DNA damage and alterations of gene expression in chronic-degenerative diseases

Chronic-degenerative diseases (CDD) recognise a variety of exogenous and endogenous risk factors interacting with the organism for many years before disease onset. We applied genomic and postgenomic molecular analyses in experimental models characterised by different contribution of exogenous and endogenous CDD risk factors. Exposure of mice to halogen light for 28 days resulted in induction of cyclobutane dimers and oxidative DNA damage in the skin. Evaluation of postgenomic alterations by cDNA arrays revealed upregulation of DNA repair pathways, increased cell division rate and protooncogenes transcription, resulting in skin tumors, 1 year later. Exposure of p53-/+ mutant mice to cigarette smoke (CS) for 28 days induced DNA adducts formation in the lung. Postgenomic alterations included decreased apoptosis and increased cell division, as compared to CS-exposed wild type mice. These phenomena resulted in lung tumors, 9 months later. Transplacental exposure of mouse foetuses to cigarette smoke induced DNA adduct formation in the liver. cDNA arrays analyses demonstrated decreased cell division, apoptosis increase, and tissue hypoxia. These phenomena resulted in growth retardation of the whole organism. Molecular alterations were investigated in human trabecular meshwork, the non-replicating ocular epithelia involved in the pathogenesis of chronic degenerative glaucoma. Results indicate increased oxidative DNA damage in glaucoma patients as compared to unaffected controls. These four experimental studies suggest that DNA damage may result in different CDD (cancer, growth retardation, glaucoma) depending on the replication rate of the target cell population.