The endocannabinoid system is implicated in a variety of physiological and pathological
conditions (inflammation, immunomodulation, analgesia, cancer and others). The main
active ingredient of cannabis, Δ(9) -tetrahydrocannabinol (Δ(9) -THC), produces its
effects through activation of CB(1) and CB(2) receptors. CB(1) receptors are expressed
at high levels in the central nervous system (CNS), whereas CB(2) receptors are concentrated
predominantly, although not exclusively, in cells of the immune system. Endocannabinoids
are endogenous lipid-signalling molecules that are generated in the cell membrane
from phospholipid precursors. The two best characterized endocannabinoids identified
to date are anandamide (AEA) and 2-arachidonoylglycerol (2-AG). Here we review the
relationship between the endocannabinoid system and anti-tumour actions (inhibition
of cell proliferation and migration, induction of apoptosis, reduction of tumour growth)
of the cannabinoids in different types of cancer. This review will focus on examining
how activation of the endocannabinoid system impacts breast, prostate and bone cancers
in both in vitro and in vivo systems. The therapeutic potential of cannabinoids for
cancer, as identified in clinical trials, is also discussed. Identification of safe
and effective treatments to manage and improve cancer therapy is critical to improve
quality of life and reduce unnecessary suffering in cancer patients. In this regard,
cannabis-like compounds offer therapeutic potential for the treatment of breast, prostate
and bone cancer in patients. Further basic research on anti-cancer properties of cannabinoids
as well as clinical trials of cannabinoid therapeutic efficacy in breast, prostate
and bone cancer is therefore warranted.
© 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological
Society.