RESISTANCE TO METHOTREXATE IS ASSOCIATED WITH SELECTIVE CHANGES OF ALPHA-2,6-SIALYLTRANSFERASE AND ALPHA-2,3-SIALYLTRANSFERASE ACTIVITIES TOWARD N-ACETYLLACTOSAMINIC SEQUENCES IN HUMAN COLON-CANCER CELL-LINE HT-29
RESISTANCE TO METHOTREXATE IS ASSOCIATED WITH SELECTIVE CHANGES OF ALPHA-2,6-SIALYLTRANSFERASE AND ALPHA-2,3-SIALYLTRANSFERASE ACTIVITIES TOWARD N-ACETYLLACTOSAMINIC SEQUENCES IN HUMAN COLON-CANCER CELL-LINE HT-29
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DOI：
10.1006/bbrc.1993.2308
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发表时间：
1993-10-29
影响因子：
3.1
通讯作者：
SERAFINICESSI, F
中科院分区：
文献类型：
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作者：
DALLOLIO, F;MALAGOLINI, N;SERAFINICESSI, F
在以前的工作中，我们确定了作用于N-乙酰乳糖胺序列的α 2，6-唾液酸转移酶[α 2，6（N）ST，E.C.在结肠细胞中，2.4.99.11的行为是一种肿瘤发育调节酶。人结肠癌细胞系HT-29的亚群适应于在10− 5 M甲氨蝶呤（MTX）中生长，当长时间保持融合时，永久保留分化为粘液分泌细胞的能力[Lesuffleuret al.等人（1991）J. Cell Biol.115，1409-14181。在这项研究中，我们比较了5种作用于亲本HT-29和10− 5 M MTX耐药变异体糖蛋白N-或O-连接链的唾液酸转移酶的活性。在生长的指数期以及长时间的融合后培养（28-30天）后研究了两种细胞系。无论培养条件如何，对10 - 5 M MTX的耐药性与α 2，6（N）ST活性的实际消失有关。这种变化导致细胞膜与来自黑接骨木的荧光凝集素的反应性显著降低，特异于α 2，6-唾液酸化结构。作用于N-乙酰氨基乳糖序列的α 2，3-唾液酸转移酶的活性在10− 5 M MTX耐药细胞的融合后培养物中增加约2倍，表明与分化程度密切相关。其他唾液酸转移酶活性无明显变化。
In previous works we established that the α2,6-sialyltransferase acting onN-acetyllactosaminic sequences [α2,6(N)ST, E.C. 2.4.99.11 behaves, in colonic cells, as an oncodevelopmentally regulated enzyme. Subpopulations of the human colon cancer cell line HT-29 adapted to grow in 10−5M methotrexate (MTX), permanently retain the ability to differentiate as mucus-secreting cells when kept confluent for extended periods of time [Lesuffleuret al.(1991)J. Cell Biol.115, 1409-14181. In this study we have compared the activities of five sialyltransferases acting onN- orO-linked chains of glycoproteins in parental HT-29 and in the 10−5M MTX-resistant variant. Both cell lines were studied during the exponential phase of growth as well as after a long period of postconfluent culture (28-30 days). Regardless the culture conditions, resistance to 10−5M MTX is associated with a virtual disappearance of α2,6(N)ST activity. This change results in a dramatic reduction of the reactivity of cell membranes with the fluorescent lectin fromSambucus nigra, specific for α2,6-sialylated structures. The activity of the α2,3-sialyltransferase which acts onN-acetyllactosaminic sequences increases about two times in postconfluent cultures of 10−5M MTX-resistant cells, suggesting a close relationship with the differentiation degree. No significative changes were observed in the activity of other sialyltransferases.