Cigarette smoke extract induces a multi-phase cell cycle arrest in normal human lung fibroblasts. Involvement of MAPK pathway

745 Cigarette smoke extract induces a multi-phase cell cycle arrest in normal human lung fibroblasts. Ivolvement of MAPK pathway G. Costanzo, C. D'Anna, D. Cigna, R. Di Giorgi, G. Bonsignore, A. M. Vignola (Palermo, Italy) Cigarette smoke, a potent source of oxidative stress, is the major risk factor for pulmonary diseases such as COPD, emphysema, asthma and lung cancer. To counteract the potential damage induced by oxidative stress, proliferating cells, such as fibroblasts, enter in a transient cell cycle arrest. Furthermore, oxidative stress activate ERK1/2, JNK and p38 which are importantly involved in both stimulation and inhibition cell proliferation. We treated normal human lung fibroblasts (HFL- 1) with cigarette smoke extract (CSE) 10% for 1, 3, 12, 24, 48 and 72 hours. We tested cell cycle and the activation of signal transduction ERK, p38 and JNK by cytofluorimetric and western blot analysies, respectively. CSE (24, 48 and 72 hrs) induced a reversible multi-phase cell cycle arrest at the G1, S, and G2/M phases not coupled with apoptosis, as confirmed by the lack of caspase3 activation. Furthermore, the time course of CSE-stimulated MAPK phosphorylation showed a decline in phosphorylation of p38 MAPK as ERK activation increased. JNK pathway did not appear to be modulated by CSE treatment. These results provide evidences that CSE treatment induces an oxidative stress which leads to a reversible multi-phase cell cycle arrest, likely due to a cross-talk between ERK1/2 and p38