Licorice may offer colon cancer prevention

NASHVILLE, March 24 (UPI) -- A chemical component of licorice may offer a new way to prevent colorectal cancer without the adverse side effects of other therapies, U.S. researchers said.

The study, published in the Journal of Clinical Investigation, shows that inhibiting the enzyme 11beta-hydroxysteroid dehydrogenase type 2 -- either by treatment with a natural compound found in licorice or by silencing the 11beta-hydroxysteroid dehydrogenase type 2 gene, prevents colorectal cancer progression in mice predisposed to the disease.

Dr. Raymond Harris, Dr. Ming-Zhi Zhang and colleagues at the Vanderbilt University Medical Center have been investigating COX-2 regulation in the kidney. They previously found that inhibiting 11betaHSD2 in the kidney suppresses COX-2 expression in that organ.

One promising target for chemoprevention is the enzyme cyclooxygenase 2, which promotes colorectal cancer progression via the action of the enzyme's inflammatory products -- the prostaglandins.

Inhibiting this enzyme with non-steroidal anti-inflammatory drugs like ibuprofen or with selective COX-2 inhibitors like Vioxx or Celebrex reduces the number and size of colon polyps in mice and in patients with an inherited predisposition to colon cancer.

However, both types of drugs cause serious adverse side effects that limit their utility for chemoprevention.

Licorice has been used for thousands of years for ailments ranging from coughs to constipation but even licorice is not without side effects; long-term consumption can lead to low blood potassium and increases in blood pressure but they are relatively minor compared to the cardiovascular side effects of COX-2 inhibitors, Harris said.