Nikhil Prasad Fact checked by:Thailand Medical News Team Oct 21, 2025 3 hours, 11 minutes ago
Medical News: Graying Hair May Be the Body’s Natural Cancer Defense
Researchers from The University of Tokyo have made a fascinating discovery that could change how we view the simple act of hair turning gray. For years, graying hair has been seen as an inevitable sign of aging, but new research shows it might actually be part of the body’s built-in defense system to reduce cancer risk.
Japanese Study Finds That Graying Hair is the Body’s Natural Cancer Defense
Throughout our lives, cells are constantly bombarded by environmental and internal stressors that can damage DNA. This type of damage plays a major role in both aging and cancer development. To understand how cells respond to DNA injury, scientists studied special cells called melanocyte stem cells, or McSCs. These are the source of melanocytes—the pigment cells that give color to our hair and skin. In their natural environment inside hair follicles, McSCs go through cycles of regeneration to maintain hair color.
According to this
Medical News report, the research team led by Professor Emi Nishimura and Assistant Professor Yasuaki Mohri discovered how these cells respond when their DNA gets damaged.
The study revealed that when McSCs experience severe DNA damage such as double-strand breaks, they go through a process called senescence-coupled differentiation, or “seno-differentiation.” This means the stem cells stop dividing, mature prematurely, and are eventually lost. The visible outcome is gray hair.
However, this response also acts as a safeguard—it prevents damaged stem cells from becoming cancerous. This mechanism is controlled by the p53–p21 pathway, a well-known molecular switch that helps protect cells from turning malignant.
The study took an unexpected turn when researchers exposed the same stem cells to certain carcinogens like ultraviolet B rays or the chemical 7,12-dimethylbenz(a)anthracene. Under these conditions, the cells ignored the protective graying process. Instead, they continued multiplying even with damaged DNA. This uncontrolled growth was supported by a molecule called the KIT ligand, secreted both by nearby tissue and the epidermis. This allowed damaged cells to survive and multiply—conditions that can lead to melanoma, a dangerous form of skin cancer.
Professor Nishimura explained that the same type of stem cell can either age and disappear or multiply and become dangerous, depending on the kind of stress it faces and the surrounding environment. In simple terms, graying hair and skin cancer are two sides of the same biological coin—one representing protection, the other potential danger.
In conclusion, the study shows that graying hair may be the body’s way of cleansing itself of damaged cells before they can turn into cancer. Far from being a mere cosmetic concern, it might actually be a reflection of the body’s self-defense system against disease.
The study findings were published in the peer-reviewed journal: Nature Cell Biology.
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https://www.nature.com/articles/s41556-025-01769-9
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Read Also:
https://www.thailandmedical.news/articles/anti-aging
https://www.thailandmedical.news/articles/cancer
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