FOOD PRESERVATIVE MAY HALT TUMOR GROWTH

The common food preservative nisin may stop or slow squamous cell head and neck cancers, according to a new study published in the journal Cancer Medicine. The findings may accelerate new cancer therapies since the U.S. Food and Drug Administration (FDA) and the World Health Organization (WHO) approved nisin as safe for human consumption decades ago.

Oral cancer is a leading cause of death worldwide, and oral squamous cell carcinoma accounts for more than 90% of oral cancers. However, survival rates for oral cancer haven't improved in decades, according to the study.

Yvonne Kapila, the study's principal investigator and professor at the University of Michigan School of Dentistry, said antibacterial agents like nisin alter cell properties in bacteria to render it harmless. However, it's only recently that scientists began looking to antibacterial agents like nisin to see if they altered properties in other types of cells, such as cancer cells or cells in tumors.

"The poor 5-year survival rates for oral cancer underscore the need to find new therapies for oral cancer," she said. "The use of small antibacterial agents, like nisin, to treat cancer is a new approach that holds great promise. Nisin is a perfect example of this potential because it has been used safely in humans for many years, and now the laboratory studies support its anti-tumor potential."

The study, which looked at the use of antimicrobials to fight cancerous tumors, suggests nisin, in part, slows cell proliferation or causes cell death through the activation of a protein called CHAC1 in cancer cells, a protein known to influence cell death. The study is the first to show CHAC1's new role in promoting cancer cell death under nisin treatment. The findings also suggest that nisin may work by creating pores in the cancer cell membranes that allow an influx of calcium. It's unclear what role calcium plays in nisin-triggered cell death, but it's well known that calcium is a key regulator in cell death and survival.

The researchers concluded nisin slows or stops tumor growth by interrupting the cell cycle in "bad" cells but not the good cells; thus nisin stops cancer cell proliferation but doesn't hurt good cells.