👤 Tatsuro Irimura

A chimeric protein of heparanase and Ig-Fc was designed as a novel tool to expand the detection of structurally heterogeneous heparan sulfate (HS) and related glycosaminoglycans. The whole mouse heparanase gene was combined with the gene segment encoding the mouse IgG1 hinge-Fc domain. A point mutation E335A was inserted to disable putative HS degradation activity. Chimeric proteins consisted of the latent form of the enzyme devoid of HS degradation activity. The chimeric proteins bound to heparin, Show less

To explore possible roles of heparanase in cancer-host crosstalk, we examined whether heparanase influences expression of inflammatory chemokines in colorectal cancer cells. Murine colorectal carcinoma cells incubated with heparanase upregulated MCP-1, KC, and RANTES genes and released MCP-1 and KC proteins. Heparanase-dependent production of IL-8 was detected in two human colorectal carcinoma cell lines. Addition of a heparanase inhibitor Heparastatin (SF4) did not influence MCP-1 production, while both latent and mature forms of heparanase augmented MCP-1 release, suggesting that heparanase catalytic activity was dispensable for MCP-1 production. In contrast, addition of heparin to the medium suppressed MCP-1 release in a dose-dependent manner. Similarly, targeted suppression of Ext1 by RNAi significantly suppressed cell surface expression of heparan sulfate and MCP-1 production in colon 26 cells. Taken together, it is concluded that colon 26 cells transduce the heparanase-mediated signal through heparan sulfate binding. We propose a novel function for heparanase independent of its endoglycosidase activity, namely as a stimulant for chemokine production. Show less