MOLECULAR MECHANISMS OF ARA-C THERAPY IN MAN

阿糖胞苷是治疗急性白血病最有效的药物之一。 骨髓性白血病。阿糖胞苷的作用机制(S)及其基础 然而，对白血病细胞的选择性仍不清楚。我们有 先前研究了Ara-C掺入白血病细胞的作用 DNA掺入的Ara-C残基充当相对的链终止剂 而掺入的程度与DNA的抑制有关 综合。细胞抑制浓度阿糖胞苷诱导人白血病细胞 在体外分化和改变特定基因的表达。致命的 较高的Ara-C浓度的影响与终止 DNA链延长。 这项工作将通过研究机制来扩展这些发现(S) Ara-C诱导人K562细胞珠蛋白基因表达的机制 红白血病细胞。我们将扩大初步研究，论证 阿糖胞苷改变人白血病细胞原癌基因的表达。这些 对特定基因表达的影响将通过监测进一步研究 Ara-C引起染色质结构的改变。阿糖胞苷对基因的影响 先前复制的DNA片段的扩增、重新复制和 染色体异常也将作为与 DNA复制中间体的积累。最后，我们将研究 大剂量持续输注治疗过程中阿糖胞苷在体内的代谢 具体目的是：1)研究Ara-C的分子机制 监测特异性珠蛋白基因诱导K562细胞分化 表达、DNA甲基化和核酸酶敏感部位；2) 监测阿糖胞苷对人白血病原癌基因表达的影响 3)研究Ara-C对DNA链延长的影响。 组蛋白表达与染色质结构的关系；4)研究组蛋白表达与染色质结构的关系 Ara-C对基因扩增、内复制和染色体畸变的影响； 5)大剂量二期试验研究阿糖胞苷的药效学 髓系白血病的持续输注治疗。

Ara-C is one of the most effective agents in the treatment of acute myelogenous leukemia. The mechanism(s) of action of ara-C and the basis for selectivity against leukemic cells, however, remains unclear. We have previously studied the effects of ara-C incorporation into leukemic cell DNA. The incorporated ara-C residue acts as a relative chain terminator and the extent of incorporation correlates with inhibition of DNA synthesis. Cytostatic concentrations of ara-C induce human leukemic cell differentiation in vitro and alter specific gene expression. Lethal effects at higher ara-C concentration are associated with termination of DNA chain elongation. The work will extend these findings by studying the mechanism(s) responsible for ara-C induced globin gene expression in human K562 erythroleukemia cells. We will extend preliminary studies demonstrating that ara-C alters proto-oncogene expression in human leukemic cells. These effects on specific gene expression will be further studied by monitoring ara-C induced changes in chromatin structure. The effects of ara-C on gene amplification, rereplication of previously replicated DNA segments and chromosomal aberrations will also be studied as events related to the accumulation of DNA replication intermediates. Finally, we will study the in vivo metabolism of ara-C during high dose continuous infusion therapy. The specific aims are: 1) To study the molecular mechanisms of ara-C induced K562 cell differentiation by monitoring specific globin gene expression, DNA methylation and nuclease hypersensitive sites; 2) To monitor the effects of ara-C on proto-oncogene expression in human leukemic cell lines; 3) To study the effects of ara-C on DNA chain elongation, histone expression and chromatin structure; 4) To study the effects of ara-C on gene amplification, endoreduplication and chromosomal aberrations; 5) To study the pharmacodynamics of ara-C in a Phase II trial of high dose continuous infusion therapy for myeloid leukemia.