Grey Hairs Might Have An Unexpected Link To Cancer

Scientists have long thought that grey hair may be linked to emotional stress.

But while that connection feels pretty well-known, I, for one, was surprised by a recent paper linking the pale strands to cancer-related stressors.

According to study leader Prof Emi Nishimura, whose work was published in Nature Cell Biology, the research “reframes hair greying and melanoma not as unrelated events, but as divergent outcomes of stem cell stress responses”. 

Grey hair might reflect a protection against DNA damage

The researchers were looking at melanocyte stem cells (McSCs) in mice when they found the apparent link. 

McSCs, which are responsible for producing hair pigment, only quit and allow hair to turn grey in the event of “DNA double-strand breaks”, or when both sides of the DNA structure are broken. 

But they kept self-renewing and didn’t form sacrificial grey hairs when affected by other stressors, like some carcinogens and UV light, even when their DNA was damaged.

That appeared to allow mutations to keep building and possibly even cloning as the McSCs reproduced, which the scientists think could lay the groundwork for cancers.

In other words, in grey hairs, the cells that would usually have created colour might have sacrificed themselves after experiencing certain types of DNA damage. This is called “senolysis” and may be protective.

But sometimes, it seemed that the stem cells linked to hair colour kept reproducing, even after sustaining damage – including that from some types of cancer.

“These findings reveal that the same stem cell population can follow antagonistic fates – exhaustion or expansion – depending on the type of stress and microenvironmental signals,” said Professor Emi Nishimura.

So – does that mean grey hair prevents cancer? 

No. It just suggests that grey hair could have been caused by the process of senolysis, which might be a protective factor.

The University of Tokyo’s page on the topic reads, “Importantly, this study does not suggest that greying hair prevents cancer, but rather that seno-differentiation represents a stress-induced protective pathway that removes potentially harmful cells.

“Conversely, when this mechanism is bypassed, the persistence of damaged McSCs may predispose to melanomagenesis.”