Gao Y, Ma J. Cytochrome P450 oxidoreductase variant A503V contributes to the increased CYP3A5 activity with tacrolimus
in vitro.
Expert Opin Drug Metab Toxicol 2022;
18:529-535. [PMID:
35946839 DOI:
10.1080/17425255.2022.2112174]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND
Tacrolimus is a calcineurin inhibitor with a strong efficacy in prevention of graft rejection after transplantation. It is well known that cytochrome P450 3A5 (CYP3A5) has a high metabolic capacity for tacrolimus, and mutations in human cytochrome P450 oxidoreductase (POR) cause altered CYP3A5 activity. Recently, clinical studies have revealed that POR*28 contributes enhanced tacrolimus clearance in CYP3A5 expressers. A503V is an amino acid sequence variant encoded by POR*28. In this study, we first evaluated the impact of A503V on CYP3A5 activity with tacrolimus as the substrate in vitro.
RESEARCH DESIGN & METHODS
Wild-type (WT) and A503V POR, with WT CYP3A5 were expressed in recombinant HepG2 cells and reconstituted proteins. Michaelis constant (Km) and maximum velocity (Vmax) of CYP3A5 with tacrolimus as substrates were determined, and catalytic efficiency is expressed as Vmax/Km.
RESULTS
WT and A503V POR both down-regulated the CYP3A5 mRNA expression, and WT POR rather than A503V down-regulated the protein expression of CYP3A5 in recombinant HepG2 cells. Compared with WT POR, A503V increased metabolism of tacrolimus by CYP3A5 in both cellular and protein level.
CONCLUSION
A503V can affect CYP3A5-catalyzed tacrolimus metabolism in vitro, which suggests that A503V has the potential to serve as a biomarker for tacrolimus treatment in transplantation recipients.
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