MOUSE STUDY TIED GRAY HAIR AND MELANOMA TO SAME STEM CELLS
Gray hair and melanoma can grow from the same stressed stem cells, University of Tokyo researchers found in mice.
The study, published online in Nature Cell Biology on October 6, 2025, was led by Professor Emi K. Nishimura and Assistant Professor Yasuaki Mohri, the University of Tokyo’s Institute of Medical Science said. The paper is titled “Antagonistic Stem Cell Fates Under Stress Govern Decisions Between Hair Greying and Melanoma.”
“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,” Nishimura said in the press release.
The cells at the center of it are melanocyte stem cells. They give rise to the pigment-producing melanocytes responsible for hair and skin color, and they live in hair follicles. In mammals, the press release placed them in the bulge–sub-bulge region.
How the cells choose their fate
The team used long-term in-vivo lineage tracing and gene-expression profiling in mice to see how the stem cells react to different kinds of DNA damage.
DNA double-strand breaks pushed the cells into what the researchers call senescence-coupled differentiation, or “seno-differentiation.” The cells irreversibly differentiate and are depleted, a process associated with hair graying. The press release said the p53–p21 pathway drives that response.
The outcome depends on the type of genotoxic damage and on signals from the cells’ surrounding niche, the researchers said. X-ray irradiation, for example, was tied to impaired self-renewal, depletion and graying.
Carcinogens played out differently. The study found they can suppress seno-differentiation even in stem cells with DNA double-strand breaks. Ultraviolet B was one of the carcinogenic exposures named.
Under those conditions, the stem cells kept their ability to self-renew and expanded clonally. The paper’s abstract framed the whole thing as a trade-off: stem-cell depletion and graying on one side, continued self-renewal and possible melanoma on the other.
“It reframes hair graying and melanoma not as unrelated events, but as divergent outcomes of stem cell stress responses,” Nishimura said.
What it does not mean
Before anyone starts celebrating a head of silver, the university was blunt: the findings do not mean gray hair prevents cancer. The press release described seno-differentiation as a stress-induced pathway that removes potentially harmful cells.
The Philippine News Agency reported the same caveat from the researchers, that gray or white hair does not directly protect a person from cancer. The experiments were done in mice.
Nishimura is no newcomer to the field. The press release said she previously discovered melanocyte stem cells in mice and humans and studied their role in hair graying. The research team is affiliated with the University of Tokyo, Institute of Science Tokyo, RIKEN and Yamagata University.
The study is listed on PubMed, and the findings were later covered by ScienceDaily.
The study’s abstract describes the mechanism this way: carcinogens suppress melanocyte stem-cell seno-differentiation through arachidonic-acid metabolism and niche-derived KIT ligand, promoting stem-cell self-renewal. The press release added that KIT ligand is secreted from both the local niche and the epidermis.
