The medicinal properties of extracts from the hemp plant Cannabis sativa have been known for centuries but only in the 90s membrane receptors for the Cannabis major principle were discovered in mammalian cells. Later on the endogenous
ligands for the
cannabinoid receptors were identified and the term '
endocannabinoid system' was coined to indicate the complex signaling system of
cannabinoid receptors, endogenous
ligands and the
enzymes responsible for their biosynthesis and inactivation. The '
endocannabinoid system' is involved in a broad range of functions and in a growing number of pathological conditions. There is increasing evidence that
endocannabinoids are able to inhibit
cancer cell growth in culture as well as in animal models. Most work has focused on the role of
endocannabinoids in regulating
tumor cell growth and apoptosis and ongoing research is addressed to further dissect the precise mechanisms of
cannabinoid antitumor action. However,
endocannabinoids are now emerging as suppressors of angiogenesis and
tumor spreading since they have been reported to inhibit angiogenesis, cell migration and
metastasis in different types of
cancer, pointing to a potential role of the
endocannabinoid system as a target for a therapeutic approach of such malignant diseases. The potential use of
cannabinoids to retard
tumor growth and spreading is even more appealing considering that they show a good safety profile, regarding toxicity, and are already used in
cancer patients as palliatives to stimulate appetite and to prevent devastating effects such as
nausea,
vomiting and
pain.