STUDIES ON THE INTERACTION BETWEEN HYALURONAN AND A RAT COLON-CANCER CELL-LINE

Binding studies with I-125-Tyr labelled hyaluronan (HA) on a cultured rat colon cancer cell line were performed to characterize the associat ion of HA to tumour cells in vitro. Results show a specific and satura ble binding (K-d = 1.36 nM) which indicates the presence of an HA bind ing receptor on the tumour cells. There is a specific constant increas e of cell-associated HA over time, which indicates that HA is specific ally taken up by the cells through endocytosis. The binding of I-125-T yr labelled HA was more effectively inhibited by unlabelled HA of high MW in relation to low MW species of the polysaccharide indicating tha t the receptor binds HA of high MW with greater affinity than low MW s pecies. In competition experiments, the HA-binding could not be inhibi ted by other polysaccharides such as chondroitin sulphate and heparin. Nor could ligands for scavenger receptors and antibodies directed tow ards ICAM-1, CD 44 and RHAMM (Receptor for HA Mediated Motility) signi ficantly inhibit the association of HA to tumour cells.