Skin tumors traced to long-lived hair follicle stem cells

Stem cells in the hair follicle divide infrequently and remain in place for long periods. That makes them unusual: unlike rapidly dividing cells that are quickly replaced, follicle stem cells can collect genetic damage over many years while staying alive.

Researchers tracked the origin of chemically induced skin tumors in mice using genetic labelling techniques. They found that the tumors did not arise from surface skin cells, but from stem cells located in the upper region of the hair follicle. The study was published in Science.

Why cell of origin matters

The upper part of the hair follicle, known as the bulge region, contains stem cells normally involved in wound repair and hair growth. These cells are usually quiescent and well-protected. But their long lifespan and low division rate make them vulnerable to the gradual accumulation of mutations caused by chemical exposures or other environmental factors.

This mechanism connects directly to aging biology. As people age, body cells that are not sperm or egg cells (somatic cells) collect mutations over time. Understanding which long-lived cell populations act as the starting point for tumors is a central question at the intersection of aging and cancer research.

Implications for detection

If skin tumors consistently arise from follicle stem cells, early detection strategies that focus only on surface-level skin changes may miss the earliest stages of tumor formation. Whether this finding translates into new screening approaches for people is not yet clear; for now, the evidence comes from a mouse model and requires further validation in human tissue.

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