Important note: Information in this article was accurate in 1994. The state of the art may have changed since the publication date.
Evidence of in vitro development of drug resistance to azidothymidine in T-lymphocytic leukemia cell lines (Jurkat E6-1/AZT-100) and in pediatric patients with HIV-1 infection.
J Acquir Immune Defic Syndr. 1993 Dec;6(12):1287-96. Unique Identifier : AIDSLINE MED/94076122 Avramis VI; Kwock R; Solorzano MM; Gomperts E; Department of Pediatrics, University of Southern California; School of Medicine, Children's Hospital Los Angeles 90027.
Abstract:
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.
Keywords: Adolescence Adult Antiviral Agents/METABOLISM Cell Division/DRUG EFFECTS Child Child, Preschool Clone Cells Drug Resistance Drug Resistance, Microbial DNA, Neoplasm/METABOLISM Human HIV Infections/*DRUG THERAPY HIV-1/*DRUG EFFECTS Infant Leukemia, T-Cell/*PATHOLOGY Support, Non-U.S. Gov't T-Lymphocytes/*DRUG EFFECTS/ENZYMOLOGY Thymidine Kinase/METABOLISM Thymine Nucleotides/METABOLISM Tumor Cells, Cultured Zidovudine/ANALOGS & DERIVATIVES/METABOLISM/*PHARMACOLOGY/ THERAPEUTIC USE JOURNAL ARTICLE 940330
M9430638
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Important note: Information in this article was accurate in 1994. The state of the art may have changed since the publication date.
