Does this mean humans whose hair greys early in life are more protected from cancer (e.g. melanoma)? I have my doubts. Possibly dubious scientific journalism by Nature!
Lower risk of DNA mutations is probably more relevant here.
"Losing our hair colour as we age might be a byproduct of an anticancer defence mechanism. In two-month-old mice, stem cells constantly replenish the pigment-producing cells that are responsible for keeping hair coloured. But when DNA damage builds up, these stem cells irreversibly mature into pigment cells. As such, the source of new pigment cells gradually dries up, which leads to grey hair and a lower risk of DNA mutations in two-year-old mice."
"The exposome, an individual’s lifelong environmental exposure, profoundly impacts health. Somatic tissues undergo functional decline with age, exhibiting characteristic ageing phenotypes, including hair greying and cancer.
However, the specific genotoxins, signals and cellular mechanisms underlying each phenotype remain largely unknown.
Here we report that melanocyte stem cells (McSCs) and their niche coordinately determine individual stem cell fate through antagonistic, stress-responsive pathways, depending on the type of genotoxic damage incurred.
McSC fate tracking in mice revealed that McSCs undergo cellular senescence-coupled differentiation (seno-differentiation) in response to DNA double-strand breaks, resulting in their selective depletion and hair greying, and effectively protecting against melanoma.
Conversely, carcinogens can suppress McSC seno-differentiation, even in cells harbouring double-strand breaks, by activating arachidonic acid metabolism and the niche-derived KIT ligand, thereby promoting McSC self-renewal.
Collectively, the fate of individual stem cell clones—expansion versus exhaustion—cumulatively and antagonistically governs ageing phenotypes through interaction with the niche."
Antagonistic stem cell fates under stress govern decisions between hair greying and melanoma (no public access, but article above contains link to PDF)
Fig. 2 | Carcinogenic stresses antagonize hair greying and McSC depletion.
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