First some background: Brain cancer refers to the uncontrolled growth of cells in the brain, mainly neurons or glial cells. Glial cells refer to brain cells which do not actually conduct the signals that give rise to bodily function, but rather play a supportive role for neurons. When cancer arises from glial cells, such as oligodendrocytes, astrocytes, microglia, and ependyma, the tumor is referred to as a glioma. Malignant gliomas are the most prominent form of life-threatening brain cancer as well as one of the most aggressive forms of cancer known; thus although gliomas are not the most common, they are one of the most deadly cancers. Additionally, unlike lung or colon cancer, there are no known environmental factors that may cause brain cancer besides vinyl chloride or radiation, which the average person is not readily exposed to; and diagnosing brain cancer involves more expensive imaging techniques. These factors combined make gliomas one of the hardest forms of cancer to battle.
The new information: This experiment aimed to elucidate changes in cannabinoid receptor expression of gliomas. It was conducted by introducing antibodies raised against the receptors to human glial tumors and measuring the rate and levels at which the antibodies bound both cannabinoid receptor 1 and 2 (CB1 and CB2). It was found that in glioblastoma multiforme (the typical glioma), levels of CB1 were decreased by 43% and levels of CB2 were increased by 765% compared to a sample of normal, healthy brain tissue.
What this means: By altering levels of cannabinoid receptors, the brain cancer cells now differentiate themselves in terms of their response to cannabinoids. It has been widely documented that cannabinoids may induce cell apoptosis via CB2 receptors, and thus this astounding increase in CB2 receptor expression by gliomas make them far more susceptible to programmed cell death than other brain cells. Thus, levels of cannabinoids that would be safe for normal brain tissue would cause death in brain cancer cells. Therefore, cannabis may have potential therapeutic effects for those diagnosed with brain cancer, and more specifically, glioblastoma multiforme (GBM).
De Jesús, M.L., et al. “Opposite changes in cannabinoid CB1 and CB2 receptor expression in human gliomas.” Neurochemistry International. 56.6-7(2010): 829-33.