Avramis V I, Kwock R, Solorzano M M, Gomperts E
Department of Pediatrics, University of Southern California School of Medicine, Children's Hospital Los Angeles 90027.
J Acquir Immune Defic Syndr (1988). 1993 Dec;6(12):1287-96.
Clinical reports indicate that the development of drug resistance to AZT after chronic administration is common. In order to study this phenomenon, the T-cell line Jurkat E6-1 was treated continuously in vitro with low, gradually increased, concentrations of azidothymidine (AZT). Initially, 1 microM AZT significantly retarded the cell line from reaching confluence. However, after 10 weeks the T-cell line was able to grow in 10 microM AZT without any evidence of growth inhibition. Subsequently, cell isolates could grow continuously in the presence of 20, 50, and 100 microM AZT without growth inhibition. These T-cell lines (Jurkat E6-1/AZT-10, Jurkat E6-1/AZT-20, Jurkat E6-1/AZT-50, and Jurkat E6-1/AZT-100) were tested for AZT anabolism using purified [3H]AZT, and the results were compared to the wild-type untreated Jurkat E6-1 cell line. Similar intracellular AZT anabolites concentrations were determined in all cell lines. However, a four- to sixfold lower cellular concentration of mono-, di-, and triphosphate anabolites of AZT was determined in the Jurkat E6-1/AZT-10 cell line after 1 microM AZT incubation and 6.5-fold lower after 10 microM AZT treatment. In general, a five- to sixfold reduction in the phosphorylation rates were estimated in the AZT resistant T-cell line. Pharmacology studies of [3H]AZT in the Jurkat E6-1/AZT-100 cell line showed a much lower level of activation of the pro-drug (28-fold), due to lack of thymidine kinase (TK) activity when compared to the Jurkat E6-1/AZT-10 T-cell line. A similar level of resistance was obtained at the thymidylate (dTMP) kinase level. Concurrently an additional mode of resistance (407-fold) was seen on the incorporation of the AZT triphosphate anabolite (AZTTP) into cellular DNA. The formation of this cell line in a period of < or = 4 months coincides with the evidence of the clinical development of "resistance" to AZT in patients who receive the drug continuously. In addition, these T-cell lines have been infected with HIV, and studies on the development of collaterally sensitive regimens are under way.
临床报告表明，长期服用齐多夫定（AZT）后产生耐药性是常见现象。为研究此现象，在体外以低浓度且逐渐增加浓度的叠氮胸苷（AZT）持续处理T细胞系Jurkat E6 - 1。最初，1微摩尔AZT显著延缓该细胞系达到汇合状态。然而，10周后该T细胞系能够在10微摩尔AZT中生长，且无任何生长抑制迹象。随后，细胞分离株能够在20、50和100微摩尔AZT存在的情况下持续生长而无生长抑制。使用纯化的[³H]AZT对这些T细胞系（Jurkat E6 - 1/AZT - 10、Jurkat E6 - 1/AZT - 20、Jurkat E6 - 1/AZT - 50和Jurkat E6 - 1/AZT - 100）进行AZT合成代谢测试，并将结果与未处理的野生型Jurkat E6 - 1细胞系进行比较。在所有细胞系中测定了相似的细胞内AZT合成代谢物浓度。然而，在1微摩尔AZT孵育后Jurkat E6 - 1/AZT - 10细胞系中AZT单磷酸盐、双磷酸盐和三磷酸盐合成代谢物的细胞浓度降低了4至6倍；在10微摩尔AZT处理后降低了6.5倍。总体而言，耐药T细胞系中的磷酸化速率估计降低了5至6倍。对Jurkat E6 - 1/AZT - 100细胞系中[³H]AZT的药理学研究表明前体药物的活化水平低得多（28倍），这是因为与Jurkat E6 - 1/AZT - 10 T细胞系相比缺乏胸苷激酶（TK）活性。在胸苷酸（dTMP）激酶水平也获得了类似程度的耐药性。同时，在将AZT三磷酸盐合成代谢物（AZTTP）掺入细胞DNA方面观察到另一种耐药模式（407倍）。在≤4个月的时间内形成该细胞系与持续接受该药的患者中临床出现对AZT“耐药性”的证据相符。此外，这些T细胞系已感染HIV，目前正在进行对协同敏感方案发展的研究。
