Laminin mediates tethering and spreading of colon cancer cells in physiological shear flow

Abstract

Under the physiological shear condition, cultured colon cancer cells bound to laminin (LM), but not to fibronectin or vitronectin. Most of the tethered cells did not roll, but arrested immediately and spread within 10-30 min on LM under the continuous presence of shear flow. The tethering of Colo201 was partially inhibited by monoclonal antibodies (mAbs) to α6 integrin and a combination of mAbs to β1 and β4 integrins, but not by mAb to 67 KD laminin receptor. Some Colo201 cells still tethered at 4°C. This suggests that α6β1 and α6β4 integrins participate in Colo201 tethering on LM, although other non-integrin molecules play roles. In contrast, the spread of Colo201 was effectively inhibited by the mAbs to integrin α2, α6 and β1 chains. The effect of anti-α2 plus anti-α6 mAbs was almost equal to anti-β1, suggesting that Colo201 cells mainly use α2β1 and α6β1 integrins for spreading on LM. When the cells were perfused on subconfluent endothelial cells (HUVEC) cultured on LM, they did not tether on HUVEC but did on coated FM exposed at intercellular gap area. Immunohistochemistry revealed that LM abundantly existed in the cytosol of human portal and hepatic vein endothelial cells. These data suggest that LM can mediate from tethering to spreading of colon cancer cells under the blood flow and plays an essential role in haematogeneous metastasis.