| Research Abstract |
Mouse Lewis lung carcinoma-derived low metastatic P29 clone exhibits tumorigenesis dependent on the fibronectin-rich stromal matrix, whereas the growth of highly metastatic LM66-H11 clone depends on the basement membranes. On adhesion to the fibronectin substratum in vitro, P29 cells show stress fiber formation, whereas LM66-H11 cells form cortex action structure. The phenotype of P29 cells is closely correlated to the expression of integrin α5β1 and syndrecan-2 having heparan sulfate side chains with specific affinity to COOH-terminal heparin-binding domain. LM66-H11 cells express the integrin at the same level to that of P29 cells, but syndecan-2 at a significantly lower level. On treatment of P29 cells in vitro with antisense oligonucleotide for syndecan-2, causing selective inhibition of its biosynthesis, the cells turn out to be indistinguishable from LM66-H11 cells as regards the phenotype. The phenotype of P29 cells is reproduced by adhesion to fibronectin recombinant fusion polypeptide (CH-271) comprising RGD cell-binding (C-274) and C-terminal heparin-binding (H271) comprising RGD cell-binding (C-274) and C-terminal heparin-binding (H271) domains whereas the phenotype of LM66-H11 cells in induced only by C-274 polypeptide, indicating that signaling through integrin α5β1 and syndecan-2 is essential for the polypeptide can be replaced by a large amount of H-271 polypeptide, or antibodies specific to syndecan-2 or heparan sulfate. Furthermore, when inoculated on a fusion polypeptide comprising C-274 polypeptide and basic FGF with strong affinity to syndecan-2 ectodomain, even LM66-H11 cells form stress fibers. These findings indicate the necessity of clustering of the two receptors for signaling for the organization of the actin cytoskeletons.
|
