Cancer research yields clues to why hair becomes gray

WASHINGTON -- Those annoying gray hairs that increasingly leer back from the bathroom mirror may have some value after all. Cancer researchers have developed a new explanation for graying hair that they hope will also shed light on the most dangerous type of skin cancer.

"Preventing the graying of hair is not our goal," said senior researcher Dr. David E. Fisher of the Dana-Farber Cancer Institute in Boston.

"What we really want is to come up with treatments for melanoma," Fisher said in a telephone interview. Melanoma is the malignant form of melanocytes, the cells that help color hair and skin, and it is particularly resistant to chemotherapy and radiation.

Fisher's team found that hair goes gray when melanocytes become depleted.

The scalp contains a reservoir of adult stem cells that provide a continuous supply of these color-making cells, they found. But as the body ages these cells become depleted and sometimes begin to develop in the wrong part of the hair follicle.

The research, published online Thursday by the journal Science, originally focused on mice. But the team also studied human scalp tissue at various ages and found a similar pattern of cell depletion.

It was known that the pigment was not well transferred into gray hair, but the actual mechanism had not been understood, Emi K. Nishimura, a co-author of the paper, said in a telephone interview.

She said a gene called Bcl 2 is essential to maintain melanocytes. The researchers found that when they raised mice lacking this gene the animals went gray quickly and dramatically shortly after birth.

Fisher suggested that people who get gray prematurely may have a mutation of this gene.

The question they now want to answer is why the melanocyte cells begin dying off as the body ages.

These cells are generally good at surviving, being able to live through ultraviolet radiation -- at the beach, for example -- that would kill many other cells. That can be good when people go to the beach because the melanocytes produce pigment that protects the skin.

Unfortunately, they retain that ability to survive when they become cancerous, Fisher said.

So, he said, the researchers wondered if they could find a back door to killing the cells by studying how they die naturally, and that's what led to their research on graying.

By understanding how genes like Bcl 2 protect the cells, what pathways they act on, Fisher said, the scientists can look for ways to block that action with a drug.

"We have a number of ideas ... the work is moving," Fisher said. "I cannot say that we have drugs in our hands, but we have targets."

The American Cancer Society expects about 55,100 people to be diagnosed this year with melanoma, the most serious form of skin cancer, with an estimated 7,910 deaths.

Melanoma can be cured when it is detected and treated early, but if the lesion penetrates deeply into the skin it is often fatal. Sun exposure is a major risk factor in the disease, which has been increasing in the past few decades.

The research was supported by the National Institutes of Health, the Charles A. King Trust of Fleet National Bank and The Medical Foundation.

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On the Net:

Science: http://www.sciencemag.org

Dana-Farber Cancer Institute: http://www.dfci.harvard.edu/