To explore the possibility of identifying potential biomarkers for the effects of cigarette smoke (CS) exposure and the individual variation of response, we used Affymetrix HG-U133A GeneChips to measure the global gene expression in cultured lymphocytes from eight subjects exposed to cigarette smoke condensate(CSC) in vitro and in uncultured lymphocytes from 36 current healthy smokers (in vivo). The exposure of phytohemagglutinin-stimulated lymphocytes to CSC for 18 h in vitro significantly changed expression levels of 2,266 genes. Of the significantly elevated expressions, genes encoding for xenobiotic functions were most notable, which were transcriptionally upregulated through Nrf2 signaling pathway. Among the most decreased expression, the cytokine and chemokine genes tended to be affected. Some of the altered gene had been reported in other microarray studies of human lymphocytes, such as ATF3, SERPIN2. Importantly, dozens of genes had also previously reported in the literature about effects of cigarette smoke on airway epithelial cells, which implied that as with targets tissues, the blood lymphocytes could be used as surrogate tissue cells. Gene Ontology and biological pathway analyses revealed that all regulated genes were mainly involved in oxidative stress-response, inflammation and immune response, apoptosis and cell cycle. Although there were no outliers for overall gene expression patterns, subject variability existed in some individual genes. When we studied the transcriptomes of uncultured lymphocytes from smokers, only 311 gene loci demonstrated a significant difference in mRNA expression between heavy and light smokers. All except three genes were upregulated in heavy smokers and 87 gene expression levels had a significant linear correlation with cig/day. The immune and inflammation response gene expressions were increased, which are different from the exposure in vitro. Based on these 311 genes, the subjects can be well clustered except that the profiles from four light smokers more resembled that of heavy smokers. More interestingly, 54 out of the 311 genes overlapped with the above 2266 CSC-associated genes and some were immune genes and xenobiotic metabolic genes. Five of them had an absolute fold-change >1.5. They were TGFB1, PPP1R15A (GADD34), G6PD, ARID1A (p270) and ZFP36L2. The data from this study demonstrates that CSC treatment in vitro changes a large set of gene expression pathways and more exposure to CS in vivo also causes a different gene expression signature. Those genes that are CS-responsive both in vitro and in vivo deserve further attention as potentially critical importance in inflammatory and/or carcinogenic pathways and as potential biomarkers for cigarette smoke exposure.
98th AACR Annual Meeting-- Apr 14-18, 2007; Los Angeles, CA