| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
Lipid raft and cytoskeletal proteins undergo remodeling during epithelial mesenchymal transition (EMT) in breast cancer cells and previously we reported that ecto-5'-nucleotidase (eN, CD73), a glycosylphosphatidylinositol anchor protein, was induced in biologically aggressive breast cancer cells. In the present study, we investigated the association between eN and vimentin, a representative EMT marker. When MDA-MB-231 cells were treated for 20 min with ConA, a specific ligand for eN, eN was partitioned into the cytoplasm and co-localized with other membrane proteins including vimentin, src and integrin β1 proteins. As this transference of eN in the cytoplasm has not been observed in vimentin-negative MDA-MB-468 cells, vimentin expressing subclone of these cells could showed the cytoplasmic partitioning, indicating that vimentin intermediate filaments were important for the moving-in eN into cytoplasm. We have compared the mRNA profiles by DNA microarray analysis, and found that mRNA profiles in MDA-MB-468 cells were distinct from those of aggressive MDA-MB-231 cells, suggesting that transfection of vimentin cDNA into MDA-MB-468 cells did not significantly changed the mRNA expression profile toward more aggressive phenotype. Furthermore, treatment with ConA promoted the tyrosine phosphorylation of vimentin as well as eN in MDA-MB-231. The tyrosine-phosphorylation of vimentin was dramatically reduced in dominant negative transfectant of src cDNA. However, phosphorylation of vimentin was independent of eN level because eN antisense transfected MDA-MB-231 clone did not affect the vimentin expression level. We conclude that although eN and vimentin may have arisen independently in aggressive breast cancer cells, however, there seem to be common functional associations in regard to src tyrosine kinase function in cancer cells.
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