The body of evidence pointing to the anti-cancer properties of cannabis continues to expand at a rapid rate, with new research indicating that THC prevents tumours from forming in the colon by blocking inflammation. Appearing in the journal iScience[i], the new study builds on previous research which has illustrated how the anti-inflammatory effects of certain cannabinoids help to curtail chronic digestive illnesses like Crohn’s disease, colitis and inflammatory bowel disease (IBD).
Many of these disorders are caused by excessive inflammation in the colon, as the body’s immune system releases a glut of inflammatory proteins known as cytokines. While this response is necessary to remove pathogens and heal injuries, it can sometimes spin out of control, causing damage to surrounding tissue and sparking the formation of tumours.
Several of these cytokines have been strongly linked to colon cancer, with a protein called Interleukin-22 (IL-22) among the main culprits.
In order to investigate the therapeutic action of THC, the study authors injected mice with a carcinogenic compound that is known to cause cancer by triggering the release of excessive amounts of cytokines in the colon. When these mice were treated with THC, however, inflammation was reduced and tumours were prevented from forming.
A more detailed analysis revealed that this response was mediated via the CB2 receptors present in the rodents’ digestive tracts. By binding to this receptor, THC caused certain immune cells known as antigen-presenting cells (APCs) to change their behaviour so that they stopped releasing IL-22.
The fact that this cancer-preventing effect relies on the CB2 receptor is particularly interesting, as THC is known to interact primarily with the CB1 receptor. In a previous study, researchers discovered that the cannabinoid causes colorectal cancer cells to die by sparking a chemical cascade that is controlled by CB1[ii]. The revelation that THC also prevents tumours from forming in the first place by binding to CB2 therefore adds a new layer to our understanding of the anti-cancer capacity of cannabis.
It’s worth noting that the ability of THC to reduce inflammation in the colon has been known about for some time, with a wealth of research pointing to its efficacy as a treatment for digestive illnesses. In one study, 11 patients with Crohn’s disease were put on an eight-week course of high-THC cannabis, with pretty spectacular results.
Ten of the eleven participants experienced a significant reduction in symptoms, five of whom went into complete remission. Three of the participants were also able to give up their regular steroid medications as a result of their THC treatment[iii].
In another study, Tetrahydrocannabinolic acid (THCA), the precursor to THC, was found to significantly reduce inflammation in colorectal cells. The authors of the paper therefore suggested that THCA should be considered as a treatment for Crohn’s, IBD and colitis, stating that they believed it to be more effective than either THC or CBD[iv].
More research is still needed in order to determine how effective THC is at preventing colon cancer in humans, and which modes of administration are most appropriate. Yet with all this encouraging research, it’s becoming increasingly clear that cannabis has a big role to play in the treatment of cancer.
[i] Becker W, Alrafas HR, Wilson K, Miranda K, Culpepper C, Chatzistamou I, Cai G, Nagarkatti M, Nagarkatti PS. Activation of cannabinoid receptor 2 prevents colitis-associated colon cancer through myeloid cell de-activation upstream of IL-22 production. iScience. 2020 Aug 27:101504. – https://www.cell.com/iscience/fulltext/S2589-0042(20)30696-9?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2589004220306969%3Fshowall%3Dtrue
[ii] Greenhough A, Patsos HA, Williams AC, Paraskeva C. The cannabinoid δ9‐tetrahydrocannabinol inhibits RAS‐MAPK and PI3K‐AKT survival signalling and induces BAD‐mediated apoptosis in colorectal cancer cells. International journal of cancer. 2007 Nov 15;121(10):2172-80. – https://onlinelibrary.wiley.com/doi/full/10.1002/ijc.22917
[iii] Naftali T, Schleider LB, Dotan I, Lansky EP, Benjaminov FS, Konikoff FM. Cannabis induces a clinical response in patients with Crohn’s disease: a prospective placebo-controlled study. Clinical Gastroenterology and Hepatology. 2013 Oct 1;11(10):1276-80. – https://www.sciencedirect.com/science/article/abs/pii/S1542356513006046https://www.sciencedirect.com/science/article/abs/pii/S1542356513006046
[iv] Nallathambi R, Mazuz M, Ion A, Selvaraj G, Weininger S, Fridlender M, Nasser A, Sagee O, Kumari P, Nemichenizer D, Mendelovitz M. Anti-inflammatory activity in colon models is derived from δ9-tetrahydrocannabinolic acid that interacts with additional compounds in cannabis extracts. Cannabis and cannabinoid research. 2017 Jul 1;2(1):167-82. – https://www.liebertpub.com/doi/full/10.1089/can.2017.0027