Nornicotine and Nicotine Induced Neovascularization via Increased VEGF/PEDF Ratio

The purpose of the current study was to evaluate the influences of nornicotine and nicotine (NT) in cigarette smoke on the expression of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) in retinal pigment epithelium cells and human umbilical vein endothelial cells (HUVECs). Furthermore, the angiogenic behaviors of endothelial cells under nornicotine and NT treatment were assessed by using in vitro methods.

ARPE-19 cells and HUVECs were treated with different concentrations of either nornicotine or NT for different periods of time. The cell proliferative effect was investigated by using the method of MTT analysis. HUVEC migration and tube formation were assessed by using the scratch assay and Matrigel models. The expressions of VEGF and PEDF gene and protein in both types of cells were examined by real-time RT-PCR and Western blot.

There was no proliferation of ARPE-19 cells following treatment with various concentrations of nornicotine or NT. In contrast, nornicotine or NT significantly stimulated HUVEC proliferation, migration and tube formation. Nornicotine and NT upregulated the expression of VEGF but suppressed the expression of PEDF at both mRNA and protein levels in a dose- and time-dependent manner in ARPE-19 cells and HUVECs.

Our results demonstrate that nornicotine and NT promoted endothelial cellular proliferation, migration and tube formation of HUVECs in vitro. These effects might be partly due to simultaneous modulation of VEGF/PEDF signaling in ARPE-19 cells and HUVECs.