Nicotine and cotinine up-regulate vascular endothelial growth factor expression in endothelial cells

Cigarette smoking is an important risk factor for both vascular disease and various forms of cancer. Vascular endothelial growth factor (VEGF) is an endothelial-specific mitogen that is normally expressed only in low levels in normal arteries but may be involved in the progression of both vascular disease and cancer. Some clinical evidence suggests that cigarette smoking may increase plasma VEGF levels, but there is a lack of basic science studies investigating this possibility. We show here, using an intact porcine common carotid artery perfusion culture model, that nicotine and cotinine, the major product of nicotine metabolism, cause a significant increase in endothelial cell VEGF expression. VEGF mRNA levels were compared between groups using reverse transcriptase-polymerase chain reaction, whereas protein level changes were demonstrated with Western blotting and immunohistochemistry. Our results showed significant increases in endothelial cell VEGF mRNA and protein levels because of nicotine and cotinine at concentrations representative of plasma concentrations seen in habitual smokers. VEGF immunostaining also paralleled these results. These findings may give a clue as to the mechanisms by which nicotine and cotinine from cigarette smoking increase vascular disease progression and tumor growth and metastasis.