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Where does skin cancer really arise?
Some of the deadliest types of skin cancer develop in hair follicles and not in layers of the skin, researchers have now found out in a study.
The NYU School of Medicine's latest investigation found that different types of skin cancer can develop in hair follicles. The results of the study were published in the English language journal "Nature Communications".
Is there a danger from our hair follicles?
Hair follicles are complex organs that are located in the layers of the skin. There immature pigment-forming cells can develop carcinogenic genetic changes, which are then exposed to normal hair growth signals in a second step.
Cancerous pigment stem cells from hair follicles?
Previous models of skin cancer had previously argued that sunlight (e.g., ultraviolet radiation) was an important risk factor for melanoma. However, the current investigation suggests that possible triggers are always present in normal follicles. The new cancerous pigment stem cells then migrate from the follicles to form melanomas in the skin surface before they spread deeper.
Oncogenic pigment cells in hair follicles as a source of melanoma
The study was conducted on genetically modified mice, and the results were confirmed in human tissue samples. "By confirming that oncogenic pigment cells in hair follicles are a real source of melanoma, we have a better understanding of the biology of this cancer and new ideas on how to counteract it," said study author Professor Mayumi Ito from the NYU School of Medicine in a press release.
What does our stem cell do?
The study results reflect the development in which a human begins as a single stem cell and becomes a fetus made up of hundreds of cell types. Along the way, stem cells divide, multiply and specialize until they finally become cells that can only play a single role.
Why are such melanomas difficult to treat?
While the flexibility of stem cells is extremely useful during development, it can be dangerous in adults if cancer cells regain aspects of earlier embryonic cells. Because of this deformability, the researchers have theorized that melanomas can arise from several stem cell types, which makes their treatment more difficult and makes it difficult to track their origin.
Melanin protects the skin
The new study looks at stem cells that mature into melanocytes, cells that form melanin. This protects the skin by absorbing some of the sun's ultraviolet, DNA-polluting rays. By absorbing some wavelengths of visible light but reflecting others, pigments also create the color of the hair.
What exactly could be observed in the model on mice?
With their model on mice, the researchers confirmed that melanoma cells can arise from melanocyte stem cells that migrate abnormally from the hair follicles into the outermost layer of the skin (epidermis). The same cells multiplied there and then migrated deeper into the skin layer (dermis). Once there, the cells lost the markers and pigments that belonged to their follicular origin, presumably in response to local signals. They also received signatures similar to nerve and skin cells and molecular properties, which were almost the same as in studies on human melanoma tissue.
Further findings from the study
The researchers temporarily eliminated individual signals in the follicular environment. So they wanted to find out if cancer was developing in their absence. In this way, the team confirmed that, although they had carcinogenic genetic mutations, follicular melanocyte stem cells did not multiply or migrate to cause melanoma unless they were also exposed to endothelin (EDN) and WNT. These signal proteins usually cause the hair to become longer and the pigment cells in the follicles to multiply.
Some melanomas have multiple stem cells
"Our mouse model is the first to show that follicular oncogenic melanocyte stem cells can establish melanoma, which promises to be useful in identifying new diagnostics and therapies for melanoma," study author Qi Sun reports. The results of the investigation must be confirmed by human testing, but make it clear that melanomas can develop in pigment stem cells that form in both follicles and skin layers. So it is possible that some melanomas have multiple stem cells. (as)
Author and source information
This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
- Qi Sun, Wendy Lee, Yasuaki Mohri, Makoto Takeo, Chae Ho Lim et al .: A novel mouse model demonstrates that oncogenic melanocyte stem cells engender melanoma resembling human disease, in Nature Communications (query: 04.11.2019), Nature Communications
- Some skin cancers may start in hair follicles, NYU School of Medicine (query: 04.11.2019), NYU School of Medicine