Health & Medicine

Study Links Tanning Gene to Elevated Risk of Testicular Cancer

Benita Matilda
First Posted: Oct 19, 2013 10:29 AM EDT

A study led by U.S. scientists highlights the association between tanning gene in humans and the increased risk of testicular cancer.

The study, conducted by scientists from the U.S. National Institutes of Health and the University of Oxford in England, links  gene p53, important in skin tanning, with the higher risk of testicular cancer in white men. Over 80 percent of the white men carry a variant form of this gene, which increases the risk of testicular cancer by threefold.

The team analyzed lab research on the subject and suspected that a variation in the biochemical pathway controlled by the gene p53 can have both positive and negative effect on human health.

In 2011, nearly 8,290 new cases of testicular cancer were seen in U.S. alone. Testicular cancer is the most common cancer in men between the ages of 20 and 34. 

"Gene variations occur naturally, and may become common in a population if they convey a health benefit," Douglas Bell, Ph.D., author on the paper and researcher at the National Institute of Environmental Health Sciences (NIEHS), part of NIH said in a statement. "It appears that this particular variant could help protect light-skinned individuals from UV skin damage, like burning or cancer, by promoting the tanning process, but it permits testicular stem cells to grow in the presence of DNA damage, when they are supposed to stop growing."

UV light activates the gene p53, stimulating skin tanning. It then binds with a particular sequence of DNA present in the gene called KIT ligand oncohene (KITLG), which stimulates the production of melanocyte, causing the skin to tan.

To conduct an analysis, the team looked at several data sets and they chose leads from intersections of more than 20,000 p53 binding sites in human genome.

"In the end, one variant in the p53 pathway was strongly associated with testicular cancer, but also, surprisingly, displayed a positive benefit that is probably related to tanning that has occurred as humans evolved," Wang noted.

After conducting several experiments to check the association between the gene variant and tanning, the researchers noted that while men with a single nucleotide variation in KITLG suffered the highest risk of having testicular cancer.  The high frequency of this allele in light skin people explains why the number of testicular cancer is high in European descent when compared to the African descent.

The new finding may even explain why it is easy to cure testicular cancer with chemotherapy.

Gareth Bond, Ph.D, Concludes saying, "Most other tumors have a mutant p53, but in these testicular cell tumors, the p53 is functioning properly, and the drugs used for testicular cancer appear to work in concert with p53's tumor suppression function to kill the cancer cells."

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