Typically thought of as a bendy black confection, the root form of licorice has long been used in traditional Chinese medicine to treat a range of conditions. Now, a new study shows that a compound from the root is highly effective at fighting pancreatic tumor growth.
Licorice root is a type of legume that's been used since ancient times to treat a range of illnesses including those afflicting the lungs, kidneys and liver, although there is only scant scientific evidence to support its use as an overall health tonic. The licorice root compound glycyrrhizin is about 50 times sweeter than cane sugar and is the substance that eventually found its way into the bendy sticks and hard candies most of us know as licorice.
Now, a different compound in the plant is gaining some attention thanks to a study out of Hong Kong Baptist University (HKBU). Using computer modeling, researchers there determined that a flavonoid called isoliquiritigenin (ISL) could have a good shot at combating pancreatic cancer, a disease that is the fourth-leading cause of cancer deaths in Hong Kong. Pancreatic cancer is known as a particularly deadly form of the disease, with only a 12% survival rate among incidences in the United States.
To test ISLs efficacy, the HKBU researchers applied two different amounts of the substance to human pancreatic cancer cells in lab tests. They found that the cells that received 12.5 micrometer (μM) concentrations of ISL died off at a rate about 50% higher than the untreated cells, while those that received 25 μM of the flavonoid died off at a rate around 80% higher than that of the untreated control group.
Moving on to mouse models, the researchers again saw impressive results. The press release reports that after 21 days "the tumor volumes of the two ISL sub-groups treated with 30mg/kg and 60mg/kg of ISL were about 500 mm3 and 300 mm3 respectively." By comparison, the tumor volumes of the control group were 1,000 mm3.
Powerful combo
Treatment with the licorice root extract was about as effective as treatment with the current standard of care: a chemotherapeutic drug known as gemcitabine (GEM). But GEM can be extremely toxic to the body and pancreatic cancer cells can grow resistant to its effects, so a natural alternative could provide a significant tool in battling the disease.
In fact, when ISL was combined with GEM in the mice, the researchers saw that it boosted the efficacy of the chemotherapy drug by 18%.
The HKBU team believes that ISL is efficient because it blocks a process known as autophagy in late-stage cancer cells. Autophagy is a process in which cells recycle and thus clean out damaged or redundant components contained within their walls. In early-stage cancer, autophagy helps prevent cancer cells from metastasizing. But in the later stages of the disease, autophagy can actually help cancer spread by boosting its motility, so blocking the process could be one way of controlling it. Previous research has found that other flavonoids contained in licorice were effective in controlling autophagy in colorectal cancer cells, which led to their death.
"The findings in this study open a new avenue for developing ISL as a novel autophagy inhibitor in the treatment of pancreatic cancer," said Joshua Ko Ka-Shun, associate professor, at HKBU's School of Chinese Medicine and lead researcher. "We hope to collaborate with other research partners to further evaluate the effectiveness and potential clinical application of ISL in treating pancreatic cancer."
The research has been published in the journal, Phytomedicine and was just presented at the Annual Congress of the European Association for Cancer Research 2023 in Torino, Italy.
Source: Hong Kong Baptist University
