High glucose suppresses ABCG1 expression by increasing oxidative stress and inducing nuclear factor-kappaB activation in vascular smooth muscle cells

OBJECTIVE: To investigate the role of high glucose in the expression of ATP-binding cassette (ABC) transporters A1 (ABCA1) and G1 (ABCG1) in human vascular smooth muscle cells (VSMCs) and its possible mechanisms. METHODS: VSMCs were incubated in the presence of glucose at the concentrations ranging from 5 to 30 mmol/L for 1 to 7 days, and real-time PCR and Western blotting were used to measure the mRNA and protein expressions of ABCA1 and ABCG1. The effects of cells pretreatment with antioxidant NAC (10 mmol/L) and nuclear factor-kappaB (NF-kappaB) inhibitors BAY 11-7085 (10 micromol/L) and TPCK (10 micromol/L) were also tested on ABCA1 and ABCG1 expressions. RESULTS: High glucose suppressed, in a time- and dose-dependent manner, ABCG1 expression in incubated human VSMCs, and this effect was abolished by pretreatment with the antioxidant and nuclear factor-kappaB (NF-kappaB) inhibitors, but ABCA1 expression was not significantly decreased in the presence of high glucose. CONCLUSION: High glucose suppresses ABCG1 expression in human VSMCs possibly due to increased oxidative stress and NF-kappaB activation induced by high glucose.