Heparan sulfate (HS) enhanced the growth of the highly metastatic (HM) 3LL cell line, but not that of the low metastatic (LM) counterpart, in a dose-dependent way. Heparin, chondroitin sulfate, hyaluronate did not produce this effect. At 4 degrees C both cell lines exhibited high affinity binding sites (Kd 10(-8) M) for exogenous HS. Unlike LM cells, the HM ones lost half of the surface-bound HS during the 24-hour incubation at 37 degrees C. HM cells in the exponential growth phase took up the bound HS at lower rate than the LM counterparts. Both cell lines fragmented the exogenous HS intracellularly, but only the HM cells were able to degrade it at the cell surface. The HM cells contained much more heparin-binding proteins--especially in the cell membrane and nuclear fraction--than the LM ones. These results clearly demonstrate that the interactions of tumor cells with exogenous HS are influenced by the invasive phenotype. We suggest also that there could be a correlation between the surface degradation, the slow uptake and the growth-promoting effect of the exogenous HS.