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ABSTRACT 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 mechanisms by which CBD regulates 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 that acts as a local immunosuppressor. Receptor profiling revealed constitutive expression of CB1 and CB2, whereas GPR55 and PPARγ expression became detectable only after CBD exposure. Functional 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 required GPR55 and CB2 activity, while being unaffected by CB1 inhibition, indicating distinct receptor pathways for classical and non-classical HLA regulation. Calcium chelation using BAPTA further demonstrated that HLA-G modulation is highly sensitive to intracellular Ca²⁺ reduction, whereas classical HLA expression required higher BAPTA concentrations to be affected. Altogether, these findings identify CBD as a dual immunomodulatory agent capable of enhancing tumor immune visibility while limiting immunotolerant HLA-G expression through receptor-specific and Ca²⁺-dependent mechanisms.