Does the smell of ripe fruit hold the key to stopping the growth of cancer cells?

A new study reveals that specific odors, such as those from ripe fruits or fermented foods, can trigger changes in how genes are expressed inside cells, beyond the nose.

The intriguing findings have prompted the question of whether inhaling certain volatile, airborne compounds may hold the key to treating cancer or slow neurodegenerative diseases.

In the study, the research team exposed fruit flies (Drosophila melanogaster) and mice to different doses of diacetyl vapors (a volatile compound secreted by yeast in fermented fruit) for 5 days, which led to widespread changes in gene expression in the flies and mice, including in brain cells. The lungs of mice and the antennae of flies.

In human cells grown in the laboratory, the team found that diacetyl can act as an inhibitor of histone deacetylase (HDAC), enzymes that help wrap DNA more tightly around histones (alkaline proteins that help regulate DNA synthesis within the nuclei of eukaryotic cells). Therefore, inhibiting them can contribute to the expression of genes more easily. HDAC inhibitors are also used as an actual treatment for leukemia.

The researchers found that diacetyl vapors stopped the growth of human neuroblastoma cells grown in a petri dish.

“The ability of a specific odor to directly alter gene expression, even in tissues that do not have odor receptors, was a big surprise,” says the study's senior author, Anandasankar Ray, a cell and molecular biologist at the University of California (UC) Riverside.

He added: "Some volatile compounds emitted from microbes and food can alter epigenetic states in neurons and other eukaryotic cells. Our report is the first of common volatiles that behave in this way."

But given other research showing that inhaled diacetyl causes changes in airway cells and even the lung disease “popcorn lung,” diacetyl may not be “an ideal candidate for treatment,” according to Ray.

“We are already working to identify other volatiles that lead to changes in gene expression,” adds Ray, who has founded two startup companies and filed several patents based on his team's work.

The study revealed that the initial practical application of the discovery may be through agriculture, as plants also contain HDAC enzymes, and other research has shown that they show a strong and surprising response to volatile chemicals in the air.

It should be noted that the study "failed to provide a comprehensive analysis of the underlying mechanisms" that could explain how odors stimulate epigenetic changes in cells beyond nasal cells, nor did it determine the long-term consequences of repeated exposure to common odors.

More studies are needed to better understand the ultimate consequences of this interesting discovery.

The study was published in the journal eLife.