How marijuana shrinks cancerous tumours

London, July 15 (IANS) Marijuana's success in shrinking tumours has remained a mystery till now. Researchers have now revealed the existence of previously unknown signalling platforms which are behind the drug's success in arresting tumour growth.

The main psychoactive ingredient in cannabis could reduce tumour, the researchers noted.

They found that two cell receptors in particular were responsible for the drug's anti-tumour effects.

The researchers used samples of human cancer cells to induce tumours in mice. They then targeted the tumours with doses of the cannabis compound THC (Tetrahydrocannabinol).

"THC, the major active component of marijuana, has anti-cancer properties. 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-tumour effects of THC," said Peter McCormick from University of East Anglia in Britain.

"We show that these effects are mediated via the joint interaction of CB2 and GPR55 - two members of the cannabinoid receptor family," McCormick noted.

The findings help explain some of the well-known but still poorly understood effects of THC at low and high doses on tumour growth.

However, cancer sufferers should not be tempted to self-medicate, McCormick cautioned.

It is hoped that the findings could help develop a synthetic equivalent with anti-cancer properties.

The findings appeared in the Journal of Biological Chemistry.