MOLECULAR MECHANISM IN RESISTANCE TO FOLATE ANALOGUES

这笔拨款的长远目标是加深对 培养细胞和肿瘤通过以下途径改变遗传特性的机制 基因扩增的过程，主要是对抗性的研究 甲氨蝶呤。将进行的研究包括：1)分析 构成二氢叶酸启动子区域的核苷酸序列 还原酶基因的合成和代谢的研究 二氢叶酸还原酶基因在细胞周期中的表达；2)分析 正常、恶性和转移性乳腺上皮倾向于 自发或诱导扩增二氢叶酸还原酶 使用荧光激活细胞分选器检测到的基因和 分子生物学技术；3)甲氨蝶呤耐药性分析 这与表型不稳定和结合能力增强有关 甲氨蝶呤在4度，具有改变的性质 甲氨蝶呤的运输，采用多种技术相结合的方式 表征假定的高产蛋白质及其基因；4)一种尝试 对拟放射药物产生抗药性，从而选择 对于DNA重组能力增强的细胞 通过基因扩增机制产生抗性表型。

The long-term objectives of this grant are to increase understanding of the mechanisms whereby cultured cells and tumors change genetic properties by the process of gene amplification, predominately with studies on resistance to methotrexate. The studies to be undertaken include: 1) an analysis of the nucleotide sequences constituting promoter regions of the dihydrofolate reductase gene, and studies on the synthesis and metabolism of the dihydrofolate reductase mRNA in the cell cycle; 2) an analysis of the propensity of normal, malignant, and metastatic breast epithelium to undergo spontaneous or induced amplification of the dihydrofolate reductase gene as detected by use of the fluorescence activated cell sorter and molecular biology technology; 3) an analysis of resistance to methotrexate that is associated with an unstable phenotype and increased ability to bind methotrexate at 4 degrees, and which has the properties of an altered transport of methotrexate, employing a combination of techniques to characterize the putative overproduced protein and its gene; 4) an attempt to generate resistance to radiomimetic drugs in such a fashion as to select for cells in which there is an increased capability for DNA recombination which results in the resistance phenotype by a gene amplification mechanism.