Study On The Relationship Of Integrin αVβ3, αVβ5 And β1 Relative Molecules Activation State With Tumor Metastasis

Malignant tumor is one of the main diseases which threat human health seriously. As the features of invasion and metastasis, malignant tumor is very difficult to be charmed away. Nowadays, ninety percent of the sufferers died of tumor metastasis and invasion. Cell adhesion molecules, especially integrin family play important roles in tumorigensis. It has been showed integrin can mediate tumor metastasis and angiogenesis by interacting with extracellular matrix. When integrin is in activation state, the affinity of integrin to its ligands is higher, and this higher affinity helps promote the adhesion and metastasis of tumor cells. Previous works approved that the mutations (Cys5Ala, Cys435Ala, Cys560Arg and Cys583Ala) among integrin β3 made aⅡbβ3 present constitutive activation state without the induction of ligand, and both the abilities of intracellular signaling transduction and the binding of ligand to the mutated integrins were stronger than that in wild type (WT), which provided that disulfide bonds existed between Cys5 and Cys435 or Cys560 and Cys583. Moreover, molecular mechanism of disulfide bonds mediating the conformational regulation and activation of aⅡbβ3 has been clarified. In this study, the expression level and activation state of wild type and mutants of aVβ3 (Cys5Ala, Cys435Ala, Cys560Arg and Cys583Ala) have been detected by flowcytometry, we found aVβ3 present the similar results to aⅡbβ3. At the same time, the expression level of aVβ3-WT was similar to that of aVβ3-Cys560Arg. Furthermore, when CHO cells were injected into SCID mouse, tumor node formed on lung surface and typical tumor focus was detected by histochemistry. Based on the homology analysis of integrin β3, β1 and β5 subunits, we have constructed β1-WT, β1-Cys7Ala, β1-Cys442Ala, β5-WT, β5-Cys5Ala and β5-Cys440Ala expression plasmids compared with the 5th and 435th cysteine of β3. And then we have succeeded in realizing the transient expression of β1-WT, β1-Cys7Ala and β1-Cys442Ala in the COS7 cell line and establishing the CHO stable cell line of aVβ5 WT and mutants which still should be tested by flowcytometry and Western Blot. The results presented in this paper provided a foundation in studying the affect of integrin activation state on tumor metastasis, and preparing the mouse anti-human monoclonal antibodies of integrin ?1, ?3 and ?5 subunits to observe the affect on tumor angiogenesis and metastasis in vitro or in vivo, eventually used in tumor therapy.