Active Ingredient in Marijuana Kills Brain Cancer Cells

ByABC News
April 1, 2009, 10:55 PM

April 2 -- WEDNESDAY, April 1 (HealthDay News) -- New research out of Spain suggests that THC -- the active ingredient in marijuana -- appears to prompt the death of brain cancer cells.

The finding is based on work with mice designed to carry human cancer tumors, as well as from an analysis of THC's impact on tumor cells extracted from two patients coping with a highly aggressive form of brain cancer.

Explaining that the introduction of THC into the brain triggers a cellular self-digestion process known as "autophagy," study co-author Guillermo Velasco said his team has isolated the specific pathway by which this process unfolds, and noted that it appears "to kill cancer cells, while it does not affect normal cells."

Velasco is with the department of biochemistry and molecular biology in the School of Biology at Complutense University in Madrid. The findings were published in the April issue of The Journal of Clinical Investigation.

The Spanish researchers focused on two patients suffering from "recurrent glioblastoma multiforme," a fast-moving form of brain cancer. Both patients had been enrolled in a clinical trial designed to test THC's potential as a cancer therapy.

Using electron microscopes to analyze brain tissue taken both before and after a 26- to 30-day THC treatment regimen, the researchers found that THC eliminated cancer cells while it left healthy cells intact.

The team also was able, in what it described as a "novel" discovery, to track the signaling route by which this process was activated.

These findings were replicated in work with mice, which had been "engineered" to carry three different types of human cancer tumor grafts.

"These results may help to design new cancer therapies based on the use of medicines containing the active principle of marijuana and/or in the activation of autophagy," Velasco said.

Outside experts suggested that more research is needed before advocating marijuana as a medicinal intervention for brain cancer.