
The development of cancer occurs 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 a strictly allocated amount of resources, 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 being divided. Before reproduction, the cell stores a “copy” of the hereditary genetic information that is located in its nucleus. The DNA strands embedded in the chromosomes inside the nucleus are doubled. And after that, the cell divides, transferring to each of its daughter copies an identical set of chromosomes. From one cell, two absolutely identical cells are obtained, and together with their genetic baggage, each of them receives “knowledge” about which path it needs to go, what function to perform and how many times in life to share.
Sometimes there are failures in the process of division — mutations. Hundreds of mutations occur in the body every day during a person’s life, 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 “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 localization 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 distinguish among the most well-known and well-studied genes whose mutations cause certain types of cancer. For example, the proto-oncogene HER2 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 mutating oncogenes that provoke colorectal cancer.
The second group is anti—oncogenes, they are also called tumor suppressor genes. They prevent the development of tumors. By 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], this particular bad habit is the cause of 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 smoking person takes about 15 years.
Improper nutrition, namely, the use of fatty, smoked or salty foods, can lead to obesity. As a result, the likelihood of developing different types of cancer increases. The fat layer leads to an overabundance of estrogen and other steroid hormones in the human body, which play a crucial role in the development of breast and endocrine cancer. A link has been established between hepatitis B and C viruses and liver cancer, herpes viruses and, for example, lymphoma, sarcoma or nasopharyngeal cancer, the bacterium Helicobacter Pylori 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. Artificial rays of a solarium are no less dangerous. Ionizing radiation can expose the DNA of cells to mutations, this process can provoke the development of cancer. Since UV rays do not have enough energy to penetrate deeply, their main effect is concentrated on the skin, so tanning and the development of malignant skin neoplasms are closely interrelated.
Many factors can be discarded – simply excluded, others – minimized. Preventive measures include maintaining a healthy weight, physical activity, quitting smoking and alcohol, limiting exposure to direct sunlight and contact with various chemical pollutants. As well as vaccinations (against HPV and hepatitis) and other types of prevention of infectious and parasitic diseases. Obtaining, processing and using genetic data is the future of medicine. Further study of DNA information is necessary for the development of prognostic scales, monitoring and early diagnosis of tumor processes, as the introduction of innovative methods will optimize the tactics of treatment of patients and increase the effectiveness of therapy.
