Direct Effects of Pure Nicotine, Cigarette Smoke Extract, Swedish-type Smokeless Tobacco (Snus) Extract and Ethanol on Human Normal Endothelial Cells and Fibroblasts

The adverse health effects of cigarette smoking are well established including the increased risk of various types of cancer. In this study, the direct effects of ethanol, pure nicotine, cigarette smoke extract and Swedish type smokeless tobacco (Snus) extract on normal cells were investigated. Materials and Methods: Primary normal adult human endothelial cells and fibroblasts at early passage were used. Upon exposure to pure nicotine, cigarette smoke extract, Snus extract and ethanol, these cells were assessed for DNA synthesis, gene expression profile and cellular morphology. Results: Normal human fibroblasts and endothelial cells have unique gene expression profiles. The effects of treatment with ethanol and nicotine from different sources was more prominent in endothelial cells than fibroblasts. The combination of alterated gene expressions and strongly inhibited DNA synthesis was only detected in cells exposed to smoke extract. In the presence and absence of ethanol, pure nicotine and Snus extract induced abnormalities in the cytoplasm without any significant degree of cell death. With similar doses of nicotine and ethanol, the additional components in smoke extract had a dominant effect. The smoke extract induced vast cellular abnormalities and massive cell death. Conclusion: Cigarette smoke induced massive cell death and various abnormalities at cellular and molecular levels in surviving endothelial cells and fibroblasts. The combination of genomic alterations and the chronic inflammatory microenvironment induced from massive cell death, will potentially promote tumourigenesis and various diseases in cigarette smokers.