How grey hair and cancer may be linked

Grey hair is an inevitable hallmark of ageing. It’s a visual reminder of the passing years and all the bodily changes that accompany it.

But emerging scientific research is challenging this simple narrative – revealing that those silver strands on our heads could be an outward sign of our body’s own intricate defences against cancer.

A new study in mice has uncovered the remarkable ways in which our bodies manage cellular damage – a process key in both ageing and cancer. In ageing, cellular damage gradually weakens and disrupts cell function. In cancer, unrepaired or faulty cells can trigger abnormal growth and tumour formation.

The work here has highlighted a surprising connection between the loss of pigment in our hair and the mechanisms that can keep deadly cancers at bay.

Melanocyte stem cells are at the heart of this discovery. These cells reside deep within the hair follicles and serve as a reservoir for melanocytes – the pigment-producing cells responsible for hair and skin colour.

Under normal circumstances, our melanocyte stem cells replenish these pigment-producing cells through cyclical regeneration, a process characterised by repeated phases of activity, resting and renewal in sync with the natural cycles of hair growth and loss. This grants a steady supply of pigment and thus vibrant hair colour throughout most of our lives.

But every day, our cells endure assaults on its own DNA (the genetic material inside our cells) from sources such as ultraviolet radiation, chemical exposure and even our own cellular metabolism process. This cellular damage contributes to both ageing and to the risk of cancers – such as melanoma, a type of skin cancer.

This new study sheds light on what happens when melanocyte stem cells deep within the supportive niche of the hair follicle sustain DNA damage – particularly a type of damage called double-strand breaks.

When this happens, the melanocyte stem cells can undergo a process called “seno-differentiation”. In essence, this means that the stem cells irreversibly mature into pigment cells – then disappear from the stem cell pool, leading to the gradual appearance of grey in our hair.

This protective process is tightly regulated by internal signalling pathways which allow the cells to communicate with each other. By removing these mature cells from the stem cell population, this prevents the accumulation and possible future spread of genetic mutations or DNA changes that could promote cancer.

In a sense, each grey hair is a small victory of bodily self-sacrifice: a cell choosing to bow out rather than risk turning malignant.

Cancer link

The story doesn’t end there, however. Not all DNA damage triggers this protective process. In their experiments, the researchers exposed melanocyte stem cells in mice to potent cancer-causing chemicals as well as UV radiation. Remarkably, under these stressors, melanocyte stem cells were found to bypass seno-differentiation altogether.

Instead, signals from the surrounding tissues actually encouraged the damaged cells to self-renew and continue dividing – despite carrying genetic damage. This created a cellular environment ripe for the emergence of melanoma.

This research suggests that the fate of melanocyte stem cells appears to hinge on both the specific kind of damage they receive and on the molecular cues present in their micro-environment. Stressors such as chemicals or UV light, which cause the cells’ DNA strands to break, also cause the melanocyte stem cells to self-destruct by default. This same process causes grey hair.

But when under the influence of cancer cells, these damaged melanocyte stem cells persist – creating seeds from which melanoma can grow. Scientists describe this dynamic as “antagonistic fates” – where the same stem cell population can take two dramatically different paths depending on the circumstances.

Importantly, these findings reframe grey hair and melanoma not as unrelated outcomes, but as twin fates of the body’s ancient struggle to balance tissue renewal and avoid cancer. Greying is not itself a shield against cancer, but instead a byproduct of a protective process that eliminates risky cells.

Conversely, when the control mechanisms falter or are subverted by carcinogens, the door is left open for malignancy. This new understanding may also help begin to explain why we’re more likely to develop cancer as we get older.

Of course, it’s crucial to note the limits of these findings. Much of the pivotal evidence comes from experiments in mice. This means research still needs to be conducted in humans to understand if our melanocyte stem cells also function in a similar way. Biological differences between species, as well as complexities of human lifestyles and genetics, mean the picture for our own hair and cancer risk is nuanced.

Still, these discoveries open exciting avenues for both cancer research and ageing science. Understanding the signals that nudge stem cells toward differentiation or risky expansion could someday enable therapies to reinforce the body’s natural safeguards, potentially lowering cancer risk as we age.

There are broader implications as well. This information could help explain why some people develop melanoma even without having been exposed to clear risk factors – and why cancers and tissue degeneration so often go hand-in-hand in later life.

The story of grey hair is not just about vanity or the inevitable march of time. It’s about evolution, adaptation and the ceaseless vigilance of our bodies’ internal guardians. Those silver strands may be telling us something profound: that amid the competition between ageing and cancer, sometimes it’s worth sacrificing a pigment cell for the sake of the whole organism.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Justin Stebbing, Anglia Ruskin University

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Justin Stebbing does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.