New Findings Explain How UV Rays Trigger Skin Cancer

Source: Cornell University

Summary: A new study finds how ultraviolet (UV) rays trigger melanoma ( a most dangerous form of skin cancer that develops from the pigment-containing cells, melanocytes.

According to Centers for Disease Control and Prevention, melanoma, a cancer of skin pigment cells (melanocytes) will strike an estimated population of 87,111 in the U.S in 2017. Till now it is known that a fraction of these melanomas come from the pre-existing moles on the body and the majority of them come from unknown sources. Under normal conditions, UV rays from the sun activate melanocytes to release melanin (protects the skin from sun’s rays). Researchers from Cornell University discovered that the melanocyte stem cells become cells where these cancers originate after accumulating a sufficient number of genetic mutations. The study was published in the journal Cell Stem Cell.

Skin Cancer

Fluorescence microscopy reveals melanoma (red, left; black, right) emerging from melanocyte stem cells. Credit: Hyeongsun Moon and Andrew White, Cornell University

It was suspected that a gene called Hgma2 is expressed in the skin pigment cells under UV rays. When Hgma2 is expressed, it facilitates melanocyte stem cells to change their location from the base of skin hair follicles to the skin’s surface that is epidermis. Researchers used mice engineered with melanocyte stem cell mutations. One set of mice with mutations and another set of mice also with mutations but Hgma2 gene is deleted. Then both the sets of mice are given a mild dose of UV radiations to trigger a tanning response. Finally, the researchers observed the mice set with Hgam2 gene intact developed melanomas and mice set with deleted Hgam2 gene remained healthy.

Asst. Prof. White said, “If you had mutations that were sufficient for melanoma, everything would be fine until you went out and got a sunburn”, “The stimuli that would normally just give you a tanning response could in fact start a melanoma instead”, and further added “We have an actual mechanism, with Hgma2, that can be explored in the future and could be a way we can prevent melanomas from happening.”

More Information: Hyeongsun Moon et al. Melanocyte Stem Cell Activation and Translocation Initiate Cutaneous Melanoma in Response to UV Exposure, Cell Stem Cell (2017). DOI: 10.1016/j.stem.2017.09.001

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