The p53 protein has not only been shown to prompt the skin to tan in response to UV light, thus deterring the development of melanoma skin cancer, but also may play a role in the desire to be in the sun. In a study published n the March 9, 2007, issue of Cell, researchers at Dana-Farber Cancer Institute reported that the p53 protein is linked to skin tanning and may decrease people's desire to be in the sun—an activity that, can reduce the risk of melanoma.
According to a report released by the Dana-Farber Cancer Institute, in a study published in 2006, researchers Fisher et al. found that UV radiation from the sun caused keratinocytes to make and secrete a hormone called α-MSH, which attaches to nearby melanocytes and spurs them to produce melanin. The chain of events within keratinocytes that led to α-MSH production, however, was a mystery. Investigators knew that α-MSH was created when another protein, known as pro-opiomelanocortin (or POMC), is split apart. They also knew that the amount of POMC within cells rises sharply when cells were exposed to UV rays but they did not know what caused the POMC to increase.
One possibility, according to the report, was the p53 protein. When Fisher and his colleagues examined the section of the gene for POMC that promotes production of the protein, they found it fit with p53—suggesting that when p53 “docks” there, it increases POMC production. Additional evidence reportedly came when the researchers exposed human and mouse keratinocytes to UV radiation: after 6 hrs, levels of both POMC and p53 were far higher than normal, and the level of pigment-stimulating α-MSH was 30 times above normal.
The institute also reports that there is a possibility that p53 protects against skin damage because it underlies people's desire to spend time in the sun. The same process that causes POMC to produce α-MSH also leads to the production of β-endorphin, a protein that binds to the body's opiate receptors and may be associated with feelings of pleasure.
"Even as p53 is causing skin to tan during sunlight exposure, it may also affect neuronal circuits," Fisher said in the report. "These proteins may provide an explicit link between the regulation of tanning and of mood. It raises the question of whether p53-mediated induction of β-endorphin is involved in sun-seeking behavior, which often increases skin cancer risk."
The research was supported by a grant from the National Institutes of Health, and the Doris Duke Charitable Foundation. For more information and the complete report, visit the Dana-Farber Cancer Institute Web site at www.dana-farber.org.
-Dana-Farber Cancer Institute
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