Cannabidiol modulates classical and non-classical HLA expression in human choriocarcinoma cell line

Cannabidiol (CBD) modulates diverse signaling pathways with potential relevance to tumor immune escape; however, its impact on the regulation of classical and non-classical HLA class I molecules remains incompletely understood. Here, we examined the effects of CBD on HLA expression in JEG-3 choriocarcinoma cells, focusing on cannabinoid-related receptors and intracellular Ca²⁺ signaling. CBD increased the expression of classical HLA class I genes, most notably HLA-C, while reducing HLA-G levels, a non-classical HLA class I molecule associated with local immunosuppressive functions. Receptor profiling revealed constitutive expression of CB1 and CB2, whereas GPR55 and PPARγ expression became detectable only after CBD exposure. Receptor inhibition assays showed that HLA-G downregulation was selectively attenuated by CB1 blockade, with no meaningful contribution from CB2 or GPR55. In contrast, CBD-induced HLA-C upregulation was significantly attenuated by GPR55 and CB2 inhibition, while remaining unaffected by CB1 blockade, suggesting distinct receptor-associated pathways for classical and non-classical HLA regulation. Calcium chelation using BAPTA further demonstrated that HLA-G modulation was highly sensitive to intracellular Ca²⁺ reduction, whereas classical HLA expression required higher BAPTA concentrations to be affected. Altogether, these findings support the possibility that CBD may promote coordinated immunomodulatory effects associated with differential regulation of classical and non-classical HLA molecules through receptor-associated and calcium-sensitive signaling pathways.