WASHINGTON: The main chemical in marijuana kills cancerous brain cells, offering hope for future anti-cancer therapies, say Spanish scientists.
A team led by Guillermo Velasco of Complutense University in Madrid, found that the active component of marijuana – tetrahydrocannabinol (THC) – kills tumour cells through a process called autophagy. This is the process that occurs when a cell self-destructs by digesting itself.
The research, which appears in the April edition of the Journal of Clinical Investigation, demonstrates that THC and related cannabinoids appear to be "a new family of potential anti-tumoral agents", the authors write.
In the study the scientists conducted most of their research on mice, in which the growth of cancer was stimulated. But the researchers also looked at two patients suffering from a highly aggressive form of brain cancer who were enrolled in a clinical trial.
A mixture of THC in saline solution and injected it into each patient's tumour for 26 or 30 days, then the researchers took samples of the brain tumours. By analysing the tumours using electron microscopy, the researchers discovered that the cancer cells had been killed off while the normal cells stayed intact.
"Although these studies were only conducted in specimens from two patients," the researchers said, "they are in line with the preclinical evidence shown [in mice] and suggest that cannabinoid administration might also trigger autophagy-mediated cell death in human tumors."
There have been previous studies that found cannabinoids curbed the growth of several types of tumours in rats and mice, but the mechanism by which is worked has been obscure until now.
Autophagy has a dual role in cancer: in some cases it promotes cancer cell survival and in other cases it inhibits cancer cell survival. This study identified the signalling route by which autophagy is activated for cell death.
The authors suggest that the study may prove useful in the development of future anti-cancer therapies based on THC or in the activation of the process that results in autophagy.