Professor uses mice to study cancer

A GW professor and her husband are simulating the effects of sun exposure on children using newborn mice.

Professor Frances Noonan, who has been conducting research on UV radiation for more than 25 years, and her husband, Edward DeFabo, exposed newborn mice to UV rays at GW Medical Center.

“The big concern about melanoma is that it is one of the fastest-increasing cancers for reasons that are not understood,” Noonan wrote in an e-mail.

Melanoma is a type of cancerous tumor that originates in melanocytes, the cells that produce the pigmentation in hair, skin and eyes, according to the Skin Cancer Foundation. The National Cancer Institute estimates that there will be more than 59,900 cases of melanoma and more than 8,000 deaths in 2007.

While melanoma is linked to sunlight exposure, the exact causes of the cancer are unknown, Noonan said. She said individual lifestyle changes and global climate changes are possible causes.

While melanoma in children is not common, the numbers seem to be increasing, Noonan said. Melanoma is also one of the most common cancers among 15 to 29 year olds. It occurs in adults of all ages, particularly older men, Noonan said.

The baby mice in Noonan’s experiment that were exposed to UV radiation later developed malignant melanoma. Unlike the adult mice, the baby mice didn’t exhibit an “inflammatory response,” according to a news release. Additionally, the adult mice that were irradiated did not develop melanoma.

Though the research on mice shows promise in discovering more about melanoma in humans, Noonan said that her team has been careful about their inferences.

“The newborn mice we use are probably closer in immunologic responses to newborn infants rather than to young children,” Noonan said. “I think it is clear from general observation that young children can get sunburned, but whether this response differs in any way from sunburn in adults is really unknown.”

Noonan said the major message is that children, as well as adults, should avoid sunburns by using sunscreen and wearing protective clothing. Noonan and DeFabo are working with colleagues at the National Institutes of Health to identify the genes that are activated by UV radiation which cause melanoma.

In her research, Noonan showed that the UV radiation damaged deoxyribonucleic acid in both adult and newborn animals.

“Identifying the genes activated by UV radiation would go a long way toward understanding the mechanism of melanoma initiation,” DeFabo said. “Once this is known, designing the most effective therapeutic approach to block or correct this defect should be possible.”

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