26 August 2009

Estrogen and breast cancer: from theory to practice

Breast cancer will be stopped in a few years
Biologists from the UK and the USA have found out how estrogen provokes the development of a breast tumor. This study may lead to the emergence of new effective drugs in the next two to three years.Alexey Timoshenko, GZT.RU

Oncologists and molecular biologists from Imperial College London, together with colleagues from the Cold Spring Harbor Laboratory in the USA, studied the process of tumor interaction with estrogen, the female sex hormone, and they were able to detect molecules that ensure the transition of a normal cell to a pathological mode of operation. This knowledge can then be used to create tumor-stopping drugs.

Management systems

In modern research in the field of pathological physiology of cancer tumors, it is often noted that there are extremely complex and intricate control systems inside the cell. Experiments, the results of which are published in the journal Proceedings of the National Academy of Science, also confirmed this idea.

In order to stop the growth of a tumor, it is necessary to block the synthesis of some proteins and start the production of others – at first glance, a fairly simple task. However, the problem becomes more complicated when you consider that the entire human genetic code encodes tens of thousands of proteins, and initially it is not known which of them should be influenced by the synthesis. The fact that scientists are aware of some factors affecting the growth of tumors helps only partially.

This diagram is from an article in PNAS (with comments and translation GZT.RU )
the sequence of events that occurs in tumor cells when interacting with estrogen is shown.

Knowing that breast tumors grow under the influence of estrogen, the female sex hormone, is not enough, because it is impossible to completely remove it from the body. It is necessary to understand why the hormone present in a healthy body suddenly begins to have such an effect. In clarifying this issue, molecular biology comes to the aid of physicians.

Scientists tracked the estrogen from the moment it got into specially grown tumor cells for research. The sex hormone bound to receptors inside the cells, activated them, then several genes were activated – and as a result, the cell synthesized molecules of the so-called microRNAs. These molecules are notable for the fact that they can suppress the synthesis of a variety of proteins, acting as a universal switch for several processes inside the tumor at once.

Moreover, the microRNA molecules studied by biologists are influenced by the very estrogen receptors that initially started their synthesis, which significantly complicates the whole scheme. In other words, scientists had to figure out the device of a system, one part of which carries two different functions and these functions may contradict each other.

From theory to practiceScientists from the UK and the USA, who have found out exactly how microRNA molecules are used by cancer cells, believe that their rather complex work is not far from a cure.

Justin Stebbing, one of the authors of the study, says that now, instead of blocking estrogen in general, which is associated with many side effects and as a result is not always effective, it will be possible to selectively, with high accuracy, block microRNAs inside the cell. And not even all in a row, namely those that are overly active in breast cancer, which in turn will radically reduce the side effects of therapy.

However, with one limitation: there are tumors that are insensitive to estrogen and use some other, not yet fully understood mechanisms for regulating their growth. But 2/3 of breast cancer cases are precisely those tumors that may be cured in a few years.

Portal "Eternal youth" http://vechnayamolodost.ru26.08.2009

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