Hepatocellular carcinoma (HCC) is the most common model of liver cancer representing approximately 75% of all liver cancer types. In HCC, a complex molecular interplay involving multiple signaling pathways such as β-catenin, STAT3, and S6k1 signals have found attributed to the development of HCC. The hindrance of such signals has been recorded as a robust therapeutic tool in many different types of malignancies. Cannabinoids (CBDs) have been emphasized with its promising therapeutic properties against numerous types of cancers. Recently, we reported that CBD has been recognized for its wide spectrum therapeutic activity as an anti-cancer for both ER (+) and Triple (-) human breast cancer cells. Herein, to investigate the antitumor activity of CBD on HCC viability and proliferation, two different liver cancer cell lines, Hep-G2 and Hep-3B, were used. Cells were treated with different concentrations of CBD increasingly and the protein expression levels of oncogenic and pro-survival signals β-catenin, STAT3 and S6K1 were detected, using the western blotting analysis. In both cell lines, CBD inhibited cell survival in a dose dependent manner as observed by Wst-1 assay and induced apoptosis, showing a significant enhancement of caspase-3 activity as well as histone release, and DNA fragmentation. Cells viability inhibition was confirmed by the morphological changes that was detected after CBD treatment for 48h. Furthermore, CBD-induced apoptosis was accompanied by down-regulation of pro-survival oncogenic expression of β-catenin, STAT3 and S6K1 in the both cell lines comparing to the untreated control cells. The crosstalk between the autophagic and apoptotic signaling pathways was also investigated and we found that beclin1 is essential for CBD-mediated apoptosis in HepG2 cells. In addition, CBD enhances the interaction between beclin1 and Vps34 that inhibits the association between beclin1 and Bcl-2, triggers the translocation of BID to the mitochondria, releases cytochrome c to the cytosol, and finally activates the intrinsic apoptotic pathway in HepG2 cells. CBD increased the generation of reactive oxygen species (ROS) and using ROS inhibitors significantly decrease the induction of apoptosis and autophagy. All in all, our data revealed an intricate interplay between apoptosis and autophagy in CBD-treated HCC cell lines, suggesting that CBD treatment induces an interplay among β-catenin, STAT3 and S6K1 in favor of apoptosis induction in both Hep-G2 and Hep-3B cells, introducing CBD as a promising treatment for different liver cancer subtypes.

Citation Format: Islam Yahiya, Kamal Kandiel, Ahmed Sultan. Cannabidiol inhibits cell viability and induces apoptosis in hepatocellular carcinoma cell lines: The interplay between apoptosis and autophagy [abstract]. In: Proceedings of the AACR Special Conference: Advances in the Pathogenesis and Molecular Therapies of Liver Cancer; 2022 May 5-8; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(17_Suppl):Abstract nr PO031.