The role of exportin 6 in cytoskeletal-mediated cell death and cell adhesion in human non-small-cell lung carcinoma cells following doxorubicin treatment

Abstract

Abstract:The actin cytoskeleton plays an important role in various cellular processes. The different forms of actin (G-actin and F-actin) participate in the organization of nuclear structure and its functions. The structure of the actin cytoskeleton is controlled by proteins involved in the translocation of actin between cytoplasm and the nucleus. In this study, we used siRNA method to investigate the role of exportin 6 in the switching between nuclear and cytoplasmic F-actin pools in H1299 cells treated with no, 1.0 or 2.5 µM doxorubicin. We showed that silencing of exportin 6 expression changed the response of H1299 to doxorubicin. Here, we observed increased population of cells affected by doxorubicin-induced necrotic cell death. Furthermore, fluorescence studies showed that downregulation of exportin 6 exerted profound DOX-induced changes in the F-actin cytoskeleton architecture. The F-actin cytoskeleton was seen in the form of small fibers or aggregates after doxorubicin treatment. Additionally, some cells lost cell adhesion properties. Downregulation of exportin 6 influenced also transcriptional activity of the cells. In cells transfected with nontargeting siRNA, we observed a higher level of 5'-fluorouridine fluorescence than in cells with silenced exportin 6 expression. In conclusion, we showed that downregulation of exportin 6 induced necrotic cell death. Moreover, the observed alterations of cell adhesion suggest the key role of cytoplasmic F-actin in maintaining intercellular junctional complexes and/or focal adhesion properties and the importance of the balance between nuclear and cytoplasmic F-actin pools.

Overexpression of lamin B1 induces mitotic catastrophe in colon cancer LoVo cells and is associated with worse clinical outcomes

“…In enlarged multinucleated cells expanded F-actin cytoskeleton was located mainly in the form of small granules and/or short fibers within the cytoplasm or in the cortical region of cells. A well-developed actin cytoskeleton in cells with the phenotype of mitotic catastrophe was also observed in other studies ( 54 – 56 ). In apoptotic cells, actin filaments are located in the whole cytoplasm and accumulated near the plasma membrane.…”

Key role of exportin 6 in exosome-mediated viral transmission from insect vectors to plants

“…Although we did not determine the accurate cleavage site of the C fragment of exportin 6, fragmented exportin 6 did not contain the two conserved domains of the IBN_N and Xpo1 superfamilies and seemed to be the predominant form in the small brown planthopper. Homologs of exportin 6 in humans ( 30 ), Xenopus oocytes ( 31 ), and Drosophila ( 32 ) have a full protein length of over 100 kDa. Interestingly, a 72-kDa protein recognized by the Drosophila exportin 6 antibody was previously revealed as an untargeted protein due to the cross-reaction ( 32 ).…”

Downregulation of FHOD1 Inhibits Metastatic Potential in A549 Cells

“…Grzanka et al have shown that changes in the expression level of ABPs: cofilin-1 and a special AT-rich sequence disturbance of F-actin transport to the nucleus sensitizes cells of the H1299 cell line to the cytotoxic effect of doxorubicin. 50 The association of FHOD1 with nuclear actin may indirectly explain the increase in apoptosis. The above-mentioned studies, together with our results, show that FHOD1 is a therapeutically interesting protein in the context of metastasis inhibition and cell death.…”