Terpenes Inhibit Liver Cancer

Terpenes Inhibit Liver Cancer
January 19, 2015

Terpenes inhibit liver cancer
As main component of essential oils, terpenes can inhibit the growth of
different cancer cells. Researchers from the Ruhr-University Bochum
headed by Prof Dr Dr Dr Hanns Hatt have analysed this process in liver
cancer cells in detail. They shed light upon the molecular mechanisms
that resulted in cancer cells stop growing, following the application of
(-)-citronellal, and they proved that the olfactory receptor OR1A2 is
the crucial molecule for that purpose. In future, the olfactory receptor
could serve as target for liver cancer diagnosis and therapy.
The researchers report their findings in the journal Archives of Biochemistry and Biophysics.

Essential oils protect not only from bacteria, viruses and fungi
Essential oils occur in many plants, protecting them through their
antibacterial, antiviral and fungicidal properties. It has been recently
discovered that terpenes, the oils' main components, can also inhibit
the growth of different cancer cells, including liver cancer. Their function had not previously been fully understood.

Olfactory receptors not just in the nose
can trigger signalling processes in cells by activating olfactory
receptors. Those receptors are mainly located in the nose, but they
have been
proved to occur in all types of human tissue, including skin, prostate
and spermatozoa. Carcinogenesis and cancer growth are likewise
significantly affected by terpenes, even though it has not been
understood which function exactly they fulfill.

Terpene triggers signalling pathway in cell
order to find this out, the researchers from Bochum utilised a cellular
model of hepatocellular carcinoma, a common liver tumour. They exposed
the cells to a subset of terpenes
with different concentrations, and monitored their reactions. It emerged
that two of the eleven terpenes tested resulted in a significant
increase in calcium concentration in the cells: (-)-citronellal and
citronellol. During a follow-up analysis, the
researchers focused on (-)-citronellal and scanned for a receptor into
which the terpene has to fit like a key into a lock. They demonstrated
that the decisive olfactory receptor OR1A2 occurs in liver cells and is
responsible for detection of the citrus scent and cellular
reaction. If the option for producing that receptor had been removed
from the cells, they did no longer react to the terpene. The
researchers, moreover, succeeded in tracking the signalling pathway
which the terpene uses for increasing calcium concentration inside the
cells, thus reducing cell growth. "These results are yet another example
for the significance of olfactory receptors outside the nose, and they
give rise to hope that new drugs with no severe side effects may be
developed for cancer therapy."

The hepatocellular carcinoma is the most common primary tumour of the
liver. It is the third most common tumour-induced cause of death.
According to current estimations, approx. 8,900 people (6,200 men, 2,700
women) contract this form of cancer in Germany every year.

More information:

D. Ma├čberg et al.: Monoterpene
(-)-citronellal affects hepatocarcinoma cell signaling via an olfactory
receptor. In: Arch. Biochem. Biophys. (2014),olfactory
receptor. In: Arch. Biochem. Biophys. (2014), DOI: 10.1016/j.abb.2014.12.004
Provided by: Ruhr-Universitaet-Bochum
Read more: medicalxpress.com/news/2015-01-terpenes-inhibit-liver-cancer

(-)-citronellal and citronellol terpenes can be found in the active compounds of some cannabis strains. Methods to isolate and safely administer these compounds are being tested today.

The calcium influx into the liver carcinoma cell can be monitored following the exposure to citronellal (pictured in pseudo-colors).