Cancer starved to death
Pyotr Smirnov, "Newspaper.Ru»Doses of poisons used to treat cancer can soon be increased without fear for the future of the whole organism.
As it turned out, a short hunger strike significantly reduces the toxic effect of these drugs on healthy cells, without giving such protection to cancer cells. Why is not yet fully clear.
The healing properties of a small hunger strike have been known for a long time. There is even a hypothesis that fasting in different religions appeared partly to improve the body. But not all biological effects of calorie restriction of food have been studied.
For example, last year several research teams, combining "hunger" with genetic modifications, achieved the prolongation of the life of yeast, worms and mice. Similar mechanisms of regulation of sugar metabolism allow scientists to believe that the same effect can be achieved for a person – if not with a total life expectancy, then at least by the number of diseases that occur.
This time, Italian and American oncologists suggest fasting for therapeutic purposes.
They found that the restriction of nutrition protects normal cells from chemotherapy, without providing such protection to tumor cells.
In fairness, it should be noted that the idea of fasting in oncology is not new: first, alternative medicine, and then even some scientists promoted low-calorie diets as a way to fight the tumor. Patricia Raffagello, who led the work, did not specify how they came up with this idea, but it became an elegant combination of classical and non-traditional methods.
Chemotherapy remains one of the leading instruments of oncology not only by itself, but also in combination with surgical interventions. The idea of the method is simple: tumor cells grow faster, and therefore, they absorb more nutrients, and any other substances. That is, theoretically, it is possible to select such a concentration of the drug in the blood at which tumor cells will die, and the threshold of toxicity for normal, healthy cells will not be reached. But this is in theory.
In practice, the toxic effect of chemotherapy on the body sometimes makes it even necessary to refuse treatment, despite all the tricks of specialists – for example, the introduction of the drug into the artery directly feeding the tumor, with the clamping of the sideways of blood supply and veins through which blood flows from the tumor.
A rather promising direction in this area is targeted drug delivery, carried out with the help of biotechnologies, or, as it has become fashionable to say recently, nanobiotechnology. But this is still far from practice.
The idea of fasting with the right approach and good contact between the doctor and the patient can bring excellent results in the near future.
In support of their hypothesis, the authors of the work published in the Proceedings of the National Academy of Science conducted a number of experiments on various models.
They started with the brewer's yeast Saccharomyces cerevisiae. Earlier, the same authors showed that a small hunger increases the resistance of yeast to oxidative stress. This time they studied the effect of reactive oxygen species on starving cells in combination with variations of proto–oncogenes - genes that control cell division and are associated with the occurrence of cancer.
Deprived of proto-oncogenes Ras2 or Sch9, "hungry" yeast turned out to be a thousand times more resistant to oxygen than their counterparts with the active form of both genes.
The same effect was observed for the TOR proto-oncogene. Scientists associate this phenomenon with the effect of the insulin regulatory cascade, which Ras systems are tied to. For IGFR – a receptor for insulin–like growth factor - its direct involvement in the regulation of life expectancy has been proven. However, the detailed mechanism of such an action of fasting remains unclear.
The scientists went further and added to the experiments the chemotherapeutic agent cyclophosphamide, a substance that turns into an active dosage form in the human liver. The results were the same: hunger increased the stability of healthy cells, but reduced that of yeast with active forms of proto-oncogenes.
After that, the scientists decided to switch from mushrooms to mice and humans. Another series of experiments was carried out in cell cultures, in which both oxidative stress and cyclophosphamide did not ruin a line of healthy glial brain cells, but they successfully coped with tumor cells, including neuroblastoma and human glioma. It is the tumors of the nervous system that, due to their inaccessibility, make up the greatest difficulty for oncologists.
Experiments on live mice also ended successfully – for scientists and for those mice that were on starvation rations before the experiments.
After the introduction of tumor cells to rodents, scientists "prescribed" a high dose of etoposide, a chemotherapeutic agent that damages DNA, to the wards. In the group that had previously starved, almost all survived, although metastases were recorded. Fully fed mice were not so lucky: about 50% died from the toxic effects of chemotherapy.
At the end of the work, scientists slightly correct the initial hypothesis, noting that the hunger strike still slightly protects tumor cells, slightly reducing their sensitivity to "chemistry". So the idea is not to starve with cancer and thereby increase the effectiveness of chemotherapy, but that a hunger strike may increase the dose of the drug, and thereby the effect on tumor cells without increasing the effect of toxic effects on the body.
Partly because of these effects, one should beware of rash fasting with chemotherapy prescribed by a doctor. In addition, it should be taken into account that these were only preliminary studies conducted on several tumor lines and only two drugs. There has been no clinical confirmation of the effect yet, but there is hardly any doubt that people will try to try out such a technique.
Portal "Eternal youth" www.vechnayamolodost.ru01.04.2008