细胞表面唾液酸及其连接方式对乳腺癌细胞黏附的影响

目的 研究肿瘤细胞总唾液酸及α2，6-连接唾液酸对乳腺癌细胞MDA-MB435黏附力的影响。方法 乳腺癌细胞MDA-MB-435转染顺义或反义α2，6唾液酸转移酶（ST6Ga1-I）cDNA，以黑接骨木凝集素SNA筛选高、低表达α2，6唾液酸细胞克隆．检测各转染细胞的同源凝集作用，并比较唾液酸酶处理前后肿瘤细胞对胶原Ⅳ黏附力的变化。结果 顺义转染克隆细胞．细胞之间的同源黏附能力下降．与胶原Ⅳ的黏附增强；反义转染克隆细胞-细胞之间同源黏附能力增强，而与胶原Ⅳ的黏附降低。唾液酸酶处理后肿瘤细胞与胶原Ⅳ的黏附力下降至未处理前的31％-57％。结论 乳腺癌MDA-MB435细胞表面唾液酸及α-2，6唾液酸化对肿瘤细胞的黏附有重要影响。

Effect of cell surface sialic acid and their linkages on adhesion of mammary carcinoma cells

OBJECTIVE: To investigate the effect of cell surface sialic acid and its linkage on the cell-cell and cell-matrix adhesion of mammary carcinoma cells MD-MB-435. METHODS: MD-MB-435 cells were sense-transfected with ST6Gal I cDNA or antisense-transfected with part of the ST6Gal I sequence inserted in pcDNA 3.1 vector, with mock transfection with pcDNA3.1 vector as the control. The cell surface alpha2, 6-linked sialylation was determined by fluorescence-activated cell sorting (FACS) using lectin SNA (Sambucus nigra agglutinin specific to alpha2, 6-linked sialic acid on N-linked glycoprotein). A significantly increased alpha2, 6-sialylation subclone in sense-transfectants and a decreased alpha2, 6-sialylation subclone in antisense-transfectants were selected for further examination of cell-cell and cell-matrix (collagen IV) adhesion. The transfectants were also treated with sialidase to compare the capacity of cell adhesion affected by cell surface sialylation. RESULTS: Sense-transfection subclone showed a reduced cell-cell aggregation but enhanced cell-matrix adhesion. In contrast, the antisense-transfection subclone exhibited increased cell-cell aggregation and decreased cell-matrix adhesion. After treatment with sialidase, the cell-matrix adhesion of all the transfectants and the parental MDA-MB-435 cells were significantly reduced to the level of 31%-57% of untreated cells. CONCLUSION: Cell surface sialic acid and alpha2, 6-linked sialylation play an important role in cell-cell and cell-matrix adhesion of mammary carcinoma cell MDA-MB-435.