Scientists now have a greater understanding of why hair turns gray with aging.

The information isn't likely to lead to raven-haired grandparents. But it may point the way to new treatments for deadly skin cancer (search).

The skin cancer known as melanoma (search) is particularly dangerous. It is a cancer that affects pigmented cells called melanocytes (search) — the same cells that give hair its color. When they become cancerous, these cells just won't die. They grow uncontrollably instead.

But in the hair, something makes these cells die off as a person ages — a finding that some day might be more valuable than preserving youthful hair color. It might save lives, suggests David E. Fisher, MD, PhD, director of the melanoma program at Dana-Farber Cancer Center in Boston.

Now Fisher's team is very close to that discovery, they report today in Sciencexpress, the online rapid-report service from the journal Science.

"Preventing the graying of hair is not our goal," Fisher says, in a news release. "Our goal is to prevent or treat melanoma. … We would love to identify a signal that would make a melanoma cell stop growing."

Fisher and colleagues — including Emi K. Nishimura, MD, PhD, who discovered the specialized melanocytes that give hair its color — studied strains of prematurely graying mice. They found that hair grays because of a defect in the stem cells that give rise to pigmented stem cells. Moreover, these self-renewing stem cells seem to become less efficient at renewing themselves and thus become depleted as a person ages.

Two cell signals seem to affect this process. By learning more about these signals, Fisher and colleagues hope to be able to make skin cancer cells die.

"Eventually we hope to be able to tap into this death pathway, thereby using drugs to mimic the aging process, to successfully treat melanoma," Fisher says.

By Daniel J. DeNoon, reviewed by Brunilda Nazario, MD

SOURCES: Nishimura, E.K. Sciencexpress, Dec. 23, 2004. News release, Dana-Farber Cancer Institute.