ABCG2 regulatory single-nucleotide polymorphisms alter in vivo enhancer activity and expression

Area of Science:

• Pharmacogenomics
• Molecular Biology
• Genetics

Background:

• The breast cancer resistance protein (ABCG2) plays a crucial role in the pharmacokinetics of various substrates.
• Understanding the impact of genetic variations on ABCG2 expression is vital for personalized medicine.

Purpose of the Study:

• To systematically investigate the effect of genetic variation on the in vitro and in vivo enhancer activity within the ABCG2 locus.
• To examine the contribution of these variations to ABCG2 expression levels.

Main Methods:

• Assessed enhancer activity using luciferase assays in HepG2 and HEK293T cell lines.
• Evaluated in vivo enhancer activity via hydrodynamic tail vein assays.
• Analyzed single-nucleotide polymorphisms (SNPs) for association with gene expression and altered protein binding using electrophoretic mobility shift assays.

Main Results:

• Identified multiple SNPs affecting ABCG2 enhancer activity in vitro.
• Observed decreased in vivo enhancer activity for four SNPs (rs9999111, rs12508471, ABCG2RE1*2, rs149713212) and increased activity for one (rs2725263).
• Found associations between SNPs rs9999111 and rs12508471 and ABCG2 expression in various cell types, with altered nuclear protein binding.

Conclusions:

• Identified SNPs in ABCG2 regulatory regions that modulate enhancer activity both in vitro and in vivo.
• Demonstrated correlation between specific SNPs, tissue-specific ABCG2 expression, and altered DNA/protein binding.
• These findings suggest a role for identified SNPs in ABCG2 expression variability, potentially impacting disease risk and substrate pharmacokinetics/pharmacodynamics.