Cytoplasmic p21CIP1/WAF1, ERK1/2 activation, and cytoskeletal remodeling are associated with the senescence-like phenotype after airborne particulate matter (PM10) exposure in lung cells

Abstract

The exposure to particulate matter with a mean aerodynamic diameter ≤10μm (PM10) from urban zones is considered to be a risk factor in the development of cancer. The aim of this work was to determine if PM10 exposure induces factors related to the acquisition of a neoplastic phenotype, such as cytoskeletal remodeling, changes in the subcellular localization of p21CIP1/WAF1, an increase in β-galactosidase activity and changes in cell cycle. To test our hypothesis, PM10 from an industrial zone (IZ) and a commercial zone (CZ) were collected, and human adenocarcinoma lung cell cultures (A549) were exposed to a sublethal PM10 concentration (10μg/cm2) for 24h and 48h. The results showed that PM10 exposure induced an increase in F-actin stress fibers and caused the cytoplasmic stabilization of p21CIP1/WAF1 via phosphorylation at Thr145 and Ser146 and the phosphorylation of ERK1/2 on Thr202. Changes in the cell cycle or apoptosis were not observed, but an increase in β-galactosidase activity was detected. The PM10 from CZ caused more dramatic effects in lung cells. We conclude that PM10 exposure induced cytoplasmic p21CIP1/WAF1 retention, ERK1/2 activation, cytoskeleton remodeling and the acquisition of a senescence-like phenotype in lung cells. These alterations could have mechanistic implications regarding the carcinogenic potential of PM10.