Promising Development in the War on Cancer

This news item caught my attention:

Cannabinoids Block Brain Tumor Angiogenesis Via VEGF Pathway

NEW YORK (Reuters Health) Aug 26 - Cannabinoids depress the VEGF pathway in brain tumors, apparently by boosting ceramide activity, according to a Spanish study in mice and in two patients.

Although past animal studies have shown cannabinoids can slow tumor angiogenesis, the mechanism by which the marijuana derivatives exert this effect has not been clear, Dr. Manuel Guzman of Complutense University in Madrid and colleagues note in the August 15th issue of Cancer Research.

Cannabinoids are known to act on the G protein-coupled receptors CB1 and CB2, the researchers add, and neuronal CB1 receptors mediate their psychoactive effects. [...]

Blocking cannabinoid-specific CB2 receptors in mouse gliomas with JWH-133 changed the expression of 10 genes related to the VEGF pathway, the investigators found. Using a series of cannabinoids in cultured glioma cells and mouse gliomas also cut VEGF production and reduced activation of the VEGF receptor (VEGFR)-2. [...]

The researchers note that cannabinoids that selectively block CB2 receptors would be ideal for cancer treatment, because they avoid psychoactive effects. "Unfortunately, very little is known about the pharmacokinetics and toxicology of the selective CB2 ligands synthesized to date, making them as yet unavailable for clinical trials," they add.

"Because blockade of the VEGF pathway constitutes one of the most promising antitumoral approaches currently available," the team concludes, the findings "provide a novel pharmacological target for cannabinoid-based therapies."

Cancer Res 2004;64:5617-5623.

Although one could not advocate use of cannabis for cancer treatment -- it is a known carcinogen -- this research shows that it would be premature to discourage research on a drug that happens to be illegal.