[Carrageenan oligosaccharides inhibit growth-factor binding and heparanase activity]

This study is designed to investigate the anti-tumor and anti-angiogenesis mechanism of carrageenan oligosaccharides. The effects of carrageenan oligosaccharides on basic fibroblast growth factor (bFGF) induced cell proliferation, heparanase activity and bFGF binding ability were evaluated in human cervical cancer cells (HeLa) and human umbilical vein endothelial cells (HUVEC). Results indicate that, at rational concentrations, carrageenan oligosaccharides showed low cytotoxic effect. At relatively low concentrations (0.2-200 microg x mL(-1)), these oligosaccharides could competitively bind bFGF and inhibit bFGF induced cell proliferation. In these samples, oligo-lambda-carrageenans (dp2-8) were the most potent bFGF antagonists. At concentration of 20 microg x mL(-1), their inhibitory ratio reached to 30%. The heparanase enzyme assay revealed that three kinds of carrageenan oligosaccharides showed different inhibitory activities to two cell lines. For HeLa cell, oligo-lambda-carrageenans showed highest inhibitory effect, but for HUVEC, oligo-kappa-carrageenans (dp9-17) were the best inhibitors. Current observations demonstrated that the biological activities of carrageenan oligosaccharides are closely related to the molecular weight, carbohydrate structure and the content and linking position of sulfur groups. Carrageenan oligosaccharides with high sulfate fraction, 2-8 units saccharide size and suitable molecular structure are able to achieve potent heparin sulfate-like compounds.