Recent research from Japan has uncovered an intriguing connection between hair greying and melanoma, suggesting that both phenomena stem from the same source of stressed stem cells. Scientists at The Institute of Medical Science at The University of Tokyo have shown that melanocyte stem cells (McSCs) respond to DNA damage in ways that can lead to either hair greying or cancer.
When McSCs experience DNA damage, they can enter a protective state known as seno-differentiation, which results in the permanent maturation of these cells and ultimately leads to grey hair. This process is regulated by the activation of the p53-p21 signaling pathway.
However, exposure to certain carcinogens, such as 7,12-dimethylbenz(a)anthracene and ultraviolet B radiation, disrupts this protective mechanism. Instead of undergoing seno-differentiation, the damaged McSCs evade this fate and continue to proliferate, leading to an increased risk of melanoma. The surrounding tissue and epidermis provide signals through KIT ligands that promote the survival and expansion of these potentially cancerous cells.
This research highlights the delicate balance between cell loss and survival in the context of stem cell responses to stress. The findings suggest that hair greying and melanoma are not unrelated occurrences but rather two divergent outcomes arising from the same cellular stress responses. The authors caution that while the presence of grey hair does not prevent cancer, seno-differentiation may serve as a critical defense mechanism that eliminates damaged stem cells before they can become harmful.
By identifying the molecular pathways that influence whether stem cells undergo protective exhaustion or dangerous expansion, this study bridges the gap between the biology of tissue aging and cancer development. Furthermore, it underscores the importance of a natural process called “senolysis,” which helps in the elimination of compromised stem cells, potentially preventing the onset of malignancies.
The complete study is published in the journal Nature Cell Biology, under the title “Antagonistic stem cell fates under stress govern decisions between hair greying and melanoma.”
