Scientists told why Smoking can cause cancer

© Fotolia / Minerva StudioВрач analyzes a chest x-rayScientists told why Smoking can cause cancer© Fotolia / Minerva Studio

Possible cause of cancer with long-term cigarette Smoking is that components of tobacco smoke are changing the job of a protein «packaging» of DNA that makes genes vulnerable to mutation accumulation, according to a paper published in the journal Cancer Cell.

«We showed that some of the changes that contribute to development of lung cancer, is not true mutations. For this reason, if a person quit Smoking, the probability to get cancer it will decrease as these harmful epigenetic changes will cease to accumulate in his cells,» says Michelle VAZ (Michelle Vaz) from Johns Hopkins University in Baltimore (USA).

The invisible hand cancer

From the time of Columbus and discovery of tobacco by Europeans among many people’s perception that Smoking is «reasonably»healthy. As a result, by the end of the 19th century more than half the population of Europe and America, including women, were smokers, and only in the mid-20th century, scientists were able to convince the public that Smoking is deadly.

As recent studies, in addition to the increased likelihood of developing lung cancer, Smoking also increases the likelihood of a heart attack eight times in the declining years of life and triples the chances of tooth loss. In addition, the tobacco and nicotine affect the lives of not only smokers themselves, but also their unborn children, changing the structure of the protein «packaging» of DNA in their germ cells.

As VAZ says, today no one doubts that Smoking increases the risk of lung cancer and becomes the direct cause of its appearance, however, the mechanism of tumor osnovaniya still a mystery to geneticists and physicians. This prevents the search of possible ways to protect smokers from illness and death.

VAZ and her colleagues have taken the first step to answer this question by observing what happens within cultures of lung cells were grown in a nutrient medium, which is the liquid equivalent to cigarette smoke.

The dose of this «smoke» was designed so that over the 15 months of observations, the cells absorb as many carcinogens as the average gets a heavy smoker, consuming about a pack of cigarettes a day for 20-30 years.

New hope

As shown by these observations, cigarette smoke and the substances initially did not cause mutations in the DNA of cells, but acted on them differently. Their «okurivanie», according to scientists, led to the fact that the lung cells include a gene and a related enzyme, EZH2, is responsible for turning on and off a number of other DNA regions through changes in the protein «wrapping» of the genome.

The genetic material of humans and all other living beings separate from the cell nucleus is Packed in special proteins-histones, which hold the folded DNA in place and do affect «readability» of individual genes.

In recent years, geneticists are finding more evidence that this «wrapping» of the DNA involved in the transfer of information between generations, and allows animals and plants to adapt quickly to new environmental conditions, and problems with the «overwrite» special marks on its surface were associated with a predisposition to homosexuality and suicide among people.

Changes in the structure of histones, as noted by WHA, may be affecting genes that protect the cell from accumulation of mutations and responsible for apoptosis induction, «a program of self-destruction», destroying it when it appears critical damage in DNA. Problems in these genes, as they note, appeared in the cell cultures of 10-day «Smoking.»

The deterioration of these genes, as shown by further experiments on «test tube» light, made the cells much more sensitive to carcinogens than they were before the start of the experiments. Due to this mutation in their genes begin to appear in them more often, which becomes a cause of lung cancer in smokers.

Interestingly, such changes in the device wrapper gene unstable. Approximately six months after completion of the experiments, the enzyme EZH2 and other related sections of the genome returned to normal. Scientists believe that this may explain why cessation of Smoking dramatically reduces the risk of cancer and other problems with lungs, even for the most avid of smokers. In addition, now scientists can develop a drug that will block the changes in EZH2 and to protect people from cancer.