Caffeine lowers risk of UV-induced skin cancer - new study

in medicine, biology

Like to drink a coffee in the morning?  How about taking a bath in light coffee? The results of a new study suggest that caffeine applied directly to the skin might help prevent damaging ultra violet (UV) light from causing skin cancer.

The study published in Proceedings of the National Academy of Sciences strengthens the theory that caffeine guards against certain skin cancers at the molecular level by inhibiting a protein enzyme in the skin, known as ATR.  ATR stands for Ataxia Telangiectasia and Rad3-related.

ATR is a replication checkpoint kinase activated by DNA stresses and is one of several targets of caffeine. Suppression of ATR, or its downstream target checkpoint kinase 1 (another enzyme), selectively sensitizes cancer cells to a cell death process known as apoptosis. According to the paper, agents that target this pathway are currently in clinical trials. The authors generated mice with diminished ATR expression to prove their hypothesis.

Prior research indicated that mice that were fed caffeinated water and exposed to lamps that generated UVB radiation that damaged the DNA in their skin cells were able to kill off a greater percentage of their badly damaged cells and reduce the risk of cells becoming cancerous.

"Although it is known that coffee drinking is associated with a decreased risk of non-melanoma skin cancer, there now needs to be studies to determine whether topical caffeine inhibits sunlight-induced skin cancer," said Allan Conney, director of the Susan Lehman Cullman Laboratory for Cancer Research.

In this newly-published study, instead of inhibiting ATR with caffeinated water, Rutgers researchers, in collaboration with researchers from the University of Washington, genetically modified and diminished ATR in one group of mice. The results: the genetically modified mice developed tumors more slowly than the unmodified mice, had 69 percent fewer tumors than regular mice and developed four times fewer invasive tumors.

The study also found, however, that when both groups of mice were exposed to chronic ultraviolet rays for an extended period of time, tumor development occurred in both the genetically modified and regular mice. What this seems to indicate, says Conney, is that inhibiting the ATR enzyme works best at the pre-cancerous stage before UV-induced skin cancers are fully developed.

According to the National Cancer Institute, sunlight-induced skin cancer is the most prevalent cancer in the United States with more than 1 million new cases each year. Although multiple human epidemiologic studies link caffeinated beverage intake with significant decreases in several different types of cancer, including skin cancer, just how and why coffee protects against the disease is unknown.

"Caffeine might become a weapon in prevention because it inhibits ATR and also acts ad as a sunscreen and directly absorbs damaging UV light," said Conney.

Source article: Protection from UV-induced skin carcinogenesis by genetic inhibition of the ataxia telangiectasia and Rad3-related (ATR) kinase. Masaoki Kawasumi et al. Proceedings of the National Academy of Sciences 2011 August. doi/10.1073/pnas.1111378108

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