| SHP-2, a cytoplasmic SH2 domain containing protein tyrosine phosphatase is involved in the signaling pathways of a variety of growth factors and cytokines. This phosphatase plays an important role in the signal transduction from the cell surface to the nucleus, and is a critical intracellular regulator in mediating cell proliferation and differentiation. SHP-2 mainly acts on the downstream of the cytokine, antigen, and extracellular matrix. This phosphatase interacts with a variety of R-protein tyrosine kinase by recognizing specially the phosphorylated tyrosine residues of the SH2 domain. SHP-2 might be positively required for signal transduction of the cytokines and growth factors; it also can stimulate differentiation and block proliferation. Previous biochemical evidence has demonstrated that the SHP-2 enzymatic activity is required for its function in signal transduction. Cysteine (Cys) at amino acid residue 459 has been identified as critical for its phosphatase activity. While the replacement of cysteine with serine (Ser) at this site completely abolishes its enzymatic activity, the capacity for this mutant molecule to bind to other signaling intermediates via its SH2 domains remains unaltered. This mutant functions thus as a dominant negative molecule over the endogenous wild type SHP-2. Overexpression of this mutant protein has been shown to break the circulation of the phosphorylation and dyphosphorylation, which improves the ability of the cell adhesion and reduces the ability of the cell migration. E-cadherin is an important cell adhesion molecule and cell signaling transduction molecule, it plays an important role in tissue morphologic formation, embryogeny and development as well as cell fate. Controlling cell migration fulfills E-cadherin as a cell adhesion molecule. Matrix metalloproteinase is a Zn2+-dependented protease system, of which the stroma collagenaseMMP-1 mainly degrades the stroma collagen, namely I ,II, III and VII, X-type collagen, but it can not degrade gelatin and IV-type collagen, MMP-9 (gelatinase B ) can degrade gelatin and basement membrane collagen (IV type collagen), it also can degrade V,VII,X-type collagen , but has no function to stroma collagen. E-cadherin and matrix metalloproteinase-1, 9 also play an important role in the process of the cell migration. But the report about the relationship between SHP-2 and E-cadherin and matrix metalloproteinase-1, 9 has not been found. SHP-2 not only can accelerate the tumor metastasis but also has functions in the development of the early stage of the embryo and the process of the cell growth. It also has correlation with the cell migration and hereditary disease. At first, we screem and establish successfully three breast cancer cell lines, namely, the GFP-MCF-7 breast cancer cell lines; the wild type SHP-2-GFP-MCF-7 breast cancer cell lines; the mutant type SHP-2/(C>S)-GFP-MCF-7 breast cancer cell lines. With some biological experiment method, such as, the cell migration test, the cell adherion experiment, Immunoprecipitation, western blotting, and so on, we analyse the change of the cell formation and the expression of the E-cadherin and matrix metalloproteinase-1, 9 of the three differet cell lines stimulated with IL-1 or without IL-1, thus we can determine whether there is relationship between the process of the cell migration stimulated by the tyrosine phosphatase SHP-2 and the expression of E-cadherin and matrix metalloproteinase-1,9. On the other hand, we analyse the function of the SHP-2 accelerating the tumor metastasis by observating the ability of the three different cell lines to make the tumor grow in the nude mice. The results show that :(1) the three breast cancer cell lines : the GFP-MCF-7 breast cancer cell lines, the wild-type SHP-2-GFP-MCF-7 breast cancer cell lines , the mutant-type SHP-2/ (C>S ) -GFP-MCF-7 breast cancer cell lines were established successfully.(2) Tyrosine phosphorylation of the SHP-2 tyrosine phosphatase in the wild-type SHP-2-GFP-MCF-7 breast cancer cell lines was the highest in the thre... |
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