Gray Hair Shares Genetic Root With Melanoma
Study finds genes that lead to both
THURSDAY, Dec. 23, 2004 (HealthDayNews) -- A cure for cancer and a cure for gray hair may not be equally urgent benefits for mankind, but scientists are reporting a discovery that could lead to both.
They have identified two genes that accelerate the death of stem cells that create melanocytes, the pigment-manufacturing cells that give people the hair color of their youth. Cancer researchers are interested in those cells because their ungoverned overgrowth causes melanoma, a particularly deadly form of skin cancer.
"Melanoma cells are extraordinarily hardy," said Dr. David E. Fisher, director of melanoma program at the Dana-Farber Cancer Institute and lead author of a paper in the Dec. 23 online issue of Science. "Cancers derived from melanocytes are very resistant to therapy. We need to find a way to open the door to generate vulnerability. The answer could come from these analyses of graying, because in older people these melanocytes are going to die."
The key discovery in these studies was made two years ago in Japan by Dr. Emi K. Nishimura, who now is at Dana-Farber. She identified the melanoma stem cells, and has continued her research on them in the United States.
"We looked at several mouse models of graying, and we identified a dramatic loss of stem cells in every model we saw," Fisher said. "We now know that the graying process is initiated by the loss of melanocyte stem cells. They die out in individuals, and their hair goes from being pigmented to not being pigmented."
The two genes that play a particularly critical role in the death of the stem cells are designed Bcl2 and MITF, Fisher said. Bcl2 acts quickly, causing the mouse cells to die in one to two months, compared to the usual aging process, which takes well over a year. MITF acts more slowly, causing the cells to die in 6 to 10 months. In each case, the result is "a very dramatic premature aging," Fisher said.
The researchers then took samples of scalp tissue from people of various ages and found that the same pattern of melanocyte death was happening in them as they grew older.
The emphasis at Dana-Farber is on using that knowledge to make melanoma cells die. "Our goal will be to identify the pathway and use drugs to mimic the normal aging type of death, but in melanoma cells," Fisher said.
But he acknowledges that some thought has been given to the commercially attractive proposition of preventing early graying in humans.
"We are sure that we are getting closer to the understanding the mechanism that is responsible for graying," Fisher said. "Knowing the accelerated process gives us clues to try to prevent it in animals. It may not be in our laboratory, but we suspect that in a reasonable time, we or some colleagues will be close to a strategy to prevent graying in humans."
Learn more about melanoma from the National Cancer Institute.