| Metastasis suppressor encoded by Metastasis suppresor gene(Msgs)is a class of proteins which play a negative regulating role in the process of tumor metastasis.Its function is to inhibit the metastasis of tumor cells in vivo,but it does not affect the formation and growth of primary tumor.In order to distinguish tumor metastasis suppressor gene from tumor suppressor gene,it is defined as tumor metastasis suppressor gene.Since the discovery of the first tumor migration suppressor gene,NM23,in 1988,More than 30 tumor metastasis suppressor genes have been identified.Different metastasis inhibitors can block the metastasis process in different sites of the metastasis process.Some metastasis suppressor genes can promote homologous cells adhesion.Some metastasis suppressor can inhibit the degradation of extracellular matrix molecules and the migration and invasion of tumor cells.Some metastasis suppressors regulate the survival and growth of tumor cells in the blood or secondary sites,inhibiting the formation of metastatic tumors.The functions of metastasis suppressor often cross each other.Some metastasis suppressor can block tumor metastasis at multi sites.The expression of metastasis suppressor gene often is down regulated or not expressed in metastatic tumor cells.To restore its expression or function can inhibit tumor cell migration in vitro and in vivo metastasis.Therefore,relevant the study of tumor metastasis inhibitory factor is a popular topic in the research field of tumor metastasis,The research focus have shift from the research on biological function and mechanism to design therapeutic strategies targeting metastasis suppressor and development of anti metastasis drugs targeting metastasis suppressor.Restoring the function of tumor metastasis suppressor for inhibiting tumor invasion and metastasis will open up a new way for clinical control of tumor metastasis.Sevrel strategies have been used to restore the function of metastasis suppressor genes.These strategies can be divided into three categories: inducing reexpression of endogenous genes,transfection of foreign genes through liposome or virus-mediated gene therapy,and direct application of recombinant protein products encoded by tumor metastasis suppressor genes and downstream pathways of targeted metastasis suppressor genes.However,so far,due to various reasons,such as technical limitations,poor efficacy,or interference with normal physiology,the therapeutic strategy of targeting tumor metastasis suppressor gene to control tumor metastasis is still in its infancy and still faces many challenges.Among the tumor metastasis suppressors,KAI1(Kang Ai 1)/ CD82 is one of the most detailed tumor metastasis suppressor.KAI 1 / CD82 is widely expressed in nomal tissues.Expression of KAI 1 / CD82 is often down-regulated or absent in tumor tissue.Unlike most other tumor metastasis suppressor,KAI 1 / CD82 can block tumor metastasis at multiple stages of metastasis cascade.KAI 1 / CD82 promote homotypic adhesion of tumor cells,inhibiting tumor cell detaching from primary tumor.KAI 1 / CD82 inhibited the degradation of extracellular matrix molecules,and inhibited the cell-extracellular matrix adhesion.KAI 1 / CD82 is a member of the family of four transmembrane proteins,consisting of four transmembrane domains,two extracellular rings,EC1 and EC2,and one intracellular ring.At present,the corresponding functions of each of the domain KAI 1 / CD82 are basically clear,but the function of small extracellular ring domain(EC1)is not well studied.Since the EC1 domain has been present in all members of the four transmembrane protein family for a long time in biological evolution,it must have an important function.To test our suppose,we synthesized the amino acid sequence mimic peptide of CD82 EC1structure(CD82-EC1-m P),and found that CD82-EC1-m P can inhibit the migration of tumor cells in vitro.In this study,we further studied the effect of CD82-EC1-m P on the metastasis behavior of tumor cells.At the same time,the anti-metastasis effect of CD 82-EC1-m P in vivo was observed.1.In vitro study,the effects of CD82-EC1-m P on aggration,adhesion,migration and of tumor cells were observed by scratch method and transwell method.Results:(1)CD82-EC1-m P promoted adhesion and aggregation of tumor cells.(2)CD82-EC1-m P inhibits the adherent of tumor cells to tissue culture plate.(3)CD82-EC1-m P inhibits the migration of tumor cellsConclusion: The inhibition of tumor cell migration in vitro by CD82-EC1-m P may be one of the main mechanisms of inhibition of tumor metastasis.2.The mechanism of CD82-EC1-m P inhibiting cell migration was studied by Western blotting and cell immunofluorescence chemistry.Results:(1)CD82-EC1-m P inhibited the expression of Vimentin,promoted the phosphorylation of Vimentin,and promoted the distribution of phosphorylated Vimentin to the cell surface.(2)CD82-EC1-m P promotes the expression of E-Cadherin.(3)CD82 EC1-m P inhibited the distribution of β-Catenin in the nucleus and promoted the distribution of β-Catenin in the cell membrane.(4)CD82-EC1-m P inhibited GSK3β phosphorylation,activated GSK3β and promoted β-Catenin phosphorylation.Conclusion: CD82-EC1-m P down-regulates Wnt signaling pathway,inhibits GSK3 β phosphorylation,activates GSK3β-catenin phosphorylation degradation,reduces β-Catenin from cytoplasm to nucleus,thus inhibits the expression of Vimentin.CD82 promotes β-Catenin distribution to cell membrane and enhances the formation of E-cadherin complex.3.The models of syngeneic mice and nude mice were established by tail vein injection,and the effect of CD82-EC1-m P on tumor metastasis in vivo was observed.Results:(1)CD82-EC1-m P inhibited lung metastasis of LLC cells in ICR mice.(2)CD82-EC1-m P inhibited lung metastasis of human lung cancer cell line H1299 in nude mice.(3)CD82-EC1-m P inhibited lung metastasis of human brest cancer cell line MDA-MB-231 in nude mice.(4)CD82-EC1-m P inhibited lung metastasis of human colon cancer cell line SW620 in nude mice.Conclusion: CD82-EC1-m P inhibited metastasis of different type tumor cells in VIVO. |
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