Beneficial Bacteria May Prevent Skin Cancer

Bacteria has been found to play many roles in the human body, both good and bad. Some bacteria fight pathogens and keep people healthy, while others can increase the risk of disease.

A new study published by Science Advances suggests that beneficial bacteria on the skin may protect against cancer.

“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,” said researcher Richard Gallo, MD, PhD. “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.”

The authors discovered a strain of S. epidermis that produces 6-N-hydroxyaminopurine (6-HAP).

In the study, mice with S. epidermis that did not produce 6-HAP were more likely to develop skin cancer after exposure to ultraviolet light compared with mice that had a strain that produced the chemical compound.

The authors noted that 6-HAP is a molecule that prevents DNA creation and blocks the spread of tumor cells. The molecule may also have the ability to stop the development of skin cancers, according to the study.

To further test this approach, mice were injected with 6-HAP every 48 hours for 2 weeks. The authors observed no evident toxicities related to the treatment.

When these mice were transplanted with melanoma cells, tumor size was 50% less compared with controls, according to the study.

“There is increasing evidence that the skin microbiome is an important element of human health. In fact, we previously reported that some bacteria on our skin produce antimicrobial peptides that defend against pathogenic bacteria such as Staph aureus,” Dr Gallo said.

The authors hypothesize S. epidermidis may also protect against cancer, but the exact mechanisms are unknown.

Additional studies are necessary to understand how the bacteria produces 6-HAP and whether the compound can be harnessed to prevent skin cancer, according to the authors. Other research should also explore whether 6-HAP loss is linked to a higher risk of cancer, according to the authors.

There are more than 1 million cases of skin cancer diagnosed in the United States annually, which highlights the importance of sun protection. While nearly all are non-melanoma cases, incidences of melanoma are also increasing, with tens of thousands affected each year.

Another recent study suggests that a rare, deadlier form of skin cancer is on the rise. From 2000 to 2013, the number of Merkel cell carcinoma (MCC) cases increased 95% compared with 57% for melanoma and 15% for other cancers. Based on current trends, the researchers project that MCC cases will increase to more than 3200 by 2025.