Folylpolyglutamate synthetase (FPGS) is the key enzyme that converts chemotherapy drug Methotrexate (MTX) into MTXPG. The expression level of FPGS directly influences MTX-sensitivity of tumor cells. Compared with B-cell acute lymphocytic leukemia (B-ALL), T-cell acute lymphocytic leukemia (T-ALL) cells express a lower level of FPGS, which results in insensitivity of the cells to MTX. Our previous work has demonstrated that 279 bp mbr element located within the 3'-UTR of the BCL2 gene possesses enhancer function. In this study, FPGS expression plasmid containing mbr element at the 5' upstream of the gene was constructed and transfected into Jurkat cells to sensitize the cells to MTX. Western blotting and MTT assay were applied to detect the FPGS expression level and suppression rate of the cellstreated by MTX, respectively. We found that the mbr enhanced the expression of FPGS significantly and increased sensitivity of Jurkat cells to MTX efficiently, while FPGS expression plasmid without mbr element had less effect. Our data provides a new clue for the clinical application of mbr regulatory element and may contribute to improvement of MTX treatment in T-ALL.%叶酰多聚谷氨酸盐合成酶(Folylpolyglutamate synthetase,FPGS)是将化疗药物甲氨蝶呤(Methotrexate,MTX)转化成甲氨蝶呤多聚谷氨酸盐(MTXPG)的关键酶,其表达水平直接影响肿瘤细胞对MTX 敏感性.与B细胞急性淋巴细胞白血病(B-ALL)相比,T 细胞急性淋巴细胞白血病(T-ALL)细胞中FPGS 表达水平低,因此对MTX 不敏感.本实验室前期研究证实,位于BCL2 基因3′-UTR 区的一段长279 bp 的 DNA 序列mbr 具有显著的增强子效应.文章构建了含有mbr 增强子样序列的FPGS 表达质粒,用其转染Jurkat 细胞后,分别以Westernblotting 和MTT 法检测FPGS 表达水平及MTX 对肿瘤细胞的抑制率.结果表明mbr 能够显著提高FPGS 表达质粒的表达水平,并有效增强Jurkat 细胞对MTX 的敏感性.这一结果为将基础研究结果应用于临床、提高MTX对T-ALL 细胞的化疗疗效提供了新的思路.
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