Gene required for radiation-induced protective pigmentation also promotes survival of melanoma cells

Nov 20, 2008

Scientists have new insight into the response of human skin to radiation and what drives the most aggressive and deadly form of skin cancer. The research, published by Cell Press in the November 21st issue of the journal Molecular Cell, may be useful in the design of new strategies for prevention of malignant melanoma.

The process of tanning involves synthesis of the pigment melanin by skin cells known as melanocytes. The melanin is dispersed to neighboring skin cells, known as keratinocytes, and acts as a natural sunscreen that provides some protection against the ultraviolet (UV) radiation in sunlight. UV radiation induces melanin production in melanocytes via activation of p53 in keratinocytes and subsequent activation of proopiomelanocortin/melanocyte-stimulating hormone (POMC/MSH). POMC/MSH initiates a series of signals leading to activation of genes controlling pigment production in melanocytes.

The protein encoded by paired-box homeotic gene 3 (PAX3) is essential for melanocyte development. Although recent research has implicated PAX3 in the process of pigmentation, the response of PAX3 to UV radiation in human skin is not well understood. "The network of genes that regulate PAX3 expression in melanocytes has not yet been elucidated," says senior study author, Dr. Rutao Cui from the Oncology Institute at Loyola University Chicago.

Previous work by Dr Cui and colleagues demonstrated that UV radiation inhibited transforming growth factor-beta (TGF-?? in human skin and also decreased melanin synthesis in melanocytes. "Our observations led us to examine the possibility that TGF-??might also participate in regulating the pigmentation response of skin to UV radiation. We postulated that cross-talk between keratinocytes and melanocytes may contribute to the pigmentation response of skin to UV radiation," explains Dr. Cui.

Dr. Cui's team found that TGF-?-Smad signaling inhibited PAX3 transcription in the skin and that PAX3 up-regulation in melanocytes resulted from a UV-independent loss of TGF-? in neighboring keratinocytes. Importantly, PAX3 overexpression was frequently observed in melanomas from sun-exposed skin compared with non-sun-exposed skin. The researchers went on to show that the TGF-?-PAX3 signaling pathway interacted with the p53-POMC/MSH-MC1R signaling pathway and that both were critical for pigmentation.

These results identify PAX3 as an important contributor to the UV pigmentation response and to melanoma cell survival and proliferation. "This study will provide a rich foundation for further research on skin cancer prevention by enabling us to identify targeted small molecules in the signaling pathways of the UV-induced melanogenic response that are highly likely to induce naturally protective pigmentation," concludes Dr. Cui.

Source: Cell Press

Explore further: Bodies of 500 sea lions found on Peruvian beach

add to favorites email to friend print save as pdf

Related Stories

Does bad behavior really hurt business?

14 minutes ago

Silicon Valley seems to have more than its share of companies behaving badly. Among up-and-comers in the tech world, privacy abuses and executive gaffes have become viral sensations. But is all that bad behavior ...

Advanced cyberspying tool dates from 2008

24 minutes ago

A highly sophisticated cyberspying tool has been used since 2008 to steal information from governments, businesses and others, security researchers said Monday.

US northeast braces for flooding after record snow

10 hours ago

Weather forecasters and emergency officials warned Sunday that melting snow would lead to heavy flooding in parts of the US northeast, with hundreds of thousands of people told to brace for fast-rising waters.

Recommended for you

Seychelles poachers go nutty for erotic shaped seed

19 hours ago

Under cover of darkness in the steamy jungles of the Seychelles thieves creep out to harvest the sizeable and valuable nuts of the famous coco de mer palm, and their activities are threatening its long-term ...

Rare new species of plant: Stachys caroliniana

Nov 21, 2014

The exclusive club of explorers who have discovered a rare new species of life isn't restricted to globetrotters traveling to remote locations like the Amazon rainforests, Madagascar or the woodlands of the ...

Mysterious glowworm found in Peruvian rainforest

Nov 21, 2014

(Phys.org) —Wildlife photographer Jeff Cremer has discovered what appears to be a new type of bioluminescent larvae. He told members of the press recently that he was walking near a camp in the Peruvian ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.