Active Ingredient in Marijuana Inhibits Cancer Growth in Early Study

The active ingredient in marijuana may help fight brain tumors, a new study suggests.

Researchers say the cannabinoids found in marijuana may aid in brain tumor treatment by targeting the genes needed for the tumors to sprout blood vessels and grow.

Their study showed that cannabinoids inhibited genes needed for the production of vascular growth factor (VEGF) in laboratory mice with glioma brain tumors and two patients with late-stage glioblastoma multiforme, a form of brain cancer.

VEGF is a protein that stimulates blood vessels to grow. Tumors need an abundant blood supply because they generally grow rapidly. So when VEGF is blocked, tumors starve from lack of blood supply and nutrients.

Blocking of VEGF constitutes one of the most promising tumor-fighting approaches currently available, says researcher Manuel Guzman, professor of biochemistry and molecular biology, at the Complutense University in Madrid, Spain, in a news release.

Guzman says the findings suggest VEGF may be a new target for cannabinoid-based treatments. Previous studies have shown that cannabinoids could inhibit the growth of tumor-associated blood vessels in mice, but until now little was known about how they worked.

The results of the study appear in the Aug. 15 issue of the journal Cancer Research.

Cannabinoids May Help Starve Tumors

In the study, researchers looked at the effects of cannabinoid treatment on gliobastoma multiforme, a form of brain cancer that affects about 7,000 Americans each year. It's considered one of the deadliest forms of cancer and usually results in death within one to two years after diagnosis.

Treatment typically involves surgery, followed by radiation and/or chemotherapy. But despite these efforts to destroy the tumor, this type of brain tumor often survives and starts growing again, which is why researchers are looking for novel ways to attack it.

In order to grow, all tumors require a network of blood vessels to feed them, and they create this network through a process known as angiogenesis. VEGF is critical to this process.

In the first part of the study, researchers induced brain cancer in mice and then treated them with cannabinoids. They then analyzed the genes associated with the growth of blood vessels in the tumor and found that cannabinoids inhibited several of the genes related to VEGF.

In the second part of the study, researchers injected cannabinoids into tumor samples taken from two human glioblastoma patients.

"In both patients, VEGF levels in tumor extracts were lower after cannabinoid inoculation," says Guzman.

Researchers say more study is needed but the results suggest that cannabinoid-based therapies may offer a new alternative for treatment of these otherwise untreatable brain tumors.