Another group of scientists has developed an artificial enzyme that repairs sun-damaged DNA. Both treatments take advantage of the fact that skin cancerdevelops years or even decades after sun-induced skin damage occurs.
Skin cancer, the most common form of cancer, accounts for fully half of new cancer diagnoses in Western populations. More than a million new cases of skin cancer are reported in the U.S. every year. Although skin cancer usually develops later in life, most sun-induced damage, which is a major cause of skin cancer, happens earlier in life.
At the annual meeting of the American Association for Cancer Research, held last week in New Orleans, U.S. researchers reported that caffeine applied directly to the skin reversed sun-induced damage in mice.
"We've been studying the effects of green and black tea on chemically induced cancer and ultraviolet light-induced cancer in mice, particularly UVB light [from the sun]," senior author Allan H. Conney, PhD, tells WebMD. Conney is director of the Laboratory for Cancer Research at Rutgers University College of Pharmacy in Piscataway, N.J.
In previous studies, Conney and colleagues determined that green and black tea prevented sun-induced skin cancer when given orally to mice. The caffeine in the tea, they found, was the active component inhibiting cancer growth. Specifically, they found that caffeine increases skin cell death, suggesting injured skin cells die before cancer has a chance to develop in them.
Conney's team also found that oral caffeine increases levels of a special gene that is involved in suppressing tumor growth.
In their new study, Conney and colleagues investigated whether caffeine applied directly to sun-damaged skin would increase the death of damaged skin cells in mice.
"We exposed [mice] to UVB and then after the UVB exposure, we applied caffeine topically," he says. "We didn't want to have caffeine act as a sunscreen or work by some other mechanism because we wanted to explore what the biological effect of caffeine was immediately after exposure." They found that the topical caffeine did increase skin cell death.
Next, Conney and colleagues will look at whether topical caffeine prevents skin cancer from developing in mice exposed to UVB. Hopefully, within a year they will proceed with studies evaluating the effects of caffeine on sun-damaged human skin.
"These are only studies in mice, and whether [caffeine] has potential in human [skin cells] or not I don't know," Conney says.
In another study presented this week in San Diego at the annual meeting of the American Chemical Society, researchers report that they have produced an artificial enzyme that repairs DNA damage in skin cells that is caused by the sun.
Lead researcher Marco Jonas, PhD, tells WebMD that people known to be at high risk for skin cancer because of genetics, fair skin and eyes, or a history of sun worshipping could be screened later in life for the presence of sun damage to the DNA in their skin cells. Those with such damage could be treated with this molecule, or a similar one, to repair this DNA damage before it becomes cancerous. Jonas is a researcher at the University of Notre Dame in Indiana.
This research is still in its infancy, however. The researchers say it will be at least another four months before the enzyme is tested in DNA, followed by several years of laboratory and clinical trials.
According to senior researcher Olaf Wiest, PhD, an assistant professor of chemistry and biochemistry at Notre Dame, "The idea in principle is that this could be a 'sunscreen for years after.' There is a very long time lag between the occurrence of the damage [to the skin] and the actual skin cancer. ... [During this time,] you could try to go in there and repair the damage that has been done."
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