The discovery, which was made by a team of researchers that included Howard Hughes Medical Institute (HHMI) investigators David J. Mangelsdorf at the University of Texas Southwestern Medical Center and Ronald M. Evans of The Salk Institute and colleagues at the University of Arizona, was reported in the May 17, 2002, issue of the journal Science.

The studies show that a specific type of bile acid, called lithocholic acid (LCA), which is a known carcinogen, activates the vitamin D receptor. When the vitamin D receptor is switched on, it triggers other proteins that detoxify the bile acid.

The research suggests that a drug that acts like vitamin D might help in preventing colon cancer by turning on the vitamin D receptor and clearing LCA from the body. One obstacle that must be overcome, however, is that high intake of vitamin D or drugs that mimic vitamin D can lead to dangerous levels of calcium in the blood.

Colon cancer expert Bert Vogelstein, an HHMI investigator at the Sidney Kimmel Comprehensive Cancer Center at The Johns Hopkins University, said, these studies provide important new clues to the relationship between vitamin D, bile acids, and colorectal cancer, and they have significant implications for colorectal cancer prevention in the future.

Mangelsdorf, Evans and their colleagues studied the effects of the bile acid, LCA, which is produced as a by-product when intestinal bacteria digest primary bile acids produced in the liver. Primary bile acids help the body digest dietary fats
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Contact: Jim Keeley
keeleyj@hhmi.org
301-215-8858
Howard Hughes Medical Institute
16-May-2002