The aim of the present study was to investigate the reorganization of
F-actin,
vimentin and
tubulin in K-562 and HL-60 cell lines during apoptosis induced by
etoposide,
doxorubicin and
taxol. The distribution of
cytoskeletal proteins was analyzed by fluorescence microscopy. Actin was also studied by confocal microscopy and at the ultrastructural level. Changes in the distribution of
cytoskeletal proteins were found to be dose-dependent and appeared to be more intense in HL-60 cells.
Etoposide- and
doxorubicin-treated cells showed similar changes in the distribution of
F-actin,
vimentin and
tubulin. The reorganization of
cytoskeletal proteins seemed to be consistent with features of apoptosis. An increase in bright staining of
F-actin,
vimentin and
tubulin at the site of apoptotic bodies formation was observed. Immunogold labeling of actin in HL-60 cells was associated with features typical for apoptosis, i.e. compaction and margination of nuclear
chromatin. K-562 cells showed cytoplasmic actin-positivity in the cytoplasm. Significant changes in morphology of HL-60 cells were found in the following concentrations:
etoposide 20, 200 microM;
doxorubicin 5, 10 microM and
taxol 2-10 microM. The investigated
proteins seemed to be involved in the above-reported apoptotic changes. Bright staining of
F-actin,
vimentin and
tubulin, concentrated at the site of apoptotic bodies formation might suggested importance of these
proteins for this process. Moreover, the increase in actin labeling in areas of
chromatin compaction and margination of nuclear
chromatin especially in HL-60 cells, which are more susceptible to apoptosis might implicate that actin might be involved in the chromatin remodeling during apoptosis.