Australasian Science: Australia's authority on science since 1938

Sunscreen Protects DNA

By Stephen Luntz

For all the effort put into promoting sunscreen, evidence that it prevents skin cancer has been inconclusive according to Dr Elke Hacker of Queensland University of Technology’s AusSun Research Laboratory. However, Hacker has now demonstrated that sunscreen protects the genes responsible for repairing the skin.

People with high rates of melanomas often report extensive use of sunscreen, according to Hacker. This has led to suggestions that while it protects against burning, sunscreen may not be useful against skin cancers.

“The only way to solve this is to get away from the epidemiology and look at the molecular basis,” Hacker says. She did this by taking samples of skin from 57 healthy individuals and exposing small patches to UV light, both with and without sunscreen, before taking a second biopsy.

Publishing in Pigment Cell and Melanoma Research, Hacker’s results were good news for the industry and public health campaigners. “As soon as our skin becomes sun-damaged, the p53 gene goes to work repairing that damage and thereby preventing skin cancer occurring,” Hacker says. “But over time, if skin is burnt regularly the p53 gene mutates and can no longer do the job it was intended for – it no longer repairs sun-damaged skin, and without this protection skin cancers are far more likely to occur.

“After 24 hours, where the sunscreen had been applied there were no DNA changes to the skin and no impact on the p53 gene,” Hacker says. Those who were not protected were not so lucky.

The study was done with a commercial sunscreen, and Hacker says the results may not be applicable to all products. However, she notes that the active ingredients of the most common brands are the same.

Hacker says the relative damage to p53 from frequent low-level exposure and occasional but more serious burns is unclear: squamous cancers seem to be produced by the former and basal cancers and melanomas by the latter.

The eventual aim of the research, says Hacker, is to produce a “super sunscreen” that can restore p53 or use the same chemical techniques to fix sun damage after it has occurred.