“The endocannabinoid system has been postulated to help restrict cancer progression and maintain osteoblastic function during bone metastasis. Herein, the effects of cannabinoid receptor (CB) type 1 and 2 activation on breast cancer cell and osteoblast interaction were investigated by using ACEA and GW405833 as CB1 and CB2 agonists, respectively. Our results showed that breast cancer cell (MDA-MB-231)-derived conditioned media markedly decreased osteoblast-like UMR-106 cell viability. In contrast, media from MDA-MB-231 cells pre-treated with GW405833 improved UMR-106 cell viability. MDA-MB-231 cells were apparently more susceptible to both CB agonists than UMR-106 cells. Thereafter, we sought to answer the question as to how CB agonists reduced MDA-MB-231 cell virulence. Present data showed that co-activation of CB1 and CB2 exerted cytotoxic effects on MDA-MB-231 cells by increasing apoptotic cell death through suppression of the NF-κB signaling pathway in an ROS-independent mechanism. ACEA or GW405833 alone or in combination also inhibited MDA-MB-231 cell migration. Thus, it can be concluded that the endocannabinoid system is able to provide protection during breast cancer bone metastasis by interfering cancer and bone cell interaction as well as by the direct suppression of cancer cell growth and migration.”

https://pubmed.ncbi.nlm.nih.gov/35513484/

“In conclusions, we have demonstrated that the ECS—which was present in bone microenvironment—provided a protection against breast cancer bone metastasis and its negative consequence on bone cell survival. Specifically, CB agonists, especially CB2 agonist, was able to prevent breast cancer-induced osteoblast suppression. Each of the two CB agonists or a combination of both could reduce breast cancer cell survival and migration through the NF-κB-dependent pathway. “

https://www.nature.com/articles/s41598-022-11116-9