SIAH-1 inhibits cell growth by altering the mitotic process

Abstract

SIAH-1, the human homologue of the drosophila seven in absentia gene, is a p53-p21 Waf-1 inducible gene. We report that stable transfection with SIAH-1 of the epithelial breast cancer cell line MCF-7 blocks its growth process. The transfectants show a redistribution of SIAH-1 protein within the nucleus, more speci®cally to the nuclear matrix, associated to dramatic changes in cell morphology and defective mitosis. Multinucleated giant cells (2 ± 12 nuclei in more than 50% cells) were a most striking observation associated with tubulin spindle disorganization and defective cytokinesis. There were also present at high frequency abortive mitotic ®gures, DNA bridges and persistance of intercellular bridges and midbodies, along with an increased expression of p21 Waf-1 . These results indicate that the mechanism of growth arrest induced by SIAH-1 in MCF-7 cells involves disorganization of the mitotic program, mainly during nuclei separation and cytokinesis.

SIAH-1 interacts with α-tubulin and degrades the kinesin Kid by the proteasome pathway during mitosis

“…These alterations included anomalies of the mitotic spindle and abnormal chromosomal segregation associated with failure of cytokinesis, leading to multinucleated giant cells (Bruzzoni-Giovanelli et al, 1999). In these cells, intercellular bridges containing DNA from non-segregated chromosomes were very common, we observed multipolar spindles evidenced by a-tubulin staining and vacuoles appear in the cytoplasm of multinucleated cells (Bruzzoni-Giovanelli et al, 1999) (Figure 5,1,2). Some mitotic alterations were comparable with those described after Polo kinase gene disruption (Glover et al, 1999) or p21 Waf-1 overexpression (Sheikh et al, 1995).…”

“…We recently reported that stable transfection of MCF-7 cells by SIAH-1 induced a speci®c phenotype including multinucleated giant cells and altered spindle formation and cytokinesis (Bruzzoni-Giovanelli et al, 1999). In order to identify the possible molecular mechanisms involved in this phenotype, we searched for SIAH-1 interacting proteins using the yeast two-hybrid system.…”

“…We previously showed, that overexpression of SIAH-1 in the epithelial breast cancer cell line MCF-7 blocked cellular growth by altering the mitotic process mainly during nuclei separation and cytokinesis, leading to multinucleated giant cell formation and tubulin spindle disorganization (Bruzzoni-Giovanelli et al, 1999). In order to elucidate the mechanisms by which SIAH-1 interferes with the mitotic process we searched for SIAH-1-interacting proteins using the yeast two-hybrid genetic approach.…”

siah-1 Protein Is Necessary for High Glucose-induced Glyceraldehyde-3-phosphate Dehydrogenase Nuclear Accumulation and Cell Death in Müller Cells

“…Other functions of siah-1 involve regulation of cell cycle and pro-survival proteins through protein degradation (22,24,49,52). Whether inhibition of high glucose-induced cell death of Müller cells by siah-1 knockdown results from the inhibition of these alternative functions of siah-1 is not known.…”

“…The role of siah-1 in both of these processes, acetylation and phosphorylation of p53, has not been determined and might just be related to transport of GAPDH to the nucleus. On the other hand, a previous study not focused on the interaction between GAPDH and siah-1 has demonstrated a role for siah-1 itself in the process of p53 activation (22). siah-1 and p53 seem to be connected and regulated via a positive feedback mechanism because siah-1 is also regulated by p53 (58).…”