A new study conducted by researchers fromUniversity of Tokyo on mice revealed an important connection between the white hair and the cancer. According to research, in fact, it would be the manifestation of a defense mechanism against the tumor.
The study
The scientists worked on profiling the gene expression of the stem cells that reside in the hair bulb and which give rise to melanocytes, i.e. those cells that produce the pigment determining the color of skin and hair. Research has shown that following serious damage to the DNA, such as a double-strand break, the stem cells of the hair bulb decide to die rather than proliferate and favor the development of melanoma. Therefore the stem cells mature into pigmented cells, and then disappear, causing the gradual appearance of gray hair. This protective process is tightly regulated by internal signaling pathways that allow cells to communicate with each other. By removing these mature cells from the stem cell population, you prevent the accumulation and possible future spread of genetic mutations or DNA alterations that could promote cancer.
The link to cancer
The study, however, revealed that not all DNA damage triggers this protective process. In their experiments, the researchers exposed melanocyte stem cells in mice to potent carcinogenic chemicals and UV radiation. Surprisingly, under stressful conditions, melanocyte stem cells were found to completely bypass breast differentiation. Instead, signals from surrounding tissues actually encouraged the damaged cells to self-renew and continue dividing, despite the genetic damage. This created a cellular environment favorable to the appearance of melanoma. This research suggests that the fate of melanocyte stem cells appears to depend on both the specific type of damage they suffer and the molecular stimuli present in their microenvironment. Stressors such as chemicals or UV light, which cause cells’ DNA strands to break, also cause melanocytes stem cells to self-destruct. This same process causes the appearance of gray hair. But when under the influence of tumor cells, these damaged melanocyte stem cells persist, creating seeds from which melanoma can grow. Scientists describe this dynamic as “antagonistic fates,” in which the same population of stem cells can take two radically different paths depending on the circumstances.
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