Scientists have long known that compounds derived from marijuana have some cancer fighting properties, but a recent discovery demonstrates how exactly one compound may fight tumors.
Published in the Journal of Biological Chemistry, the research reveals two previously unknown "signaling platforms" in cells that allow THC, the psychoactive ingredient in cannabis known for producing the "high" sensation, to shrink some cancerous tumors.
“THC, the major active component of marijuana, has anti-cancer properties," Dr. Peter McCormick, a researcher from University of East Anglia in England and co-author of the study, said in a statement. "This compound is known to act through a specific family of cell receptors called cannabinoid receptors. However, it was unclear which of these receptors were responsible for the anti-tumor effects of THC."
When the researchers applied THC to tumors induced in mice using human breast cancer cells, the interaction between two cannabinoid cell receptors -- CB2 and GPR55 -- were responsible for THC's anti-tumor benefits.
"Our findings help explain some of the well-known but still poorly understood effects of THC at low and high doses on tumor growth," McCormick added. He emphasized in an email to The Huffington Post that dosage is critical to outcome, since the wrong protocol can sometimes increase tumor growth, he said.
"So, the ideal would be either the purified THC in an effective dose provided by a health care provider to reduce the known cognitive side effects and still deliver the appropriate reduction in tumor growth, or a synthetic homolog that provides the same effects," McCormack said. He added that the research team didn't screen all tumors and that some types may not respond to this treatment if they do not have compatible receptors expressed.
The endocannabinoid (EC) system is a communications network in the brain and body that is involved in a number of physiological processes that affect a person's feelings, motor skills and memory. The EC system is responsive to the body's naturally-occurring endocannabinoids as well as the cannabinoids found in marijuana, like THC. And scientists have found that the CB2 receptor specifically is sensitive to the therapeutic properties of marijuana-based compounds.
This isn't the first time scientists have found that marijuana can be effective at fighting cancer. Previous studies have found that THC cuts tumor growth in lung cancer in half and also prohibited the cancer from spreading. THC has also been shown to induce death in brain cancer cells.
But THC is just one of many cannabinoids found in marijuana. Others, like CBD, a non-toxic, non-psychoactive chemical compound in the cannabis plant, has also shown promise in the battle against cancer. Researchers in California found that CBD could stop metastasis in many kinds of aggressive cancer.
In the United Kingdom, a team of scientists found that six different purified cannabinoids -- CBD (Cannabidiol), CBDA (Cannabidiolic acid), CBG (Cannbigerol), CBGA (Cannabigerolic acid), CBGV (Cannabigevarin) and CBGVA (Cannabigevaric acid) -- showed a wide range of therapeutic qualities that "target and switch off" pathways that allow cancers to grow.
A number of studies in recent years have demonstrated the medical potential of pot beyond cancer treatment. Purified forms of cannabis has been tied to better blood sugar control, and may help slow the spread of HIV. Legalization of the plant for medical purposes may even lead to lower suicide rates.
McCormack told HuffPost that the researchers are moving toward clinical trials but that it would be at least five years before those would begin.