人肝癌细胞HepG2与正常肝细胞L02的O-糖链的比较分析

以培养的原发性肝细胞癌HepG2细胞和正常肝细胞L02为研究对象, 用细胞裂解液提取总蛋白, 然后采用Carlson还原性β-消除法释放O-糖链, 以阳离子交换柱结合C₁₈柱纯化分离O-糖链, 用电喷雾电离质谱(ESI-MS)和串联质谱(MS/MS)对O-糖链进行序列鉴定, 以β-环糊精为内标对2种细胞系的O-糖链进行定量比较分析. 结果表明, 在肝癌细胞系HepG2中检测到10种O-糖链, 正常细胞系L02中检测到9种O-糖链, 其中9种O-糖链是2种细胞系中共有的, 但HepG2中存在癌细胞中特有的缩短的O-糖链N1A1(NeuAc-GalNAc, sialyl Tn 抗原). t检验结果表明, HepG2与L02相比, 在检测到的10种O-糖链中有5种的含量具有极显著性差异(P<0.01), 2种的含量具有显著性差异(P<0.05).

Comparative Analysis of O-glycans from Human Hepatocellular Carcinoma HepG2 and Normal Liver Cells L02†

HepG2(a primary hepatocellular carcinoma cell line) and L02(ones derived from normal liver tissue) cells were chosen as model cell lines for research. The O-glycans of the total proteins extracted from HepG2 and L02 cells were released by Carlson reductive β-elimination. The released O-glycans previously purified by Dowex 50 WX8-400 cation exchange resin and C₁₈ cartridges were identified by electrospray ionization mass spectrometry(ESI-MS)and MS/MS. For comparision studies, β-cyclodextrin was used as the internal standard for relative quantitative analysis of the O-glycans derived from HepG2 and L02 cells by MS. As results, 10 O-glycans were observed in HepG2 cell line and 9 O-glycans were detected in L02 cell line. Moreover, 9 O-glycans were observed in both HepG2 and L02 cells, wherears 1 truncated O-glycan assigned as H1A1(NeuAc-GalNAc, sialyl Tn antigen, ubiquitous in cancer cells), was only found in HepG2 cells. t-Test results show that 5 and 2 O-glycans in HepG2 cells have significant differences(P<0.01 and P<0.05, recpectively), when compared to those of L02 cells. Our studies show methodological significance in structural investigation of O-glycans expressed in hepatocellular carcinoma and early biomarker discovery in clinical diagnose.