Researchers investigated previously published studies to examine the anti-cancer effects of cannabinoids and their potential role in treatment efforts.
The latest discoveries on cannabinoids and their anticancer properties were examined in a research review recently published in Current Oncology. A team of researchers, led by Dr. Guillermo Velasco of Complutense University of Madrid, focused on the molecular mechanisms of action that cannabinoids use to elicit their anti-cancer effects.
The review begins by explaining the body’s endocannabinoid system and how cannabinoids like tetrahydrocannabinol (THC) and cannabidiol (CBD) interact with the system’s cannabinoid-specific receptors CB1 and CB2 to stimulate a series of chemical reactions that suppress tumor growth.
Several studies highlighted in the review show that the CB1 receptor is related to tumor growth. In one animal study, the deletion of CB1 receptors accelerated the growth of a tumor in the intestines. In another, administering cannabinoids that activate the CB1 receptor were effective at reducing levels of cancerous precursors. Findings also show that when the enzymes that degrade cannabinoids are removed, the growth of tumors in mice are reduced significantly.
According to findings in the review, cannabinoids binding to CB1 and CB2 receptors effectively impair the progression of tumors. Studies indicate that cannabinoids induce the death of cancer cells by apoptosis and inhibit cancer cells from spreading.
Preclinical studies have found that by binding to the cannabinoid receptors, THC and other cannabinoids stimulate the production of an apoptosis-inducing compound known as ceramide. Cannabinoids also enhance the expression of the stress-regulated protein p8 (NUPR 1), which has been implicated in the stimulation of autophagy-mediated cancer cell death and in the regulation of tumorigenesis and tumor progression. Studies have found the p8-mediated autophagy pathway to be instrumental in the anti-tumor effects of cannabinoids in glioma cells, pancreatic and hepatic cancer cells, and melanoma cells. In hormone-dependent tumors, evidence suggests that cannabinoids are able to interfere with the activation of growth factor receptors.
The review found that CBD, a non-psychoactive cannabinoid, promotes the apoptotic death of cancer cells. However, because of CBD’s low affinity for cannabinoid receptors, the compound elicits these effects independently of the CB1 and CB2 receptors. The mechanism by which CBD produces an anti-cancer effect is still not well understood, though researchers believe it’s likely related to the cannabinoid’s ability to enhance the production of reactive oxygen species in cancer cells.
Evidence also shows that cannabinoids work synergistically with other anticancer drugs to reduce tumor growth. The combining of THC and CBD with radiotherapy or cancer drugs like temozolomide, gemcitabine, paclitaxel, and 5-fluorouracil have produced strong anti-cancer effects.
These clear anti-cancer properties of cannabinoids found in preclinical studies prompted Velasco to end his review urging for more clinical research.
“To summarize, cannabinoids induce tumour cell death and inhibit tumour angiogenesis and invasion in animal models of cancer, and there are indications that they act similarly in patients with glioblastoma,” Velasco concludes in the review. “Given that cannabinoids show an acceptable safety profile, clinical trials testing them as single drugs, or ideally, in combination therapies in glioblastoma and other types of cancer are both warranted and urgently needed.”
You can access the entire study, “Anticancer mechanisms of cannabinoids,” via National Center for Biotechnology Information.
Learn more about previous research investigating cannabinoids’ anti-cancer properties by visiting our education page.