α2,6-唾液酸对结肠癌细胞同源凝集的影响

The effect of cell surface α2,6-sialylation on the homotypic aggregation of colon carcinoma cells

目的研究结肠癌细胞LS174T的α2,6-连接的唾液酸水平对肿瘤细胞同源黏附功能的影响。方法结肠癌细胞株LS174T转染α2,6-唾液酸转移酶(ST6Gal-I)cDNA或ST6Gal-I cDNA的部分反义序列以及空载体pcDNA3.1,以流式细胞仪检测转染细胞表面α2,6-连接唾液酸含量并进行克隆分选,比较顺义、反义以及空载体转染细胞的贴壁时间以及细胞-细胞之间的同源凝集效应。结果转染顺义的ST6Gal-I cDNA的细胞克隆显示ST6Gal-I mRNA的表达增强,SNA(一种特异性识别α2,6-连接唾液酸的植物凝集素)与细胞表面成分的结合增加;另一方面,细胞转染反义ST6Gal-I cDNA后其ST6Gal-I mRNA表达减少,SNA与细胞表面成分的结合力降低。与空载体转染相比,顺义转染的细胞克隆同源凝集作用降低,与细胞外成分的黏附作用增强,贴壁速度加快;反义转染细胞克隆同源凝集作用显著增强,与细胞外成分的黏附作用降低,传代后4 h的贴壁率仅为空载体的53.7%。结论本实验结果显示,肿瘤细胞α2,6-唾液酸转移酶(ST6Gal-I)的表达将有效影响细胞表面α2,6-连接的唾液酸水平并调节肿瘤细胞的黏附功能。

Objective To investigate the α2,6- linked sialylation of colon carcinoma cell LS174T and their influence to the cell- cell aggregation of tumor cells. Methods Colon carcinoma cell LS174T were sense - transfected with ST6GalⅠ cDNA or antisense - transfected with a part of the ST6GalⅠ sequence inserted in pcDNA 3.1 vector. Tumor cells were also mock - transfected with pcDNA 3.1 vector as control. The α2,6-linked sialylation of cell surface were determined by FACS using lectin SNA （sambucus nigra agglutinin, specific for α2,6- linked sialic acid on N - linked glycoprotein）. We further compare the number of cells that attached to the dish wall 4 h after inoculation. In addition, the cell - cell homotypic aggregation test of sense - , antisense- , and mock- transfectants were analyzed. Results Clones transfected with ST6Gal Ⅰ in sense direction showed an enhanced ST6GalⅠ mRNA expression as wen as an increased binding of lectin SNA to cell surface components. Sense - transfectants showed a decreased homotypic aggregation but rapid attachment to the dish wall of cell culture. On the other hand, transfection with ST6GalⅠ in antisense direction resulted in a reduced ST6GalⅠ mRNA expression, less SNA - reactivity, a significant increased homotypic aggregation but much less adherence to extracenular substances at 4h of cen inoculation. Conclusion Expression of sialyltransferase ST6Gal Ⅰ of tumor cells directly affects α2,6- - sialylation of cell surface and further regulates the adhesion properties of tumor cells.