Study Of β₁ Integrin's Redistribution And Directional Migration In Hepatoma Cells

Constant cell morphological deformation, unstable adhesion, increased migration rate and frequently changed migration direction are the characteristics of the invasion and metastasis of tumor cells in culture. Integrin is the key proteins involved in the process of tumor cell invasion and metastasis. Therefore in order to better understand the mechanism of tumor cell invasion and metastasis, it is very important to clarify the roles of integrin in the adhesion and migration of tumor cells. According to the principle of basement membrane deformation, we developed a single axis cell stretch device. By indirect immunofluorescent technique and laser scanning confocal microscope to investigate the hepatoma cells'integrins expression level and change of position, and finally, using immunohistochemistry technique to examine the distribution of cytoskeleton(F-actin).Through experimental results and references, we could get details as follow:1) Analysis integrin of distribution in hepatoma cells , the result shows that integrin of distribution increase from top to down. Compared distribution of integrin in different shape cells, we findβ1 integrin expression of a single cell in groups is the strongest, followed by a single spreading cells, a single round is the weakest, but integrin of round cells on free surface is more than it on basement. Integrin was much more concentrated and brighter when it transferred to cellular basal layer and created a large fusion of focal adhesion after 5 hours'exposure to strain. After removing cyclic stretch 1h,β1 integrin distribution is diffusion and integrin increase in free surface.2) After coated with FN, we found Hep G2 cellβ1 integrin significant increase.β1 integrin has the same characteristics in different shape cells, that is to say integrin in basement were more than free surface. There are point-fluorescent areas in the cells'basement. The combinationβ1 integrin and ligand made integrin reorganization, and formed adhesion plaque. The basement surface integrin of the groups cells were greater than the free surface in different states (static control and mechanical stimulation, coated with FN). Integrin distribution of round cells were greatest impacted after coated FN.3) The cyclic stretch which was characterize by 10% elongation at 30 cycles/min could promote hepatoma cells'area, ration of major and minor axis, depress cells'deform factor, and cells'angle perpendicular to strain direction. After removing cyclic stretch 1h, cells'morphological parameter have significant recovery phenomenon.4) The experiment showed that cyclic stretch could promote cytoskeleton rearrangement of hepatoma cells. Under the cyclic mechanical stretch, cytoskeleton would make corresponding adjustment, and perpendicular to strain direction. After removing cyclic stretch 1h, cytoskeleton had significant depolymerization phenomenon. The results suggested that cyclic stretch could be the combination progress of stretch and relaxation. When cells were stretched, cytoskeleton (stress fibers) made corresponding adjustment, the stress fibers of perpendicular to strain direction gained advantage, and finally cells adjusted their orientations.Conclusion:1) Integrin redistribution was the response to adaptation environment, integrin of hepatoma cells diversion to basement surface and assembly of stress fiber have direct correlation.2) The junction of cell-cell have advanced effect for integrin diversion to basement surface.3) Integrin distribution character(diffusion and much in free surface) of single round cells were suited to invasion and metastasis of tumor cells.