A bacteria that commonly lives on the surface of people's skin may provide protection against cancer, findings of a new study published on Science Advances on Feb. 28 revealed.
Bacterial Strain Produces Chemical That Suppresses Spread Of Tumor Cells
Study researcher Richard Gallo, from the University of California, San Diego, and colleagues found that the strain of human bacteria called Staphylococcus epidermidis appears to help prevent skin cancer by suppressing the spread of tumor cells caused by overexposure to ultraviolet rays.
Experiments on mice showed that the skin bacteria produces a chemical that attacks cancer cells but not normal skin cells.
In animal experiments, the researchers injected mice with the chemical known as 6-N-hydroxyaminopurine (6-HAP) and found that the substance was not toxic.
The researchers then introduced melanoma cells to the animals that were injected with 6-HAP and found that the tumors were over 50 percent smaller than the mice that were not injected with the substance.
Gallo and colleagues also found that the mice that had not been injected with 6-HAP-producing strain of Staphylococcus epidermidis experienced rapid tumor growth when the animals were exposed to UV light. Those that were injected with the bacteria, on the other hand, appeared to have significantly reduced number of pre-malignant skin tumors
"We have identified a strain of Staphylococcus epidermidis, common on healthy human skin, that exerts a selective ability to inhibit the growth of some cancers," Gallo said. "This unique strain of skin bacteria produces a chemical that kills several types of cancer cells but does not appear to be toxic to normal cells."
Common Skin Bacteria May Protect Against Skin Cancer
Staphylococcus epidermidis is commonly found on human skin, but researchers said that only about 20 percent of healthy humans likely have the strain that produces 6-HAP. Gallo and colleagues said that their findings suggest that this common skin bacteria can help guard against the development of skin cancer.
"S. epidermidis strains producing 6-HAP were found in the metagenome from multiple healthy human subjects, suggesting that the microbiome of some individuals may confer protection against skin cancer," the researchers wrote in their study. "These findings show a new role for skin commensal bacteria in host defense."
Over 1 million people in the United States get diagnosed skin cancer every year. Of these, more than 95 percent are non-melanoma skin cancer, which is often caused by overexposure to the sun. Melanoma, which starts in the pigment-producing skin cells called melanocytes, is the most serious of skin cancers.