Abstract
The ATP-binding cassette, subfamily G, member 2 (ABCG2) transporter, or breast cancer resistance protein (BCRP), plays a crucial role in the absorption and distribution of various compounds, including anti-seizure medications (ASMs). ABCG2 genetic polymorphisms have been shown to affect the pharmacokinetics of several drugs, including anti-cancer drugs and statins. Clinical studies suggested an association between the ABCG2 variations and ASMs pharmacokinetics. Thus, the aim of the present study was to evaluate the effect of the coding ABCG2 variants, 742T > G and 886G > C on the ABCG2-mediated transport of ASMs, carbamazepine and N-desmethyl clobazam by employing cell-based bidirectional transport experiments. Human cerebral microvascular endothelial cells (hCMEC/D3) were transfected with ABCG2, carrying either the wild-type allele (742T, 886G) or its mutated counterparts (742G or 886 C). The cells overexpressing ABCG2 variants exhibited significant reduction in mRNA and protein expression levels compared to those with wild-type protein (742T, 886G). This suggests that ABCG2 variants lead to a downregulation in ABCG2 expression. ABCG2 wild-type protein (742T, 886G) actively transported DCLB, with an efflux ratio > 2 that significantly decreased upon addition of ABCG2-specific inhibitor Ko143, confirming its role in DCLB transport. In contrast, CBZ showed an efflux ratio < 1.5 with no notable reduction upon ABCG2 inhibition. ABCG2 742T > G or 886G > C variants markedly reduced the efflux ratio of DCLB to 1, compared to wild-type protein. In contrast, these variants did not affect CBZ transport. These findings indicate that the ABCG2 genetic polymorphisms studied may account for variability in individual ASM responses, supporting more personalized therapy for epilepsy patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10616-026-00909-9.