Scientists find cannabis compounds may promote cancer growth
Cannabis users take note: smoking marijuana may suppress your body's immune functions, increasing your risk of developing cancer or other infections, according to a new international study. The research was recently presented in the European Journal of Immunology.
Researchers put cannabinoids, a group of compounds found inside the cannabis plant, under the microscope. Cannabinoids is also found inside THC (delta-9 tetrahydrocannabinol), which is used in the medical field as a pain reliever.
'Cannabis is one of the most widely used drugs of abuse worldwide and it is already believed to suppress immune functions making the user more susceptible to infections and some types of cancer,' said research leader Dr Prakash Nagarkatti of the University of South Carolina in the US. 'We believe the key to this suppression is a unique type of immune cell, which has only recently been identified by immunologists, called myeloid-derived suppressor cells, MDSCs.'
Most immune cells go up against tumours and infections to ensure the host's safety, but MDSCs do the opposite by actively suppressing the immune system, according to the researchers. Experts recognise that the presence of MDSCs intensifies in patients fighting cancer. They also know that MDSCs may have a hand in suppressing the immune system against cancer therapy, making it easier for tumours to grow.
Dr Nagarkatti and his colleagues showed that cannabinoids stimulate MDSCs by activating cannabinoid receptors. Thanks to their findings, the team determined that marijuana cannabinoids may keep the immune system in check by activating the MDSCs.
'These results raise interesting questions on whether increased susceptibility to certain types of cancers or infections caused from smoking marijuana results from induction of MDSCs,' Dr Nagarkatti explained. 'MDSCs seem to be unique and important cells that may be triggered by inappropriate production of certain growth factors by cancer cells or other chemical agents such as cannabinoids, which lead to a suppression of the immune system's response.'
In an another study, Dr Christian Vosshenrich from the Institut Pasteur in France provided insight into how another molecule, called Interleukin-1 beta, also stimulates MDSCs. The research showed that MDSCs generated during cancer growth also suppress the ability of immune cells to kill cancer cells.
'Marijuana cannabinoids present us with a double edged sword,' Dr Nagarkatti said. 'On one hand, due to their immunosuppressive nature, they can cause increased susceptibility to cancer and infections. However, further research of these compounds could provide opportunities to treat a large number of clinical disorders where suppressing the immune response is actually beneficial.'