Fucoidan-dependent Increased Membrane Components in HepG2 Cells: Effect of Fucoidan Is Not Due to Gene Expression

Background: The precise mechanism of the therapeutic effects of fucoidan (sulphated polyfucose) on cultured hepatocarcinoma HepG2 cells is as yet unclear. Materials and Methods: Protein components between fucoidan-treated and non-treated HepG2 cells were compared through a quantitative micro-sequencing method. Results: A dramatic and immediate increment of the membrane compartment and a decrement of RNA virus by fucoidan, as an effect of the Ishi-Mozuku (an edible brown seaweed Mozuku of Japan), are demonstrated. The ratio of membrane glycoproteins to total cellular proteins increases from 28.9% to 43.2% (1.5-fold), and the positive-sense single-stranded RNA viral proteins among the total cellular proteins decrease from 5.3% to 0.29% (18-fold), respectively, in response to 0.102 mg/ml fucoidan in HepG2 cells over three days' period. Conclusion: Fucoidan seems to retard the growth of HepG2 cells through membrane glycoprotein metabolism. Therefore, fucoidan could be expected to have a therapeutic effect on hepatocellular carcinoma. Our research group has previously shown that covalent binding of the proteins to glass-fiber disk is very important for quantitative direct-microsequencing (1). Direct-microsequencing using l-ethyl-3-(3-dimethyl- aminopropyl)-carbodiimide (EDC) (2) has been successfully applied to protein component analysis in the human bile and human pancreatic juice (3).