Integrin betal mediates hepatocellular carcinoma cells chemotaxis to laminin

BACKGROUND: Chemotaxis is an important step durin the invasion of carcinoma cells. And integrins are most im portant receptors mediating interaction between cells an extracellular matrix ( ECM). This study was designed t study integrin betal mediating chemotaxis of hepatocellula carcinoma (HCC) cells to laminin (LN). METHODS: A micropipette technique was adopted to in vestigate the effect of blockade of integrin betal on pseudo pod protrusion of HCC cells in response to LN stimulation Chemotactic pseudopod protrusion of a HCC cell was eva luated using a dual-pipette set-up, in which two pipette filled with LN solution were positioned in close contact wit the same cell, and pseudopod protrusion into each pipett was viewed dynamically and recorded with a tape recorder The lengths of pseudopods were measured and plotte against time to obtain a pseudopod growth curve. The in tegrin betal subunit on the surfaces of HCC cells were ana lyzed by flow cytometry. RESULTS: In dual pipette chemotaxis experiment, whe the two pipettes were filled with LN(50 μg/ml, 200 μg/ml) pseudopods extended from the HCC cell into each of th pipettes nearly symmetrically, ie, with nearly identica maximum pseudopod length and similar pseudopod growth curves. Upon addition of anti-CD29 (20 μg/ml) to one o the pipettes, pseudopod protrusion was blocked nearly completely while protrusion into the opposite pipette be came more evidently, with a larger maximum length. Ex pression of integrin betal was up to 95.78% to cells chosen in the experiment. CONCLUSION: Integrin betal subunit was an importan constituent receptor subunit for mediating chemotactic pseudopod protrusion of HCC cell to LN.

Adhesive properties of hepatoma cells to collagen Ⅳ coated surfaces

Objectives: To quantitatively study the adhesive pro- perties of hepatoma cells to collagen Ⅳ coated artifi- cial basement membrane and to investigate the rele- vance of cell adhesive forces to the concentration of collagen Ⅳ. Methods: Synchronous G1 and S phase cells were a- chieved using thymine-2-desoxyriboside and cochicine sequential blockage method and double thymine-2- desoxyriboside blockage method respectively. The adhesive forces of hepatoma cells were investigated by micropipette aspiration technique. Results: The adhesive forces of hepatoma cells to ar- tificial basement membrane were (107.78±65.44) ×10^(-10)N, (182.60±107.88)×10^(-10)N, (298.91± 144.13)×10^(-10)N when the concentration of the membrane coated by 1, 2, 5μg/ml collagen Ⅳ re- spectively (P<0.001). The adhesive forces of G1 and S phases hepatoma cells to artificial basement membrane were (275.86±232.80)×10^(-10)N and (161.16±120.40)×10^(-10)N respectively when the concentration of the membrane coated by 5μg/ml collagen Ⅳ (P<0.001). Conclusions: The adhesive forces of hepatoma cells to artifical basement membrane in direct proportion to the concentration of collagen Ⅳ suggests that the in- crease of basement membrane might be conducive to the chemotactic motion and adhesiveness of tumor cells. G1 phase cells are more capable of adhering to basement membrane than S phase cells. Hepatoma cells, especially G1 phase cells, may survive in blood circulation, and sequest and adhere in microcircula- tion, and get through basement membrane for re- mote metastasis.