低氧诱导引发乳腺肿瘤细胞MDA-MB-231 N-糖链表达差异研究

Differential expression of N-glycans in hypoxia-induced human malignant breast tumor cells MDA-MB-231

低氧是肿瘤组织中常见的病理现象之一,低氧微环境能改变细胞内葡萄糖代谢途径,增加胞内葡萄糖摄取,提高核苷酸糖含量。以人源恶性乳腺肿瘤细胞MDA-MB-231为研究对象,发现低氧培养较常氧培养的细胞形态呈纤维化,细胞迁移能力提高,上皮细胞标志物β-catenin表达下调,间质细胞标志物fibronectin表达上调,说明低氧促进了细胞发生上皮间质转化。利用基质辅助激光解析电离飞行时间质谱(MALDI-TOF-MS)比较低氧前后细胞内N-糖链表达差异,发现常氧和低氧培养MDA-MB-231细胞中均鉴定到17种N-糖链结构,但糖链丰度存在差异;且在低氧培养细胞中高甘露糖型、复合型中四天线型N-糖链表达升高,而杂合型、平分型、复合型(包括二天线型和三天线型)、岩藻糖化和唾液酸化N-糖链的表达降低。凝集素Con A和LCA细胞荧光染色结果与质谱分析一致。表明低氧可改变乳腺肿瘤细胞中N-糖链的表达,为进一步寻找肿瘤特征性糖链、探索低氧诱导N-糖链表达差异的分子机理提供前期基础。

Tumor hypoxia is a common pathological feature in many cancers. Hypoxic microenvironments dramatically shift the pattern of intracellular glucose metabolism,which increase glucose uptake and nucleotide sugar levels. In this study,hypoxia-induced malignant breast tumor（ MDA-MB-231） cell model was established. Under hypoxia conditions,MDA-MB-231 cells showed the fibrosis morphology. Expression level of β-catenin in hypoxia-treated cells was reduced,fibronectin was increased,and cell motility was enhanced,which indicated that hypoxia induces the epithelial-mesenchymal transition. The structures of N-glycans from normoxia and hypoxia-treated cells were further analyzed by matrix-assisted laser desorption ionization time of flight mass spectrometry（ MALDI-TOFMS）. Seventeen N-glycans were differentially expressed in normoxia and hypoxia-treated MDA-MB-231 cells. The high-mannose and tetra-antennary type of N-glycans were increased,while the hybrid type,bisecting type,biantennary type,triantennary type,fucosylation and sialylation of N-glycans were decreased in hypoxia-treated MDA-MB-231 cells. The study of lectin Con A and LCA fluorescence staining consistented with MS analysis. The present research indicates that hypoxia alters the expression of N-glycans in malignant breast tumor cells,which may provide the fundamental observations for further understanding functional roles of differential expression of N-glycans in hypoxia-treated cells.