The use of toxicogenomics to identify biomarkers of exposure in an airway epithelium model exposed to tobacco smoke components

A novel toxicological tool, which consists of a differentiated, 3-D, in vitro model of human respiratory epithelia, i.e. EpiAirway-100 cells (MatTek Corp., USA), was utilized to examine the early gene response(s) following exposure to tobacco smoke components (TSC). EpiAirway-100 cells were exposed at the air/liquid interface to representative particle (nicotine [thrombogenic]; cadmium [cytotoxic]) and vapour phase (formaldehyde and urethane [xenobiotic metabolism]) components of cigarette smoke. Toxicogenomics was carried out to identify early molecular markers for events in pulmonary injury. It was necessary to optimize the dose and exposure time since the objective was to identify biomarkers involved with toxicant stress rather than studying dead or dying cells using conventional toxicology. Microarray technology (SuperArray) was employed to compare patterns of mRNA expression of human genes associated with toxicology and drug resistance, simultaneously, from control and TSC-treated respiratory epithelia (n=5 per dose). Using gene array software and stringent statistical analyses, a candidate gene list was generated. The resultant gene lists were sub-classified into functional groups (e.g. Apoptosis, Cell Cycle and Cell Growth, Proliferation and Differentiation), to facilitate the investigations into the mechanisms/biological endpoints for individual TSC, i.e. intelligent biomarkers