• A Single Cell Shines New Light on How #Cancers Develop - The New York Times
    http://www.nytimes.com/2016/01/29/health/how-skin-cancer-develops-melanoma-zebra-fish.html?smid=tw-nythealth&smtyp=c

    “More and more data suggest that just having mutations is not sufficient to cause cancer,” said Dr. Kornelia Polyak, a breast cancer researcher at the Dana Farber Cancer institute, who was not associated with the new study. “You need the right context.”

    That was where Dr. Zon and his colleagues began 10 years ago. They were investigating melanoma by creating it in zebra fish, tiny transparent creatures that allow researchers to see cells and organs without cutting the fish open. The researchers put human BRAF and P53 genes in every melanocyte, the pigmented skin cells, of the fish. If genes were all that was needed for cancer, the fish would explode with melanoma. But the researchers found only one to three melanomas per fish.

    “That told us there has to be an additional event,” Dr. Zon said.

    By luck, they found it. The pigmented skin cells that became cancerous had turned on a gene, crestin, that is normally activated only in cells that are part of the neural crest, a group of cells pinched off early in embryonic life from a region adjacent to the brain. These primitive cells, depending on where they are in the embryo, can turn into pigmented skin cells or a variety of other types of cells, like those that make up bones and teeth, the covering of the brain or those that sheath and insulate nerve cells. Once cells develop into their mature tissue type — pigmented skin cell, bone or tooth, for example — the crestin gene shuts down. Those pigmented skin cells in the fish that had an active crestin gene had reverted back to that primitive state when they were malleable, their fates still wide open.