Cytoskeletal changes in cultured human fibroblasts following exposure to 2,5-hexanedione

In the present study, the effects of the 2,5-hexanedione (HD) on the various cytoskeletal components of human eukaryotic cells were investigated. Primary cultures of human fibroblasts from three healthy donors were exposed to 2.8 nM HD for 14 days; unexposed cultures were used as controls. At different time intervals, cells were counted and the growth curves compared. After 14 days of treatment, the cultures were processed for immunoblotting, immunocytochemistry and ultrastructural studies. As compared to controls, morphological abnormalities induced by HD consisted of modification of the cell shape, formation of tangles composed by 10 nm filaments and cytoplasmic segregation of microtubules and membrane-bound organelles. By immunocytochemistry, the tangles of cytoplasmic filaments were stained by an antibody specific for vimentin. By immunoblotting, the anti-vimentin antibody recognized only bands of 50-60 kDa. Comparison of growth curves between treated and control fibroblasts clearly revealed an interference of HD with the cell cycle. The present results demonstrate that the cytotoxicity of HD is not restricted to intermediate filaments, but affects other cytoskeletal components, such as microtubules, as suggested by the impairment of cell division cycle.