Cannabidiol Targets Colorectal Cancer Cells via Cannabinoid Receptor 2, Independent of Common Mutations

Cannabidiol (CBD) is a non-neurotoxic, phytocannabinoid from cannabis with reported medicinal properties, including antiepileptic and anti-inflammatory activity. Several in vitro and in vivo studies have shown that CBD has antitumor potential against colorectal cancer (CRC), the third deadliest cancer in the world. However, as different mutations influence the antitumor effects and CBD can bind a variety of receptors, it is yet to be determined whether specific CRC mutations affect CBD's efficacy in treatment of CRC. To investigate this, we selected four CRC cell lines, including HCT116, HT-29, LS174T, and LS153, which harbor distinct mutations. Cells were treated with a range of concentrations of CBD to evaluate its cytotoxic effects and impact on cell proliferation, migration, and invasion by using a live-cell imaging system. IC₅₀ values were then calculated for each parameter. The level of endoplasmic reticulum (ER) stress pathway markers was also measured using qRTPCR. The requirements for CB1 or CB2 receptor-medicated signaling were investigated using the selective inhibitors AM251 and SR144528, respectively. Our results demonstrate that CBD induces apoptosis and halts proliferation, migration, and invasion of CRC cell lines in a concentration-dependent manner. CBD showed potent antitumor effects in the tested cell lines with no obvious effect from different mutations such as KRAS, BRAF, APC, PTEN, etc. CBD also induced ER stress in CRC cells but not in healthy intestinal organoids. Cotreatment with SR144528 inhibited the effects of indicating involvement of CB2 receptor activation in the anticancer effects of CBD. Together, these results demonstrated that CBD could be effective for CRC regardless of the underlying mutation through CB2 receptor activation.