Liver Cancer Institute, Zhongshan Hospital, Fudan University, Shanghai, China.
Acta Biochim Biophys Sin (Shanghai). 2011 Jul;43(7):528-34. doi: 10.1093/abbs/gmr038. Epub 2011 May 23.
Glycosylation, which regulates the configuration and function of glycoproteins, is the most important post-translational modification. The aim of this study was to observe the differential patterns in glycan and protein parts of the serum haptoglobin-β subunit (Hp-β) purified from patients with hepatitis B virus (HBV) infection, liver cirrhosis (LC), or hepatocellular carcinoma (HCC). 2-D gel electrophoresis and multiplexed proteomics staining technique were employed to investigate whether the Hp-β glycan level was proportional to the protein level. Multi-lectin blot, high-performance liquid chromatography (HPLC), and western blot analysis were carried out to identify the glycoform of Hp-β quantitatively. Our experiments showed that the ratio of total serum Hp-β to the glycosylated form of Hp-β varied among the patients with different liver diseases. The total Hp-β protein expression level was much higher in HCC than LC, while an incremental proportion of fucosylated Hp-β was also observed in LC and HCC patients compared with that in HBV and healthy controls. Differential fucosylation was further identified as a Lewis X structure by HPLC and anti-human Sialyl-Lewis X antibody. In conclusion, the aberrant alternation of Hp-β glycan and total protein expression may be a promising biomarker for early hepatocarcinogenesis.
糖基化是一种最重要的翻译后修饰，可调节糖蛋白的结构和功能。本研究旨在观察乙型肝炎病毒（HBV）感染、肝硬化（LC）或肝细胞癌（HCC）患者血清触珠蛋白-β亚基（Hp-β）中聚糖和蛋白部分的差异模式。采用二维凝胶电泳和多重蛋白质组学染色技术研究 Hp-β 聚糖水平是否与蛋白水平成正比。通过凝集素印迹、高效液相色谱（HPLC）和 Western blot 分析对 Hp-β 的糖型进行定量鉴定。我们的实验表明，不同肝病患者的总血清 Hp-β与 Hp-β 糖型的比值不同。与 HBV 和健康对照组相比，LC 和 HCC 患者的总 Hp-β 蛋白表达水平明显更高，同时也观察到 LC 和 HCC 患者的 Hp-β 中岩藻糖基化比例增加。通过 HPLC 和抗人 Sialyl-Lewis X 抗体进一步鉴定差异岩藻糖基化为 Lewis X 结构。总之，Hp-β 聚糖和总蛋白表达的异常改变可能是早期肝癌发生的有前途的生物标志物。
