Carbon nanotubes are new members of carbon allotropes with unique physical properties used for novel applications in the electronics, aerospace and computer industries. Previously, we have reported that exposure of BEAS-2B cells to single wall carbon nanotubes (SWCNT) caused ultra-structural and morphological changes, cytotoxicity, apoptosis, and induced oxidative stress as shown by the formation of free radicals, accumulation of peroxidative products, and depletion of antioxidants. In this study, we have investigated the effect of SWCNT on alterations in gene expression. Exponentially growing human bronchial epithelial cells were exposed to 0.06, 0.12 or 0.24 mg/ml of SWCNT for 18 h. Total RNA was used for the preparation of double stranded cDNA. A biotin labeled cRNA transcript was synthesized, fragmented and hybridized to Affymetrix U133A oligonucleotide microarray. The arrays were stained with streptavidin-phycoerythrin and biotinylated anti-streptavidin antibodies. The differential gene expression data analysis was per-formed using Affymetrix microarray suite 5.0 software. The 3'/5' cRNA transcript ratios for both GAPDH and ?-actin were found to be consistent between control and treatment groups over a period of 18 h exposure. Altered gene expression patterns were observed in 187 RNA transcripts with a signal log ratio of at least 0.8 (1.7 fold change). Altered genes include genes involved in metabolism (CYP1B1, aspargine synthetase, NNMT), cell cycle control (p21, CD24, GAS1, PA26) and others (matrix metalloproteinase, ferrodoxin reductase, cathepsin L2). In conformity with our earlier study, it appears that SWCNT alter a variety of genes that include those involved in oxidative stress.
The Toxicologist. Society of Toxicology 43nd Annual Meeting and ToxExpo, March 21-25, 2004, Baltimore, Maryland