Cigarette smoke induces senescence in alveolar epithelial cells

T Tsuji, K Aoshiba, A Nagai - American journal of respiratory cell …, 2004 - atsjournals.org
T Tsuji, K Aoshiba, A Nagai
American journal of respiratory cell and molecular biology, 2004atsjournals.org
Cellular senescence is a state of irreversible growth arrest induced either by telomere
shortening (replicative senescence) or by telomere-independent signals (stress-induced
senescence). The alveolar epithelium is often injured by a variety of inhaled toxins, including
cigarette smoke (CS). In the present study, we investigated whether exposure to CS induces
senescence of alveolar epithelial cells. In vitro experiments showed that exposure of A549
cells or normal human alveolar epithelial cells to sublethal concentrations of aqueous CS …
Cellular senescence is a state of irreversible growth arrest induced either by telomere shortening (replicative senescence) or by telomere-independent signals (stress-induced senescence). The alveolar epithelium is often injured by a variety of inhaled toxins, including cigarette smoke (CS). In the present study, we investigated whether exposure to CS induces senescence of alveolar epithelial cells. In vitro experiments showed that exposure of A549 cells or normal human alveolar epithelial cells to sublethal concentrations of aqueous CS extracts induced cellular senescence. The senescence was characterized by a dose- and time-dependent increase in senescence-associated β-galactosidase activity, senescence-associated changes in cell morphology, an increase in cell size and lysosomal mass, accumulation of lipofuscin, overexpression of p21CIP1/WAF1/Sdi1 protein, and irreversible growth arrest. In vivo experiments in Institute for Cancer Research mice showed that inhalation of CS for 2 wk induced increases in senescence-associated β-galactosidase activity, lipofuscin accumulation, and p21CIP1/WAF1/Sdi1 protein expression in alveolar epithelial cells. These results suggest that CS induces a phenotype that is indistinguishable from that of senescence in alveolar epithelial cells. The induction of cellular senescence by CS may contribute to impaired re-epithelialization, leading to CS-related chronic lung diseases.
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