Inhibition by sulfated chitin derivatives of invasion through extracellular matrix and enzymatic degradation by metastatic melanoma cells

We have investigated the effects of sulfated chitin derivatives and heparin on the invasion of B16-BL6 melanoma cells through reconstituted basement membrane Matrigel which contains laminin, type IV collagen, heparin sulfate proteoglycan, and entactin. 6-O-sulfated chitin (S-chitin) and 6-O-sulfated and carboxymethyl chitin (SCM-chitin) significantly inhibited the penetration of tumor cells through Matrigel in parallel with the increased degree of sulfation. However, 6-O- and N-sulfated but partially N-deacetylated chitin derivative (SCM-chitosan) and CM-chitin had no effect. SCM-chitin with a high degree of sulfation (SCM-chitin III), which exhibited fairly low levels of anticoagulant activity, was more effective than intact heparin. SCM-chitin III and heparin were also shown to block the attachment and migration of tumor cells to laminin-coated substrates, which are considered to be involved in tumor invasion. The inhibition of cell attachment and migration by SCM-chitin III and heparin is likely to depend upon their specific binding to laminin molecules (possibly the heparin-binding domain). Degradation of heparan sulfate by heparanase was inhibited by SCM-chitin III and heparin in a dose-dependent manner. Surprisingly, SCM-chitin III could inhibit type IV collagenolytic activity of tumor cells more potently than heparin. Thus, nontoxic SCM-chitin III of low anticoagulant properties may provide a promising basis for the prevention of cancer metastasis.