Cannabidivarin and cannabigerol induce unfolded protein response and angiogenesis dysregulation in placental trophoblast HTR-8/SVneo cells.

Cannabidivarin (CBDV) and cannabigerol (CBG) are minor phytocannabinoids from Cannabis sativa, whose health benefits have been reported. However, studies about the impact of these cannabinoids on fundamental cellular processes in placentation are scarce. Placental development involves physiological endoplasmic reticulum (ER) stress, however when exacerbated it can lead to altered angiogenesis and pregnancy disorders, such as intrauterine growth restriction and preeclampsia. In this work, the effects of CBDV and CBG (1-10 µM) on placental extravillous trophoblasts were studied, using the in vitro model HTR-8/SVneo cells. Both cannabinoids induced anti-proliferative effects and reactive oxygen/nitrogen species generation, which was dependent on transient receptor potential vanilloid 1 (TRPV1) activation. Moreover, CBDV and CBG significantly upregulated, in a TRPV-1 dependent manner, the gene expression of HSPA5/Glucose-regulated protein 78 (GRP78/BiP), a critical chaperone involved in ER stress and unfolded protein response (UPR) activation. Nevertheless, the UPR pathways were differentially activated. Both cannabinoids were able to recruit the IRE branch, while only CBDV enhanced the expression of downstream effectors of the PERK pathway, namely p-eIF2α, ATF4 and CHOP. It also augmented the activity of the apoptotic initiator caspases-8 and -9, though the effector caspases-3/-7 were not activated. TRB3 expression was increased by CBDV, which may hinder apoptosis termination. Moreover, both compounds upregulated the mRNA levels of the angiogenic factors VEGFA, PGF and sFLT1, and disrupted the endothelial-like behavior of HTR-8/SVneo cells, by reducing tube formation. Thus, CBDV and CBG treatment interferes with EVTs functions and may have a negative impact in placentation and in pregnancy outcome.