Metabolic responses of three distinct melanoma cell lines to UVA radiation and cannabigerol

The limited efficacy of standard melanoma therapies has fueled growing interest in new/adjunctive therapeutic strategies, including those utilizing plant-derived compounds. Therefore, the aim of this study was to analyze the effect of the phytocannabinoid - cannabigerol (CBG) on cooperative metabolic pathways related to redox balance/inflammation/apoptotic signaling in melanoma cells (SK-MEL-5, A375, SK-MEL-1) characterized by diverse phenotypes following exposure to UVA radiation. Especially after UVA exposure, CBG reduces ROS levels and oxidative stress, as indicated by the lipid peroxidation product 4-HNE particularly in SK-MEL-5 cells. By modifying the levels of activators [p21, p62, KAP1, p38] and inhibitors of the transcription factor Nrf2 [Keap1, Bach1, PGAM5], CBG modulates the biosynthesis of antioxidants, including heme oxygenase [HO-1]. This is accompanied by inhibition of inflammation on the NF-κB-TNFα axis (most pronounced in A375/SK-MEL-1), resulting from reduced levels of NF-κB activators [NLRP3, PGAM5, p62]. This occurs alongside with the changes in PUFA metabolism, including CBG/UVA-increased levels of PGD2 (SK-MEL-5/SK-MEL-1) as well as PGE2 (A375). Moreover, increased proapoptotic signaling (SK-MEL-1) was clearly observed, with increased expression of caspase-3 (UVA) and caspase-8 (CBG or UVA). Thus, CBG does not explicitly promote apoptosis but influences it by regulating oxidative and inflammatory processes in a cell-type-dependent manner.