20 cigarettes a day equals 150 mutations in the lungs

Anna Stavina, XX2 century, based on Medical News Today: Twenty cigarettes daily for 1 year equals 150 lung cell mutations

In-depth genetic research has shown how smoking is associated with the development of cancer in a variety of organs. The relationship between the number of cigarettes smoked and the number of mutations in tumor DNA was revealed.

The negative effects of smoking are well known, they have been carefully studied many times. Every year, about 6 million people die from smoking-related diseases. If this trend continues, then, according to the forecasts of the World Health Organization (WHO), the total number of deaths from smoking in the XXI century will be about 1 billion people.

However, it is still unclear exactly how a huge number of cancers occur in different parts of the body. To date, smoking is associated with 17 types of cancer, but the genetic mechanisms of this connection are still unclear.

Scientists from the Wellcome Trust Sanger Institute and King's College London, together with colleagues from Los Alamos National Laboratory, recently conducted an in-depth study of the genetic characteristics of cancer associated with smoking. The results of the work were published in the journal Science (Alexandrov et al., Mutational signatures associated with tobacco smoking in human cancer).

The conducted research has become the most detailed in its field. Scientists examined the DNA of 5 thousand tumors, compared tumors that arose in non-smokers with tumors of smokers and studied genetic differences.

The specialists also had the opportunity to study mutational signatures and count the number of mutations in each tumor.

Counting mutations associated with smoking

Thanks to the available data, the researchers were able to count the number of mutations caused by one cigarette. It turned out that a pack of cigarettes a day is the cause of a certain and quite predictable number of mutations that appear during the year in lung cells.

"Previously, we had extensive epidemiological evidence linking smoking and cancer, and now we can observe and evaluate the molecular changes in DNA that occur during smoking," says the head of the study, Dr. Ludmil Alexandrov from Los Alamos.

"In the course of this study, we found that people who smoke a pack of cigarettes a day, on average, receive 150 additional mutations in the lungs. This explains why the risk of lung cancer in smokers is so high."

– reports the co-author of the study, Professor David Phillips (David Phillips) from King's College in London.

The group of researchers also described what mutations cigarettes cause in other organs. Scientists have concluded that a pack a day leads to:

• 97 mutations in every cell of the larynx;
• 39 mutations in each pharyngeal cell;
• 23 mutations in every cell of the mouth;
• 18 mutations in each cell of the bladder;
• 6 mutations in each liver cell.

Previously, it was difficult to determine how mutations affect organs other than the lungs. A new study has demonstrated the mechanism by which tobacco causes tumors in various organs and tissues.

"Mutations caused by the direct influence of tobacco carcinogens were found mainly in organs in contact with inhaled smoke. The remaining cells of the body suffer mainly from indirect exposure. Smoking affects the most important cellular processes, which leads to the development of mutations in DNA," notes David Phillips.

One of the five mechanisms of DNA damage as a result of smoking, the most common, also underlies the development of cancer diseases not related to smoking. Scientists have found that smoking "accelerates" the cellular clock and leads to premature accumulation of mutations in DNA.

The Future of cancer research

Scientists are surprised by some of the results. Oncological diseases associated with smoking turned out to be more complex than expected.

Professor Mike Stratton from the Sanger Institute, the second head of the study, says: "This study on smoking has shown that studying the DNA of tumors can provide new information regarding the development of cancer and, possibly, its prevention."

Dr. Lyudmila Alexandrov, answering a question from a correspondent of Medical News Today about future research, said:

– This work has shown that the determination of the molecular profile of cancer patients can be used to identify the mechanisms by which carcinogens cause cancer. We plan to study other known factors of cancer development. For example, we are now investigating the impact of obesity on the development of cancer.

And when Dr. Alexandrov was asked what he would do if he had an unlimited amount of time and money for research, he replied:

– I would create molecular profiles of all people in the world living with cancer diagnoses. This would help to better understand the causes of cancer and develop new strategies to combat it.

The results have become an important milestone in the study of the effects of cancer associated with smoking on DNA. There is still a lot of work ahead, but such discoveries bring us closer to understanding and preventing cancer at the molecular level.

Portal "Eternal youth" http://vechnayamolodost.ru 08.11.2016