For the first time ever scientists have been able to use the olfactory system of an insect to detect cancer cells. This international research team, lead by the neurobiologist and zoologist Professor Dr. Giovanni Galizia of the University of Konstanz, Switzerland, along with scientists from the University La Sapienza of Rome, Dr. Galizia’s hometown, published their results in the scientific journal, Scientific Report.
In their paper they describe how fruit flies are capable of detecting cancer cells via their antennas.
Following the discovery that dogs can detect cancer in various tissue samples, there has been a whole new suite of experiments into the world of chemosensing, the detection of chemical signals in an environment, wrote the research team. However, using these animals has its limitations, as recording results using man’s best friend’s sense of smell depends on observing the dog’s behavior in the presence of its trainer.
Drosophila, on the other hand, do not need to be trained to respond to chemical stimuli, meaning behavioral biases are from far affect with the outcome of the research. These tiny little flies, often found buzzing around your fruit bowl in the summer months, are equipped with a keen olfactory sense thanks to their sensitive antennae, with a receptive range greater than any man made gas sensors.
Using a technique known as calcium imaging, the team was able to directly record the activity within a fly’s antenna, thus making the results more accurate with the absence of the aforementioned behavioral biases in previous experiments.
Calcium imaging allows scientists to record the activity of nerves within neuronal circuits, as calcium levels within a cell are correlated with the amount of neural activity. Any change in calcium concentration can be viewed thanks to reporter proteins, which, when bonded to a fluorescent marker, emits a wavelength of light in the presence of calcium.
The research relied on the fact that cancer cells are metabolically altered compared to healthy cells. As a result, cancer cells release very unique and distinct volatile substances, which effectively allows these cells to be recognized by their “scent.”
When a volatile chemical is captured by an olfactory receptor, it activates the nerves associated with the receptor and sends a signal to the brain where it would eventually be processed.
The scientists used the calcium imaging to record the activation pattern on the antenna of their test subjects when detecting volatile chemicals, such as compounds from a cancerous origin, which would be outside their normal environment.
Thus, various different odorant compounds created varying patterns depending on the neurons they activated. The researchers used five different types of breast cancer for analysis, using healthy breast tissue as a comparison, which showed distinctly divergent activation patterns from one another.
These results meant that cancer could be detected via the olfactory system of the fruit flies, and also the type of cancer present, explained Alja Lüdke during the press release by the University of Konstanz, who worked on the paper as part of the research unit.
This type of sensing would go beyond what is currently available, with methods such as gas chromatography requiring strong concentrations of the volatile compounds, while electronic noses are yet to be universal and are only good at detecting chemicals within their receptive range and sensitivity.
In addition, the results from the fruit flies were quickly obtained, which means that this research unit is on the path of creating a “cheap, fast and highly-efficient pre-screening that can detect cancer cells well before we can discover them with the present diagnostic imaging techniques,” explained Dr. Giovani Galizia.
How would you like to see this research used in other aspects of health care?