Study Explains How Sunburn Causes Skin Cancer

US researchers have found a new mechanism that explains not only how the body repairs damage done by the sun but might explain why some people are more prone to cancer.

This study was tested only to mice but researchers believe their findings will translate to human beings. According to the team, the body has many known mechanisms for fixing damaged DNA in cells or killing damaged cells so they do not start the out-of-control growth that leads to tumors.

“We have shown that the body has an innate defense against the accumulation of genetic mutations that arise from sun exposure. You get DNA damage almost everytime you go out. This can be translated over to mutations. If you can get rid of the cells containing the DNA damage, you get rid of the cancer,” said Laurie Owen-Schaub of the M.D. Anderson Cancer Center at the University of Texas in Houston.

Writing in the journal Science, Owen-Schaub’s team explained the key genetic players in the fight against cell damage. They said a gene called p53 causes damaged cells to die. It controls another gene, called Fas. Another critically important gene, called Fas ligand or FasL works independently of p53. This is how the study was conducted : Researchers shaved laboratory mice, zapped them with a dose of ultraviolet light, roughly equivalent to 45-minute exposures of humans at noon on a sunny day. Within 3 to 6 hours, skin cells of mice were producing both Fas and FasL. When the group tested mice bred to lack FasL, the mice had much more damage to their cells, even if p53 kicked in and tried to kill off the damaged cells.

The group also subjected both kinds of mice to regular ultraviolet exposure, about an hour and a half a day, for a week or two. Results showed five percent of the normal mice had genetic damage to their skin cells, as approved to 70 percent of the mice lacking FasL.

“Fas is like the lock and FasL is like the key. If you lose the key, you can’t undergo cell death. When this defense mechanism fails or is inactivated, sunlight exposure induces the genetic alterations that they persist, eventually resulting in skin cancer.”