03 March 2008

Cigarettes renew the lungs

Pyotr Smirnov, "Newspaper.Ru»

Opponents of smoking have another argument at their disposal, and European legislators have scientific support for their numerous restrictions and prohibitions, which society often meets with hostility. Scientists from the University of California have proved that cigarette smoke leads to unlimited division of lung epithelial cells, and have established the molecular mechanism that causes these undesirable changes. The work of scientists is published in the March issue of The FASEB Journal.

Tobacco companies, of course, do not claim that smoking is harmless to health, but there are not enough high–quality works confirming and, most importantly, explaining its harmful effect on the human body, oddly enough. If the undesirable effect of nicotine on the body as a whole has been established, then lung cancer, which opponents of smoking constantly rest on, still remains in question.

Although the fighters for clean air claim that smoking is the main cause of lung cancer, the overwhelming part of the evidence comes down to statistical research, and of the "fundamental" components, so far only changes in the expression of certain genes and the carcinogenic effect of tobacco smoke on cells in culture have been shown. But many other carcinogenic substances that have become an integral part of modern life have the same, and often more pronounced effect.

Californians noticed that in addition to tar and nicotine, cigarette smoke contains hydrogen peroxide. It has the highest oxidizing potential, and remains one of the strongest oxidizing agents in biology. The problem with hydrogen peroxide for humans is that, unlike plants, the enzyme peroxidase (in humans, glutathione peroxidase) is not so active in our body, capable of destroying it to oxygen and water.

Now peroxide has another unpleasant property. Previously, scientists believed that it only triggers the reaction of fat peroxidation. Now he is also "accused" of increased cell division.

As it turned out, hydrogen peroxide, which is included in tobacco smoke, even in small concentrations activates a receptor responsible for the reaction of lung epithelial cells to the so–called growth factor - a signaling molecule with which the body controls the renewal of the surface of our lungs. As a result, the cell mistakes the component of tobacco smoke for a call to share more actively.

From a molecular point of view, this activation consists in the phosphorylation reaction of the protein from which the receptor is formed. In a healthy body, for such activation, as for other receptor interactions, a very specific and precise binding to the growth factor itself is necessary. Smokers, both active and passive, simply do not need a normal regulation scheme – because tobacco smoke triggers a cascade of growth and division reactions without a key link – a growth factor.

And the body, with all its desire, can no longer influence this process in any way – regulation on the principle of feedback is turned off at all levels.

If the increased division is caused by an excess of growth factor, then its formation or release can be reduced. But in smokers, the receptor is activated without a growth factor, and thus it will no longer be possible to control the renewal of the epithelium. It is also impossible to turn the receptor into an inactive form: peroxide changes the receptor so much that it makes it impossible to bind to the c-Cbl enzyme responsible for the reverse process.

In addition to this, the smoke also triggers the Akt and ERK1/2 cascades, which also provoke the development of cancer. And if the process gets out of control, then the ending is often the same - unlimited division in most cases leads to the development of a tumor, which in the case of the epithelium very quickly becomes malignant.

In fairness, it should be noted that high mortality from lung cancer is a Western statistic, in our country, changes in the bronchi that appear earlier, leading to breathing problems, and then to disruption of the supply of all tissues, including the heart, with oxygen, are no less a problem.

It has not yet been possible to develop any methods of prevention and, moreover, treatment of the above-described changes, in addition to natural antioxidants. So it remains to sympathize with doctors who face hundreds of thousands of such cases every day. Well, whether it is worth sympathizing with the smokers themselves, who voluntarily poison the lives of themselves and others, everyone decides for himself.

Portal "Eternal youth" www.vechnayamolodost.ru29.02.2008

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