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Scientists discover mitochondrial cell 'calculator' capable of detecting cancer

Experts note that the mitochondrial genome can be inherited only on the maternal side, has many copies and is prone to quick mutation

MOSCOW, October 17. /TASS/. An international group of scientists led by a professor at the Institute of Living Systems at the Kant Baltic Federal University (Kaliningrad) and a senior scientist at the Federal Polytechnic University of Lausanne, Konstantin Popadin, has discovered a way of identifying potentially dangerous cells that, by dividing quickly, can cause cancer or cancer metastases, the university's press service reported on Thursday. 

“Theoretically it is possible to examine individual cells from tissue and by the number of mutations [nucleotides] from "A to G” to determine potentially most dangerous cell (with a minimum number of mutations “from A to G”), the rapid division of which can cause cancer or metastases. If we ce can locate it, it means that in the future there might be a way to quickly neutralize it," the press service quoted Popadin as saying.

The research, he noted, began with the scientists trying to understand the mutations emerging in the mitochondrial DNA.

“I would like to note that the mitochondria exhisting in each of our cells have has their own separate genome, which significantly differs from our major nuclear genome. Firstly, the mitochondrial genome is inherited only on the maternal side. Secondly, it has a lot of copies. And thirdly, it mutates quite quickly — approximately ten times faster than the nuclear genome. Thus, due to these characterictics, the mitochondria are a kind of marker for the development of cell lines," the scientist explained. 

By observing mitochondria, one can determine from which particular cell the remaining cells of a particular tissue originated. "This connection has been discovered quite a long time ago, however, we decided to go further and check whether mitochondrial mutations are somehow related to the functional features of tissues," said Popadin.

Detecting the marker 

In the process of studying different types of tissue affected by cancer, it turned out that in the slowly dividing cells, out of 12 possible types of conversion of one nucleotide to another, the type of mutation significantly prevails, in which nucleotide A is replaced by nucleotide G.

“We can coclude that the mutations "from A to G" mark long-living cells. This surprised us, and we decided to continue the study at a different level - we began to analyze the mitochondria of the egg cells: women who gave birth, relatively speaking, to 20 and 40 years old,” he said.

Since the eggs do not divide after embryonic development, the age of fertilization of a woman [the age when a child is born — TASS] equals the egg's age. It turned out that in the case of 40-year-old mothers, “from A to G” type mutations significantly prevailed in mitochondria. Thus, the eggs accumulate mutations with age, mainly the type "from A to G". At the next stage, the researchers investigated the mitochondria mutations of various kinds of animals. In particular, mice, elephants and whales. The latter have a very long (dozens of years) lifespan of eggs. The mitochondria of elephants and whales also showed a predominant mutation with nucleotide A being replaced by nucleotide G.

"And when we got the research results at three different levels, we made a conclusion that we discovered the rules for mitochondrial mutation. If a cell divides slowly, then it will have many mutations of the "A to G" type. We can assume that a kind of a calculator is working inside us showing how long the cell have lived," noted the scientist.

The chemical mechanism of the conversion of nucleotide A to nucleotide G is not completely clear as of now, it is obvious, although, that such a mitochondrial “calculator” can be used for an early diagnosis of cancer, the researcher believes.