This work, published Thursday in the journal Science, are also likely to open the way to new treatments that target the tumor before it starts to develop.

“The great mystery is the fact of why cells in the body already have mutations observed in a cancer but do not behave as such, “notes Dr. Charles Kaufman, a researcher at Zon Laboratory at Children’s Hospital Boston, lead author of the study.

” We discovered that the cancer off after activation of a carcinogen or the loss of a tumor suppressor, which can occur when a single cell is up to the stem cell state, “he explains.

Several genes involved in this process, which may be targeted to prevent the cancer from start to develop, say the researchers.

For this study, they used zebrafish, a major study model, whose embryos are transparent, to track the birth of a melanoma.

All fish used in this work had been genetically engineered to be carrying a human cancer mutation found in most moles. They had also lost the tumor suppressor gene called p53.

The authors genetically these zebrafish for the cells to light of a fluorescent green if a gene called Crestin was activated. This signals the activation of a genetic program characteristic of stem cells. These cells, somehow virgins can create all the tissues and organs of the body.

Normally the program stops working after the development of the embryo, but it can sometimes, for unknown reasons , go off again in some cells.

“We have occasionally seen green fluorescent dots on some of these fish, and all those which we then followed became in 100% of cases of tumors cancer, “said Leonard Zon, director of the research laboratory on stem cells at Children’s Hospital Boston, a lead author of this discovery.

These researchers found that the cancer cells are very early similar to those in stem cells form pigmented melanocytes which the skin.

This group of genes is also active in the human melanoma and zebra fish 30 in which this phenomenon was observed all developed a melanoma, they explain.

According to these scientists, a cell in tens of millions who are in a mole will become a melanoma, says Dr. Kaufman.

These researchers believe their discovery could help develop new genetic tests to determine whether suspicious moles can become cancerous and also produce treatments to prevent to evolve cancer.