Study on the biotinidase competitive inhibition constant in liver cancer, and its control by a sugar chain

1.褐藻糖胶对体外培养的肝癌细胞株的抑制作用MTT法结果显示，褐藻糖胶对Hep G2细胞、Huh 7细胞和Chang细胞（正常肝细胞）均有抑制作用，且呈剂量依赖性。岩藻依聚糖硫酸酯对细胞增殖的抑制作用在这三种细胞系中是相似的。大分子岩藻聚糖硫酸酯对Chang细胞和Huh 7细胞的抑制作用强于HepG2细胞。结论：1.从HepG2细胞和Chang细胞的TUNEL染色来看，天然岩藻聚糖硫酸酯诱导细胞凋亡的作用较低。褐藻糖胶对甲胎蛋白（肝细胞癌的肿瘤标志物）产生的影响用不同浓度的褐藻糖胶（0%、1%、2%、4%、10%、20%）处理HepG 2细胞和Huh 7细胞，并在处理后24小时后测定中甲胎蛋白水平。因此，褐藻糖胶。以剂量依赖性方式降低HepG2细胞的中甲胎蛋白水平。与天然和小分子岩藻聚糖相比，大分子岩藻聚糖主要降低甲胎蛋白水平。天然岩藻聚糖、大分子岩藻聚糖和小分子岩藻聚糖均能剂量依赖性地降低中甲胎蛋白水平。Huh 7细胞中甲胎蛋白的western blotting显示天然岩藻聚糖硫酸酯对甲胎蛋白有明显的抑制作用，而黑曲霉寡糖对甲胎蛋白的抑制作用不明显。另一方面，黑曲霉寡糖并没有降低甲胎蛋白水平的Huh？细胞和HepG2细胞。岩藻多糖对生物素酶活性的影响天然岩藻多糖可显著降低HepG2细胞和Huh7细胞生物素酶Ki值，提示岩藻多糖可能通过调节生物素酶的酶动力学而发挥抗肿瘤作用。

1. Anti-tumor effect of fucoidan on cultured hepatoma cell linesAccording to the results of MTT assay, natural fucoidan showed an inhibitory effect in dose dependent manner on Hep G2 cells, Huh7 cells, and Chang cells (normal hepatocyte). The inhibitory effect of fucoidan on cell proliferation is similar among these three cell lines. Large molecular fucoidan exerted a stronger inhibitory effect on Chang cells and Huh7cells than in HepG2 cells. Judging from TUNEL stain using HepG2 cells and Chang cells, apoptosis induction by natural fucoidan was milder than that by nigero-oligosaccharide.2. Effect of fucoidan on a fetoprotein production (a tumor marker for hepatocellular carcinoma)HepG2cells and Huh7cells were treated with various concentrations of fucoidan (0%, 1%, 2%, 4%, 10%, 20%), and medium a fetoprotein levels were determined after 24 h after treatment. Consequently, fucoidan. reduced medium α fetoprotein levels of HepG2 cells in a dose dependent manner. Comparing to native and small molecular fucoidans, large molecular fucoidan reduced predominantly α fetoprotein levels. Medium α fetoprotein levels were decrease by natural, large molecular and small molecular fucoidans in dose dependent manner. The western blotting of α fetoprotein in Huh7 cells showed marked reduction of α fetoprotein by natural fucoidan, but not by nigero-oligosaccharide. On the other hand, nigero-oligosaccharide did not decrease α fetoprotein levels of Huh? cells and HepG2 cells.3. Changes of biotinidase enzyme activity by fucoidanNatural fucoidan markedly decreased biotinidase Ki of HepG2 cells and Huh7 cells.These data suggested that fucoidan may demonstrate anti-tumor activity through modulating the enzyme kinetics of biotinidase.