Cannabis compound clue to colon cancer
06 August 2008
NewScientist.com news service
SMOKING hash or marijuana may not be the healthiest way to do it, but taking substances similar to those found in cannabis might one day help to treat colon cancer.
Raymond DuBois and colleagues at the University of Texas, Houston, discovered that a key receptor for cannabinoids - compounds similar to the active ingredient of cannabis - is turned off in most types of human colon cancer cells. Similarly, mice genetically engineered to develop colon tumours developed more of them if the receptor, called CB1, was knocked out (Cancer Research, DOI: 10.1158/0008-5472.CAN-08-0896). What's more, tumours shrank when the genetically engineered mice were injected with a cannabinoid.
One suggestion is that lack of CB1 encourages tumour growth because the receptor normally interacts with cannabinoids made by the body to prompt cells to die. This opens up a possible two-step treatment for colon cancer. First, switch CB1 back on using decitibine, a drug already approved for use in humans which DuBois and his team showed stops blockage of the receptor in human colon cancer cells. Then give the patient cannabinoids to activate CB1.
The research also casts a shadow on the weight-loss drug rimonabant. The drug suppresses appetite by blocking CB1, which is involved in hunger as well as tumour growth. DuBois suggests that anyone on the drug be screened for colon cancer.
http://www.newscientist.com/article.ns?id=mg19926685.000