Berlin (dpa) – Usually it comes in the dirty thirties – in some cases a bit earlier, sometimes the following decade – but the sight of those first flecks of grey more often than not brings with it the despondent realization that ageing is kicking in. But according to scientists at the University of Tokyo, grey hair should probably be regarded as a welcome sight as it "may reflect a natural defense against cancer risk." The cells, which are in hair follicles, seem to change color and "exit the system" rather than to continue dividing, which brings with it the risk of tumours forming. "Somatic tissues undergo functional decline with age, exhibiting characteristic ageing phenotypes, including hair greying and cancer," the researchers say in a paper published by Nature Cell Biology. Hair-greying, like melanoma, is possibly down to "how pigment-producing stem cells respond” to the damage inflicted on DNA as people get on in years, the researchers say, clarifying that there is no indication that greying hair prevents cancer. ”While such DNA damage is known to contribute to both ageing and cancer, the precise connection—particularly how damaged stem cells shape long-term tissue health—has remained elusive," the team says. “These findings reveal that the same stem cell population can follow antagonistic fates—exhaustion or expansion—depending on the type of stress and micro-environmental signals,” says the University of Tokyo’s Emi Nishimura. "It reframes hair greying and melanoma not as unrelated events, but as divergent outcomes of stem cell stress responses,” she says. The following information is not intended for publication dpa spr arw
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