Features of senescence and cell death induced by doxorubicin in A549 cells: organization and level of selected cytoskeletal proteins

Senescence and cell death are fail-safe mechanisms protecting against tumorigenesis. Both these forms of cellular response could be induced in cancer cells, thus suppressing tumor progression. Therefore, to fully understand chemotherapeutic effects, not only symptoms of cell death, but also of senescence should be evaluated. Since the involvement of cytoskeleton components in these processes has been reported, changes in the organization and level of some cytoskeletal proteins may be indicative of cell fate. We analyzed selected markers of senescence and cell death, including possible alterations in vimentin and G-actin cytoskeleton in A549 cells after treatment with doxorubicin. Light (SA-beta-galactosidase), fluorescent (vimentin and G-actin labeling) and electron microscopic examinations along with flow cytometry methods (TUNEL, Annexin V/PI staining, cell cycle analysis, intracellular level of vimentin) were employed to determine the outcome of the treatment. Uncoupling between senescent cell morphology and stable cell cycle arrest occurred. Some differences in the organization and level of cytoskeletal proteins, especially of vimentin, like fluctuations in its level, were observed. On the other hand, G-actin seemed to be more stable than vimentin. G-actin stability may imply its potential usefulness for permanent senescence detection. Along with slight to moderate cytoskeletal alterations, the obtained results suggest transient senescence-like state induction, followed by morphology typical of mitotic catastrophe in part of the A549 cells.