A novel AMPK activator, WS070117, improves lipid metabolism discords in hamsters and HepG2 cells

Abstract

Background: WS070117 is a novel small molecule compound that significantly improves lipid metabolism disorders in high-fat-diet (HFD) induced hyperlipidemia in hamsters.

Methods and results: We evaluated liver/body weight ratio, liver histology, serum and hepatic lipid content in HFD-fed hamsters treated with WS070117 for 8 weeks. Comparing with HFD fed hamsters, WS070117 (2 mg/kg per day and above) reduced serum triglyceride (TAG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and hepatic cholesterol and triglyceride contents. Oil Red O staining of liver tissue also showed that WS070117 improved lipid accumulation. We then carried out an experiment in the oleic acid (OLA)-induced steatosis model in HepG2 cell to investigate the lipid-lowering effect of WS070117. Oleic acid (0.25 mM) markedly induced lipid accumulation in HepG2 cells, but WS070117 (10 μM) inhibited cellular lipid accumulation. In OLA-treated HepG2 cells, WS070117 (above 1 μM) treatment reduced lipid contents which synthesized from [1-(14)C] labeled acetic acid. Because WS070117 is an analog of adenosine, we evaluated the effect of WS070117 on AMP-activated protein kinase (AMPK) signaling. The results showed that the activation of AMPK in OLA-induced steatosis in HepG2 cells was up-regulated by treatment with 0.1, 1 and 10 μM WS070117. The hepatic cellular AMPK phosphorylation is also up regulated by WS070117 (6 and 18 mg/kg) treatment in HFD fed hamsters.

Conclusion: These new findings identify WS070117 as a novel molecule that regulates lipid metabolism in the hyperlipidemia hamster model. In vitro and in vivo studies suggested that WS070117 may regulate lipid metabolism through stimulating the activation of AMPK and its downstream pathways.

Figure 1

A novel structure compound, WS070117, activated AMPK in HepG2 cells. A: Structure of WS070117; B: Effect of WS070117 on AMPK activity in HepG2 cells detected by AMPK activity assays with SAMS peptide and [γ-32P]ATP used as substrates. HepG2 cells were treated with WS070117 (10 μM) for 1h, 6h and 12h. C: Effect of 12h treatment of WS070117 (1,10,100 μM) or AICAR (1 mM) on AMPK activity of HepG2 cells. AMPK activities are expressed relative to activity detected in HepG2 cells lysate. Each point is the mean (± SEM) of 3 separate experiments. **P < 0.01, *P < 0.05 as compared with control.

Figure 2

Effects of WS070117 on hepatic lipids accumulation in HFD fed hamsters. A: Representative frozen tissue sections of liver taken from hamsters fed chow diet, HDF diet, HFD+ simvastatin (2 mg/kg) and HFD+WS070117 (18 mg/kg) were stained with Oil Red-O to demonstrate the reduction in lipid droplets. B: Hepatic TC and TAG were measured in liver samples of control (n = 5), HFD, 8-weeks WS070117 (2, 6, 18 mg/kg) or simvastatin (positive control; 2 mg/kg) treated HFD fed hamsters (n = 8). **P < 0.01, *P < 0.05 as compared with HFD model. ^##P < 0.01 as compared with control.

Figure 3

Effects of WS070117 on steatosis and de novo lipids synthesis in OLA-HepG2 cells. A: Oil Red O stain of 0.25 mM OLA-induced cellular lipid accumulation in WS070117 treated HepG2 cells. 12h treatment of WS070117 (10 μM) reduced the lipid droplets amount in HepG2 cells. B: TAG and TC synthesis was measured by the lipid accumulated from [1-¹⁴C] acetic acid, and was measured in control and WS070117 (0.1, 1, 10 μM) 12-h-treated OLA-HepG2 cells. **P < 0.01, *P < 0.05 as compared with OLA or HFD models.

Figure 4

WS070117 treatment increases AMP-activated protein kinase (AMPK) phosphorylation in OLA-induced HepG2 cells and HFD fed hamster livers. Data depict at least 3 experiments. **P < 0.01 as compared with OLA and HFD groups. ^##P < 0.01 as compared with control groups.