  The syndecans represent an ongoing research field focused on their regulatory
roles in normal and pathological conditions. Syndecan's role in cancer
progression becomes well-documented, implicating their importance in diagnosis
and even proposing various cancer potential treatments. Thus, the
characterization of the unbinding properties at the single molecules level will
appeal to their use as targets for therapeutics. In our study, syndecan-1 and
syndecan-4 were measured during the interaction with the vitronectin HEP II
binding site. Our findings show that syndecans are calcium ion-dependent
molecules that reveal distinct, unbinding properties indicating the alterations
in heparin sulfate chain structure, possibly in the chain sequence or sulfation
pattern. In that way, we suppose that HS chain affinity to ECM proteins may
govern cancer invasion by altering syndecan ability to interact with
cancer-related receptors present in the tumor microenvironment, thereby
promoting the activation of various signaling cascades regulating tumor cell
behavior.
