Cooperative Effects of Cannabidiol and Cannabigerol on Autophagy in Epithelial Cells

Cannabidiol (CBD) and cannabigerol (CBG) are non-psychoactive cannabinoids that exert diverse biological activities in both normal and cancerous epithelial cells. Although autophagy plays a pivotal role in maintaining cellular homeostasis, the effects of combined CBD–CBG treatment on autophagic regulation across epithelial cell types remain largely unexplored. In this study, GFP-LC3-RFP reporter assays and ATG9-deficient cell models were employed to examine the influence of CBD and CBG on autophagy in Ca9-22 and HaCaT cells. Certain concentrations of either compound alone failed to induce autophagy and, in some cases, appeared to suppress autophagic activity. In contrast, their combined administration markedly enhanced autophagic flux in both cell lines. Low-dose CBG or high-dose CBD promoted differential greater cell survival in HaCaT-WT cells compared to their ATG9-KO counterparts. Collectively, these findings provide novel insights into the cooperative regulation of autophagy by CBD and CBG, underscoring their combined effects on cellular autophagic responses in cancer or normal epithelial cells. Highlights In both Ca9-22 and HaCaT cells, certain doses of CBD alone failed to induce autophagy, whereas CBG at some concentrations showed a trend toward autophagy suppression. Sub-effective doses of CBD and CBG in combination enhance autophagic flux in Ca9-22 and HaCaT cells, with some combinations exceeding the flux induced by higher doses of either compound alone. CBD and CBG exhibit distinct dose-dependent effects on the survival of HaCaT ATG9-deficient cells compared with HaCaT-WT cells, indicating differential ATG9-dependence.