Comparative changes in breast cancer cell proliferation and signalling following somatostatin and cannabidiol treatment.

Breast cancer is the most commonly diagnosed cancer and a leading cause of cancer-related death among women worldwide. Somatostatin (SST) and Cannabinoids have an anti-proliferative and pro-apoptotic effect, but the mechanisms of their actions remain elusive. In the present study, we have evaluated the effects of SST, Cannabidiol (CBD) alone or in combination on receptor expression, cell proliferation and apoptosis and related downstream signalling pathways in MDA-MB-231 and MCF-7 breast cancer cells. The results presented here demonstrate the cell type and agonist-dependent changes in receptor expression at the cell membrane, inhibition of cell proliferation and increased apoptosis following treatment with SST and CBD alone and in combination. In comparison to MDA-MB-231 cells, MCF-7 cells treated with SST alone and in combination with CBD exhibited inhibition of phosphorylated Protein Kinase B (pAKT) and phosphorylated-Phosphoinositide 3-Kinase (pPI3K) expression. Importantly, inhibition of PI3K/AKT activation was accompanied by enhanced PTEN expression in MCF-7 cells. These results highlight the possible interaction between SSTR and CBR subtypes with the implication in the modulation of receptor expression, cell viability and signal transduction pathways in a breast cancer cell type-dependent manner.