Gelsolin is a potential cellular target for cotinine to regulate the migration and apoptosis of A549 and T24 cancer cells.

In the present work, we have investigated the effect of cotinine, the major metabolite of nicotine on the A549 and T24 cell lines in the context of structural and quantitative changes of F-actin, gelsolin and vimentin. The chosen cell lines constitute the established experimental models for lung and bladder cancers, respectively, in the case of which, smoking cigarettes is one of the key factor increasing their incidence rate significantly. In order to evaluate the impact of cotinine on the viability and proliferation of A549 and T24 cells, the MTT assay was performed. The organization and distribution of F-actin, gelsolin and vimentin were examined using conventional and confocal fluorescence microscopy. The levels of F-actin and gelsolin as well as the percentages of apoptotic and dead cells were assessed using the image-based cytometer. The ultrastructural changes of cotinine-treated A549 and T24 cells were visualized under the transmission electron microscopy. We have shown here that cotinine enhances the survival and proliferation rate of A549 and T24 cells. We have also found that in A549 cells, but not in T24 cell line, cotinine acted stimulating on the vimentin filament network. Furthermore, the increase in the fluorescence intensity of gelsolin upon the addition of cotinine to the T24 cells was found to be correlated with the lack of apoptosis induction as well as the increase of migration potential of these cells. On the other hand, the cotinine-induced decrease in the fluorescence intensity of gelsolin was associated with the increase in the percentages of apoptotic A549 cells and the decreased migratory ability of these cells. Based on the obtained results, we propose that the gelsolin is an important cellular target for cotinine, through which this compound influences on the basic processes involved in neoplastic transformation and metastasis, such as migration and apoptosis.