Cells responsible for our hair colour could also be the starting point for some of the deadliest skin cancers.
Scientists in the US have discovered an unexpected origin of deadly skin cancers. In a paper published to Nature Communications, a team from NYU showed that some of these cancers may originate in stem cells in the hair follicles that give it colour, rather than in skin layers.
Hair follicles exist within skin layers as complex organs, but the study has shown that immature pigment-making cells may develop cancer-causing genetic changes, exacerbated by exposure to normal hair growth signals.
Previous models of this disease had put forward the idea that ultraviolet radiation through sunlight was a major risk factor in melanoma. However, this latest study argued that triggers may always be there in hair follicles. Unlike normal follicles, newly cancerous pigment stem cells migrate up and out of the follicles to establish melanomas in nearby surface skin before spreading deeper, it said.
The team’s focus was on stem cells that mature into melanocytes, cells that make the protein pigment melanin, which typically protect skin by absorbing the sun’s damaging rays. By absorbing some wavelengths of visible light but reflecting others, pigments ‘create’ hair colour.
Potential treatment for melanoma
In testing, specially bred mice were used with an ability to edit genes in follicular melanocyte stem cells only, which could be easily tracked. This confirmed melanoma cells can arise from melanocyte stem cells, which abnormally migrate up and out of hair follicles to enter the outermost layer of the skin.
They continued to move deeper into the skin layer where they not only shed their follicular origins, but also acquired signatures similar to neurons and skin cells almost exactly like those seen in human melanoma tissue.
By knowing where to look for the original, cancer-causing event, the researchers temporarily eliminated signals one by one in the follicular environment to see if cancer still formed in their absence.
“Our mouse model is the first to demonstrate that follicular oncogenic melanocyte stem cells can establish melanomas, which promises to make it useful in identifying new diagnostics and treatments for melanoma,” said the study’s first author Qi Sun.
“While our findings will require confirmation in further human testing, they argue that melanoma can arise in pigment stem cells originating both in follicles and in skin layers, such that some melanomas have multiple stem cells of origin.”