Project description:Cigarette smoking remains the leading cause of non-small cell lung carcinoma. Studies involving acute exposure of smoke on lung cells revealed induction of pre- cancerous state in lung cells. Recently few studies have reported the chronic effect of cigarette smoke in inducing cellular transformation. Yet no systemic study has been performed to understand the molecular alterations in lung cells due to cigarette smoke. Hence it is both important and necessary to study the chronic effect of cigarette smoke in a temporal setting to understand the molecular alterations. In this study, we carried out TMT based proteomic profiling of lung cells which were exposed to cigarette smoke condensate (CSC) for upto 12 months. We identified 2621 proteins in total, of which 145, 114, 87, 169 and 671 proteins were differentially expressed (p<0.05, 1.5 fold) in 2nd, 4th, 6th, 8th and 12th month respectively. Pathway analysis revealed enrichment of xenobiotic metabolism signaling for the first 8 months of smoke treatment, where as continued exposure of smoke for 12 months revealed mitochondrial reprogramming in cells which includes dysregulation of oxidative phosphorylation machinery leading to enhanced reactive oxygen species and higher expression of enzymes involved in tricarboxylic acid cycle (TCA). In addition, chronic exposure of smoke led to overexpression of enzymes involved in glutamine metabolism, fatty acid degradation and lactate synthesis. This could possibly explain the availability of alternative source of carbon in TCA cycle apart from glycolytic pyruvate. Our data indicates that chronic exposure to cigarette smoke induces mitochondrial metabolic transformation in cells to support growth and survival.
Project description:We have investigated the effects of cigarette smoke exposure in three different strains of mice. DBA/2 and C57Bl/6J are susceptible to smoke and develop different lung changes in response to chronic exposure, while ICR mice are resistant to smoke and do not develop emphysema. The present study was carried out to determine early changes in the gene expression profile of mice exposed to cigarette smoke with either a susceptible or resistant phenotype.
Project description:These studies tested the hypotheses that smoke induces changes in mRNA profiles that are dependent on sex and the health status of the lung, and that the effects of smoke are different after 1 day compared to 5 days of smoke exposure. The ways in which the lungs modulate their response to cigarette smoke after repeated exposures are important for understanding the toxicology of smoke, for developing biomarkers of chronic smoke exposure, and for understanding the therapeutic potential in regulatory signaling pathways that are beneficial or detrimental to lung health. Sex-matched 5-7-week old wildtype (WT) and Scnn1b-overexpressing (BENaC) littermates were exposed to cigarette smoke or sham (room air) exposure. Exposure occurred in a plexiglass chamber attached to a smoke delivery device using an exposure chamber and smoking machine (inExpose Exposure System, SCIREQ, Chandler, AZ). Mice were exposed to mainstream + sidestream smoke from 6 reference cigarettes with filters removed per day (3R4F research cigarettes, University of Kentucky). Each cigarette was puffed for 2 sec every 25 sec, using the standard Federal Trade Commission smoking machine protocol. The sham-exposed control mice were exposed to room air in the exposure chamber for a time equivalent to that needed for active smoke exposure. Mice were exposed to cigarette or sham smoke for 1 day or 5 consecutive days. Samples were harvested 4 hours after the completion of the final smoke exposure. The right lung was used for gene expression analysis.