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Turning on CB1

Conquest - Fall 2008

New preclinical research shows that cannabinoid cell surface receptor CB1 plays a tumor-suppressing role in human colorectal cancer.

Raymond DuBois, M.D., Ph.D., was the senior author on a study that may lead to new paths for colorectal cancer prevention or treatment. The study was funded by grants from the National Cancer Institute and the National Colorectal Cancer Research Alliance.

CB1 is well established for relieving pain and nausea, elevating mood and stimulating appetite by serving as a docking station for the cannabinoid group of signaling molecules. It now may serve as a new path for cancer prevention or treatment.

“We’ve found that CB1 expression is lost in most colorectal cancers, and when that happens a cancer-promoting protein is free to inhibit cell death,” says senior author Raymond DuBois, M.D., Ph.D., provost and executive vice president of M. D. Anderson.

DuBois and collaborators from Vanderbilt-Ingram Cancer Center also show that CB1 expression can be restored with an existing drug, decitabine. They found that mice prone to developing intestinal tumors that also have functioning CB1 receptors develop fewer and smaller tumors when treated with a drug that mimics a cannabinoid receptor ligand.

Ligands are molecules that function by binding to specific receptors. Agonists are synthetic molecules that mimic the action of a natural molecule.

“Potential application of cannabinoids as anti-tumor drugs is an exciting prospect, because cannabinoid agonists are being evaluated now to treat the side effects of chemotherapy and radiation therapy,” DuBois says. “Turning CB1 back on and then treating with a cannabinoid agonist could provide a new approach to colorectal cancer treatment or prevention.”

Cannabinoids are a group of ligands that serve a variety of cell-signaling roles. The body produces some internally. External cannabinoids include man-made versions and those present in plants, most famously the active ingredient in marijuana.

Reported in the Aug. 1 issue of the journal Cancer Research.

© 2015 The University of Texas MD Anderson Cancer Center