Worshipped by the ancients (and beach-goers everywhere), the sun provides warmth, energy and the occasional rainbow. But for those not careful with their exposure, it also holds the potential to damage skin and even cause cancer.
Ultraviolet light is the source of this skin damage, and now City of Hope researchers have shown why ultraviolet B, or UVB, light appears to cause more skin cancers than UVA light.
City of Hope scientists Ahmad Besaratinia, Ph.D., Sang-In Kim and Gerd Pfeifer, Ph.D., the Lester M. and Irene C. Finkelstein Chair in Biology, recently showed that UVB rays cause more lasting damage to skin cells’ DNA than UVA rays do. The researchers published their work in the July issue of The FASEB Journal, the journal of the Federation of American Societies for Experimental Biology.
|Technician Sang-In Kim conducts research in Gerd Pfeifer’s lab. (Photo by Darrin S. Joy)|
UVB rays are more intense in summer and midday and can quickly cause sunburn, but UVA rays make up most of the mix of sunlight that reaches the Earth — and they can also alter the skin. City of Hope researchers wanted to better understand how UVB does its damage and how that damage is linked to cancer.
The scientists exposed mouse cells with three different types of light: UVA, UVB and a sort of simulated sunlight that combines the two types of rays. Researchers found that the DNA damage caused by UVA rays was quickly removed, but the UVB light-induced damage was more persistent and resistant to repair.
They also compared the irradiated cells to those in human melanoma and non-melanoma tumor samples and found that the DNA mutations inflicted by UVB rays were closer to those seen in most skin cancers.
“Our study is novel in that it fills the gaps in knowledge of mechanisms involved in sunlight-associated skin cancers, which cover various aspects of DNA damage and repair and genetic alterations,” Besaratinia said.
Despite the study’s findings that UVB rays are more harmful, researchers noted that UVA light also can cause damage. They advise protecting the skin by limiting sun exposure, wearing sun-protective clothing and using sunscreen products that offer protection for both UVA and UVB light.
A grant from the National Institute of Environmental Health Sciences supported the research.